Because Brian argues that the file contains a description of the wui as well as of the wapi, and because the name "webapi.txt" might be more obvious to the untrained eye.
results page that summarizes any problems that were encountered. All
long-running deep-traversal operations, including deep-check, use a
start-and-poll mechanism, to avoid depending upon a single long-lived HTTP
-connection. docs/frontends/wapi.txt has details.
+connection. docs/frontends/webapi.txt has details.
** Configuration Changes: single INI-format tahoe.cfg file
web.port = (strports string, optional)
This controls where the node's webserver should listen, providing filesystem
- access and node status as defined in wapi.txt . This file contains a
+ access and node status as defined in webapi.txt . This file contains a
Twisted "strports" specification such as "3456" or
"tcp:3456:interface=127.0.0.1". The 'tahoe create-client' command sets the
web.port to "tcp:3456:interface=127.0.0.1" by default, and is overridable by
+++ /dev/null
-
-= The Tahoe REST-ful Web API =
-
-1. Enabling the web-API port
-2. Basic Concepts: GET, PUT, DELETE, POST
-3. URLs, Machine-Oriented Interfaces
-4. Browser Operations: Human-Oriented Interfaces
-5. Welcome / Debug / Status pages
-6. Static Files in /public_html
-7. Safety and security issues -- names vs. URIs
-8. Concurrency Issues
-
-
-== Enabling the web-API port ==
-
-Every Tahoe node is capable of running a built-in HTTP server. To enable
-this, just write a port number into the "[node]web.port" line of your node's
-tahoe.cfg file. For example, writing "web.port = 3456" into the "[node]"
-section of $NODEDIR/tahoe.cfg will cause the node to run a webserver on port
-3456.
-
-This string is actually a Twisted "strports" specification, meaning you can
-get more control over the interface to which the server binds by supplying
-additional arguments. For more details, see the documentation on
-twisted.application.strports:
-http://twistedmatrix.com/documents/current/api/twisted.application.strports.html
-
-Writing "tcp:3456:interface=127.0.0.1" into the web.port line does the same
-but binds to the loopback interface, ensuring that only the programs on the
-local host can connect. Using
-"ssl:3456:privateKey=mykey.pem:certKey=cert.pem" runs an SSL server.
-
-This webport can be set when the node is created by passing a --webport
-option to the 'tahoe create-client' command. By default, the node listens on
-port 3456, on the loopback (127.0.0.1) interface.
-
-== Basic Concepts ==
-
-As described in architecture.txt, each file and directory in a Tahoe virtual
-filesystem is referenced by an identifier that combines the designation of
-the object with the authority to do something with it (such as read or modify
-the contents). This identifier is called a "read-cap" or "write-cap",
-depending upon whether it enables read-only or read-write access. These
-"caps" are also referred to as URIs.
-
-The Tahoe web-based API is "REST-ful", meaning it implements the concepts of
-"REpresentational State Transfer": the original scheme by which the World
-Wide Web was intended to work. Each object (file or directory) is referenced
-by a URL that includes the read- or write- cap. HTTP methods (GET, PUT, and
-DELETE) are used to manipulate these objects. You can think of the URL as a
-noun, and the method as a verb.
-
-In REST, the GET method is used to retrieve information about an object, or
-to retrieve some representation of the object itself. When the object is a
-file, the basic GET method will simply return the contents of that file.
-Other variations (generally implemented by adding query parameters to the
-URL) will return information about the object, such as metadata. GET
-operations are required to have no side-effects.
-
-PUT is used to upload new objects into the filesystem, or to replace an
-existing object. DELETE it used to delete objects from the filesystem. Both
-PUT and DELETE are required to be idempotent: performing the same operation
-multiple times must have the same side-effects as only performing it once.
-
-POST is used for more complicated actions that cannot be expressed as a GET,
-PUT, or DELETE. POST operations can be thought of as a method call: sending
-some message to the object referenced by the URL. In Tahoe, POST is also used
-for operations that must be triggered by an HTML form (including upload and
-delete), because otherwise a regular web browser has no way to accomplish
-these tasks. In general, everything that can be done with a PUT or DELETE can
-also be done with a POST.
-
-Tahoe's web API is designed for two different consumers. The first is a
-program that needs to manipulate the virtual file system. Such programs are
-expected to use the RESTful interface described above. The second is a human
-using a standard web browser to work with the filesystem. This user is given
-a series of HTML pages with links to download files, and forms that use POST
-actions to upload, rename, and delete files.
-
-== URLs ==
-
-Tahoe uses a variety of read- and write- caps to identify files and
-directories. The most common of these is the "immutable file read-cap", which
-is used for most uploaded files. These read-caps look like the following:
-
- URI:CHK:ime6pvkaxuetdfah2p2f35pe54:4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a:3:10:202
-
-The next most common is a "directory write-cap", which provides both read and
-write access to a directory, and look like this:
-
- URI:DIR2:djrdkfawoqihigoett4g6auz6a:jx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq
-
-There are also "directory read-caps", which start with "URI:DIR2-RO:", and
-give read-only access to a directory. Finally there are also mutable file
-read- and write- caps, which start with "URI:SSK", and give access to mutable
-files.
-
-(later versions of Tahoe will make these strings shorter, and will remove the
-unfortunate colons, which must be escaped when these caps are embedded in
-URLs).
-
-To refer to any Tahoe object through the web API, you simply need to combine
-a prefix (which indicates the HTTP server to use) with the cap (which
-indicates which object inside that server to access). Since the default Tahoe
-webport is 3456, the most common prefix is one that will use a local node
-listening on this port:
-
- http://127.0.0.1:3456/uri/ + $CAP
-
-So, to access the directory named above (which happens to be the
-publically-writable sample directory on the Tahoe test grid, described at
-http://allmydata.org/trac/tahoe/wiki/TestGrid), the URL would be:
-
- http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/
-
-(note that the colons in the directory-cap are url-encoded into "%3A"
-sequences).
-
-Likewise, to access the file named above, use:
-
- http://127.0.0.1:3456/uri/URI%3ACHK%3Aime6pvkaxuetdfah2p2f35pe54%3A4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a%3A3%3A10%3A202
-
-In the rest of this document, we'll use "$DIRCAP" as shorthand for a read-cap
-or write-cap that refers to a directory, and "$FILECAP" to abbreviate a cap
-that refers to a file (whether mutable or immutable). So those URLs above can
-be abbreviated as:
-
- http://127.0.0.1:3456/uri/$DIRCAP/
- http://127.0.0.1:3456/uri/$FILECAP
-
-The operation summaries below will abbreviate these further, by eliding the
-server prefix. They will be displayed like this:
-
- /uri/$DIRCAP/
- /uri/$FILECAP
-
-
-=== Child Lookup ===
-
-Tahoe directories contain named children, just like directories in a regular
-local filesystem. These children can be either files or subdirectories.
-
-If you have a Tahoe URL that refers to a directory, and want to reference a
-named child inside it, just append the child name to the URL. For example, if
-our sample directory contains a file named "welcome.txt", we can refer to
-that file with:
-
- http://127.0.0.1:3456/uri/$DIRCAP/welcome.txt
-
-(or http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/welcome.txt)
-
-Multiple levels of subdirectories can be handled this way:
-
- http://127.0.0.1:3456/uri/$DIRCAP/tahoe-source/docs/wapi.txt
-
-In this document, when we need to refer to a URL that references a file using
-this child-of-some-directory format, we'll use the following string:
-
- /uri/$DIRCAP/[SUBDIRS../]FILENAME
-
-The "[SUBDIRS../]" part means that there are zero or more (optional)
-subdirectory names in the middle of the URL. The "FILENAME" at the end means
-that this whole URL refers to a file of some sort, rather than to a
-directory.
-
-When we need to refer specifically to a directory in this way, we'll write:
-
- /uri/$DIRCAP/[SUBDIRS../]SUBDIR
-
-
-Note that all components of pathnames in URLs are required to be UTF-8
-encoded, so "resume.doc" (with an acute accent on both E's) would be accessed
-with:
-
- http://127.0.0.1:3456/uri/$DIRCAP/r%C3%A9sum%C3%A9.doc
-
-Also note that the filenames inside upload POST forms are interpreted using
-whatever character set was provided in the conventional '_charset' field, and
-defaults to UTF-8 if not otherwise specified. The JSON representation of each
-directory contains native unicode strings. Tahoe directories are specified to
-contain unicode filenames, and cannot contain binary strings that are not
-representable as such.
-
-All Tahoe operations that refer to existing files or directories must include
-a suitable read- or write- cap in the URL: the wapi server won't add one
-for you. If you don't know the cap, you can't access the file. This allows
-the security properties of Tahoe caps to be extended across the wapi
-interface.
-
-== Slow Operations, Progress, and Cancelling ==
-
-Certain operations can be expected to take a long time. The "t=deep-check",
-described below, will recursively visit every file and directory reachable
-from a given starting point, which can take minutes or even hours for
-extremely large directory structures. A single long-running HTTP request is a
-fragile thing: proxies, NAT boxes, browsers, and users may all grow impatient
-with waiting and give up on the connection.
-
-For this reason, long-running operations have an "operation handle", which
-can be used to poll for status/progress messages while the operation
-proceeds. This handle can also be used to cancel the operation. These handles
-are created by the client, and passed in as a an "ophandle=" query argument
-to the POST or PUT request which starts the operation. The following
-operations can then be used to retrieve status:
-
-GET /operations/$HANDLE?output=HTML (with or without t=status)
-GET /operations/$HANDLE?output=JSON (same)
-
- These two retrieve the current status of the given operation. Each operation
- presents a different sort of information, but in general the page retrieved
- will indicate:
-
- * whether the operation is complete, or if it is still running
- * how much of the operation is complete, and how much is left, if possible
-
- Note that the final status output can be quite large: a deep-manifest of a
- directory structure with 300k directories and 200k unique files is about
- 275MB of JSON, and might take two minutes to generate. For this reason, the
- full status is not provided until the operation has completed.
-
- The HTML form will include a meta-refresh tag, which will cause a regular
- web browser to reload the status page about 60 seconds later. This tag will
- be removed once the operation has completed.
-
- There may be more status information available under
- /operations/$HANDLE/$ETC : i.e., the handle forms the root of a URL space.
-
-POST /operations/$HANDLE?t=cancel
-
- This terminates the operation, and returns an HTML page explaining what was
- cancelled. If the operation handle has already expired (see below), this
- POST will return a 404, which indicates that the operation is no longer
- running (either it was completed or terminated). The response body will be
- the same as a GET /operations/$HANDLE on this operation handle, and the
- handle will be expired immediately afterwards.
-
-The operation handle will eventually expire, to avoid consuming an unbounded
-amount of memory. The handle's time-to-live can be reset at any time, by
-passing a retain-for= argument (with a count of seconds) to either the
-initial POST that starts the operation, or the subsequent GET request which
-asks about the operation. For example, if a 'GET
-/operations/$HANDLE?output=JSON&retain-for=600' query is performed, the
-handle will remain active for 600 seconds (10 minutes) after the GET was
-received.
-
-In addition, if the GET includes a release-after-complete=True argument, and
-the operation has completed, the operation handle will be released
-immediately.
-
-If a retain-for= argument is not used, the default handle lifetimes are:
-
- * handles will remain valid at least until their operation finishes
- * uncollected handles for finished operations (i.e. handles for operations
- which have finished but for which the GET page has not been accessed since
- completion) will remain valid for one hour, or for the total time consumed
- by the operation, whichever is greater.
- * collected handles (i.e. the GET page has been retrieved at least once
- since the operation completed) will remain valid for ten minutes.
-
-
-== Programmatic Operations ==
-
-Now that we know how to build URLs that refer to files and directories in a
-Tahoe virtual filesystem, what sorts of operations can we do with those URLs?
-This section contains a catalog of GET, PUT, DELETE, and POST operations that
-can be performed on these URLs. This set of operations are aimed at programs
-that use HTTP to communicate with a Tahoe node. The next section describes
-operations that are intended for web browsers.
-
-=== Reading A File ===
-
-GET /uri/$FILECAP
-GET /uri/$DIRCAP/[SUBDIRS../]FILENAME
-
- This will retrieve the contents of the given file. The HTTP response body
- will contain the sequence of bytes that make up the file.
-
- To view files in a web browser, you may want more control over the
- Content-Type and Content-Disposition headers. Please see the next section
- "Browser Operations", for details on how to modify these URLs for that
- purpose.
-
-=== Writing/Uploading A File ===
-
-PUT /uri/$FILECAP
-PUT /uri/$DIRCAP/[SUBDIRS../]FILENAME
-
- Upload a file, using the data from the HTTP request body, and add whatever
- child links and subdirectories are necessary to make the file available at
- the given location. Once this operation succeeds, a GET on the same URL will
- retrieve the same contents that were just uploaded. This will create any
- necessary intermediate subdirectories.
-
- To use the /uri/$FILECAP form, $FILECAP be a write-cap for a mutable file.
-
- In the /uri/$DIRCAP/[SUBDIRS../]FILENAME form, if the target file is a
- writable mutable file, that files contents will be overwritten in-place. If
- it is a read-cap for a mutable file, an error will occur. If it is an
- immutable file, the old file will be discarded, and a new one will be put in
- its place.
-
- When creating a new file, if "mutable=true" is in the query arguments, the
- operation will create a mutable file instead of an immutable one.
-
- This returns the file-cap of the resulting file. If a new file was created
- by this method, the HTTP response code (as dictated by rfc2616) will be set
- to 201 CREATED. If an existing file was replaced or modified, the response
- code will be 200 OK.
-
- Note that the 'curl -T localfile http://127.0.0.1:3456/uri/$DIRCAP/foo.txt'
- command can be used to invoke this operation.
-
-PUT /uri
-
- This uploads a file, and produces a file-cap for the contents, but does not
- attach the file into the virtual drive. No directories will be modified by
- this operation. The file-cap is returned as the body of the HTTP response.
