Getting Started for Developers

You are reading the CRX 2.1 version of Getting Started for Developers.
This documentation is also available for the following versions: CRX 2.3 CRX 2.2

Note

This information is intended as an introduction to developing with CRX and assumes previous experience in development.

Introductions to CRXDE and CRXDE Lite

CRXDE Lite is embedded in CRX and enables you to perform standard development tasks in the browser. See Developing with CRXDE Lite for an introduction.

CRXDE is the Eclipse based version, a standalone product that works with CRX and offers additional functionality; for example, debugging and code-completion.

The example Developing a Simple Blog uses CRXDE Lite so will introduce certain basic tasks as well.

Developing a Simple Blog

Learning by doing is often an efficient method - here a very simple example highlights some central issues and is followed by more detailed information (and links) about the concepts.

This example is intended as basic introduction to developing with CRX (together with CRXDE Lite). We will develop a simple Blog covering:

Creation of the root page.
Creation of individual pages for each post. The properties title and body will hold the content to be displayed.
We will use a self-imposed tree structure (you can choose your own).
Develop scripts to display the title and body of each post (as HTML), together with links to child posts.
We will use JSP scripts, other languages and scripting languages can also be used, including ESP and Java.
Imposing a style with CSS.
Basic error handling.
Adding images.
Multiple renderings of the same page.
Adding a user comment.
Creating a Web Syndication Feed. To illustrate the use of other scripting languages, we will use an *.esp script.

Note

The example uses a standard installation at:
http://localhost:7402/

If you have installed CRX at another location, then substitute this with:
http://<server-name>:<port-number>/
for example http://localhost:4502/

Note

This is a very simple blog, for real life usage extension would be necessary.

Creating the Root Page

For ease of usage we are going to create the entire blog under one page.

Using CRXDE Lite, navigate to /content in the repository.

Select /content then using the context menu (usually the right mouse button) select Create... followed by Create Node.... The dialog that opens allows you to specify:

Name: as required, for example myBlog.
Type: select nt:unstructured

Click OK to save.

Select the new node myBlog.

Create a new property:

Name: title
Type: String
Value: as required; for example, My Blog

Click Add (the green plus icon) to add the property to the list.

Create another new property:

Name: body
Type: String
Value: as required; for example, Mine, all mine.

Click Add (the green plus icon)to add the property to the list.

Click Save All.

Creating Individual Pages for each Post

Under the root page we will create a (self-imposed) structure for the individual posts. As this is a chronological blog we can use a simple structure based on dates.

Under the node myBlog create a new node:

Name: 2010
Type: nt:unstructured
Properties:
- Name: title
- Type: String
- Value: 2010
- Name: body
- Type: String
- Value: All entries for 2010.

Under the node 2010 create a new node:

Name: March
Type: nt:unstructured
Properties:
- Name: title
- Type: String
- Value: March 2010
- Name: body
- Type: String
- Value: All entries for March 2010.

Under the node March create a new node:

Name: 01March2010
Type: nt:unstructured
Properties:
- Name: title
- Type: String
- Value: 1st March 2010
- Name: body
- Type: String
- Value: Sunny.<br>First day of meteorological spring.

Under the node March create another new node:

Name: 02March2010
Type: nt:unstructured
Properties:
- Name: title
- Type: String
- Value: 2nd March 2010
- Name: body
- Type: String
- Value: Cloudy with sunny spells.

Click Save All.

Rendering your Blog as HTML Pages

How a resource is rendered depends on the extension and selector used. These are used to select the script used for the rendering.

To render a resource as HTML the resource is selected with the extension .html, this then uses the script html.jsp. As we have not explicitly defined the sling:resourceType property on any of our nodes, the script will be taken from /apps/myBlog (the path is derived from the content path /content/myBlog).

Displaying the title and body

As a basic example we want to display the contents of the two properties title and body.

Under the node /apps create a new node:

Name: myBlog
Type: nt:folder

Select /apps/myBlog, then using the context menu select Create... followed by Create File.... The dialog that opens allows you to specify:

Name: html.jsp

Click OK. The file is created and opened for edit in the right pane.

