Connected Data Objects

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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.

Model Integration Features[edit]

  • 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 meta model and descendants

User Interface Features[edit]

  • 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[edit]

  • 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[edit]

  • 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[edit]

  • 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)

DB Store Features[edit]

  • 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

External links[edit]