-
- If "mutable=true" is in the query arguments, the operation will create a
- mutable file, and return its write-cap in the HTTP respose. The default is
- to create an immutable file, returning the read-cap as a response.
-
-=== Creating A New Directory ===
-
-POST /uri?t=mkdir
-PUT /uri?t=mkdir
-
- Create a new empty directory and return its write-cap as the HTTP response
- body. This does not make the newly created directory visible from the
- virtual drive. The "PUT" operation is provided for backwards compatibility:
- new code should use POST.
-
-POST /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir
-PUT /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir
-
- Create new directories as necessary to make sure that the named target
- ($DIRCAP/SUBDIRS../SUBDIR) is a directory. This will create additional
- intermediate directories as necessary. If the named target directory already
- exists, this will make no changes to it.
-
- This will return an error if a blocking file is present at any of the parent
- names, preventing the server from creating the necessary parent directory.
-
- The write-cap of the new directory will be returned as the HTTP response
- body.
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=NAME
-
- Create a new empty directory and attach it to the given existing directory.
- This will create additional intermediate directories as necessary.
-
- The URL of this form points to the parent of the bottom-most new directory,
- whereas the previous form has a URL that points directly to the bottom-most
- new directory.
-
-=== Get Information About A File Or Directory (as JSON) ===
-
-GET /uri/$FILECAP?t=json
-GET /uri/$DIRCAP?t=json
-GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json
-GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json
-
- This returns a machine-parseable JSON-encoded description of the given
- object. The JSON always contains a list, and the first element of the list
- is always a flag that indicates whether the referenced object is a file or a
- directory. If it is a file, then the information includes file size and URI,
- like this:
-
- GET /uri/$FILECAP?t=json :
- GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json :
-
- [ "filenode", { "ro_uri": file_uri,
- "size": bytes,
- "mutable": false,
- "metadata": {"ctime": 1202777696.7564139,
- "mtime": 1202777696.7564139
- }
- } ]
-
- If it is a directory, then it includes information about the children of
- this directory, as a mapping from child name to a set of data about the
- child (the same data that would appear in a corresponding GET?t=json of the
- child itself). The child entries also include metadata about each child,
- including creation- and modification- timestamps. The output looks like
- this:
-
- GET /uri/$DIRCAP?t=json :
- GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json :
-
- [ "dirnode", { "rw_uri": read_write_uri,
- "ro_uri": read_only_uri,
- "mutable": true,
- "children": {
- "foo.txt": [ "filenode", { "ro_uri": uri,
- "size": bytes,
- "metadata": {
- "ctime": 1202777696.7564139,
- "mtime": 1202777696.7564139
- }
- } ],
- "subdir": [ "dirnode", { "rw_uri": rwuri,
- "ro_uri": rouri,
- "metadata": {
- "ctime": 1202778102.7589991,
- "mtime": 1202778111.2160511,
- }
- } ]
- } } ]
-
- In the above example, note how 'children' is a dictionary in which the keys
- are child names and the values depend upon whether the child is a file or a
- directory. The value is mostly the same as the JSON representation of the
- child object (except that directories do not recurse -- the "children"
- entry of the child is omitted, and the directory view includes the metadata
- that is stored on the directory edge).
-
- Then the rw_uri field will be present in the information about a directory
- if and only if you have read-write access to that directory,
-
-
-=== Attaching an existing File or Directory by its read- or write- cap ===
-
-PUT /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri
-
- This attaches a child object (either a file or directory) to a specified
- location in the virtual filesystem. The child object is referenced by its
- read- or write- cap, as provided in the HTTP request body. This will create
- intermediate directories as necessary.
-
- This is similar to a UNIX hardlink: by referencing a previously-uploaded
- file (or previously-created directory) instead of uploading/creating a new
- one, you can create two references to the same object.
-
- The read- or write- cap of the child is provided in the body of the HTTP
- request, and this same cap is returned in the response body.
-
- The default behavior is to overwrite any existing object at the same
- location. To prevent this (and make the operation return an error instead of
- overwriting), add a "replace=false" argument, as "?t=uri&replace=false".
- With replace=false, this operation will return an HTTP 409 "Conflict" error
- if there is already an object at the given location, rather than overwriting
- the existing object. Note that "true", "t", and "1" are all synonyms for
- "True", and "false", "f", and "0" are synonyms for "False". the parameter is
- case-insensitive.
-
-=== Deleting a File or Directory ===
-
-DELETE /uri/$DIRCAP/[SUBDIRS../]CHILDNAME
-
- This removes the given name from its parent directory. CHILDNAME is the
- name to be removed, and $DIRCAP/SUBDIRS.. indicates the directory that will
- be modified.
-
- Note that this does not actually delete the file or directory that the name
- points to from the tahoe grid -- it only removes the named reference from
- this directory. If there are other names in this directory or in other
- directories that point to the resource, then it will remain accessible
- through those paths. Even if all names pointing to this object are removed
- from their parent directories, then someone with possession of its read-cap
- can continue to access the object through that cap.
-
- The object will only become completely unreachable once 1: there are no
- reachable directories that reference it, and 2: nobody is holding a read-
- or write- cap to the object. (This behavior is very similar to the way
- hardlinks and anonymous files work in traditional unix filesystems).
-
- This operation will not modify more than a single directory. Intermediate
- directories which were implicitly created by PUT or POST methods will *not*
- be automatically removed by DELETE.
-
- This method returns the file- or directory- cap of the object that was just
- removed.
-
-== Browser Operations ==
-
-This section describes the HTTP operations that provide support for humans
-running a web browser. Most of these operations use HTML forms that use POST
-to drive the Tahoe node.
-
-Note that for all POST operations, the arguments listed can be provided
-either as URL query arguments or as form body fields. URL query arguments are
-separated from the main URL by "?", and from each other by "&". For example,
-"POST /uri/$DIRCAP?t=upload&mutable=true". Form body fields are usually
-specified by using <input type="hidden"> elements. For clarity, the
-descriptions below display the most significant arguments as URL query args.
-
-=== Viewing A Directory (as HTML) ===
-
-GET /uri/$DIRCAP/[SUBDIRS../]
-
- This returns an HTML page, intended to be displayed to a human by a web
- browser, which contains HREF links to all files and directories reachable
- from this directory. These HREF links do not have a t= argument, meaning
- that a human who follows them will get pages also meant for a human. It also
- contains forms to upload new files, and to delete files and directories.
- Those forms use POST methods to do their job.
-
-=== Viewing/Downloading a File ===
-
-GET /uri/$FILECAP
-GET /uri/$DIRCAP/[SUBDIRS../]FILENAME
-
- This will retrieve the contents of the given file. The HTTP response body
- will contain the sequence of bytes that make up the file.
-
- If you want the HTTP response to include a useful Content-Type header,
- either use the second form (which starts with a $DIRCAP), or add a
- "filename=foo" query argument, like "GET /uri/$FILECAP?filename=foo.jpg".
- The bare "GET /uri/$FILECAP" does not give the Tahoe node enough information
- to determine a Content-Type (since Tahoe immutable files are merely
- sequences of bytes, not typed+named file objects).
-
- If the URL has both filename= and "save=true" in the query arguments, then
- the server to add a "Content-Disposition: attachment" header, along with a
- filename= parameter. When a user clicks on such a link, most browsers will
- offer to let the user save the file instead of displaying it inline (indeed,
- most browsers will refuse to display it inline). "true", "t", "1", and other
- case-insensitive equivalents are all treated the same.
-
- Character-set handling in URLs and HTTP headers is a dubious art[1]. For
- maximum compatibility, Tahoe simply copies the bytes from the filename=
- argument into the Content-Disposition header's filename= parameter, without
- trying to interpret them in any particular way.
-
-
-GET /named/$FILECAP/FILENAME
-
- This is an alternate download form which makes it easier to get the correct
- filename. The Tahoe server will provide the contents of the given file, with
- a Content-Type header derived from the given filename. This form is used to
- get browsers to use the "Save Link As" feature correctly, and also helps
- command-line tools like "wget" and "curl" use the right filename. Note that
- this form can *only* be used with file caps; it is an error to use a
- directory cap after the /named/ prefix.
-
-=== Get Information About A File Or Directory (as HTML) ===
-
-GET /uri/$FILECAP?t=info
-GET /uri/$DIRCAP/?t=info
-GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR/?t=info
-GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=info
-
- This returns a human-oriented HTML page with more detail about the selected
- file or directory object. This page contains the following items:
-
- object size
- storage index
- JSON representation
- raw contents (text/plain)
- access caps (URIs): verify-cap, read-cap, write-cap (for mutable objects)
- check/verify/repair form
- deep-check/deep-size/deep-stats/manifest (for directories)
- replace-conents form (for mutable files)
-
-=== Creating a Directory ===
-
-POST /uri?t=mkdir
-
- This creates a new directory, but does not attach it to the virtual
- filesystem.
-
- If a "redirect_to_result=true" argument is provided, then the HTTP response
- will cause the web browser to be redirected to a /uri/$DIRCAP page that
- gives access to the newly-created directory. If you bookmark this page,
- you'll be able to get back to the directory again in the future. This is the
- recommended way to start working with a Tahoe server: create a new unlinked
- directory (using redirect_to_result=true), then bookmark the resulting
- /uri/$DIRCAP page. There is a "Create Directory" button on the Welcome page
- to invoke this action.
-
- If "redirect_to_result=true" is not provided (or is given a value of
- "false"), then the HTTP response body will simply be the write-cap of the
- new directory.
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=CHILDNAME
-
- This creates a new directory as a child of the designated SUBDIR. This will
- create additional intermediate directories as necessary.
-
- If a "when_done=URL" argument is provided, the HTTP response will cause the
- web browser to redirect to the given URL. This provides a convenient way to
- return the browser to the directory that was just modified. Without a
- when_done= argument, the HTTP response will simply contain the write-cap of
- the directory that was just created.
-
-
-=== Uploading a File ===
-
-POST /uri?t=upload
-
- This uploads a file, and produces a file-cap for the contents, but does not
- attach the file into the virtual drive. No directories will be modified by
- this operation.
-
- The file must be provided as the "file" field of an HTML encoded form body,
- produced in response to an HTML form like this:
- <form action="/uri" method="POST" enctype="multipart/form-data">
- <input type="hidden" name="t" value="upload" />
- <input type="file" name="file" />
- <input type="submit" value="Upload Unlinked" />
- </form>
-
- If a "when_done=URL" argument is provided, the response body will cause the
- browser to redirect to the given URL. If the when_done= URL has the string
- "%(uri)s" in it, that string will be replaced by a URL-escaped form of the
- newly created file-cap. (Note that without this substitution, there is no
- way to access the file that was just uploaded).
-
- The default (in the absence of when_done=) is to return an HTML page that
- describes the results of the upload. This page will contain information
- about which storage servers were used for the upload, how long each
- operation took, etc.
-
- If a "mutable=true" argument is provided, the operation will create a
- mutable file, and the response body will contain the write-cap instead of
- the upload results page. The default is to create an immutable file,
- returning the upload results page as a response.
-
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=upload
-
- This uploads a file, and attaches it as a new child of the given directory.
- The file must be provided as the "file" field of an HTML encoded form body,
- produced in response to an HTML form like this:
- <form action="." method="POST" enctype="multipart/form-data">
- <input type="hidden" name="t" value="upload" />
- <input type="file" name="file" />
- <input type="submit" value="Upload" />
- </form>
-
- A "name=" argument can be provided to specify the new child's name,
- otherwise it will be taken from the "filename" field of the upload form
- (most web browsers will copy the last component of the original file's
- pathname into this field). To avoid confusion, name= is not allowed to
- contain a slash.
-
- If there is already a child with that name, and it is a mutable file, then
- its contents are replaced with the data being uploaded. If it is not a
- mutable file, the default behavior is to remove the existing child before
- creating a new one. To prevent this (and make the operation return an error
- instead of overwriting the old child), add a "replace=false" argument, as
- "?t=upload&replace=false". With replace=false, this operation will return an
- HTTP 409 "Conflict" error if there is already an object at the given
- location, rather than overwriting the existing object. Note that "true",
- "t", and "1" are all synonyms for "True", and "false", "f", and "0" are
- synonyms for "False". the parameter is case-insensitive.
-
- This will create additional intermediate directories as necessary, although
- since it is expected to be triggered by a form that was retrieved by "GET
- /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
- already exist.
-
- If a "mutable=true" argument is provided, any new file that is created will
- be a mutable file instead of an immutable one. <input type="checkbox"
- name="mutable" /> will give the user a way to set this option.
-
- If a "when_done=URL" argument is provided, the HTTP response will cause the
- web browser to redirect to the given URL. This provides a convenient way to
- return the browser to the directory that was just modified. Without a
- when_done= argument, the HTTP response will simply contain the file-cap of
- the file that was just uploaded (a write-cap for mutable files, or a
- read-cap for immutable files).
-
-POST /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=upload
-
- This also uploads a file and attaches it as a new child of the given
- directory. It is a slight variant of the previous operation, as the URL
- refers to the target file rather than the parent directory. It is otherwise
- identical: this accepts mutable= and when_done= arguments too.
-
-POST /uri/$FILECAP?t=upload
-
-=== Attaching An Existing File Or Directory (by URI) ===
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=uri&name=CHILDNAME&uri=CHILDCAP
-
- This attaches a given read- or write- cap "CHILDCAP" to the designated
- directory, with a specified child name. This behaves much like the PUT t=uri
- operation, and is a lot like a UNIX hardlink.
-
- This will create additional intermediate directories as necessary, although
- since it is expected to be triggered by a form that was retrieved by "GET
- /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
- already exist.
-
-=== Deleting A Child ===
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=delete&name=CHILDNAME
-
- This instructs the node to delete a child object (file or subdirectory) from
- the given directory. Note that the entire subtree is removed. This is
- somewhat like "rm -rf" (from the point of view of the parent), but other
- references into the subtree will see that the child subdirectories are not
- modified by this operation. Only the link from the given directory to its
- child is severed.