Copy the following code to html.jsp, then click Save All:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
  pageEncoding="ISO-8859-1"%><%
%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/ TR/html4/loose.dtd"><% 
%>

<%@page session="false"%>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0"%>
<sling:defineObjects/>

<%@ page import="javax.jcr.Repository,
                   javax.jcr.Session,
                   javax.jcr.SimpleCredentials,
                   javax.jcr.Node,
                   java.net.URLEncoder,
                   java.util.List,
                   java.util.Iterator,
                   javax.jcr.Value,
                   javax.jcr.RepositoryException"%>

<html>
<head> 
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
  <title><%= currentNode.getProperty("title").getString() %></title> 
</head> 
<body> 
  <div>
    <h1><%= currentNode.getProperty("title").getString() %></h1>
    <br>
    <%= currentNode.getProperty("body").getString() %>
  </div>
</body> 
</html>

From a browser access the node 2010 as html using:

http://localhost:7402/content/myBlog/2010.html

The tab name will show the contents of the property title, with the page content showing the contents of both the properties title and body:

You can also select the other nodes:

http://localhost:7402/content/myBlog.html
http://localhost:7402/content/myBlog/2010/March.html
http://localhost:7402/content/myBlog/2010/March/01March2010.html
http://localhost:7402/content/myBlog/2010/March/02March2010.html

All nodes will be rendered using the same script.

Showing Links to Child Pages

To allow a visitor to navigate through the blog, for each post we can provide links to all child pages.

Replace the contents of html.jsp with the following code; again click Save All:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
  pageEncoding="ISO-8859-1"%><%
%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/ TR/html4/loose.dtd"><% 
%>

<%@page session="false"%>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0"%>
<sling:defineObjects/>

<%@ page import="javax.jcr.Repository,
                   javax.jcr.Session,
                   javax.jcr.SimpleCredentials,
                   javax.jcr.Node,
                   javax.jcr.NodeIterator,
                   java.net.URLEncoder,
                   java.util.List,
                   java.util.Iterator,
                   javax.jcr.Value,
                   javax.jcr.RepositoryException"%>

<html>
<head> 
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
  <title><%= currentNode.getProperty("title").getString() %></title> 
</head> 
<body> 
  <div>
    <h1><%= currentNode.getProperty("title").getString() %></h1>
    <br>
    <%= currentNode.getProperty("body").getString() %>
    <br><br>
    <%
    NodeIterator ni = currentNode.getNodes(); 

    while (ni.hasNext()) {
      Node nii = ni.nextNode();
      String printNodePath = nii.getPath(); 
      String printNodeTitle = nii.getProperty("title").getString();
      %>
      <a href="<%= printNodePath %>.html"><%= printNodeTitle %></a>
      <br>
      <%
    }
    %>
  </div>
</body> 
</html>

This adds the following to the script:

the page imports needed to use node iterators


                   javax.jcr.NodeIterator,

the instructions to loop through all child nodes and show the title as a link

    <br><br>
    <%
    NodeIterator ni = currentNode.getNodes(); 

    while (ni.hasNext()) {
      Node nii = ni.nextNode();
      String printNodePath = nii.getPath(); 
      String printNodeTitle = nii.getProperty("title").getString();
      %>
      <a href="<%= printNodePath %>.html"><%= printNodeTitle %></a>
      <br>
      <%
    }
    %>

From a browser access the node 2010 as html, again using:

http://localhost:7402/content/myBlog/2010.html

The page will have been updated with links to the child nodes:

You can also select the other nodes:

http://localhost:7402/content/myBlog.html
http://localhost:7402/content/myBlog/2010/March.html
http://localhost:7402/content/myBlog/2010/March/01March2010.html
http://localhost:7402/content/myBlog/2010/March/02March2010.html

Links to child nodes will be shown where available.

Imposing a Style

Adding, and linking to a CSS file will impose a predefined style across all pages.

Select /apps/myBlog, then using the context menu select Create... followed by Create File.... The dialog that opens allows you to specify:

Name: style.css

Click OK to create the file; it will be opened for edit in the right pane.

