The Pcd GL is a JNDI compatible directory with special features for the SAP J2EE application server environment. It is part of the SAP J2EE server infrastructure and can be used by all portal/SAP J2EE applications.

The data in the Pcd GL is organized hierarchically. A JNDI based API allows to build and traverse "folder" hierachies, and create, modify, read and delete objects. The data are physically stored in a database.

If you need to learn more about JNDI, a good starting point for you might be SUN's JNDI tutorial. Many details on JNDI are found in the JNDI API documentation.

Applications that use the Pcd GL fall into two groups: consumers and object providers.

An object provider provides a Java implementation of its own semantic object (that's trivial), and conversion functionality, so-called state and object factories, that allow to convert instances of this semantic object into the low-level data model of the Pcd, and vice versa.

A consumer uses the JNDI API with or without the Pcd specific extensions to lookup and work with the objects that are stored in the Pcd. Consumers do typically not work with the low-level data-model of the Pcd, but with the respective semantic objects of the object providers.

The API comprises four packages:

`com.sapportals.portal.pcd.gl`	Pcd-specific extensions of the package javax.naming.directory
`com.sapportals.portal.pcd.gl.admin`	Miscellaneous administration interfaces
`com.sapportals.portal.pcd.gl.notif`	Using this implementation of the observer pattern, the semantic objects can be notified of any (direct or indirect) change to their underlying persistence object
`com.sapportals.portal.pcd.gl.spi`	Classes that are valid return values in the StateFactory-call. In bind or rebind calls, the object providers use these classes to indicate that a non-standard object should be created in the persistency

The Pcd GL extends the functionality of the standard JNDI API in following ways:

Pre-defined set of value types for the attributes, including one for multi-lingual texts
Relations with special support for where-used lists
Deltalinks (inheritance for hierarchical data structures)
Transport (generic support for the portal's transport feature; !!link to the javadoc of the transport service)
Personalization (generic support for personalization of all data)
Locking (generic support for the portal's lock feature)
Permission checks (generic support for ACL checks)
Cache (cluster aware cache implementation strongly reduces the database traffic)
Static filtering allows applications to influence the returned child list of a node
Performance optimization possible for declared read-only aspects
Unit concept allows to subdivide the full JNDI hierarchy into semantic entities (subtrees)

See the package description of the package com.sapportals.portal.pcd.gl for more information.