-
-=== Renaming A Child ===
-
-POST /uri/$DIRCAP/[SUBDIRS../]?t=rename&from_name=OLD&to_name=NEW
-
- This instructs the node to rename a child of the given directory. This is
- exactly the same as removing the child, then adding the same child-cap under
- the new name. This operation cannot move the child to a different directory.
-
- This operation will replace any existing child of the new name, making it
- behave like the UNIX "mv -f" command.
-
-=== Other Utilities ===
-
-GET /uri?uri=$CAP
-
- This causes a redirect to /uri/$CAP, and retains any additional query
- arguments (like filename= or save=). This is for the convenience of web
- forms which allow the user to paste in a read- or write- cap (obtained
- through some out-of-band channel, like IM or email).
-
- Note that this form merely redirects to the specific file or directory
- indicated by the $CAP: unlike the GET /uri/$DIRCAP form, you cannot
- traverse to children by appending additional path segments to the URL.
-
-GET /uri/$DIRCAP/[SUBDIRS../]?t=rename-form&name=$CHILDNAME
-
- This provides a useful facility to browser-based user interfaces. It
- returns a page containing a form targetting the "POST $DIRCAP t=rename"
- functionality described above, with the provided $CHILDNAME present in the
- 'from_name' field of that form. I.e. this presents a form offering to
- rename $CHILDNAME, requesting the new name, and submitting POST rename.
-
-GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri
-
- This returns the file- or directory- cap for the specified object.
-
-GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=readonly-uri
-
- This returns a read-only file- or directory- cap for the specified object.
- If the object is an immutable file, this will return the same value as
- t=uri.
-
-=== Debugging and Testing Features ===
-
-These URLs are less-likely to be helpful to the casual Tahoe user, and are
-mainly intended for developers.
-
-POST $URL?t=check
-
- This triggers the FileChecker to determine the current "health" of the
- given file or directory, by counting how many shares are available. The
- page that is returned will display the results. This can be used as a "show
- me detailed information about this file" page.
-
- If a verify=true argument is provided, the node will perform a more
- intensive check, downloading and verifying every single bit of every share.
-
- If an output=JSON argument is provided, the response will be
- machine-readable JSON instead of human-oriented HTML. The data is a
- dictionary with the following keys:
-
- storage-index: a base32-encoded string with the objects's storage index,
- or an empty string for LIT files
- summary: a string, with a one-line summary of the stats of the file
- results: a dictionary that describes the state of the file. For LIT files,
- this dictionary has only the 'healthy' key, which will always be
- True. For distributed files, this dictionary has the following
- keys:
- count-shares-good: the number of good shares that were found
- count-shares-needed: 'k', the number of shares required for recovery
- count-shares-expected: 'N', the number of total shares generated
- count-good-share-hosts: the number of distinct storage servers with
- good shares. If this number is less than
- count-shares-good, then some shares are doubled
- up, increasing the correlation of failures. This
- indicates that one or more shares should be
- moved to an otherwise unused server, if one is
- available.
- count-wrong-shares: for mutable files, the number of shares for
- versions other than the 'best' one (highest
- sequence number, highest roothash). These are
- either old ...
- count-recoverable-versions: for mutable files, the number of
- recoverable versions of the file. For
- a healthy file, this will equal 1.
- count-unrecoverable-versions: for mutable files, the number of
- unrecoverable versions of the file.
- For a healthy file, this will be 0.
- count-corrupt-shares: the number of shares with integrity failures
- list-corrupt-shares: a list of "share locators", one for each share
- that was found to be corrupt. Each share locator
- is a list of (serverid, storage_index, sharenum).
- needs-rebalancing: (bool) True if there are multiple shares on a single
- storage server, indicating a reduction in reliability
- that could be resolved by moving shares to new
- servers.
- servers-responding: list of base32-encoded storage server identifiers,
- one for each server which responded to the share
- query.
- healthy: (bool) True if the file is completely healthy, False otherwise.
- Healthy files have at least N good shares. Overlapping shares
- (indicated by count-good-share-hosts < count-shares-good) do not
- currently cause a file to be marked unhealthy. If there are at
- least N good shares, then corrupt shares do not cause the file to
- be marked unhealthy, although the corrupt shares will be listed
- in the results (list-corrupt-shares) and should be manually
- removed to wasting time in subsequent downloads (as the
- downloader rediscovers the corruption and uses alternate shares).
- sharemap: dict mapping share identifier to list of serverids
- (base32-encoded strings). This indicates which servers are
- holding which shares. For immutable files, the shareid is
- an integer (the share number, from 0 to N-1). For
- immutable files, it is a string of the form
- 'seq%d-%s-sh%d', containing the sequence number, the
- roothash, and the share number.
-
-POST $URL?t=start-deep-check (must add &ophandle=XYZ)
-
- This initiates a recursive walk of all files and directories reachable from
- the target, performing a check on each one just like t=check. The result
- page will contain a summary of the results, including details on any
- file/directory that was not fully healthy.
-
- t=start-deep-check can only be invoked on a directory. An error (400
- BAD_REQUEST) will be signalled if it is invoked on a file. The recursive
- walker will deal with loops safely.
-
- This accepts the same verify= argument as t=check.
-
- Since this operation can take a long time (perhaps a second per object),
- the ophandle= argument is required (see "Slow Operations, Progress, and
- Cancelling" above). The response to this POST will be a redirect to the
- corresponding /operations/$HANDLE page (with output=HTML or output=JSON to
- match the output= argument given to the POST). The deep-check operation
- will continue to run in the background, and the /operations page should be
- used to find out when the operation is done.
-
- Detailed check results for non-healthy files and directories will be
- available under /operations/$HANDLE/$STORAGEINDEX, and the HTML status will
- contain links to these detailed results.
-
- The HTML /operations/$HANDLE page for incomplete operations will contain a
- meta-refresh tag, set to 60 seconds, so that a browser which uses
- deep-check will automatically poll until the operation has completed.
-
- The JSON page (/options/$HANDLE?output=JSON) will contain a
- machine-readable JSON dictionary with the following keys:
-
- finished: a boolean, True if the operation is complete, else False. Some
- of the remaining keys may not be present until the operation
- is complete.
- root-storage-index: a base32-encoded string with the storage index of the
- starting point of the deep-check operation
- count-objects-checked: count of how many objects were checked. Note that
- non-distributed objects (i.e. small immutable LIT
- files) are not checked, since for these objects,
- the data is contained entirely in the URI.
- count-objects-healthy: how many of those objects were completely healthy
- count-objects-unhealthy: how many were damaged in some way
- count-corrupt-shares: how many shares were found to have corruption,
- summed over all objects examined
- list-corrupt-shares: a list of "share identifiers", one for each share
- that was found to be corrupt. Each share identifier
- is a list of (serverid, storage_index, sharenum).
- list-unhealthy-files: a list of (pathname, check-results) tuples, for
- each file that was not fully healthy. 'pathname' is
- a list of strings (which can be joined by "/"
- characters to turn it into a single string),
- relative to the directory on which deep-check was
- invoked. The 'check-results' field is the same as
- that returned by t=check&output=JSON, described
- above.
- stats: a dictionary with the same keys as the t=start-deep-stats command
- (described below)
-
-POST $URL?t=check&repair=true
-
- This performs a health check of the given file or directory, and if the
- checker determines that the object is not healthy (some shares are missing
- or corrupted), it will perform a "repair". During repair, any missing
- shares will be regenerated and uploaded to new servers.
-
- This accepts the same verify=true argument as t=check. When an output=JSON
- argument is provided, the machine-readable JSON response will contain the
- following keys:
-
- storage-index: a base32-encoded string with the objects's storage index,
- or an empty string for LIT files
- repair-attempted: (bool) True if repair was attempted
- repair-successful: (bool) True if repair was attempted and the file was
- fully healthy afterwards. False if no repair was
- attempted, or if a repair attempt failed.
- pre-repair-results: a dictionary that describes the state of the file
- before any repair was performed. This contains exactly
- the same keys as the 'results' value of the t=check
- response, described above.
- post-repair-results: a dictionary that describes the state of the file
- after any repair was performed. If no repair was
- performed, post-repair-results and pre-repair-results
- will be the same. This contains exactly the same keys
- as the 'results' value of the t=check response,
- described above.
-
-POST $URL?t=start-deep-check&repair=true (must add &ophandle=XYZ)
-
- This triggers a recursive walk of all files and directories, performing a
- t=check&repair=true on each one.
-
- Like t=start-deep-check without the repair= argument, this can only be
- invoked on a directory. An error (400 BAD_REQUEST) will be signalled if it
- is invoked on a file. The recursive walker will deal with loops safely.
-
- This accepts the same verify=true argument as t=start-deep-check. It uses
- the same ophandle= mechanism as start-deep-check. When an output=JSON
- argument is provided, the response will contain the following keys:
-
- finished: (bool) True if the operation has completed, else False
- root-storage-index: a base32-encoded string with the storage index of the
- starting point of the deep-check operation
- count-objects-checked: count of how many objects were checked
-
- count-objects-healthy-pre-repair: how many of those objects were completely
- healthy, before any repair
- count-objects-unhealthy-pre-repair: how many were damaged in some way
- count-objects-healthy-post-repair: how many of those objects were completely
- healthy, after any repair
- count-objects-unhealthy-post-repair: how many were damaged in some way
-
- count-repairs-attempted: repairs were attempted on this many objects.
- count-repairs-successful: how many repairs resulted in healthy objects
- count-repairs-unsuccessful: how many repairs resulted did not results in
- completely healthy objects
- count-corrupt-shares-pre-repair: how many shares were found to have
- corruption, summed over all objects
- examined, before any repair
- count-corrupt-shares-post-repair: how many shares were found to have
- corruption, summed over all objects
- examined, after any repair
- list-corrupt-shares: a list of "share identifiers", one for each share
- that was found to be corrupt (before any repair).
- Each share identifier is a list of (serverid,
- storage_index, sharenum).
- list-remaining-corrupt-shares: like list-corrupt-shares, but mutable shares
- that were successfully repaired are not
- included. These are shares that need
- manual processing. Since immutable shares
- cannot be modified by clients, all corruption
- in immutable shares will be listed here.
- list-unhealthy-files: a list of (pathname, check-results) tuples, for
- each file that was not fully healthy. 'pathname' is
- relative to the directory on which deep-check was
- invoked. The 'check-results' field is the same as
- that returned by t=check&repair=true&output=JSON,
- described above.
- stats: a dictionary with the same keys as the t=start-deep-stats command
- (described below)
-
-POST $DIRURL?t=start-manifest (must add &ophandle=XYZ)
-
- This operation generates a "manfest" of the given directory tree, mostly
- for debugging. This is a table of (path, filecap/dircap), for every object
- reachable from the starting directory. The path will be slash-joined, and
- the filecap/dircap will contain a link to the object in question. This page
- gives immediate access to every object in the virtual filesystem subtree.
-
- This operation uses the same ophandle= mechanism as deep-check. The
- corresponding /operations/$HANDLE page has three different forms. The
- default is output=HTML.
-
- If output=text is added to the query args, the results will be a text/plain
- list. The first line is special: it is either "finished: yes" or "finished:
- no"; if the operation is not finished, you must periodically reload the
- page until it completes. The rest of the results are a plaintext list, with
- one file/dir per line, slash-separated, with the filecap/dircap separated
- by a space.
-
- If output=JSON is added to the queryargs, then the results will be a
- JSON-formatted dictionary with six keys. Note that because large directory
- structures can result in very large JSON results, the full results will not
- be available until the operation is complete (i.e. until output["finished"]
- is True):
-
- finished (bool): if False then you must reload the page until True
- origin_si (base32 str): the storage index of the starting point
- manifest: list of (path, cap) tuples, where path is a list of strings.
- verifycaps: list of (printable) verify cap strings
- storage-index: list of (base32) storage index strings
- stats: a dictionary with the same keys as the t=start-deep-stats command
- (described below)
-
-POST $DIRURL?t=start-deep-size (must add &ophandle=XYZ)
-
- This operation generates a number (in bytes) containing the sum of the
- filesize of all directories and immutable files reachable from the given
- directory. This is a rough lower bound of the total space consumed by this
- subtree. It does not include space consumed by mutable files, nor does it
- take expansion or encoding overhead into account. Later versions of the
- code may improve this estimate upwards.
-
- The /operations/$HANDLE status output consists of two lines of text:
-
- finished: yes
- size: 1234
-
-POST $DIRURL?t=start-deep-stats (must add &ophandle=XYZ)
-
- This operation performs a recursive walk of all files and directories
- reachable from the given directory, and generates a collection of
- statistics about those objects.
-
- The result (obtained from the /operations/$OPHANDLE page) is a
- JSON-serialized dictionary with the following keys (note that some of these
- keys may be missing until 'finished' is True):
-
- finished: (bool) True if the operation has finished, else False
- count-immutable-files: count of how many CHK files are in the set
- count-mutable-files: same, for mutable files (does not include directories)
- count-literal-files: same, for LIT files (data contained inside the URI)
- count-files: sum of the above three
- count-directories: count of directories
- size-immutable-files: total bytes for all CHK files in the set, =deep-size
- size-mutable-files (TODO): same, for current version of all mutable files
- size-literal-files: same, for LIT files
- size-directories: size of directories (includes size-literal-files)
- size-files-histogram: list of (minsize, maxsize, count) buckets,
- with a histogram of filesizes, 5dB/bucket,
- for both literal and immutable files
- largest-directory: number of children in the largest directory
- largest-immutable-file: number of bytes in the largest CHK file
-
- size-mutable-files is not implemented, because it would require extra
- queries to each mutable file to get their size. This may be implemented in
- the future.
-
- Assuming no sharing, the basic space consumed by a single root directory is
- the sum of size-immutable-files, size-mutable-files, and size-directories.
