Hi Alex,
Here is another solution which I would like to quote. I will not disturb
the current repository configuration, yet I know the XML format for each
WebdavRequest to communicate with. So when a user does a put request, I will
override the AbstractWebdavServlet doPut() with my custom doPut which indeed
extends AbstractWebdavServlet and write my custom code in it to store the file
in DFS and respond with a success XML to the user. Its what a basic webdav
server does I hope so.
Regards,
MadhuSudhanan I.
www.zoho.com
'If you wanna walk quick Walk Alone, if you wanna walk far Walk Together ..."
---- On Mon, 16 Feb 2009 Alexander Klimetschek <[email protected]> wrote ----
> Hi,
>
> (I only answer questions publicly, so this goes back to the Jackrabbit list)
>
> On Mon, Feb 16, 2009 at 3:39 PM, imadhusudhanan
> <[email protected]> wrote:
> > Currently we use Hadoop API to access files from Distributed File
> > System. I would like to enable Webdav to the same DFS that I use using
> > JR.
> > May I know how I can make it possible ??
>
> Jackrabbit is not a generic WebDAV to file system mapper as you might
> think. Since it is a JCR repository, it must allow for all the
> fine-grained JCR features (nodes and residual properties, versioning,
> node types, locking etc.) that cannot be mapped onto simple OS file
> systems or simple filesystem abstractions (as what Hadoop contains for
> example). Theoretically that might be possible, but it's not an option
> for a performant implementation. Therefore Jackabbit has its own
> persistence abstraction (mainly around the PersistenceManager
> interface [1]), which is driven by the internal architecture to
> support the full JCR API.
>
> [1]
> http://jackrabbit.apache.org/api/1.5/org/apache/jackrabbit/core/persistence/PersistenceManager.html
>
>
>
> > Also Hadoop DFS has its own FileSystem. I guess that an entry in
> > repository.xml <FileSystem> tag will change the file system to what ever I
> > specify say the org.apache.hadoop.fs.LocalFileSystem etc.
>
> No, you cannot use it. FileSystem is just a common name for
> persistence abstractions, but in this case, Hadoop's FileSystem (base
> class org.apache.hadoop.fs.FileSystem) and Jackrabbit's FileSystem
> (interface org.apache.jackrabbit.core.fs.FileSystem) are two
> completely different things.
>
> Also, Jackrabbit's FileSystem is somewhat deprecated and today not
> used for actual persistence - that's handled by PersistenceManagers
> which are at a low-level where they no longer "know" about the
> hierarchy, but solely work with uuids and node bundles.
>
> This means writing a PersistenceManager that works with a Hadoop
> FileSystem is probably very difficult or even impossible. Not sure how
> Marcel's implementation works, but it seems to use a different Hadoop
> API (not the Filesystem).
>
> There are two options that might work for you, but both involve some
> coding effort: one is to use Jackrabbit's WebDAV server "library" to
> build your own server-side implementation of WebDAV that connects to a
> Hadoop FileSystem. The other option would be to implement the full JCR
> API via Jackrabbit SPI [2], which is a simpler API than the full JCR
> API, and build this on top of a Hadoop FileSystem - but this is a
> rather huge effort.
>
> http://jackrabbit.apache.org/jackrabbit-spi.html
>
> Have a look at the following links if you are interested in more
> informations about Jackrabbit's architecture:
>
> http://jackrabbit.apache.org/jackrabbit-architecture.html
> http://jackrabbit.apache.org/how-jackrabbit-works.html
> http://jackrabbit.apache.org/jackrabbit-configuration.html
>
> Regards,
> Alex
>
> --
> Alexander Klimetschek
> [email protected]
