[Cosmo] preserving data during cosmo 0.3 upgrade

Jeffrey Harris jeffrey at osafoundation.org
Tue Feb 7 15:42:05 PST 2006


Hi Brian,

Looks like a good plan to me.  Thanks for giving so much detail.

Sincerely,
Jeffrey

Brian Moseley wrote:
> as part of the proposed cosmo 0.3 release, we'd like to guarantee that
> upgrading from 0.2 will not require the existing data to be wiped.
> 
> since the repository schema has changed greatly in 0.3, we'll need to
> provide a tool that can convert an existing repository from the 0.2
> format to the 0.3 format. such a tool could be be run while the server
> is offline or as a component of the application server that executes
> at startup time. i argue that the offline approach is the right
> choice, since the tool would be more easily scriptable by deployers
> and won't require any extra configuration of the server environment.
> 
> complicating factors include:
> 
>  * user account and security info are stored in an embedded hsql db in
> 0.2 but are stored in the repository in 0.3
> 
>  * the repository schema has changed significantly in 0.3 - the dav
> and caldav node types have become mixins, and some property
> definitions have changed - jackrabbit doesn't have a good mechanism
> for changing existing schema definitions like sql's ALTER TABLE
> command
> 
> here is my proposal for the offline upgrade tool:
> 
>  * it will be written in java since it needs to use the jcr api to
> access the repositories
> 
>  * it will be packaged together with all dependencies and run via shell script
> 
>  * it will not attempt to convert a 0.2 repository "in place" but
> rather will copy the data out the 0.2 repository and user db into a
> new, blank 0.3 repository
> 
>  * it will accept as input (via command line options) the locations of
> the data directories and config files for the source (0.2) repository
> and destination (0.3) repository
> 
>  * at the end of the process, the 0.2 repository and user db will have
> exactly the same data as they did at the beginning
> 
> the upgrade process will be broken into the following tasks:
> 
>  1) get the root user's details from the 0.2 user db and update the
> out-of-the-box root user's details in the 0.3 repository
> 
>  2) get the rest of the user details from the 0.2 user db and add a
> user+homedir node for each into the 0.3 repository
> 
>  3) iterate through the homedir nodes in the 0.2 repository, copying
> all content for each (calendars, events, collections, resources,
> tickets) to the corresponding homedir node in the 0.3 repository
> 
> since passwords are stored in an encrypted format in the 0.2 user db,
> we'll have to extend the 0.3 internal apis to allow the creation of a
> user with an encrypted password (the existing api only allows a user
> to be created with a plaintext password).
> 
> in the long term i think we'll want an upgrade tool that can convert
> from an arbitrary older version, so that one could upgrade a 0.2
> server to 0.6 with the same tool rather than requiring 4 separate
> tools. this implies an upgrade framework of some sort. since we really
> want to release 0.3 in two weeks or less, i think we should punt on
> this and then revisit it as a primary tenet for a later release.
> 
> i estimate that building the upgrade tool as proposed, testing on
> copies of the foxcloud and/or cosmo-demo repositories, and fixing
> found bugs will take 3-4 days.
> 
> thoughts on the proposal?
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