- The actual disk space used by the shares is larger, because of the
- following sources of overhead:
-
- integrity data
- expansion due to erasure coding
- share management data (leases)
- backend (ext3) minimum block size
-
-== Other Useful Pages ==
-
-The portion of the web namespace that begins with "/uri" (and "/named") is
-dedicated to giving users (both humans and programs) access to the Tahoe
-virtual filesystem. The rest of the namespace provides status information
-about the state of the Tahoe node.
-
-GET / (the root page)
-
-This is the "Welcome Page", and contains a few distinct sections:
-
- Node information: library versions, local nodeid, services being provided.
-
- Filesystem Access Forms: create a new directory, view a file/directory by
- URI, upload a file (unlinked), download a file by
- URI.
-
- Grid Status: introducer information, helper information, connected storage
- servers.
-
-GET /status/
-
- This page lists all active uploads and downloads, and contains a short list
- of recent upload/download operations. Each operation has a link to a page
- that describes file sizes, servers that were involved, and the time consumed
- in each phase of the operation.
-
- A GET of /status/?t=json will contain a machine-readable subset of the same
- data. It returns a JSON-encoded dictionary. The only key defined at this
- time is "active", with a value that is a list of operation dictionaries, one
- for each active operation. Once an operation is completed, it will no longer
- appear in data["active"] .
-
- Each op-dict contains a "type" key, one of "upload", "download",
- "mapupdate", "publish", or "retrieve" (the first two are for immutable
- files, while the latter three are for mutable files and directories).
-
- The "upload" op-dict will contain the following keys:
-
- type (string): "upload"
- storage-index-string (string): a base32-encoded storage index
- total-size (int): total size of the file
- status (string): current status of the operation
- progress-hash (float): 1.0 when the file has been hashed
- progress-ciphertext (float): 1.0 when the file has been encrypted.
- progress-encode-push (float): 1.0 when the file has been encoded and
- pushed to the storage servers. For helper
- uploads, the ciphertext value climbs to 1.0
- first, then encoding starts. For unassisted
- uploads, ciphertext and encode-push progress
- will climb at the same pace.
-
- The "download" op-dict will contain the following keys:
-
- type (string): "download"
- storage-index-string (string): a base32-encoded storage index
- total-size (int): total size of the file
- status (string): current status of the operation
- progress (float): 1.0 when the file has been fully downloaded
-
- Front-ends which want to report progress information are advised to simply
- average together all the progress-* indicators. A slightly more accurate
- value can be found by ignoring the progress-hash value (since the current
- implementation hashes synchronously, so clients will probably never see
- progress-hash!=1.0).
-
-GET /provisioning/
-
- This page provides a basic tool to predict the likely storage and bandwidth
- requirements of a large Tahoe grid. It provides forms to input things like
- total number of users, number of files per user, average file size, number
- of servers, expansion ratio, hard drive failure rate, etc. It then provides
- numbers like how many disks per server will be needed, how many read
- operations per second should be expected, and the likely MTBF for files in
- the grid. This information is very preliminary, and the model upon which it
- is based still needs a lot of work.
-
-GET /helper_status/
-
- If the node is running a helper (i.e. if [helper]enabled is set to True in
- tahoe.cfg), then this page will provide a list of all the helper operations
- currently in progress. If "?t=json" is added to the URL, it will return a
- JSON-formatted list of helper statistics, which can then be used to produce
- graphs to indicate how busy the helper is.
-
-GET /statistics/
-
- This page provides "node statistics", which are collected from a variety of
- sources.
-
- load_monitor: every second, the node schedules a timer for one second in
- the future, then measures how late the subsequent callback
- is. The "load_average" is this tardiness, measured in
- seconds, averaged over the last minute. It is an indication
- of a busy node, one which is doing more work than can be
- completed in a timely fashion. The "max_load" value is the
- highest value that has been seen in the last 60 seconds.
-
- cpu_monitor: every minute, the node uses time.clock() to measure how much
- CPU time it has used, and it uses this value to produce
- 1min/5min/15min moving averages. These values range from 0%
- (0.0) to 100% (1.0), and indicate what fraction of the CPU
- has been used by the Tahoe node. Not all operating systems
- provide meaningful data to time.clock(): they may report 100%
- CPU usage at all times.
-
- uploader: this counts how many immutable files (and bytes) have been
- uploaded since the node was started
-
- downloader: this counts how many immutable files have been downloaded
- since the node was started
-
- publishes: this counts how many mutable files (including directories) have
- been modified since the node was started
-
- retrieves: this counts how many mutable files (including directories) have
- been read since the node was started
-
- There are other statistics that are tracked by the node. The "raw stats"
- section shows a formatted dump of all of them.
-
- By adding "?t=json" to the URL, the node will return a JSON-formatted
- dictionary of stats values, which can be used by other tools to produce
- graphs of node behavior. The misc/munin/ directory in the source
- distribution provides some tools to produce these graphs.
-
-GET / (introducer status)
-
- For Introducer nodes, the welcome page displays information about both
- clients and servers which are connected to the introducer. Servers make
- "service announcements", and these are listed in a table. Clients will
- subscribe to hear about service announcements, and these subscriptions are
- listed in a separate table. Both tables contain information about what
- version of Tahoe is being run by the remote node, their advertised and
- outbound IP addresses, their nodeid and nickname, and how long they have
- been available.
-
- By adding "?t=json" to the URL, the node will return a JSON-formatted
- dictionary of stats values, which can be used to produce graphs of connected
- clients over time. This dictionary has the following keys:
-
- ["subscription_summary"] : a dictionary mapping service name (like
- "storage") to an integer with the number of
- clients that have subscribed to hear about that
- service
- ["announcement_summary"] : a dictionary mapping service name to an integer
- with the number of servers which are announcing
- that service
- ["announcement_distinct_hosts"] : a dictionary mapping service name to an
- integer which represents the number of
- distinct hosts that are providing that
- service. If two servers have announced
- FURLs which use the same hostnames (but
- different ports and tubids), they are
- considered to be on the same host.
-
-
-== Static Files in /public_html ==
-
-The wapi server will take any request for a URL that starts with /static
-and serve it from a configurable directory which defaults to
-$BASEDIR/public_html . This is configured by setting the "[node]web.static"
-value in $BASEDIR/tahoe.cfg . If this is left at the default value of
-"public_html", then http://localhost:3456/static/subdir/foo.html will be
-served with the contents of the file $BASEDIR/public_html/subdir/foo.html .
-
-This can be useful to serve a javascript application which provides a
-prettier front-end to the rest of the Tahoe wapi.
-
-
-== safety and security issues -- names vs. URIs ==
-
-Summary: use explicit file- and dir- caps whenever possible, to reduce the
-potential for surprises when the virtual drive is changed while you aren't
-looking.
-
-The vdrive provides a mutable filesystem, but the ways that the filesystem
-can change are limited. The only thing that can change is that the mapping
-from child names to child objects that each directory contains can be changed
-by adding a new child name pointing to an object, removing an existing child
-name, or changing an existing child name to point to a different object.
-
-Obviously if you query tahoe for information about the filesystem and then
-act upon the filesystem (such as by getting a listing of the contents of a
-directory and then adding a file to the directory), then the filesystem might
-have been changed after you queried it and before you acted upon it.
-However, if you use the URI instead of the pathname of an object when you act
-upon the object, then the only change that can happen is when the object is a
-directory then the set of child names it has might be different. If, on the
-other hand, you act upon the object using its pathname, then a different
-object might be in that place, which can result in more kinds of surprises.
-
-For example, suppose you are writing code which recursively downloads the
-contents of a directory. The first thing your code does is fetch the listing
-of the contents of the directory. For each child that it fetched, if that
-child is a file then it downloads the file, and if that child is a directory
-then it recurses into that directory. Now, if the download and the recurse
-actions are performed using the child's name, then the results might be
-wrong, because for example a child name that pointed to a sub-directory when
-you listed the directory might have been changed to point to a file (in which
-case your attempt to recurse into it would result in an error and the file
-would be skipped), or a child name that pointed to a file when you listed the
-directory might now point to a sub-directory (in which case your attempt to
-download the child would result in a file containing HTML text describing the
-sub-directory!).
-
-If your recursive algorithm uses the uri of the child instead of the name of
-the child, then those kinds of mistakes just can't happen. Note that both the
-child's name and the child's URI are included in the results of listing the
-parent directory, so it isn't any harder to use the URI for this purpose.
-
-In general, use names if you want "whatever object (whether file or
-directory) is found by following this name (or sequence of names) when my
-request reaches the server". Use URIs if you want "this particular object".
-
-== Concurrency Issues ==
-
-Tahoe uses both mutable and immutable files. Mutable files can be created
-explicitly by doing an upload with ?mutable=true added, or implicitly by
-creating a new directory (since a directory is just a special way to
-interpret a given mutable file).
-
-Mutable files suffer from the same consistency-vs-availability tradeoff that
-all distributed data storage systems face. It is not possible to
-simultaneously achieve perfect consistency and perfect availability in the
-face of network partitions (servers being unreachable or faulty).
-
-Tahoe tries to achieve a reasonable compromise, but there is a basic rule in
-place, known as the Prime Coordination Directive: "Don't Do That". What this
-means is that if write-access to a mutable file is available to several
-parties, then those parties are responsible for coordinating their activities
-to avoid multiple simultaneous updates. This could be achieved by having
-these parties talk to each other and using some sort of locking mechanism, or
-by serializing all changes through a single writer.
-
-The consequences of performing uncoordinated writes can vary. Some of the
-writers may lose their changes, as somebody else wins the race condition. In
-many cases the file will be left in an "unhealthy" state, meaning that there
-are not as many redundant shares as we would like (reducing the reliability
-of the file against server failures). In the worst case, the file can be left
-in such an unhealthy state that no version is recoverable, even the old ones.
-It is this small possibility of data loss that prompts us to issue the Prime
-Coordination Directive.
-
-Tahoe nodes implement internal serialization to make sure that a single Tahoe
-node cannot conflict with itself. For example, it is safe to issue two
-directory modification requests to a single tahoe node's wapi server at the
-same time, because the Tahoe node will internally delay one of them until
-after the other has finished being applied. (This feature was introduced in
-Tahoe-1.1; back with Tahoe-1.0 the web client was responsible for serializing
-web requests themselves).
-
-For more details, please see the "Consistency vs Availability" and "The Prime
-Coordination Directive" sections of mutable.txt, in the same directory as
-this file.
-
-
-[1]: URLs and HTTP and UTF-8, Oh My
-
- HTTP does not provide a mechanism to specify the character set used to
- encode non-ascii names in URLs (rfc2396#2.1). We prefer the convention that
- the filename= argument shall be a URL-encoded UTF-8 encoded unicode object.
- For example, suppose we want to provoke the server into using a filename of
- "f i a n c e-acute e" (i.e. F I A N C U+00E9 E). The UTF-8 encoding of this
- is 0x66 0x69 0x61 0x6e 0x63 0xc3 0xa9 0x65 (or "fianc\xC3\xA9e", as python's
- repr() function would show). To encode this into a URL, the non-printable
- characters must be escaped with the urlencode '%XX' mechansim, giving us
- "fianc%C3%A9e". Thus, the first line of the HTTP request will be "GET
- /uri/CAP...?save=true&filename=fianc%C3%A9e HTTP/1.1". Not all browsers
- provide this: IE7 uses the Latin-1 encoding, which is fianc%E9e.
-
- The response header will need to indicate a non-ASCII filename. The actual
- mechanism to do this is not clear. For ASCII filenames, the response header
- would look like:
-
- Content-Disposition: attachment; filename="english.txt"
-
- If Tahoe were to enforce the utf-8 convention, it would need to decode the
- URL argument into a unicode string, and then encode it back into a sequence
- of bytes when creating the response header. One possibility would be to use
- unencoded utf-8. Developers suggest that IE7 might accept this:
-
- #1: Content-Disposition: attachment; filename="fianc\xC3\xA9e"
- (note, the last four bytes of that line, not including the newline, are
- 0xC3 0xA9 0x65 0x22)
-
- RFC2231#4 (dated 1997): suggests that the following might work, and some
- developers (http://markmail.org/message/dsjyokgl7hv64ig3) have reported that
- it is supported by firefox (but not IE7):
-
- #2: Content-Disposition: attachment; filename*=utf-8''fianc%C3%A9e
-
- My reading of RFC2616#19.5.1 (which defines Content-Disposition) says that
- the filename= parameter is defined to be wrapped in quotes (presumeably to
- allow spaces without breaking the parsing of subsequent parameters), which
- would give us:
-
- #3: Content-Disposition: attachment; filename*=utf-8''"fianc%C3%A9e"
-
- However this is contrary to the examples in the email thread listed above.
-
- Developers report that IE7 (when it is configured for UTF-8 URL encoding,
- which is not the default in asian countries), will accept:
-
- #4: Content-Disposition: attachment; filename=fianc%C3%A9e
-
- However, for maximum compatibility, Tahoe simply copies bytes from the URL
- into the response header, rather than enforcing the utf-8 convention. This
- means it does not try to decode the filename from the URL argument, nor does
- it encode the filename into the response header.
--- /dev/null
+
+= The Tahoe REST-ful Web API =
+
+1. Enabling the web-API port
+2. Basic Concepts: GET, PUT, DELETE, POST
+3. URLs, Machine-Oriented Interfaces
+4. Browser Operations: Human-Oriented Interfaces
+5. Welcome / Debug / Status pages
+6. Static Files in /public_html
+7. Safety and security issues -- names vs. URIs
+8. Concurrency Issues
+
+
+== Enabling the web-API port ==
+
+Every Tahoe node is capable of running a built-in HTTP server. To enable
+this, just write a port number into the "[node]web.port" line of your node's
+tahoe.cfg file. For example, writing "web.port = 3456" into the "[node]"
+section of $NODEDIR/tahoe.cfg will cause the node to run a webserver on port
+3456.
