2008-12 OJUG JCR Demo

1. JAVA CONTENT REPOSITORY WITH JACKRABBIT Omaha Java Users Group 2008-12-09 Paul Heaberlin paul@heaberlin.net

2. Overview • Intro What is JCR? What can you use JCR for? • JCR Basic Structure Repositories, Workspaces and Nodes Galore! • JSR-170 Compliance Levels Level 1 - Read Only Repository Level 2 - Read and Write Optional - Versioning, Transactions and More • Demo!

3. What is JCR? • JSR-170 deﬁnes the Java Content Repository (JCR) API • First approved June 17, 2005, last updated March 1, 2006 • JCR is just an API, it is NOT a Content Repository • Jackrabbit IS a Content Repository, that implements JSR-170 • JCR provides a universal way to access content within a repository • Similar to what JDBC did for RDBMS, JCR does for content repositories

4. What can you use JCR for? • Common access multiple Content Repositories from different Providers • Other things...

5. JCR Basic Structure • A Repository has Workspaces • A Workspace is a tree of Items • An Item is a Node or Property • A Property can only be a leaf • Property Values hold the data • A Session is used to access a Workspace in the Repository • Nodes can have Types

6. Level 1 Compliance - Read Only Repository • Access the Repository • Read Repository Content • Export Repository Content • Search the Repository (via XPath) • Discover conﬁgured Node Types • Remap Namespaces within Session

7. Level 2 Compliance - Level 1 + Edits • Add, Remove or Modify Nodes and Properties • Import Repository Content • Assign Node Types to Nodes • Add, Remove or Modify Namespaces

8. Optional Features • Can be part of Level 1 or Level 2 compliant implementation • Transactions: Adhere to JTA Spec, support container & user managed • Versioning: Allow checkin and checkout of Nodes • Observation: Applications can “register interest in events that describe changes to a workspace, and then monitor and respond” to them • Locking: Allow temporary locking of Nodes to prevent changes • Search via SQL: Use SQL to query in addition to XPath

9. Demo! • Follow Jackrabbit First Hops • Add in some Versioning • Do some Querying

10. Demo - Jackrabbit Hops • FirstHop.java Access the Repository Find and display features of this implementation • SecondHop.java Add Nodes Add a Property Get a Node and Property Navigate over the Repository

11. JCR Demo - Versioning • VersionDemo.java Try to find a Node If not found, add it Once have Node, modify a Property • Execute this with the following arguments to see the Node change 1: default versioning versionThis quot;this is my first valuequot; 2: default versioning versionThis quot;I have been changed!quot; • Look at final line of ouput, should see 1: versionThis = this is my first value 2: versionThis = I have been changed!

12. JCR Demo - Fun with Queries • QueryDemo.java Run an XPath query on a Workspace Display the results • After executing the VersionDemo, the workspace has Nodes to query • Run this with the following arguments 1: default quot;//versioningquot; • This will display 2 results: A table like below, & all properties of the Node | jcr:primaryType || jcr:path || jcr:score | ________________________________________________________________________ | nt:unstructured || /versioning || 1000 |

13. Other Cool Stuff • Apache Sling: JCR + REST = something that quot;is almost painfully hip, in a way only a dedicated nerd could appreciatequot; Home: http://incubator.apache.org/sling/ Overview: http://www.unc.edu/home/adamc/sling-overview.html • JCROM/Jackrabbit OCM: Object-content mapping, like JPA for the JCR http://jackrabbit.apache.org/jackrabbit-ocm.html http://code.google.com/p/jcrom/ • JSR-283: JCR 2.0 - adding enhancements like federation, remoting, more standard node types, and better access control. Spec: http://jcp.org/en/jsr/detail?id=283

14. Resources • JSR-170 Speciﬁcation: Deﬁnes JCR 1.0 Spec: http://jcp.org/en/jsr/detail?id=170 API: http://www.day.com/maven/jsr170/javadocs/jcr-1.0/ • Apache Jackrabbit: Reference Implementation for JSR-170 Home: http://jackrabbit.apache.org/ API: http://jackrabbit.apache.org/api/1.5/ (as of last night, Dec 8) • Introducing the Java Content Repository API http://www.ibm.com/developerworks/java/library/j-jcr/ • Catch Jackrabbit and the Java Content Repository API http://www.artima.com/lejava/articles/contentrepository.html

15. More Resources • What is Java Content Repository? http://www.onjava.com/pub/a/onjava/2006/10/04/what-is-java-contentrepository.html • Advanced Java Content Repository API http://www.onjava.com/pub/a/onjava/2006/11/08/advanced-java- content-repository.html • Day Dev Blog: Lead contributors to Jackrabbit, Sling and all things JCR http://dev.day.com/ • Post: http://paul.heaberlin.net/2008/12/ojug-presentation-on-jcr.html Slides: http://www.slideshare.net/lobsterboy1980 Demo Code: http://cid-61cb9c642b07d62e.skydrive.live.com/ browse.aspx/OJUG