Copy the following to style.css then click Save All:

body { 
    margin-bottom:1px;
    font-family:georgia,times;
    color: red;
} 

a {
    padding: 5px; 
    color: blue;
}

a .small {
    padding: 2px;
    border: none;       
}

div {
    padding:5px; 
}

h1 {
    font-size: 150%;
    border-bottom: solid grey 1px;  
    color: green;    
}

Add the following line to the <head> section of html.jsp; again click Save All:

  <link rel="stylesheet" href="/apps/myBlog/style.css" type="text/css">

The script will now contain:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
  pageEncoding="ISO-8859-1"%><%
%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/ TR/html4/loose.dtd"><% 
%>

<%@page session="false"%>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0"%>
<sling:defineObjects/>

<%@ page import="javax.jcr.Repository,
                   javax.jcr.Session,
                   javax.jcr.SimpleCredentials,
                   javax.jcr.Node,
                   javax.jcr.NodeIterator,
                   java.net.URLEncoder,
                   java.util.List,
                   java.util.Iterator,
                   javax.jcr.Value,
                   javax.jcr.RepositoryException"%>
<html>
<head> 
  <link rel="stylesheet" href="/apps/myBlog/style.css" type="text/css">
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
  <title><%= currentNode.getProperty("title").getString() == null ? "Title" : currentNode.getProperty("title").getString() %></title> 
</head> 
<body> 
  <h1><%= currentNode.getProperty("title").getString() == null ? "Title" : currentNode.getProperty("title").getString() %></h1>
  <div  class="body">
    <br>
    <%= currentNode.getProperty("body").getString() == null ? "Body" : currentNode.getProperty("body").getString() %>
    <br><br>
    <%
    NodeIterator ni = currentNode.getNodes(); 

    while (ni.hasNext()) {
      Node nii = ni.nextNode();
      String printNodePath = nii.getPath(); 
      String printNodeTitle = nii.getProperty("title").getString();
      %>
      <a href="<%= printNodePath %>.html"><%= printNodeTitle %></a>
      <br>
      <%
    }
    %>
  </div>
</body> 
</html>

Now when you access the node 2010 from a browser using:

http://localhost:7402/content/myBlog/2010.html

The style will have changed, in particular the fonts and colors used:

You can also select the other nodes:

http://localhost:7402/content/myBlog.html
http://localhost:7402/content/myBlog/2010/March.html
http://localhost:7402/content/myBlog/2010/March/01March2010.html
http://localhost:7402/content/myBlog/2010/March/02March2010.html

The same styles are applied to all pages.

Basic Error Handling

To increase the stability of the rendering script you can introduce some basic error handling:

check that the properties exist
check that the properties are not null

To test the error handling you can create a new node under /content/myBlog/2010:

Name: April
Type: nt:unstructured

Do not create any properties for this node.

Click Save All.

Access the node April from a browser using:

http://localhost:7402/content/myBlog/2010/April.html

An error message is seen as the script tries to access properties that do not exist:

title (500)

The requested URL /content/myBlog/2010/April.html resulted in an error in /apps/myBlog/html.jsp.
Exception:

javax.jcr.PathNotFoundException: title

Now replace the entire contents of html.jsp with the following code and click Save All.

This:

Sets default texts, to be used if the properties do not exist.
Tests to confirm that the properties title and body do exist.
Tests all properties and paths for null; if the value is null a standard text is taken for display.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
  pageEncoding="ISO-8859-1"%><%
%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/ TR/html4/loose.dtd"><% 
%>

<%@page session="false"%>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0"%>
<sling:defineObjects/>

<%@ page import="javax.jcr.Repository,
                   javax.jcr.Session,
                   javax.jcr.SimpleCredentials,
                   javax.jcr.Node,
                   javax.jcr.NodeIterator,
                   java.net.URLEncoder,
                   java.util.List,
                   java.util.Iterator,
                   javax.jcr.Value,
                   javax.jcr.RepositoryException"%>

<html>
<head> 
  <link rel="stylesheet" href="/apps/myBlog/style.css" type="text/css">
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
  <% 
  String currentNodeTitle = "Title Missing";
  String currentNodeBody = "Body Missing";
  if (currentNode.hasProperty("title")) {
    currentNodeTitle = currentNode.getProperty("title").getString() == null ? "Title Missing" : currentNode.getProperty("title").getString();
  }
  if (currentNode.hasProperty("body")) {
    currentNodeBody = currentNode.getProperty("body").getString() == null ? "Body Missing" : currentNode.getProperty("body").getString();
  }
  %>
  <title><%= currentNodeTitle %></title> 
</head> 
<body> 
  <h1><%= currentNodeTitle %></h1>
  <div  class="body">
    <br>
    <%= currentNodeBody %>
    <br><br>
    <%
    NodeIterator ni = currentNode.getNodes(); 

    while (ni.hasNext()) {
      Node nii = ni.nextNode();
      String printNodePath = (nii.getPath() == null ? "Path" : nii.getPath());
      String printNodeTitle = "Title missing";
      if (nii.hasProperty("title")) {
        printNodeTitle = nii.getProperty("title").getString() == null ? "Title Missing" : nii.getProperty("title").getString();
      }
      %>
      <a href="<%= printNodePath %>.html"><%= printNodeTitle %></a>
      <br>
      <%
    }

