Connected Data Objects (CDO) is a free implementation of a

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on top of the

Eclipse Modeling Framework Eclipse Modeling Framework (EMF) is an Eclipse (software), Eclipse-based Model-driven architecture, modeling framework and Automatic programming, code generation facility for building tools and other applications based on a structured data model. ...

(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.

Model integration features

* 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

User interface features

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

Client side features

* 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)

Network protocol features

* 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

Server side features

* Pluggable storage adapters * Multiple repositories per server * Multiple models (packages) per repository * Multiple resources (instance documents) per repository * Expressive

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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)

DB store features

* Supports all optional features of the CDO Server * Pluggable SQL dialect adapters * Includes support for Derby, HSQLDB,

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and

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(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

External links

CDO Homepage
Eclipse (software)