Jcr Storage

Goal

XWiki works on Java Content Repository.

JCR node hierarchy

Similar to Alternative Page Store and Web DAV Service. format: node or property name (jcr node type).

• (jcr workspace) = single xwiki in multiwiki setup.
  • / (jcr:root)
    • <space> (xwiki:space)
      • <documentName> (xwiki:document)
        • <document properties>
        • objects
          • <class.name>
            • <number> (xwiki:object)
              • <object properties>
        • attachments
          • <filename> (xwiki:attachment extends nt:file)
        • translations
          • <language> (xwiki:document)
        • lock (xwiki:lock)
          • author
          • date

Store classes

• use value objects for storage (from xwiki data model proposal: sandbox/org.xwiki.model): org.xwiki.store.value.DocumentValue, ObjectValue, etc
  • value objects allow us to eliminate xwiki-core dependency in jcrstore. we can reuse value objects in new data model later as in sandbox/org.xwiki.model
• put all storage specific code in DAO classes: DocumentDAO, ObjectDAO, etc
• Implement a clean xwiki stores with only business code and delegate storage specific code to DAO classes
• convert value objects to/from xwiki business objects: org.xwiki.store.value.ValueConverter, DocumentValue <-> XWikiDocument, etc.

JCR specific code

Many ideas are from springmodules-jcr.

• RepositoryProvider provides a jcr repository.
• SessionFactory create/manage jcr sessions.
• JcrTemplate execute jcr code via callbacks/closures.

Quering

Use our QueryManager for quering. Add JCRSQL2 language to it. Translate XWQL to JCRSQL2.

Problems

• XWQL needs JCRSQL2 query language from JCRv2. JCRv1 has very limited quering power. But JCRv2 is late. Release was planed at September 2008.
  • Without XWQL/JCRSQL2 it is almost impossible to run xwiki on jcr because it contains very much queries which need to be rewritten on xpath (not always possible).

Status

• JcrStore prototype located in sandbox/jcrstore
  • Contains DefaultStore, basic JCR and InMemory DAOs, some tests of it on jackrabbit.