Xydra is a generic, embeddable application data model that runs

• seamlessly in Java (makes testing easy),
• on Google AppEngine (GAE/J), and also via
• Google Web Toolkit (GWT) as JavaScript in a browser.

Xydra Features

• Persistence (currently: in-memory, in GAE data store)
• Events (for all added, removed, or changed entites)
• Commands (which can be serialized, too)
• Transactions (over as many entities as you like)
• Versioning (including a full change log)
• Access Rights Management (with powerful resources hierarchies and nested user groups)
• Synchronisation of state between client and server (in strict or relaxed mode)

Who needs Xydra?

• Web developers who build rich web clients using GWT,
• Cloud application developers who use Google AppEngine and need versioning of data and/or access rights,
• Social application developers who need to sync several clients (in GWT or Java) on the same set of data,
• Or developers needing all of that.

Get started

• Get a Xydra5MinuteTutorial!
• Then check out the XydraBasics.
• Read ModuleOverview to see what good stuff we have in this SVN
• Have a look at the JavaDocs of Xydra

Projects that can be used without Xydra

These projects have no dependency to any Xydra component. They are used by Xydra, but they don't depend on Xydra.

• RestLess - Fast-loading, lightweight Java REST framework for AppEngine
• XydraLog - Unified logging for Java, AppEngine and GWT
• GaeMyAdmin - Easy-to-install AppEngine version to manage your live app in the browser
• XydraIndex - Multi-level index structures (e.g. triple index) that run also in GWT