+
+This string is actually a Twisted "strports" specification, meaning you can
+get more control over the interface to which the server binds by supplying
+additional arguments. For more details, see the documentation on
+twisted.application.strports:
+http://twistedmatrix.com/documents/current/api/twisted.application.strports.html
+
+Writing "tcp:3456:interface=127.0.0.1" into the web.port line does the same
+but binds to the loopback interface, ensuring that only the programs on the
+local host can connect. Using
+"ssl:3456:privateKey=mykey.pem:certKey=cert.pem" runs an SSL server.
+
+This webport can be set when the node is created by passing a --webport
+option to the 'tahoe create-client' command. By default, the node listens on
+port 3456, on the loopback (127.0.0.1) interface.
+
+== Basic Concepts ==
+
+As described in architecture.txt, each file and directory in a Tahoe virtual
+filesystem is referenced by an identifier that combines the designation of
+the object with the authority to do something with it (such as read or modify
+the contents). This identifier is called a "read-cap" or "write-cap",
+depending upon whether it enables read-only or read-write access. These
+"caps" are also referred to as URIs.
+
+The Tahoe web-based API is "REST-ful", meaning it implements the concepts of
+"REpresentational State Transfer": the original scheme by which the World
+Wide Web was intended to work. Each object (file or directory) is referenced
+by a URL that includes the read- or write- cap. HTTP methods (GET, PUT, and
+DELETE) are used to manipulate these objects. You can think of the URL as a
+noun, and the method as a verb.
+
+In REST, the GET method is used to retrieve information about an object, or
+to retrieve some representation of the object itself. When the object is a
+file, the basic GET method will simply return the contents of that file.
+Other variations (generally implemented by adding query parameters to the
+URL) will return information about the object, such as metadata. GET
+operations are required to have no side-effects.
+
+PUT is used to upload new objects into the filesystem, or to replace an
+existing object. DELETE it used to delete objects from the filesystem. Both
+PUT and DELETE are required to be idempotent: performing the same operation
+multiple times must have the same side-effects as only performing it once.
+
+POST is used for more complicated actions that cannot be expressed as a GET,
+PUT, or DELETE. POST operations can be thought of as a method call: sending
+some message to the object referenced by the URL. In Tahoe, POST is also used
+for operations that must be triggered by an HTML form (including upload and
+delete), because otherwise a regular web browser has no way to accomplish
+these tasks. In general, everything that can be done with a PUT or DELETE can
+also be done with a POST.
+
+Tahoe's web API is designed for two different consumers. The first is a
+program that needs to manipulate the virtual file system. Such programs are
+expected to use the RESTful interface described above. The second is a human
+using a standard web browser to work with the filesystem. This user is given
+a series of HTML pages with links to download files, and forms that use POST
+actions to upload, rename, and delete files.
+
+== URLs ==
+
+Tahoe uses a variety of read- and write- caps to identify files and
+directories. The most common of these is the "immutable file read-cap", which
+is used for most uploaded files. These read-caps look like the following:
+
+ URI:CHK:ime6pvkaxuetdfah2p2f35pe54:4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a:3:10:202
+
+The next most common is a "directory write-cap", which provides both read and
+write access to a directory, and look like this:
+
+ URI:DIR2:djrdkfawoqihigoett4g6auz6a:jx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq
+
+There are also "directory read-caps", which start with "URI:DIR2-RO:", and
+give read-only access to a directory. Finally there are also mutable file
+read- and write- caps, which start with "URI:SSK", and give access to mutable
+files.
+
+(later versions of Tahoe will make these strings shorter, and will remove the
+unfortunate colons, which must be escaped when these caps are embedded in
+URLs).
+
+To refer to any Tahoe object through the web API, you simply need to combine
+a prefix (which indicates the HTTP server to use) with the cap (which
+indicates which object inside that server to access). Since the default Tahoe
+webport is 3456, the most common prefix is one that will use a local node
+listening on this port:
+
+ http://127.0.0.1:3456/uri/ + $CAP
+
+So, to access the directory named above (which happens to be the
+publically-writable sample directory on the Tahoe test grid, described at
+http://allmydata.org/trac/tahoe/wiki/TestGrid), the URL would be:
+
+ http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/
+
+(note that the colons in the directory-cap are url-encoded into "%3A"
+sequences).
+
+Likewise, to access the file named above, use:
+
+ http://127.0.0.1:3456/uri/URI%3ACHK%3Aime6pvkaxuetdfah2p2f35pe54%3A4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a%3A3%3A10%3A202
+
+In the rest of this document, we'll use "$DIRCAP" as shorthand for a read-cap
+or write-cap that refers to a directory, and "$FILECAP" to abbreviate a cap
+that refers to a file (whether mutable or immutable). So those URLs above can
+be abbreviated as:
+
+ http://127.0.0.1:3456/uri/$DIRCAP/
+ http://127.0.0.1:3456/uri/$FILECAP
+
+The operation summaries below will abbreviate these further, by eliding the
+server prefix. They will be displayed like this:
+
+ /uri/$DIRCAP/
+ /uri/$FILECAP
+
+
+=== Child Lookup ===
+
+Tahoe directories contain named children, just like directories in a regular
+local filesystem. These children can be either files or subdirectories.
+
+If you have a Tahoe URL that refers to a directory, and want to reference a
+named child inside it, just append the child name to the URL. For example, if
+our sample directory contains a file named "welcome.txt", we can refer to
+that file with:
+
+ http://127.0.0.1:3456/uri/$DIRCAP/welcome.txt
+
+(or http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/welcome.txt)
+
+Multiple levels of subdirectories can be handled this way:
+
+ http://127.0.0.1:3456/uri/$DIRCAP/tahoe-source/docs/webapi.txt
+
+In this document, when we need to refer to a URL that references a file using
+this child-of-some-directory format, we'll use the following string:
+
+ /uri/$DIRCAP/[SUBDIRS../]FILENAME
+
+The "[SUBDIRS../]" part means that there are zero or more (optional)
+subdirectory names in the middle of the URL. The "FILENAME" at the end means
+that this whole URL refers to a file of some sort, rather than to a
+directory.
+
+When we need to refer specifically to a directory in this way, we'll write:
+
+ /uri/$DIRCAP/[SUBDIRS../]SUBDIR
+
+
+Note that all components of pathnames in URLs are required to be UTF-8
+encoded, so "resume.doc" (with an acute accent on both E's) would be accessed
+with:
+
+ http://127.0.0.1:3456/uri/$DIRCAP/r%C3%A9sum%C3%A9.doc
+
+Also note that the filenames inside upload POST forms are interpreted using
+whatever character set was provided in the conventional '_charset' field, and
+defaults to UTF-8 if not otherwise specified. The JSON representation of each
+directory contains native unicode strings. Tahoe directories are specified to
+contain unicode filenames, and cannot contain binary strings that are not
+representable as such.
+
+All Tahoe operations that refer to existing files or directories must include
+a suitable read- or write- cap in the URL: the wapi server won't add one
+for you. If you don't know the cap, you can't access the file. This allows
+the security properties of Tahoe caps to be extended across the wapi
+interface.
+
+== Slow Operations, Progress, and Cancelling ==
+
+Certain operations can be expected to take a long time. The "t=deep-check",
+described below, will recursively visit every file and directory reachable
+from a given starting point, which can take minutes or even hours for
+extremely large directory structures. A single long-running HTTP request is a
+fragile thing: proxies, NAT boxes, browsers, and users may all grow impatient
+with waiting and give up on the connection.
+
+For this reason, long-running operations have an "operation handle", which
+can be used to poll for status/progress messages while the operation
+proceeds. This handle can also be used to cancel the operation. These handles
+are created by the client, and passed in as a an "ophandle=" query argument
+to the POST or PUT request which starts the operation. The following
+operations can then be used to retrieve status:
+
+GET /operations/$HANDLE?output=HTML (with or without t=status)
+GET /operations/$HANDLE?output=JSON (same)
+
+ These two retrieve the current status of the given operation. Each operation
+ presents a different sort of information, but in general the page retrieved
+ will indicate:
+
+ * whether the operation is complete, or if it is still running
+ * how much of the operation is complete, and how much is left, if possible
+
+ Note that the final status output can be quite large: a deep-manifest of a
+ directory structure with 300k directories and 200k unique files is about
+ 275MB of JSON, and might take two minutes to generate. For this reason, the
+ full status is not provided until the operation has completed.
+
+ The HTML form will include a meta-refresh tag, which will cause a regular
+ web browser to reload the status page about 60 seconds later. This tag will
+ be removed once the operation has completed.
+
+ There may be more status information available under
+ /operations/$HANDLE/$ETC : i.e., the handle forms the root of a URL space.
+
+POST /operations/$HANDLE?t=cancel
+
+ This terminates the operation, and returns an HTML page explaining what was
+ cancelled. If the operation handle has already expired (see below), this
+ POST will return a 404, which indicates that the operation is no longer
+ running (either it was completed or terminated). The response body will be
+ the same as a GET /operations/$HANDLE on this operation handle, and the
+ handle will be expired immediately afterwards.
+
+The operation handle will eventually expire, to avoid consuming an unbounded
+amount of memory. The handle's time-to-live can be reset at any time, by
+passing a retain-for= argument (with a count of seconds) to either the
+initial POST that starts the operation, or the subsequent GET request which
+asks about the operation. For example, if a 'GET
+/operations/$HANDLE?output=JSON&retain-for=600' query is performed, the
+handle will remain active for 600 seconds (10 minutes) after the GET was
+received.
+
+In addition, if the GET includes a release-after-complete=True argument, and
+the operation has completed, the operation handle will be released
+immediately.
+
+If a retain-for= argument is not used, the default handle lifetimes are:
+
+ * handles will remain valid at least until their operation finishes
+ * uncollected handles for finished operations (i.e. handles for operations
+ which have finished but for which the GET page has not been accessed since
+ completion) will remain valid for one hour, or for the total time consumed
+ by the operation, whichever is greater.
+ * collected handles (i.e. the GET page has been retrieved at least once
+ since the operation completed) will remain valid for ten minutes.
+
+
+== Programmatic Operations ==
+
+Now that we know how to build URLs that refer to files and directories in a
+Tahoe virtual filesystem, what sorts of operations can we do with those URLs?
+This section contains a catalog of GET, PUT, DELETE, and POST operations that
+can be performed on these URLs. This set of operations are aimed at programs
+that use HTTP to communicate with a Tahoe node. The next section describes
+operations that are intended for web browsers.
+
+=== Reading A File ===
+
+GET /uri/$FILECAP
+GET /uri/$DIRCAP/[SUBDIRS../]FILENAME
+
+ This will retrieve the contents of the given file. The HTTP response body
+ will contain the sequence of bytes that make up the file.
+
+ To view files in a web browser, you may want more control over the
+ Content-Type and Content-Disposition headers. Please see the next section
+ "Browser Operations", for details on how to modify these URLs for that
+ purpose.
+
+=== Writing/Uploading A File ===
+
+PUT /uri/$FILECAP
+PUT /uri/$DIRCAP/[SUBDIRS../]FILENAME
+
+ Upload a file, using the data from the HTTP request body, and add whatever
+ child links and subdirectories are necessary to make the file available at
+ the given location. Once this operation succeeds, a GET on the same URL will
+ retrieve the same contents that were just uploaded. This will create any
+ necessary intermediate subdirectories.
+
+ To use the /uri/$FILECAP form, $FILECAP be a write-cap for a mutable file.
+
+ In the /uri/$DIRCAP/[SUBDIRS../]FILENAME form, if the target file is a
+ writable mutable file, that files contents will be overwritten in-place. If
+ it is a read-cap for a mutable file, an error will occur. If it is an
+ immutable file, the old file will be discarded, and a new one will be put in
+ its place.
+
+ When creating a new file, if "mutable=true" is in the query arguments, the
+ operation will create a mutable file instead of an immutable one.
+
+ This returns the file-cap of the resulting file. If a new file was created
+ by this method, the HTTP response code (as dictated by rfc2616) will be set
+ to 201 CREATED. If an existing file was replaced or modified, the response
+ code will be 200 OK.
+
+ Note that the 'curl -T localfile http://127.0.0.1:3456/uri/$DIRCAP/foo.txt'
+ command can be used to invoke this operation.
+
+PUT /uri
+
+ This uploads a file, and produces a file-cap for the contents, but does not
+ attach the file into the virtual drive. No directories will be modified by
+ this operation. The file-cap is returned as the body of the HTTP response.
+
+ If "mutable=true" is in the query arguments, the operation will create a
+ mutable file, and return its write-cap in the HTTP respose. The default is
+ to create an immutable file, returning the read-cap as a response.
+
+=== Creating A New Directory ===
+
+POST /uri?t=mkdir
+PUT /uri?t=mkdir
+
+ Create a new empty directory and return its write-cap as the HTTP response
+ body. This does not make the newly created directory visible from the
+ virtual drive. The "PUT" operation is provided for backwards compatibility:
+ new code should use POST.
+
+POST /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir
+PUT /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir
+
+ Create new directories as necessary to make sure that the named target
+ ($DIRCAP/SUBDIRS../SUBDIR) is a directory. This will create additional
+ intermediate directories as necessary. If the named target directory already
+ exists, this will make no changes to it.
+
+ This will return an error if a blocking file is present at any of the parent
+ names, preventing the server from creating the necessary parent directory.
+
+ The write-cap of the new directory will be returned as the HTTP response
+ body.
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=NAME
+
+ Create a new empty directory and attach it to the given existing directory.
+ This will create additional intermediate directories as necessary.
+
+ The URL of this form points to the parent of the bottom-most new directory,
+ whereas the previous form has a URL that points directly to the bottom-most
+ new directory.
