Connected Data Objects

Connected Data Objects (CDO) is a free implementation of a Distributed Shared Model on top of the Eclipse Modeling Framework (EMF).

With CDO, programmers can easily enhance existing EMF models in such a way that they can be stored and subsequently maintained in a central model repository. While object relational mapping against a JDBC data source on the server side is the shipped default, CDO provides for pluggable storage adapters that allow you to develop and use different mappers (like Hibernate- or OODB-based). On the client side, CDO provides a default integration with EMF, the Eclipse Modeling Framework, although other model integrations on top of the CDO protocol are imaginable as well.

• EMF integration at model level (as opposed to the edit level)
• Support for generated models (just switch two .genmodel properties)
• Support for dynamic models (just load .ecore file and commit to repository)
• Support for legacy models (for compiled models without access to .genmodel)
• Support for the Ecore meta model and descendants

• Eclipse view for working with CDO sessions, transactions, views and resources
• Package Manager dialog per session
• Eclipse editor for working with resources and objects

• Multiple sessions to multiple repositories on multiple servers
• Multiple transactions per session
• Multiple read-only views per session
• Multiple audit views per session (an audit is a view that shows a consistent, historical version of a repository)
• Multiple resources per view (a view is always associated with its own EMF ResourceSet)
• Inter-resource proxy resolution
• Multiple root objects per resource
• Object state shared among all views of a session
• Object graph internally unconnected (unused parts of the graph can easily be reclaimed by the garbage collector)
• Only new and modified objects committed in a transaction
• Transactions can span multiple resources
• Demand loading of objects (resources are populated as they are navigated)
• Partial loading of collections (chunk size can be configured per session)
• Adaptable pre-fetching of objects (different intelligent usage analyzers are available)
• Asynchronous object invalidation (optional)
• Clean API to work with sessions, views, transactions and objects
• CDOResources are EObjects as well
• Objects carry meta information like id, state, version and life span
• Support for OSGi environments (headless, Eclipse RCP, ...)
• Support for standalone applications (non-OSGi)

• Net4j based binary application protocol
• Pluggable transport layer (shipped with NIO socket transport and JVM embedded transport)
• Pluggable fail over support
• Pluggable authentication (shipped with challenge/response negotiation)
• Multiple acceptors per server

• Pluggable storage adapters
• Multiple repositories per server
• Multiple models (packages) per repository
• Multiple resources (instance documents) per repository
• Expressive XML configuration file
• Configurable storage adapter per repository (see below)
• Configurable caching per repository
• Clean API to work with repositories, sessions, views, transactions and revisions
• Support for OSGi environments (usually headless)
• Support for standalone applications (non-OSGi)

• Supports all optional features of the CDO Server
• Pluggable SQL dialect adapters
• Includes support for Derby, HSQLDB, MySQL and Oracle (TBD)
• Pluggable mapping strategies
• Includes horizontal mapping strategy (one table per concrete class)
• Includes vertical mapping strategy (TBD, one table per class in hierarchy)
• Supports different mapping modes for collections

• CDO Homepage