Package org.apache.jackrabbit.core

Contains the core classes that provide the implementation of the JCR API.

See: Description

Package org.apache.jackrabbit.core Description

Contains the core classes that provide the implementation of the JCR API.

The following table lists the core JCR interfaces and the corresponding Jackrabbit implementation classes found in this package.

JCR interface Implementation class
Repository RepositoryImpl
Session SessionImpl
Workspace WorkspaceImpl
Item ItemImpl
Property PropertyImpl
Node NodeImpl

A Jackrabbit repository instance can be created using the static RepositoryImpl.create(RepositoryConfig) method. The RepositoryHelper and other classes in the org.apache.jackrabbit.core.jndi package provide a mechanism for binding a Jackrabbit repository in a JNDI directory context.

A SessionImpl instance is created upon successfully login to the Repository (see Repository#login(Credentials, String)).

A Session is always tied to the Workspace specified in the Repository#login(Credentials, String) call. A workspace represents a persistent tree of repository items (i.e. Nodes and Propertys). The items in a workspace are 'visible' to all sessions accessing it (subject to their access rights, of course). A WorkspaceImpl instance represents a specifc workspace as seen by the session that accesses it.

Every repository item is uniquely identified by its ItemId. The id of a node (NodeId) consists of the node's uuid. The id of a property (PropertyId) consists of the parent node's uuid and the name of the property.

Item managers

Every SessionImpl instance has its own ItemManager. The per-session instance of ItemManager acts as item factory (i.e. it creates NodeImpl and PropertyImpl instances) and provides item access by item id and item caching.

The data (or state) of an item is represented by the following classes in the subpackage state:

There's one SharedItemStateManager for every workspace. It provides item state caching and it guarantees that there's only one (persistent) item state instance for any distinct item id in that workspace.

Every session has its own SessionItemStateManager that consists of the session's TransientItemStateManager and the workspace's SharedItemStateManager.

Each item (i.e. NodeImpl and PropertyImpl) instance is holding an ItemState instance. When e.g. a session is modifying a property by changing the property's value, a new transient item state is created by the session's TransientItemStateManager. This transient state is actually wrapping the (old) shared state (copy on write). The PropertyImpl's state is then replaced by the new transient state.

Transient (i.e. unsaved) modifications are 'session-local', i.e. they are not visible to other sessions. When the modifications are saved they become instantly visible to all sessions accessing the same workspace.

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