+
+=== Get Information About A File Or Directory (as JSON) ===
+
+GET /uri/$FILECAP?t=json
+GET /uri/$DIRCAP?t=json
+GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json
+GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json
+
+ This returns a machine-parseable JSON-encoded description of the given
+ object. The JSON always contains a list, and the first element of the list
+ is always a flag that indicates whether the referenced object is a file or a
+ directory. If it is a file, then the information includes file size and URI,
+ like this:
+
+ GET /uri/$FILECAP?t=json :
+ GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json :
+
+ [ "filenode", { "ro_uri": file_uri,
+ "size": bytes,
+ "mutable": false,
+ "metadata": {"ctime": 1202777696.7564139,
+ "mtime": 1202777696.7564139
+ }
+ } ]
+
+ If it is a directory, then it includes information about the children of
+ this directory, as a mapping from child name to a set of data about the
+ child (the same data that would appear in a corresponding GET?t=json of the
+ child itself). The child entries also include metadata about each child,
+ including creation- and modification- timestamps. The output looks like
+ this:
+
+ GET /uri/$DIRCAP?t=json :
+ GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json :
+
+ [ "dirnode", { "rw_uri": read_write_uri,
+ "ro_uri": read_only_uri,
+ "mutable": true,
+ "children": {
+ "foo.txt": [ "filenode", { "ro_uri": uri,
+ "size": bytes,
+ "metadata": {
+ "ctime": 1202777696.7564139,
+ "mtime": 1202777696.7564139
+ }
+ } ],
+ "subdir": [ "dirnode", { "rw_uri": rwuri,
+ "ro_uri": rouri,
+ "metadata": {
+ "ctime": 1202778102.7589991,
+ "mtime": 1202778111.2160511,
+ }
+ } ]
+ } } ]
+
+ In the above example, note how 'children' is a dictionary in which the keys
+ are child names and the values depend upon whether the child is a file or a
+ directory. The value is mostly the same as the JSON representation of the
+ child object (except that directories do not recurse -- the "children"
+ entry of the child is omitted, and the directory view includes the metadata
+ that is stored on the directory edge).
+
+ Then the rw_uri field will be present in the information about a directory
+ if and only if you have read-write access to that directory,
+
+
+=== Attaching an existing File or Directory by its read- or write- cap ===
+
+PUT /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri
+
+ This attaches a child object (either a file or directory) to a specified
+ location in the virtual filesystem. The child object is referenced by its
+ read- or write- cap, as provided in the HTTP request body. This will create
+ intermediate directories as necessary.
+
+ This is similar to a UNIX hardlink: by referencing a previously-uploaded
+ file (or previously-created directory) instead of uploading/creating a new
+ one, you can create two references to the same object.
+
+ The read- or write- cap of the child is provided in the body of the HTTP
+ request, and this same cap is returned in the response body.
+
+ The default behavior is to overwrite any existing object at the same
+ location. To prevent this (and make the operation return an error instead of
+ overwriting), add a "replace=false" argument, as "?t=uri&replace=false".
+ With replace=false, this operation will return an HTTP 409 "Conflict" error
+ if there is already an object at the given location, rather than overwriting
+ the existing object. Note that "true", "t", and "1" are all synonyms for
+ "True", and "false", "f", and "0" are synonyms for "False". the parameter is
+ case-insensitive.
+
+=== Deleting a File or Directory ===
+
+DELETE /uri/$DIRCAP/[SUBDIRS../]CHILDNAME
+
+ This removes the given name from its parent directory. CHILDNAME is the
+ name to be removed, and $DIRCAP/SUBDIRS.. indicates the directory that will
+ be modified.
+
+ Note that this does not actually delete the file or directory that the name
+ points to from the tahoe grid -- it only removes the named reference from
+ this directory. If there are other names in this directory or in other
+ directories that point to the resource, then it will remain accessible
+ through those paths. Even if all names pointing to this object are removed
+ from their parent directories, then someone with possession of its read-cap
+ can continue to access the object through that cap.
+
+ The object will only become completely unreachable once 1: there are no
+ reachable directories that reference it, and 2: nobody is holding a read-
+ or write- cap to the object. (This behavior is very similar to the way
+ hardlinks and anonymous files work in traditional unix filesystems).
+
+ This operation will not modify more than a single directory. Intermediate
+ directories which were implicitly created by PUT or POST methods will *not*
+ be automatically removed by DELETE.
+
+ This method returns the file- or directory- cap of the object that was just
+ removed.
+
+== Browser Operations ==
+
+This section describes the HTTP operations that provide support for humans
+running a web browser. Most of these operations use HTML forms that use POST
+to drive the Tahoe node.
+
+Note that for all POST operations, the arguments listed can be provided
+either as URL query arguments or as form body fields. URL query arguments are
+separated from the main URL by "?", and from each other by "&". For example,
+"POST /uri/$DIRCAP?t=upload&mutable=true". Form body fields are usually
+specified by using <input type="hidden"> elements. For clarity, the
+descriptions below display the most significant arguments as URL query args.
+
+=== Viewing A Directory (as HTML) ===
+
+GET /uri/$DIRCAP/[SUBDIRS../]
+
+ This returns an HTML page, intended to be displayed to a human by a web
+ browser, which contains HREF links to all files and directories reachable
+ from this directory. These HREF links do not have a t= argument, meaning
+ that a human who follows them will get pages also meant for a human. It also
+ contains forms to upload new files, and to delete files and directories.
+ Those forms use POST methods to do their job.
+
+=== Viewing/Downloading a File ===
+
+GET /uri/$FILECAP
+GET /uri/$DIRCAP/[SUBDIRS../]FILENAME
+
+ This will retrieve the contents of the given file. The HTTP response body
+ will contain the sequence of bytes that make up the file.
+
+ If you want the HTTP response to include a useful Content-Type header,
+ either use the second form (which starts with a $DIRCAP), or add a
+ "filename=foo" query argument, like "GET /uri/$FILECAP?filename=foo.jpg".
+ The bare "GET /uri/$FILECAP" does not give the Tahoe node enough information
+ to determine a Content-Type (since Tahoe immutable files are merely
+ sequences of bytes, not typed+named file objects).
+
+ If the URL has both filename= and "save=true" in the query arguments, then
+ the server to add a "Content-Disposition: attachment" header, along with a
+ filename= parameter. When a user clicks on such a link, most browsers will
+ offer to let the user save the file instead of displaying it inline (indeed,
+ most browsers will refuse to display it inline). "true", "t", "1", and other
+ case-insensitive equivalents are all treated the same.
+
+ Character-set handling in URLs and HTTP headers is a dubious art[1]. For
+ maximum compatibility, Tahoe simply copies the bytes from the filename=
+ argument into the Content-Disposition header's filename= parameter, without
+ trying to interpret them in any particular way.
+
+
+GET /named/$FILECAP/FILENAME
+
+ This is an alternate download form which makes it easier to get the correct
+ filename. The Tahoe server will provide the contents of the given file, with
+ a Content-Type header derived from the given filename. This form is used to
+ get browsers to use the "Save Link As" feature correctly, and also helps
+ command-line tools like "wget" and "curl" use the right filename. Note that
+ this form can *only* be used with file caps; it is an error to use a
+ directory cap after the /named/ prefix.
+
+=== Get Information About A File Or Directory (as HTML) ===
+
+GET /uri/$FILECAP?t=info
+GET /uri/$DIRCAP/?t=info
+GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR/?t=info
+GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=info
+
+ This returns a human-oriented HTML page with more detail about the selected
+ file or directory object. This page contains the following items:
+
+ object size
+ storage index
+ JSON representation
+ raw contents (text/plain)
+ access caps (URIs): verify-cap, read-cap, write-cap (for mutable objects)
+ check/verify/repair form
+ deep-check/deep-size/deep-stats/manifest (for directories)
+ replace-conents form (for mutable files)
+
+=== Creating a Directory ===
+
+POST /uri?t=mkdir
+
+ This creates a new directory, but does not attach it to the virtual
+ filesystem.
+
+ If a "redirect_to_result=true" argument is provided, then the HTTP response
+ will cause the web browser to be redirected to a /uri/$DIRCAP page that
+ gives access to the newly-created directory. If you bookmark this page,
+ you'll be able to get back to the directory again in the future. This is the
+ recommended way to start working with a Tahoe server: create a new unlinked
+ directory (using redirect_to_result=true), then bookmark the resulting
+ /uri/$DIRCAP page. There is a "Create Directory" button on the Welcome page
+ to invoke this action.
+
+ If "redirect_to_result=true" is not provided (or is given a value of
+ "false"), then the HTTP response body will simply be the write-cap of the
+ new directory.
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=CHILDNAME
+
+ This creates a new directory as a child of the designated SUBDIR. This will
+ create additional intermediate directories as necessary.
+
+ If a "when_done=URL" argument is provided, the HTTP response will cause the
+ web browser to redirect to the given URL. This provides a convenient way to
+ return the browser to the directory that was just modified. Without a
+ when_done= argument, the HTTP response will simply contain the write-cap of
+ the directory that was just created.
+
+
+=== Uploading a File ===
+
+POST /uri?t=upload
+
+ This uploads a file, and produces a file-cap for the contents, but does not
+ attach the file into the virtual drive. No directories will be modified by
+ this operation.
+
+ The file must be provided as the "file" field of an HTML encoded form body,
+ produced in response to an HTML form like this:
+ <form action="/uri" method="POST" enctype="multipart/form-data">
+ <input type="hidden" name="t" value="upload" />
+ <input type="file" name="file" />
+ <input type="submit" value="Upload Unlinked" />
+ </form>
+
+ If a "when_done=URL" argument is provided, the response body will cause the
+ browser to redirect to the given URL. If the when_done= URL has the string
+ "%(uri)s" in it, that string will be replaced by a URL-escaped form of the
+ newly created file-cap. (Note that without this substitution, there is no
+ way to access the file that was just uploaded).
+
+ The default (in the absence of when_done=) is to return an HTML page that
+ describes the results of the upload. This page will contain information
+ about which storage servers were used for the upload, how long each
+ operation took, etc.
+
+ If a "mutable=true" argument is provided, the operation will create a
+ mutable file, and the response body will contain the write-cap instead of
+ the upload results page. The default is to create an immutable file,
+ returning the upload results page as a response.
+
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=upload
+
+ This uploads a file, and attaches it as a new child of the given directory.
+ The file must be provided as the "file" field of an HTML encoded form body,
+ produced in response to an HTML form like this:
+ <form action="." method="POST" enctype="multipart/form-data">
+ <input type="hidden" name="t" value="upload" />
+ <input type="file" name="file" />
+ <input type="submit" value="Upload" />
+ </form>
+
+ A "name=" argument can be provided to specify the new child's name,
+ otherwise it will be taken from the "filename" field of the upload form
+ (most web browsers will copy the last component of the original file's
+ pathname into this field). To avoid confusion, name= is not allowed to
+ contain a slash.
+
+ If there is already a child with that name, and it is a mutable file, then
+ its contents are replaced with the data being uploaded. If it is not a
+ mutable file, the default behavior is to remove the existing child before
+ creating a new one. To prevent this (and make the operation return an error
+ instead of overwriting the old child), add a "replace=false" argument, as
+ "?t=upload&replace=false". With replace=false, this operation will return an
+ HTTP 409 "Conflict" error if there is already an object at the given
+ location, rather than overwriting the existing object. Note that "true",
+ "t", and "1" are all synonyms for "True", and "false", "f", and "0" are
+ synonyms for "False". the parameter is case-insensitive.
+
+ This will create additional intermediate directories as necessary, although
+ since it is expected to be triggered by a form that was retrieved by "GET
+ /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
+ already exist.
+
+ If a "mutable=true" argument is provided, any new file that is created will
+ be a mutable file instead of an immutable one. <input type="checkbox"
+ name="mutable" /> will give the user a way to set this option.
+
+ If a "when_done=URL" argument is provided, the HTTP response will cause the
+ web browser to redirect to the given URL. This provides a convenient way to
+ return the browser to the directory that was just modified. Without a
+ when_done= argument, the HTTP response will simply contain the file-cap of
+ the file that was just uploaded (a write-cap for mutable files, or a
+ read-cap for immutable files).
+
+POST /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=upload
+
+ This also uploads a file and attaches it as a new child of the given
+ directory. It is a slight variant of the previous operation, as the URL
+ refers to the target file rather than the parent directory. It is otherwise
+ identical: this accepts mutable= and when_done= arguments too.
+
+POST /uri/$FILECAP?t=upload
+
+=== Attaching An Existing File Or Directory (by URI) ===
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=uri&name=CHILDNAME&uri=CHILDCAP
+
+ This attaches a given read- or write- cap "CHILDCAP" to the designated
+ directory, with a specified child name. This behaves much like the PUT t=uri
+ operation, and is a lot like a UNIX hardlink.
+
+ This will create additional intermediate directories as necessary, although
+ since it is expected to be triggered by a form that was retrieved by "GET
+ /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
+ already exist.
+
+=== Deleting A Child ===
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=delete&name=CHILDNAME
+
+ This instructs the node to delete a child object (file or subdirectory) from
+ the given directory. Note that the entire subtree is removed. This is
+ somewhat like "rm -rf" (from the point of view of the parent), but other
+ references into the subtree will see that the child subdirectories are not
+ modified by this operation. Only the link from the given directory to its
+ child is severed.
+
+=== Renaming A Child ===
+
+POST /uri/$DIRCAP/[SUBDIRS../]?t=rename&from_name=OLD&to_name=NEW
+
+ This instructs the node to rename a child of the given directory. This is
+ exactly the same as removing the child, then adding the same child-cap under
+ the new name. This operation cannot move the child to a different directory.
+
+ This operation will replace any existing child of the new name, making it
+ behave like the UNIX "mv -f" command.
+
+=== Other Utilities ===
+
+GET /uri?uri=$CAP
+
+ This causes a redirect to /uri/$CAP, and retains any additional query
+ arguments (like filename= or save=). This is for the convenience of web
+ forms which allow the user to paste in a read- or write- cap (obtained
+ through some out-of-band channel, like IM or email).
+
+ Note that this form merely redirects to the specific file or directory
+ indicated by the $CAP: unlike the GET /uri/$DIRCAP form, you cannot
+ traverse to children by appending additional path segments to the URL.
