Rapid JCR Applications Development with Sling

Rapid JCR Applications Development with Sling Felix Meschberger ApacheCon US 09

About

Senior Developer at Day
fmeschbe@apache.org
http://blog.meschberger.ch
Apache Projects:

Sling
Felix
Jackrabbit

Contents

Introduction to JCR
Sling Overview
Single Script Blog
ESP Blog
Questions

Intro to JCR

JCR = Java Content Repository
Specifications

JSR-170 / JCR 1.0
JSR-283 / JCR 2.0

Everything is Content

JCR manages it in trees of Nodes & Properties
Rich Data Types

JSR-170

Content Repository for Java TM technology API
Spec Lead: David Nüscheler, Day Software
Final Release: 17 June 2005
Expert Group:

JSR-283

Content Repository for Java TM Technology API Version 2.0
Spec Lead: David Nüscheler, Day Software
Final Release: 25 September 2009
Expert Group:

JCR in 21 Words

The API should be a standard, implementation independent way to access content bidirectionally on a granular level to a Content Repository.

JCR = DB + FS + more access control streams locking hierar-chies write read query structure tx obser-vation full text versions item order unstruc-tured multi value integrity JCR DB FS

Implementations

Implementations

Apache Jackrabbit
Day CRX
Oracle XML DB
IBM FileNet P8
IBM CM
Exo ECMS Platform
Xythos Repository
Alfresco ECM

Connectors:

Interwoven Repository
EMC Documentum
MS Sharepoint
OpenText Livelink
Vignette V7

100s of TCKs registered

Some known Applications

JCR code excerpt

Repository repository = new TransientRepository(); Session session = repository. login (...); // Create content Node root = session. getRootNode (); Node hello = root. addNode ("hello"); Node world = hello.addNode("world"); world. setProperty ("message", "Hello, World!"); session. save (); // Retrieve content Node node = root. getNode ("hello/world"); print(node. getPath ()); print(node. getProperty ("message").getString());

Contents

Introduction to JCR
Sling Overview
Single Script Blog
ESP Blog
Questions

Sling builds on top of JCR

Scriptable applications layer
OSGi based industrial strength
Simple, powerful, JCR inside
Runs on Apache Jackrabbit by default
Sling == REST over JCR

Sling URL decomposition /content/cars/audi/s4.details.html

Sling Architecture OSGi Framework Felix Web Console WebDAV Server browser filesystem debugger HTTP JSR-170/283 API JCR repository resource resolution servlet resolution standard servlets custom servlets JSR223 Scripting JSP javascript etc.

Demo Preparation

Get Sling 5 Standalone from http://sling.apache.org/site/downloads.cgi
Upgrade to Web Console 2.0.2 from http://felix.apache.org/site/downloads.cgi
Compile and Install the Path based Resource Type Provider (from the samples/path-based-rtp folder)

Contents

Introduction to JCR
Sling Overview
Single Script Blog
ESP Blog
Questions

Minimal Sling blog

One Script (blog.esp)
JavaScript
46 Lines of Code (!)
http://sling.apache.org/site/46-line-blog.html

Sling POST servlet

# POST to Sling curl -F title=hello http://localhost:8888/foo -> 200 OK # GET created node in json format curl http:/ /localhost:8888/foo.tidy.json { "jcr:primaryType": "nt:unstructured", "title": "hello" }

Blog Step 1: Create Content

<form method=“ POST “> Title: <input type=“text“ name=“ title “ /> Text: <textarea name=“ text ></textarea> <input type=“submit“ /> <input type=“hidden“ name=“:redirect“ value=“*.html“ /> </form>

Blog Step 2: Retrieve Content

Blog Step 3: Navigation

<ul> <li> <a href=“ /content/blog/*.html “> [Create new post]</a> </li> <script> var posts = Sling. getContent („/content/blog“, 2); for (var post in posts) { document.write(„<li><a href='“ + post + „.html'>“ + posts[post].title </a></li>“); } </script> </ul>

We Got a Blog ! html form + Sling.wizard() + Sling.getContent()

Contents

Introduction to JCR
Sling Overview
Single Script Blog
ESP Blog
Questions

The ESP Blog Sample

ESP (Server side JavaScript) scripting
Java
JavaScript
OSGi Bundle
Initial Content
WebDAV
Observation
http://tinyurl.com/slingblogesp2

ESP Blog Demo

ESP Blog Source Files

admin.esp
edit.esp
html.esp
list.esp
menu.esp
xml.esp (RSS)
constants.esp
header.esp

pom.xml
ThumbnailGenerator.java
espblog.css
sling-logo.png

ESP Blog Content Structure

ESP Blog Edit Script

<% pageTitle = currentNode.title; load("header.esp"); %> <body> <form method="POST" action="<%= currentNode%>"> <p><label>Title</label> <input name="title" type="text" value="<%= currentNode.title %>"></p> ... <input type="hidden" name="created"/> <input name=":redirect" type="hidden" value="/content/espblog/posts.admin.html"/> <input type="submit" value="Post" class="button"> </form> ...

ESP Blog Thumbnails: OSGi DS Component

/** * Observe the espblog content for changes, and generate * thumbnails when images are added. * * maven-scr-plugin uses annotations to generate the OSGi * Declarative Services XML configuration files * @scr.component immediate="true" * */ public class ThumbnailGenerator implements EventListener {

ESP Blog Thumbnails: JCR Observation

/** @scr.reference (framework injects it automatically) */ private SlingRepository repository; /** called by framework when service is activated */ protected void activate(ComponentContext context) { Session s = repository.loginAdministrative(null); // Listen for nt:file NODE_ADDED repository events ObservationManager m = s.getWorkspace().getObservationManager(); String[] types = { "nt:file" }; m.addEventListener( this, Event.NODE_ADDED, contentPath, true, null, types, false);

ESP Blog Thumbnails: NODE_ADDED

/** Called by JCR Observation manager for events that this * EventListener registered for */ public void onEvent(EventIterator it) { while (it.hasNext()) { Event event = it.nextEvent(); if (event.getType() == Event.NODE_ADDED && !(event.getPath().contains("thumbnails"))) { String p = event.getPath(); Node n = session.getRootNode().getNode(p); createThumbnails(addedNode); } } ...

We got a typical Sling Application!