From: Kevan Carstensen Date: Tue, 2 Aug 2011 02:20:56 +0000 (-0700) Subject: docs: amend configuration, webapi documentation to talk about MDMF X-Git-Tag: trac-5200~19 X-Git-Url: https://git.rkrishnan.org/components/architecture.txt?a=commitdiff_plain;h=85a00b2d373bbb41a395d172c4b8e62046ce9b59;p=tahoe-lafs%2Ftahoe-lafs.git docs: amend configuration, webapi documentation to talk about MDMF --- diff --git a/docs/configuration.rst b/docs/configuration.rst index 72f38118..b9f14458 100644 --- a/docs/configuration.rst +++ b/docs/configuration.rst @@ -326,6 +326,23 @@ Client Configuration (Mutable files use a different share placement algorithm that does not currently consider this parameter.) +``mutable.format = sdmf or mdmf`` + + This value tells Tahoe-LAFS what the default mutable file format should + be. If ``mutable.format=sdmf``, then newly created mutable files will be + in the old SDMF format. This is desirable for clients that operate on + grids where some peers run older versions of Tahoe-LAFS, as these older + versions cannot read the new MDMF mutable file format. If + ``mutable.format`` is ``mdmf``, then newly created mutable files will use + the new MDMF format, which supports efficient in-place modification and + streaming downloads. You can overwrite this value using a special + mutable-type parameter in the webapi. If you do not specify a value here, + Tahoe-LAFS will use SDMF for all newly-created mutable files. + + Note that this parameter only applies to mutable files. Mutable + directories, which are stored as mutable files, are not controlled by + this parameter and will always use SDMF. We may revisit this decision + in future versions of Tahoe-LAFS. Frontend Configuration ====================== diff --git a/docs/frontends/webapi.rst b/docs/frontends/webapi.rst index df2a8645..8e7b2265 100644 --- a/docs/frontends/webapi.rst +++ b/docs/frontends/webapi.rst @@ -365,10 +365,17 @@ Writing/Uploading A File To use the /uri/$FILECAP form, $FILECAP must be a write-cap for a mutable file. In the /uri/$DIRCAP/[SUBDIRS../]FILENAME form, if the target file is a - writeable mutable file, that file's 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. + writeable mutable file, that file's 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. If the target file is a writable mutable + file, you may also specify an "offset" parameter -- a byte offset that + determines where in the mutable file the data from the HTTP request + body is placed. This operation is relatively efficient for MDMF mutable + files, and is relatively inefficient (but still supported) for SDMF + mutable files. If no offset parameter is specified, then the entire + file is replaced with the data from the HTTP request body. For an + immutable file, the "offset" parameter is not valid. 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. @@ -389,7 +396,16 @@ Writing/Uploading A File 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. + to create an immutable file, returning the read-cap as a response. If + you create a mutable file, you can also use the "mutable-type" query + parameter. If "mutable-type=sdmf", then the mutable file will be created + in the old SDMF mutable file format. This is desirable for files that + need to be read by old clients. If "mutable-type=mdmf", then the file + will be created in the new MDMF mutable file format. MDMF mutable files + can be downloaded more efficiently, and modified in-place efficiently, + but are not compatible with older versions of Tahoe-LAFS. If no + "mutable-type" argument is given, the file is created in whatever + format was configured in tahoe.cfg. Creating A New Directory @@ -1082,7 +1098,13 @@ Uploading a File 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. + returning the upload results page as a response. If you create a + mutable file, you may choose to specify the format of that mutable file + with the "mutable-type" parameter. If "mutable-type=mdmf", then the + file will be created as an MDMF mutable file. If "mutable-type=sdmf", + then the file will be created as an SDMF mutable file. If no value is + specified, the file will be created in whatever format is specified in + tahoe.cfg. ``POST /uri/$DIRCAP/[SUBDIRS../]?t=upload``