+
+GET /uri/$DIRCAP/[SUBDIRS../]?t=rename-form&name=$CHILDNAME
+
+ This provides a useful facility to browser-based user interfaces. It
+ returns a page containing a form targetting the "POST $DIRCAP t=rename"
+ functionality described above, with the provided $CHILDNAME present in the
+ 'from_name' field of that form. I.e. this presents a form offering to
+ rename $CHILDNAME, requesting the new name, and submitting POST rename.
+
+GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri
+
+ This returns the file- or directory- cap for the specified object.
+
+GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=readonly-uri
+
+ This returns a read-only file- or directory- cap for the specified object.
+ If the object is an immutable file, this will return the same value as
+ t=uri.
+
+=== Debugging and Testing Features ===
+
+These URLs are less-likely to be helpful to the casual Tahoe user, and are
+mainly intended for developers.
+
+POST $URL?t=check
+
+ This triggers the FileChecker to determine the current "health" of the
+ given file or directory, by counting how many shares are available. The
+ page that is returned will display the results. This can be used as a "show
+ me detailed information about this file" page.
+
+ If a verify=true argument is provided, the node will perform a more
+ intensive check, downloading and verifying every single bit of every share.
+
+ If an output=JSON argument is provided, the response will be
+ machine-readable JSON instead of human-oriented HTML. The data is a
+ dictionary with the following keys:
+
+ storage-index: a base32-encoded string with the objects's storage index,
+ or an empty string for LIT files
+ summary: a string, with a one-line summary of the stats of the file
+ results: a dictionary that describes the state of the file. For LIT files,
+ this dictionary has only the 'healthy' key, which will always be
+ True. For distributed files, this dictionary has the following
+ keys:
+ count-shares-good: the number of good shares that were found
+ count-shares-needed: 'k', the number of shares required for recovery
+ count-shares-expected: 'N', the number of total shares generated
+ count-good-share-hosts: the number of distinct storage servers with
+ good shares. If this number is less than
+ count-shares-good, then some shares are doubled
+ up, increasing the correlation of failures. This
+ indicates that one or more shares should be
+ moved to an otherwise unused server, if one is
+ available.
+ count-wrong-shares: for mutable files, the number of shares for
+ versions other than the 'best' one (highest
+ sequence number, highest roothash). These are
+ either old ...
+ count-recoverable-versions: for mutable files, the number of
+ recoverable versions of the file. For
+ a healthy file, this will equal 1.
+ count-unrecoverable-versions: for mutable files, the number of
+ unrecoverable versions of the file.
+ For a healthy file, this will be 0.
+ count-corrupt-shares: the number of shares with integrity failures
+ list-corrupt-shares: a list of "share locators", one for each share
+ that was found to be corrupt. Each share locator
+ is a list of (serverid, storage_index, sharenum).
+ needs-rebalancing: (bool) True if there are multiple shares on a single
+ storage server, indicating a reduction in reliability
+ that could be resolved by moving shares to new
+ servers.
+ servers-responding: list of base32-encoded storage server identifiers,
+ one for each server which responded to the share
+ query.
+ healthy: (bool) True if the file is completely healthy, False otherwise.
+ Healthy files have at least N good shares. Overlapping shares
+ (indicated by count-good-share-hosts < count-shares-good) do not
+ currently cause a file to be marked unhealthy. If there are at
+ least N good shares, then corrupt shares do not cause the file to
+ be marked unhealthy, although the corrupt shares will be listed
+ in the results (list-corrupt-shares) and should be manually
+ removed to wasting time in subsequent downloads (as the
+ downloader rediscovers the corruption and uses alternate shares).
+ sharemap: dict mapping share identifier to list of serverids
+ (base32-encoded strings). This indicates which servers are
+ holding which shares. For immutable files, the shareid is
+ an integer (the share number, from 0 to N-1). For
+ immutable files, it is a string of the form
+ 'seq%d-%s-sh%d', containing the sequence number, the
+ roothash, and the share number.
+
+POST $URL?t=start-deep-check (must add &ophandle=XYZ)
+
+ This initiates a recursive walk of all files and directories reachable from
+ the target, performing a check on each one just like t=check. The result
+ page will contain a summary of the results, including details on any
+ file/directory that was not fully healthy.
+
+ t=start-deep-check can only be invoked on a directory. An error (400
+ BAD_REQUEST) will be signalled if it is invoked on a file. The recursive
+ walker will deal with loops safely.
+
+ This accepts the same verify= argument as t=check.
+
+ Since this operation can take a long time (perhaps a second per object),
+ the ophandle= argument is required (see "Slow Operations, Progress, and
+ Cancelling" above). The response to this POST will be a redirect to the
+ corresponding /operations/$HANDLE page (with output=HTML or output=JSON to
+ match the output= argument given to the POST). The deep-check operation
+ will continue to run in the background, and the /operations page should be
+ used to find out when the operation is done.
+
+ Detailed check results for non-healthy files and directories will be
+ available under /operations/$HANDLE/$STORAGEINDEX, and the HTML status will
+ contain links to these detailed results.
+
+ The HTML /operations/$HANDLE page for incomplete operations will contain a
+ meta-refresh tag, set to 60 seconds, so that a browser which uses
+ deep-check will automatically poll until the operation has completed.
+
+ The JSON page (/options/$HANDLE?output=JSON) will contain a
+ machine-readable JSON dictionary with the following keys:
+
+ finished: a boolean, True if the operation is complete, else False. Some
+ of the remaining keys may not be present until the operation
+ is complete.
+ root-storage-index: a base32-encoded string with the storage index of the
+ starting point of the deep-check operation
+ count-objects-checked: count of how many objects were checked. Note that
+ non-distributed objects (i.e. small immutable LIT
+ files) are not checked, since for these objects,
+ the data is contained entirely in the URI.
+ count-objects-healthy: how many of those objects were completely healthy
+ count-objects-unhealthy: how many were damaged in some way
+ count-corrupt-shares: how many shares were found to have corruption,
+ summed over all objects examined
+ list-corrupt-shares: a list of "share identifiers", one for each share
+ that was found to be corrupt. Each share identifier
+ is a list of (serverid, storage_index, sharenum).
+ list-unhealthy-files: a list of (pathname, check-results) tuples, for
+ each file that was not fully healthy. 'pathname' is
+ a list of strings (which can be joined by "/"
+ characters to turn it into a single string),
+ relative to the directory on which deep-check was
+ invoked. The 'check-results' field is the same as
+ that returned by t=check&output=JSON, described
+ above.
+ stats: a dictionary with the same keys as the t=start-deep-stats command
+ (described below)
+
+POST $URL?t=check&repair=true
+
+ This performs a health check of the given file or directory, and if the
+ checker determines that the object is not healthy (some shares are missing
+ or corrupted), it will perform a "repair". During repair, any missing
+ shares will be regenerated and uploaded to new servers.
+
+ This accepts the same verify=true argument as t=check. When an output=JSON
+ argument is provided, the machine-readable JSON response will contain the
+ following keys:
+
+ storage-index: a base32-encoded string with the objects's storage index,
+ or an empty string for LIT files
+ repair-attempted: (bool) True if repair was attempted
+ repair-successful: (bool) True if repair was attempted and the file was
+ fully healthy afterwards. False if no repair was
+ attempted, or if a repair attempt failed.
+ pre-repair-results: a dictionary that describes the state of the file
+ before any repair was performed. This contains exactly
+ the same keys as the 'results' value of the t=check
+ response, described above.
+ post-repair-results: a dictionary that describes the state of the file
+ after any repair was performed. If no repair was
+ performed, post-repair-results and pre-repair-results
+ will be the same. This contains exactly the same keys
+ as the 'results' value of the t=check response,
+ described above.
+
+POST $URL?t=start-deep-check&repair=true (must add &ophandle=XYZ)
+
+ This triggers a recursive walk of all files and directories, performing a
+ t=check&repair=true on each one.
+
+ Like t=start-deep-check without the repair= argument, this can only be
+ invoked on a directory. An error (400 BAD_REQUEST) will be signalled if it
+ is invoked on a file. The recursive walker will deal with loops safely.
+
+ This accepts the same verify=true argument as t=start-deep-check. It uses
+ the same ophandle= mechanism as start-deep-check. When an output=JSON
+ argument is provided, the response will contain the following keys:
+
+ finished: (bool) True if the operation has completed, else False
+ root-storage-index: a base32-encoded string with the storage index of the
+ starting point of the deep-check operation
+ count-objects-checked: count of how many objects were checked
+
+ count-objects-healthy-pre-repair: how many of those objects were completely
+ healthy, before any repair
+ count-objects-unhealthy-pre-repair: how many were damaged in some way
+ count-objects-healthy-post-repair: how many of those objects were completely
+ healthy, after any repair
+ count-objects-unhealthy-post-repair: how many were damaged in some way
+
+ count-repairs-attempted: repairs were attempted on this many objects.
+ count-repairs-successful: how many repairs resulted in healthy objects
+ count-repairs-unsuccessful: how many repairs resulted did not results in
+ completely healthy objects
+ count-corrupt-shares-pre-repair: how many shares were found to have
+ corruption, summed over all objects
+ examined, before any repair
+ count-corrupt-shares-post-repair: how many shares were found to have
+ corruption, summed over all objects
+ examined, after any repair
+ list-corrupt-shares: a list of "share identifiers", one for each share
+ that was found to be corrupt (before any repair).
+ Each share identifier is a list of (serverid,
+ storage_index, sharenum).
+ list-remaining-corrupt-shares: like list-corrupt-shares, but mutable shares
+ that were successfully repaired are not
+ included. These are shares that need
+ manual processing. Since immutable shares
+ cannot be modified by clients, all corruption
+ in immutable shares will be listed here.
+ list-unhealthy-files: a list of (pathname, check-results) tuples, for
+ each file that was not fully healthy. 'pathname' is
+ relative to the directory on which deep-check was
+ invoked. The 'check-results' field is the same as
+ that returned by t=check&repair=true&output=JSON,
+ described above.
+ stats: a dictionary with the same keys as the t=start-deep-stats command
+ (described below)
+
+POST $DIRURL?t=start-manifest (must add &ophandle=XYZ)
+
+ This operation generates a "manfest" of the given directory tree, mostly
+ for debugging. This is a table of (path, filecap/dircap), for every object
+ reachable from the starting directory. The path will be slash-joined, and
+ the filecap/dircap will contain a link to the object in question. This page
+ gives immediate access to every object in the virtual filesystem subtree.
+
+ This operation uses the same ophandle= mechanism as deep-check. The
+ corresponding /operations/$HANDLE page has three different forms. The
+ default is output=HTML.
+
+ If output=text is added to the query args, the results will be a text/plain
+ list. The first line is special: it is either "finished: yes" or "finished:
+ no"; if the operation is not finished, you must periodically reload the
+ page until it completes. The rest of the results are a plaintext list, with
+ one file/dir per line, slash-separated, with the filecap/dircap separated
+ by a space.
+
+ If output=JSON is added to the queryargs, then the results will be a
+ JSON-formatted dictionary with six keys. Note that because large directory
+ structures can result in very large JSON results, the full results will not
+ be available until the operation is complete (i.e. until output["finished"]
+ is True):
+
+ finished (bool): if False then you must reload the page until True
+ origin_si (base32 str): the storage index of the starting point
+ manifest: list of (path, cap) tuples, where path is a list of strings.
+ verifycaps: list of (printable) verify cap strings
+ storage-index: list of (base32) storage index strings
+ stats: a dictionary with the same keys as the t=start-deep-stats command
+ (described below)
+
+POST $DIRURL?t=start-deep-size (must add &ophandle=XYZ)
+
+ This operation generates a number (in bytes) containing the sum of the
+ filesize of all directories and immutable files reachable from the given
+ directory. This is a rough lower bound of the total space consumed by this
+ subtree. It does not include space consumed by mutable files, nor does it
+ take expansion or encoding overhead into account. Later versions of the
+ code may improve this estimate upwards.
+
+ The /operations/$HANDLE status output consists of two lines of text:
+
+ finished: yes
+ size: 1234
+
+POST $DIRURL?t=start-deep-stats (must add &ophandle=XYZ)
+
+ This operation performs a recursive walk of all files and directories
+ reachable from the given directory, and generates a collection of
+ statistics about those objects.
+
+ The result (obtained from the /operations/$OPHANDLE page) is a
+ JSON-serialized dictionary with the following keys (note that some of these
+ keys may be missing until 'finished' is True):
+
+ finished: (bool) True if the operation has finished, else False
+ count-immutable-files: count of how many CHK files are in the set
+ count-mutable-files: same, for mutable files (does not include directories)
+ count-literal-files: same, for LIT files (data contained inside the URI)
+ count-files: sum of the above three
+ count-directories: count of directories
+ size-immutable-files: total bytes for all CHK files in the set, =deep-size
+ size-mutable-files (TODO): same, for current version of all mutable files
+ size-literal-files: same, for LIT files
+ size-directories: size of directories (includes size-literal-files)
+ size-files-histogram: list of (minsize, maxsize, count) buckets,
+ with a histogram of filesizes, 5dB/bucket,
+ for both literal and immutable files
+ largest-directory: number of children in the largest directory
+ largest-immutable-file: number of bytes in the largest CHK file
+
+ size-mutable-files is not implemented, because it would require extra
+ queries to each mutable file to get their size. This may be implemented in
+ the future.
+
+ Assuming no sharing, the basic space consumed by a single root directory is
+ the sum of size-immutable-files, size-mutable-files, and size-directories.
+ The actual disk space used by the shares is larger, because of the
+ following sources of overhead:
+
+ integrity data
+ expansion due to erasure coding
+ share management data (leases)
+ backend (ext3) minimum block size
+
+== Other Useful Pages ==
+
+The portion of the web namespace that begins with "/uri" (and "/named") is
+dedicated to giving users (both humans and programs) access to the Tahoe
+virtual filesystem. The rest of the namespace provides status information
+about the state of the Tahoe node.