    %>
  </div>
</body> 
</html>

When you now access the node April from a browser using:

http://localhost:7402/content/myBlog/2010/April.html

The default texts can be seen for the properties that do not exist on this node:

Adding an Image

Using WebDAV copy a (small) graphic file into /apps/myBlog. Call it myBlog.png.

Insert the following line immediately under the <body> line in the script:

<a href="/content/myBlog.html"><img src="/apps/myBlog/myBlog.png" width="80px" height="60px" border="0" alt="myBlog" /></a>

When you access any of the nodes in the browser the image appears. The underlying link will take you back to /content/myBlog.html.

Multiple Renderings of the same Page

As CRX uses Sling, the same principles of URL decomposition and Request Processing apply.

Certain renderings are available as standard with CRX:

XML

The XML format can be accessed with the extension *.xml; for example:

http://localhost:7402/content/myBlog/2010.xml

− <_x0032_010 jcr:primaryType="nt:unstructured" body="All entries for 2010." title="2010">
  − <March jcr:primaryType="nt:unstructured" body="All entries for March 2010." title="March 2010">
    <_x0030_1March2010 jcr:primaryType="nt:unstructured" body="Sunny<br>First day of meteorological spring." title="1st March 2010"/>
    <_x0030_2March2010 jcr:primaryType="nt:unstructured" body="Cloudy with sunny spells." title="2nd March 2010"/>
  </March>
  <April jcr:primaryType="nt:unstructured"/>
</_x0032_010>

JSON

The JSON format can be accessed with the extension *.json or *.infinity.json; for example:

http://localhost:7402/content/myBlog/2010.json
to show details of the current node only

{"title":"My Blog","body":"Mine, all mine.","jcr:primaryType":"nt:unstructured"}

http://localhost:7402/content/myBlog/2010.infinity.json
to show details of the current node and all nodes underneath

{
  "title":"My Blog",
  "body":"Mine, all mine.",
  "jcr:primaryType":"nt:unstructured",
  "2010":{
    "title":"2010",
    "body":"All entries for 2010.",
    "jcr:primaryType":"nt:unstructured",
    "March":{
      "title":"March 2010",
      "body":"All entries for March 2010.",
      "jcr:primaryType":"nt:unstructured",
      "01March2010":{
        "title":"1st March 2010",
        "body":"Sunny<br>First day of meteorological spring.",
        "jcr:primaryType":"nt:unstructured"
      },
      "02March2010":{
        "title":"2nd March 2010",
        "body":"Cloudy with sunny spells.",
        "jcr:primaryType":"nt:unstructured"
      }
    },
    "April":{
      "jcr:primaryType":"nt:unstructured"
    }
  },
  "comment":{
    "name":"me",
    "comment":"my comment.",
    "jcr:primaryType":"nt:unstructured"
  }
}

Creating a Customized Rendering

To display a (more easily) printable version of your HTML page you can use the selector print together with the extension html:

http://localhost:7402/content/myBlog/2010.print.html

This will select a script:

print.html.jsp - if available
html.jsp - if print.html.jsp is not available

Select /apps/myBlog then using the context menu select Create... followed by Create File.... The dialog that opens allows you to specify:

Name: print.html.jsp

print.html.jsp will be opened for edit in the right pane. Copy the following code to the new file, then click Save All:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" 
  pageEncoding="ISO-8859-1"%><%
%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/ TR/html4/loose.dtd"><% 
%>

<%@page session="false"%>
<%@taglib prefix="sling" uri="http://sling.apache.org/taglibs/sling/1.0"%>
<sling:defineObjects/>

