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From conflue...@apache.org
Subject [CONF] Apache Jackrabbit: Frequently Asked Questions (page edited)
Date Fri, 29 Feb 2008 10:50:02 GMT
Frequently Asked Questions (JCR) edited by Marcel Reutegger
      Page: http://cwiki.apache.org/confluence/display/JCR/Frequently+Asked+Questions
   Changes: http://cwiki.apache.org/confluence/pages/diffpagesbyversion.action?pageId=75346&originalVersion=2&revisedVersion=3


Started Query FAQ

Change summary:

Started Query FAQ

Change summary:

Started Query FAQ

Change summary:

Started Query FAQ

Change summary:

Started Query FAQ


h2. General

h3. What is JCR?

JCR is the acronym of the JSR 170: Content           Repository for Java technology API, a
standard interface           for accessing content repositories.

h3. What is a content repository?

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 system,           common services of a content repository are versioning,        
  access control, full text searching, and event monitoring.A content repository isnota content
management           system (CMS), although most of the existing CMSs contain a          
more or less featured custom content repository implementation.           A CMS uses a content
repository as an underlying component           for presentation, business logic, and other

h3. What is Apache Jackrabbit?

The Apache Jackrabbit is a fully featured content repository that           implements all
of the JCR API. The Jackrabbit project was started           whenDay Software, the JSR-170
          specification lead, licensed their initial implementation of the           JCR reference
implementation. Since then the Jackrabbit codebase           has been used for the official
reference implementation (RI) and            technology compatibility kit (TCK) released along
with the final           JCR API.

h2. Building Jackrabbit

h3. How do I build the Apache Jackrabbit sources?

See the [Building Jackrabbit] section         of theJackrabbit documentation for         detailed
build instructions.

h2. Using Jackrabbit

h3. How do I do X with JCR/Jackrabbit?

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

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.

h3. How do I use transactions with JCR?

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.

h3. How do I create new workspaces in Jackrabbit?

The JCR 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 JackrabbitWorkspaceImpl class. You can then use the WorkspaceImpl.createWorkspace(String)
method to create new workspaces.

h3. How do I delete a workspace in Jackrabbit?

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

h2. Access control

h3. How do I use LDAP, Kerberos, or some other authentication mechanism         with Jackrabbit?

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.

h3. How do I manage the access rights of authenticated users?

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.

h2. Persistence managers

h3. What is a persistence manager?

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

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

h3. What is a Jackrabbit file system?

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).

h3. Can I use a persistence manager to access an existing data source?

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).

h3. How smart should a persistence manager be?

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.

h2. Query

h3. I've configured textFilterClasses but my query still doesn't work, what's wrong?

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|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.

h3. Why doesn't {{//*\[jcr:contains(@jcr:data, 'foo')]}} return matches for binary content?

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.
//element(*, nt:resource)[jcr:contains(., 'foo')] 
//element(*, nt:file)[jcr:contains(jcr:content, 'foo')] 

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