+
+GET / (the root page)
+
+This is the "Welcome Page", and contains a few distinct sections:
+
+ Node information: library versions, local nodeid, services being provided.
+
+ Filesystem Access Forms: create a new directory, view a file/directory by
+ URI, upload a file (unlinked), download a file by
+ URI.
+
+ Grid Status: introducer information, helper information, connected storage
+ servers.
+
+GET /status/
+
+ This page lists all active uploads and downloads, and contains a short list
+ of recent upload/download operations. Each operation has a link to a page
+ that describes file sizes, servers that were involved, and the time consumed
+ in each phase of the operation.
+
+ A GET of /status/?t=json will contain a machine-readable subset of the same
+ data. It returns a JSON-encoded dictionary. The only key defined at this
+ time is "active", with a value that is a list of operation dictionaries, one
+ for each active operation. Once an operation is completed, it will no longer
+ appear in data["active"] .
+
+ Each op-dict contains a "type" key, one of "upload", "download",
+ "mapupdate", "publish", or "retrieve" (the first two are for immutable
+ files, while the latter three are for mutable files and directories).
+
+ The "upload" op-dict will contain the following keys:
+
+ type (string): "upload"
+ storage-index-string (string): a base32-encoded storage index
+ total-size (int): total size of the file
+ status (string): current status of the operation
+ progress-hash (float): 1.0 when the file has been hashed
+ progress-ciphertext (float): 1.0 when the file has been encrypted.
+ progress-encode-push (float): 1.0 when the file has been encoded and
+ pushed to the storage servers. For helper
+ uploads, the ciphertext value climbs to 1.0
+ first, then encoding starts. For unassisted
+ uploads, ciphertext and encode-push progress
+ will climb at the same pace.
+
+ The "download" op-dict will contain the following keys:
+
+ type (string): "download"
+ storage-index-string (string): a base32-encoded storage index
+ total-size (int): total size of the file
+ status (string): current status of the operation
+ progress (float): 1.0 when the file has been fully downloaded
+
+ Front-ends which want to report progress information are advised to simply
+ average together all the progress-* indicators. A slightly more accurate
+ value can be found by ignoring the progress-hash value (since the current
+ implementation hashes synchronously, so clients will probably never see
+ progress-hash!=1.0).
+
+GET /provisioning/
+
+ This page provides a basic tool to predict the likely storage and bandwidth
+ requirements of a large Tahoe grid. It provides forms to input things like
+ total number of users, number of files per user, average file size, number
+ of servers, expansion ratio, hard drive failure rate, etc. It then provides
+ numbers like how many disks per server will be needed, how many read
+ operations per second should be expected, and the likely MTBF for files in
+ the grid. This information is very preliminary, and the model upon which it
+ is based still needs a lot of work.
+
+GET /helper_status/
+
+ If the node is running a helper (i.e. if [helper]enabled is set to True in
+ tahoe.cfg), then this page will provide a list of all the helper operations
+ currently in progress. If "?t=json" is added to the URL, it will return a
+ JSON-formatted list of helper statistics, which can then be used to produce
+ graphs to indicate how busy the helper is.
+
+GET /statistics/
+
+ This page provides "node statistics", which are collected from a variety of
+ sources.
+
+ load_monitor: every second, the node schedules a timer for one second in
+ the future, then measures how late the subsequent callback
+ is. The "load_average" is this tardiness, measured in
+ seconds, averaged over the last minute. It is an indication
+ of a busy node, one which is doing more work than can be
+ completed in a timely fashion. The "max_load" value is the
+ highest value that has been seen in the last 60 seconds.
+
+ cpu_monitor: every minute, the node uses time.clock() to measure how much
+ CPU time it has used, and it uses this value to produce
+ 1min/5min/15min moving averages. These values range from 0%
+ (0.0) to 100% (1.0), and indicate what fraction of the CPU
+ has been used by the Tahoe node. Not all operating systems
+ provide meaningful data to time.clock(): they may report 100%
+ CPU usage at all times.
+
+ uploader: this counts how many immutable files (and bytes) have been
+ uploaded since the node was started
+
+ downloader: this counts how many immutable files have been downloaded
+ since the node was started
+
+ publishes: this counts how many mutable files (including directories) have
+ been modified since the node was started
+
+ retrieves: this counts how many mutable files (including directories) have
+ been read since the node was started
+
+ There are other statistics that are tracked by the node. The "raw stats"
+ section shows a formatted dump of all of them.
+
+ By adding "?t=json" to the URL, the node will return a JSON-formatted
+ dictionary of stats values, which can be used by other tools to produce
+ graphs of node behavior. The misc/munin/ directory in the source
+ distribution provides some tools to produce these graphs.
+
+GET / (introducer status)
+
+ For Introducer nodes, the welcome page displays information about both
+ clients and servers which are connected to the introducer. Servers make
+ "service announcements", and these are listed in a table. Clients will
+ subscribe to hear about service announcements, and these subscriptions are
+ listed in a separate table. Both tables contain information about what
+ version of Tahoe is being run by the remote node, their advertised and
+ outbound IP addresses, their nodeid and nickname, and how long they have
+ been available.
+
+ By adding "?t=json" to the URL, the node will return a JSON-formatted
+ dictionary of stats values, which can be used to produce graphs of connected
+ clients over time. This dictionary has the following keys:
+
+ ["subscription_summary"] : a dictionary mapping service name (like
+ "storage") to an integer with the number of
+ clients that have subscribed to hear about that
+ service
+ ["announcement_summary"] : a dictionary mapping service name to an integer
+ with the number of servers which are announcing
+ that service
+ ["announcement_distinct_hosts"] : a dictionary mapping service name to an
+ integer which represents the number of
+ distinct hosts that are providing that
+ service. If two servers have announced
+ FURLs which use the same hostnames (but
+ different ports and tubids), they are
+ considered to be on the same host.
+
+
+== Static Files in /public_html ==
+
+The wapi server will take any request for a URL that starts with /static
+and serve it from a configurable directory which defaults to
+$BASEDIR/public_html . This is configured by setting the "[node]web.static"
+value in $BASEDIR/tahoe.cfg . If this is left at the default value of
+"public_html", then http://localhost:3456/static/subdir/foo.html will be
+served with the contents of the file $BASEDIR/public_html/subdir/foo.html .
+
+This can be useful to serve a javascript application which provides a
+prettier front-end to the rest of the Tahoe wapi.
+
+
+== safety and security issues -- names vs. URIs ==
+
+Summary: use explicit file- and dir- caps whenever possible, to reduce the
+potential for surprises when the virtual drive is changed while you aren't
+looking.
+
+The vdrive provides a mutable filesystem, but the ways that the filesystem
+can change are limited. The only thing that can change is that the mapping
+from child names to child objects that each directory contains can be changed
+by adding a new child name pointing to an object, removing an existing child
+name, or changing an existing child name to point to a different object.
+
+Obviously if you query tahoe for information about the filesystem and then
+act upon the filesystem (such as by getting a listing of the contents of a
+directory and then adding a file to the directory), then the filesystem might
+have been changed after you queried it and before you acted upon it.
+However, if you use the URI instead of the pathname of an object when you act
+upon the object, then the only change that can happen is when the object is a
+directory then the set of child names it has might be different. If, on the
+other hand, you act upon the object using its pathname, then a different
+object might be in that place, which can result in more kinds of surprises.
+
+For example, suppose you are writing code which recursively downloads the
+contents of a directory. The first thing your code does is fetch the listing
+of the contents of the directory. For each child that it fetched, if that
+child is a file then it downloads the file, and if that child is a directory
+then it recurses into that directory. Now, if the download and the recurse
+actions are performed using the child's name, then the results might be
+wrong, because for example a child name that pointed to a sub-directory when
+you listed the directory might have been changed to point to a file (in which
+case your attempt to recurse into it would result in an error and the file
+would be skipped), or a child name that pointed to a file when you listed the
+directory might now point to a sub-directory (in which case your attempt to
+download the child would result in a file containing HTML text describing the
+sub-directory!).
+
+If your recursive algorithm uses the uri of the child instead of the name of
+the child, then those kinds of mistakes just can't happen. Note that both the
+child's name and the child's URI are included in the results of listing the
+parent directory, so it isn't any harder to use the URI for this purpose.
+
+In general, use names if you want "whatever object (whether file or
+directory) is found by following this name (or sequence of names) when my
+request reaches the server". Use URIs if you want "this particular object".
+
+== Concurrency Issues ==
+
+Tahoe uses both mutable and immutable files. Mutable files can be created
+explicitly by doing an upload with ?mutable=true added, or implicitly by
+creating a new directory (since a directory is just a special way to
+interpret a given mutable file).
+
+Mutable files suffer from the same consistency-vs-availability tradeoff that
+all distributed data storage systems face. It is not possible to
+simultaneously achieve perfect consistency and perfect availability in the
+face of network partitions (servers being unreachable or faulty).
+
+Tahoe tries to achieve a reasonable compromise, but there is a basic rule in
+place, known as the Prime Coordination Directive: "Don't Do That". What this
+means is that if write-access to a mutable file is available to several
+parties, then those parties are responsible for coordinating their activities
+to avoid multiple simultaneous updates. This could be achieved by having
+these parties talk to each other and using some sort of locking mechanism, or
+by serializing all changes through a single writer.
+
+The consequences of performing uncoordinated writes can vary. Some of the
+writers may lose their changes, as somebody else wins the race condition. In
+many cases the file will be left in an "unhealthy" state, meaning that there
+are not as many redundant shares as we would like (reducing the reliability
+of the file against server failures). In the worst case, the file can be left
+in such an unhealthy state that no version is recoverable, even the old ones.
+It is this small possibility of data loss that prompts us to issue the Prime
+Coordination Directive.
+
+Tahoe nodes implement internal serialization to make sure that a single Tahoe
+node cannot conflict with itself. For example, it is safe to issue two
+directory modification requests to a single tahoe node's wapi server at the
+same time, because the Tahoe node will internally delay one of them until
+after the other has finished being applied. (This feature was introduced in
+Tahoe-1.1; back with Tahoe-1.0 the web client was responsible for serializing
+web requests themselves).
+
+For more details, please see the "Consistency vs Availability" and "The Prime
+Coordination Directive" sections of mutable.txt, in the same directory as
+this file.
+
+
+[1]: URLs and HTTP and UTF-8, Oh My
+
+ HTTP does not provide a mechanism to specify the character set used to
+ encode non-ascii names in URLs (rfc2396#2.1). We prefer the convention that
+ the filename= argument shall be a URL-encoded UTF-8 encoded unicode object.
+ For example, suppose we want to provoke the server into using a filename of
+ "f i a n c e-acute e" (i.e. F I A N C U+00E9 E). The UTF-8 encoding of this
+ is 0x66 0x69 0x61 0x6e 0x63 0xc3 0xa9 0x65 (or "fianc\xC3\xA9e", as python's
+ repr() function would show). To encode this into a URL, the non-printable
+ characters must be escaped with the urlencode '%XX' mechansim, giving us
+ "fianc%C3%A9e". Thus, the first line of the HTTP request will be "GET
+ /uri/CAP...?save=true&filename=fianc%C3%A9e HTTP/1.1". Not all browsers
+ provide this: IE7 uses the Latin-1 encoding, which is fianc%E9e.
+
+ The response header will need to indicate a non-ASCII filename. The actual
+ mechanism to do this is not clear. For ASCII filenames, the response header
+ would look like:
+
+ Content-Disposition: attachment; filename="english.txt"
+
+ If Tahoe were to enforce the utf-8 convention, it would need to decode the
+ URL argument into a unicode string, and then encode it back into a sequence
+ of bytes when creating the response header. One possibility would be to use
+ unencoded utf-8. Developers suggest that IE7 might accept this:
+
+ #1: Content-Disposition: attachment; filename="fianc\xC3\xA9e"
+ (note, the last four bytes of that line, not including the newline, are
+ 0xC3 0xA9 0x65 0x22)
+
+ RFC2231#4 (dated 1997): suggests that the following might work, and some
+ developers (http://markmail.org/message/dsjyokgl7hv64ig3) have reported that
+ it is supported by firefox (but not IE7):
+
+ #2: Content-Disposition: attachment; filename*=utf-8''fianc%C3%A9e
+
+ My reading of RFC2616#19.5.1 (which defines Content-Disposition) says that
+ the filename= parameter is defined to be wrapped in quotes (presumeably to
+ allow spaces without breaking the parsing of subsequent parameters), which
+ would give us:
+
+ #3: Content-Disposition: attachment; filename*=utf-8''"fianc%C3%A9e"
+
+ However this is contrary to the examples in the email thread listed above.
+
+ Developers report that IE7 (when it is configured for UTF-8 URL encoding,
+ which is not the default in asian countries), will accept:
+
+ #4: Content-Disposition: attachment; filename=fianc%C3%A9e
+
+ However, for maximum compatibility, Tahoe simply copies bytes from the URL
+ into the response header, rather than enforcing the utf-8 convention. This
+ means it does not try to decode the filename from the URL argument, nor does
+ it encode the filename into the response header.
<h1>The WAPI</h1>
- <p>Want to program your Tahoe node to do your bidding? Easy! See <a href="frontends/wapi.txt">wapi.txt</a>.</p>
+ <p>Want to program your Tahoe node to do your bidding? Easy! See <a href="frontends/webapi.txt">webapi.txt</a>.</p>
<p>P.S. "WAPI" is pronounced "wappy".</p>
if ophandle in self.timers and self.timers[ophandle].active():
self.timers[ophandle].cancel()
self.timers.pop(ophandle, None)
- self.handles.pop(ophandle, None)
+ # self.handles.pop(ophandle, None)
class ReloadMixin:
REFRESH_TIME = 1*MINUTE
projects / tahoe-lafs / tahoe-lafs.git / commitdiff