<%@ page import="javax.jcr.Repository,
                   javax.jcr.Session,
                   javax.jcr.SimpleCredentials,
                   javax.jcr.Node,
                   javax.jcr.NodeIterator,
                   java.net.URLEncoder,
                   java.util.List,
                   java.util.Iterator,
                   javax.jcr.Value,
                   javax.jcr.RepositoryException"%>

<html>
<head> 
  <link rel="stylesheet" href="/apps/myBlog/style.css" type="text/css">
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"> 
  <% 
  String currentNodeTitle = "Title Missing";
  String currentNodeBody = "Body Missing";
  if (currentNode.hasProperty("title")) {
    currentNodeTitle = currentNode.getProperty("title").getString() == null ? "Title Missing" : currentNode.getProperty("title").getString();
  }
  if (currentNode.hasProperty("body")) {
    currentNodeBody = currentNode.getProperty("body").getString() == null ? "Body Missing" : currentNode.getProperty("body").getString();
  }
  %>
  <title><%= currentNodeTitle %></title> 
</head> 
<body> 
  <h1><%= currentNodeTitle %></h1>
  <div  class="body">
    <br>
    <%= currentNodeBody %>
    <br><br>
    <%
    NodeIterator ni = currentNode.getNodes(); 

    while (ni.hasNext()) {
      Node nii = ni.nextNode();
      String printNodePath = (nii.getPath() == null ? "Path" : nii.getPath());
      String printNodeTitle = "Title missing";
      if (nii.hasProperty("title")) {
        printNodeTitle = nii.getProperty("title").getString() == null ? "Title Missing" : nii.getProperty("title").getString();
      }
      %>
      <a href="<%= printNodePath %>.html"><%= printNodeTitle %></a>
      <br>
      <%
    }
    %>
    <br><br>
    <form>
      <input type="button" value=" Print this page " onclick="window.print();" />
    </form>
  </div>
</body> 
</html>

Now you can access the node 2010 from a browser using:

http://localhost:7402/content/myBlog/2010.print.html

Adding the print selector to the uri presents you with a slightly different rendering of the page:

the image is not displayed
a print button is provided at the bottom of the page

You can also select the other nodes:

http://localhost:7402/content/myBlog.print.html
http://localhost:7402/content/myBlog/2010/March.print.html
http://localhost:7402/content/myBlog/2010/March/01March2010.print.html
http://localhost:7402/content/myBlog/2010/March/02March2010.print.html

The same rendering is applied to all pages.

Note

If you delete, or rename, print.html.jsp and reselect http://localhost:7402/content/myBlog/2010.print.html it will be rendered using html.jsp.

Adding a User Comment

Allowing visitors to your site to post information can be achieved with forms.

Select /apps/myBlog, then using the context menu select Create... followed by Create File.... The dialog that opens allows you to specify:

Name: comment.html

comment.html will be created and opened for edit in the right pane. Copy the following code to the new file, then click Save All:

<html>
<head><title>Simple write example</title>
  <link rel="stylesheet" href="/apps/myBlog/style.css" type="text/css">
</head>
<body>
  <h1>Simple Write</h1>
    
  <!-- post your form to the content repository -->
  <form action="/content/myBlog/comment" method="POST">
    <!-- title -->
    <h2>Name</h2>
    <input type="text" name="name" />

    <!-- description -->
    <h2>Comment</h2>
    <textarea rows="5" name="comment"></textarea>
        
    <p><input type="submit" value="Submit"></p>
  </form><br>
    
  <div class="note">
    This page does not use any custom client-side or server-side code
    to create content, the above HTML form is sufficient for this. 
  </div>
        
</body>
</html>

Add the following line to your html.jsp script. Insert it just before the final </div>.

<br>
<a href="/apps/myBlog/comment.html">Comment</a>

Select a page, for example http://localhost:7402/content/myBlog/2010.html.

A new link Comment will be shown:

Click on Comment, a new page will open allowing you to submit your name and a comment.

Enter your Name and a Comment then click Submit.

Using CRXDE Lite navigate to /content/myBlog. A new node comment has been created, with two properties name and comment, holding the details you have just entered.

Creating a Web Syndication Feed

A web syndication feed can be added. The following is a very simple example to show the general principles.

To illustrate the use of other scripting languages we will use ESP for this example.

