This document introduces the Java Content Repository (JCR), which provides a standardized API for storing and managing content. It discusses how JCR addresses limitations of traditional storage methods like file systems and databases by providing features like a flexible content model, full text search, transactions, versioning, and observation capabilities. The document also introduces Apache Jackrabbit, an open source JCR implementation, and outlines its goals and upcoming releases.

1. File system on steroids an introduction to JCR Jukka Zitting Apache Jackrabbit

2. Agenda Big Picture Content Repository Repository Features Apache Jackrabbit

3. The Big Picture User Interface Processing Storage

4. Our Focus: Storage Main requirements Persistence Consistency Scalability Performance Main alternatives File system Database Network

5. Introducing The Content Repository File system Database Content Repository read write transactions structured integrity query hierarchical streams access control locking observation versioning full text unstructured

6. JCR, JSR 170, JSR 283 Content Repository for Java Technology API Not just the Java API, but also the content repository semantics POSIX file system defined as a C API Accessible from other environments JVM: Groovy, JRuby, Scala, etc. Network: WebDAV, Ajax (JSON)‏ Ports planned: .NET, PHP

7. Why Something New? Goal: Single API for all storage Universal access No content silos Existing systems don't cover all needs Reiser: “Storage layers above the FS: A sure symptom the FS developer has failed” Solution: Content repository

8. Content Repository Semantics Everything is content Hierarchy of named and typed nodes Content in named and typed properties Superset of file system semantics Can be used to store files and folders, and more Can be mounted as a file system With many database semantics

9. Granularity of Content

10. Granularity of Content, 1/2 File systems are typically best with coarse grained content Small files in ReiserFS, NTFS, etc. Extended properties in many systems XML & co for fine grained content DJB: “Don't parse”

11. Granularity of Content, 2/2 Databases are best with fine grained content Blobs are becoming better supported Often special limitations for search, access, etc. Content repository: Uniform interface for both stream and scalar properties

12. Structure vs. Flexibility

13. Structure vs. Flexibility File systems have no constraints Any file or directory can go anywhere Naming conventions and access control Databases have nothing but constraints Structure of content is predefined Content repository: Both structured and unstructured content

14. Search

15. Search Traditionally no search in file systems Custom indexers and search APIs Google Desktop Search Mac OS X Spotlight Lucene in many applications Content repository: Built-in search with full text indexing

16. Transactions

17. Transactions File systems have limited support for atomic updates The copy-and-move trick No transactions that cover multiple changes Journaling is internal to the system Content repository: Change sets, distributed transactions

18. Versioning

19. Versioning Typically no tracking of previous versions of content Snapshots in ZFS & co. Version control systems Backups for archival vs. restore purpose Mac OS X Time Machine Content repository: Built-in versioning

20. Observation

21. Observation File system change monitoring File Alteration Monitor Polling Event APIs Triggers in databases Content repository: Standard observation API

22. Apache Jackrabbit

23. Apache Jackrabbit Fully featured JCR content repository Releases 1.0 in 2006 1.4 available since January 2008 1.5 (with explorer) planned for Q2 2.0 (with JCR 2.0) planned for 2008 Focus on conformance and flexibility

24. Image credits Images from the morgueFile archive, used as licensed http://morguefile.com/archive/?display=96733 , Infographe_Elle http://morguefile.com/archive/?display=81906 , msxo http://morguefile.com/archive/?display=132988 , imelenchon http://morguefile.com/archive/?display=95446 , ronnieb http://morguefile.com/archive/?display=175657 , seriousfun http://morguefile.com/archive/?display=135511 , rollingroscoe http://morguefile.com/archive/?display=134540 , cohdra http://morguefile.com/archive/?display=196920 , penywise http://morguefile.com/archive/?display=48096 , bluekdesign http://morguefile.com/archive/?display=128133 , gracey

25. Thank you! Questions / Comments?