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From "Stefan Guggisberg" <stefan.guggisb...@gmail.com>
Subject Re: Role of the FileSystem
Date Thu, 14 Jun 2007 08:19:56 GMT
hi derek,

sorry for the late reply...

On 6/9/07, Derek Jean-Baptiste <derek@jeanbaptiste.org> wrote:
> Hello and please pardon me if this is already in an FAQ somewhere (I
> have looked but did not find anything that really answers this).
> What is the role of the FileSystem in the Repository, Version and
> Workspace?

FileSystem is a an abstraction (i.e. a virtual filesystem) that can be
used by the different components (Repository, Versioning & Workspace)
for persisting their state.

some historical background information:
in early days there were only filesystem based persistence managers
(XMLPersistenceManager & ObjectPersistenceManager). since those
create many small files we soon ran into limitations of the underlying
native file system (mainly windows:(  in order to avoid those issues
we introduced the FileSystem abstraction which enabled us to
experiment with different implementations (e.g. a unix-style java
filesystem-in-a-single-file or a db-based filesystem). we then used
the FileSystem abstraction in all components that used to access
the native filesystem (i.e. java.io.File).

> Is any information permanently stored there?

that depends on the component. global repository state (namespace
mappings, custom node types, etc) is persisted in the virtual FileSystem.

on a workspace level it depends on the PersistenceManager implementation.

while XMLPersistenceManager & ObjectPersistenceManager do use the
FileSystem, SimpleDbPersistenceManager for example doesn't.

> If you use SimpleDBPersistenceManager and a LocalFileSystem and lose the
> LocalFileSystem, can you recover from that loss?

yes, assuming you can restore the workspace.xml (which is located in the
LocalFileSystem) and you store blobs in the database (externalBLOBs=false).


> Thanks
> Derek

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