Frequently Asked Questions
JCR is the acronym of the Content Repository for Java technology API, a standard interface for accessing content repositories. JCR version 1.0 was specified in Java Specification Request 170 (JSR 170), and version 2.0 is currently under work in JSR 283.
A content repository is an information management system that provides various services for storing, accessing, and managing content. In addition to a hierarchically structured storage, common services of a content repository are versioning, access control, full text searching, and event monitoring. A content repository is not a content management system (CMS), although most existing CMSs contain a custom content repository implementation, often based on the file system or a relational database.
Apache Jackrabbit is a fully featured content repository that implements the entire JCR API. The Jackrabbit project was started when Day Software, the JSR-170 specification lead, licensed their initial implementation of the JCR reference implementation. The Jackrabbit codebase was used for the official reference implementation (RI) and technology compatibility kit (TCK) released along with the final JCR API.
Please ask questions on the Jackrabbit mailing lists. There is the users list for questions around using JCR and Jackrabbit and the dev list for the development of Jackrabbit itself and for people starting to extend Jackrabbit or other advanced topics.
See the Building Jackrabbit page for detailed build instructions.
See the JCR specification, the JCR API documentation, or the Examples page on the Jackrabbit wiki for information on how to perform various operation using the JCR API.
For Jackrabbit features (like access control and node type management) not covered by the JCR API, see the Examples page on the wiki, the Jackrabbit javadocs, or contact the Jackrabbit mailing list.
See the mailing list announcement for a simple example on using the JTA support in Jackrabbit. For a more complete explanation of the transaction features, please see section 8.1 Transactions of the JCR specification.
The JCR 2.0 API has two Workspace.createWorkspace() methods for that.
The JCR 1.0 API does not contain features for creating or managing workspaces, so you need to use Jackrabbit-specific functionality for creating new workspaces. You can create a new workspace either manually or programmatically.
The manual way is to create a new workspace directory within the repository home directory and to place a new workspace.xml configuration file in that folder. You can use the configuration file of an existing workspace as an example, just remember to change the name of the workspace in the Workspace name="..." tag. See the Jackrabbit Configuration page for configuration details. Note also that you need to restart the repository instance to access the new workspace.
The programmatic way is to acquire a Workspace instance using the normal JCR API and to cast the instance to the JackrabbitWorkspace interface. You can then use the createWorkspace(String) method to create new workspaces.
There is currently no programmatic way to delete workspaces. You can delete a workspace by manually removing the workspace directory when the repository instance is not running.
- Download jcr-1.0.jar and put it into <tomcat-install-dir>/shared/lib.
- Get the WAR distribution from the Downloads page and deploy it into Tomcat.
- Point your browser to http://localhost:8080/jackrabbit-webapp-<version>/
Jackrabbit uses the Java Authentication and Authorization Service (JAAS) for authenticating users. You should be able to use any JAAS LoginModule implementation (e.g. the LoginModules in thecom.sum.security.auth.modulepackage) for authentication. See the JAAS documentation for configuration instructions.
The current JackrabbitSimpleAccessManager class only supports three access levels: anonymous, normal, and system. Anonymous users have read access while normal and system users have full read-write access. You need to implement a custom AccessManager class to get more fine-grained access control.
A persistence manager (PM) is an internal Jackrabbit component that handles the persistent storage of content nodes and properties. Each workspace of a Jackrabbit content repository uses a separate persistence manager to store the content in that workspace. Also the Jackrabbit version handler uses a separate persistence manager.The persistence manager sits at the very bottom layer of the Jackrabbit system architecture. Reliability, integrity and performance of the PM are crucial to the overall stability and performance of the repository. If e.g. the data that a PM is based upon is allowed to change through external means the integrity of the repository would be at risk (think of referential integrity / node references e.g.).
In practice, a persistence manager is any Java class that implements the PersistenceManager interface and the associated behavoural contracts. Jackrabbit contains a set of built-in persistence manager classes that cover most of the deployment needs. There are also a few contributed persistence managers that give additional flexibility.
A Jackrabbbit file system (FS) is an internal component that implements standard file system operations on top of some underlying storage mechanism (a normal file system, a database, a webdav server, or a custom file format). A file system component is any Java class that implements the FileSystem interface and the associated behavioral contracts. File systems are used in Jackrabbit both as subcomponents of the persistence managers and for general storage needs (for example to store the full text indexes).
No. The persistence manager interface was never intended as being a general SPI that you could implement in order to integrate external data sources with proprietary formats (e.g. a customers database). The reason why we abstracted the PM interface was to leave room for future performance optimizations that would not affect the rest of the implementation (e.g. by storing the raw data in a b-tree based database instead of individual file).
A persistence manager should not be intelligent, i.e. it should not interpret the content it is managing. The only thing it should care about is to efficiently, consistently, and reliably store and read the content encapsulated in the passed NodeState and PropertyState objects. Though it might be feasible to write a custom persistence manager to represent existing legacy data in a level-1 (read-only) repository, I don't think the same is possible for a level-2 repository and I certainly would not recommend it.
Make sure you changed existing workspace.xml files as well. The workspace element in repository.xml only acts as a template for new workspaces.
Verify that you also put the jar files into the classpath that jackrabbit depends on for text extraction. You can find all required jar files inside the jackrabbit-webapp war file (the WEB-INF/lib folder). Go to the downloads page to get the war file.
Some documents may still not be searchable for various reasons: the document is corrupt, bug in one of the libraries that extract text, document is encrypted or otherwise protected, etc.
Extracted text from binary content is only indexed on the parent node of the @jcr:data property. Use jcr:contains() on the nt:resource node.
No, you cannot. Even though Jackrabbit uses a Lucene index, the fields for JCR properties do not map 1:1 to Lucene fields. Instead you can use the following:
You probably forgot to prefix your statement with /jcr:root.
JSR 170 says in section 22.214.171.124:
The context node of an XPath query is the XML node relative to which the query expression is evaluated.
A relative XPath statement (one that does not have a leading /) will be interpreted relative to the root node of the workspace, which, in the XML document view is the top-most XML element, <jcr:root>. This means that one should not include jcr:root as the first segment in a relative XPath statement, since that element is already the default context node.
An absolute XPath (one with a leading /), in contrast, will be interpreted relative to a position one level above <jcr:root>. This means that an absolute XPath must either begin with // or with /jcr:root in order to match anything at all.
Forcing a consistency check may be useful when you think the index is inconsistent. You need to add two parameters to the SearchIndex section in the workspace.xml configuration file:
Then restart Jackrabbit and watch the log file for possible repair messages. Don't forget to remove the parameters again when you are done.
A JCR implementation may return -1 when the size is unknown. Starting with 2.0 Jackrabbit will return -1 for some query statements when there is potential for a more optimized query execution. If you still want a size information you can append an order by clause to your statement. This will force Jackrabbit to calculate the result size.