PUBLIC MARKS with tag jcr

Announcement of PHPCR available, using iterators, PHP 5.3 namespaces. This is the future storage backend for the Symfony2 CMF.

There are several approaches that I could take when discussing the JCR. In this article, I examine the features offered by the JSR-170 specification from a developer's perspective, focusing on the available API and the interfaces that allow a programmer to efficiently use the JSR-170 repository in designing a content application. As an artificial example, I'll implement a trivial back end for a Wikipedia-like encyclopedia system, called JCRWiki, with support for binary content, versioning, backup, and search. I use Apache Jackrabbit, an open source implementation of JSR-170, to develop this application.

JSR-170 explicitly allows for numerous different deployment models, meaning that it is entirely up to the repository implementation to suggest certain models. Jackrabbit is built to support a variety of different deployment models, some of the possibilities on how to deploy Jackrabbit will be outlined here...

It is extremely common for applications to store various pieces of information, most of the time in relational databases. While they do a great job when working with regular data types, they are not very efficient when dealing with binary data, for example images or documents. File systems can be used as an alternative and while they offer better performance, there is neither a query language for searching information nor a notion of relationship or transaction.

The Java Content Repository specification (JSR-170) focuses on "content services," where these not only manage data, but offer author based versioning, full-text searches, fine grained access control, content categorization and content event monitoring. Programmers can use repositories in many ways just like a JDBC connection accesses a database: programmers obtain a connection to a repository, open a session, use the session to access a set of data, and then close the session. The JCR specification has multiple levels of compliance; the most simple level offers read-only access to a repository, XPath-like queries, and some other elements, while other levels of the specification offer a SQL-like query syntax, write capabilities, and more advanced features.

Apache Jackrabbit is a fully conforming implementation of the Content Repository for Java Technology API (JCR). A content repository is a hierarchical content store with support for structured and unstructured content, full text search, versioning, transactions, observation, and more. Typical applications that use content repositories include content management, document management, and records management systems. Version 1.0 of the JCR API was specified by the Java Specification Request 170 (JSR 170) and work on the JCR version 2.0 has begun in JSR 283. Apache Jackrabbit is a project of the Apache Software Foundation.