Page History

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The repository has the following use cases:

• Checkout, which checks out a specific (or the latest, if you don't specify anything) version.
• Update, which updates an existing object to the latest one (or a specific one, if you specify a version).
• Commit, which commits the changed object to a new version, possibly dealing with conflicts in the process.

What manipulation is actually required, depends:

• A client will do the most complex manipulations:
  • filtering the graph to show only relevant subsets
  • querying the graph to find certain objects
  • editing the graph
  • access control that restricts visibility and/or edit-ability of the graph
• A relay server will only get part of the graph
• A server, or anything that talks to management agents, will do specific queries

Context

Possible solutions

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For the manipulation, we need a system that can do queries on streams, and a system that can do it on object graphs in memory. We have several options here:

• JXPath, which can operate on XML or object graphs.
• JoSQL, a SQL dialect that operates on object graphs.
• LDAP queries, as included in OSGi.

Also, we need to define where to do the actual access control. We have two choices here:

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Let's start by doing access control on the client. If we really run into problems we can always move that code to the server.

Conclusion

• Use XStream as a repository implementation.
• Start with LDAP or JXPath for querying.