Select /apps/myBlog, then using the context menu select Create... followed by Create File.... The dialog that opens allows you to specify:

Name: rss.esp

rss.esp will be created and opened for edit in the right pane. Copy the following code to the new file, then click Save All:

<?xml version="1.0"?>
<rss version="2.0">
<channel>
<%
var currentNodeTitle = "Title Missing";
var currentNodeBody = "Body Missing";
var currentNodePath = currentNode.getPath();
if (currentNode.hasProperty("title")) {
  currentNodeTitle = currentNode.getProperty("title").getString();
}
if (currentNode.hasProperty("body")) {
  currentNodeBody = currentNode.getProperty("body").getString();
}
%>
  <item>
    <title><%= currentNodeTitle %></title>
    <description><%= currentNodeBody %></description>
    <link>http://localhost:7402<%= currentNodePath %>.html</link>
  </item>
</channel>
</rss>

You can now select the feed for a page using the extension *.rss; for example, http://localhost:7402/content/myBlog/2010.rss:

This will show:

the page title; this also functions as a link to the page content itself
the page body content

Access Control

Access Control for developers is covered under Access Rights.

Additionally you can read how access rights are administered in CRX - together with user and group accounts.

A Jackrabbit based document management system with dynamic ACLs is also discussed under The ACL is Dead.

Node Types

As CRX is a JCR repository, node types are fully documented under 3.7 Node Types of the JCR 2.0 specification.

WebDAV

WebDAV access gives you direct access to the content repository through your desktop. You can access the contents of the respository as with a standard file-system, using an Explorer or Finder window.

Files dropped into the repository through the WebDAV connection are automatically full-text indexed and can be searched with the standard search interfaces through the standard Java APIs.

OSGi and Sling

OSGi

OSGi is a fundamental element in the technology stack of CRX. It is used to control the composite bundles of CRX and their configuration.

OSGi "provides the standardized primitives that allow applications to be constructed from small, reusable and collaborative components. These components can be composed into an application and deployed".

OSGI for beginners also provides an introduction to the general concepts, while OSGi at dev.day covers many aspects.

For CRX this allows easy management of bundles as they can be stopped, installed, started individually. The interdependencies are handled automatically. Each OSGi Component (see the OSGi Specification) is contained in one of the various bundles. For CRX you can manage the configuration settings for such bundles by either:

configuring content-nodes in the repository (recommended).
using the Apache Felix Web Console.

The CQ documentation covers OSGi configuration, again these principles can be applied to CRX and its bundles.

Sling

CRX is built using Sling, a Web application framework based on REST principles that provides easy development of content-oriented applications. Sling is based upon OSGi and uses a JCR repository, such as Apache Jackrabbit, or Day's CRX, as its data store.

Sling Request Processing is covered in the CQ documentation - these general principles are the same and can be applied to CRX too.
dev.day covers many Sling details of interest to a developer.
Apache Con also archives various presentations including:
- Embrace OSGi - A Developer's Quickstart
- Rapid JCR applications development with Sling

Creating Bundles

As Sling is based upon OSGi, bundles are an integral concept.

The following locations contain information and examples about creating and deploying bundles:

Third Party Libraries

Custom CQ5 Workflow that integrates Twitter and Jabber illustrates an example of working with third party libraries.

Observation Listeners

File Uploads in Sling (JCR EventListeners) illustrates observation listeners.

Schedulers

The Apache Sling Scheduler enables you to easily schedule jobs within your application. Jobs can be executed at a specific time, regularly at a given period or at the time given by a cron expression by leveraging the Sling scheduler service.

A coding example is also given on dev.day.

Setting up Services

The following introduce services:

Summary of Information Sources...

Some have been referenced above, but the following are all valuable sources of information:

Your comments are welcome!

Did you notice a way we could improve the documentation on this page? Is something unclear or insufficiently explained? Please leave your comments below and we will make the appropriate changes. Comments that have been addressed, by improving the documentation accordingly, will then be removed.

COMMENTS

By Lili - 10:09 PM on Nov 23, 2010 Reply
Hi, I need to create a fairly complicated blog. I'd like to borrow the existing blog template but where can I find the .jsp?? Otherwise, if I follow the steps described in the post, I found the "myBlog" dir can't be moved into /apps/mysite/myBlog and content/mysite/myBlog - they gave me not found error. Please advise. Thanks.
By Brant - 2:04 AM on Dec 17, 2010 Reply
when i create the html.jsp page for rendering my html file it doesn't actually work.

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