WCM tutorial: creating index pages

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The official documentation is at: http://docs.alfresco.com

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Table of Contents

• 1 Status


• 2 Overview
  
  
  
  • 2.1 web.xml
  
  
  • 2.2 pr.tld
  
  
  • 2.3 Util.java
  
  
  • 2.4 PressReleaseBean.java
  
  
  • 2.5 index.jsp
  
  

Status

Alfresco has just begun to integrate web content management (WCM) features into its core repository and interface. As always, your feedback is appreciated!

CAVEAT:  This page is seriously out of date..

Overview

Alfresco published a 'WCM Preview Release' in October of 2006 that contains a sample website which illustrates a technique for creating a JSP-based index page.

After you load alfresco-sample-website.zip into a 'staging' sandbox, take note of the following set of files:

•   ROOT/WEB-INF/web.xml
  
•   ROOT/WEB-INF/pr.tld
  
•   ROOT/WEB-INF/classes/org/alfresco/web/pr/Util.java
  
•   ROOT/WEB-INF/classes/org/alfresco/web/pr/PressReleaseBean.java
  
•   ROOT/media/releases/index.jsp
  

Let's examine them one at a time.

web.xml

Within this file you should see a snippet that reads:

 <taglib>
     <taglib-uri>http://www.alfresco.org/pr</taglib-uri>
     <taglib-location>/WEB-INF/pr.tld</taglib-location>
 </taglib>

This creates an association between the  http://www.alfresco.org/pr  tag library, and its tag library definition file  /WEB-INF/pr.tld.  The index.jsp file will make use of this association later.

pr.tld

The press release tag definition library associates a tag library URI (e.g.:  http://www.alfresco.org/pr) with a set of functions.  For example, the first function defined is:

 <function>
     <name>getPressReleases</name>
     <function-class>org.alfresco.web.pr.Util</function-class>
     <function-signature>
         java.util.List
             getPressReleases(javax.servlet.jsp.PageContext)
     </function-signature>
 </function>

This says:

• getPressReleases is declared as a function visible within JSPs
  
• org.alfresco.web.pr.Util is the class implementing this function
  
• java.util.List getPressReleases(javax.servlet.jsp.PageContext) is the Java API
  

There's another function defined in this file as well called getCompanyFooters (see the pr.tld file for details).  Both of these functions are associated with the tag library URI  http://www.alfresco.org/pr.  The point being illustrated here is that you can define as many functions in a tag library definition file as you'd like.

Util.java

Contains implementations of the functions used by the tag libraries.

TODO:  remove everything but the low-level operations (e.g.:  loadXMLDocuments)  from this file, and modify pr.tld accordingly.  The webapp-specific convenience functions should be sequestered elsewhere.

PressReleaseBean.java

This file provides the implementation of the java bean returned by the function getPressReleases.  This bean has getter functions that are used by JSP's expression language (e.g.: statements within a JSP of the form:

  ${...}

index.jsp

An index file that constructs a dynamic list of files within Alfresco's repository.  Note that this index page begins with the following declaration:

<jsp:root version='1.2'
            xmlns:jsp='http://java.sun.com/JSP/Page'
            xmlns:c='http://java.sun.com/jsp/jstl/core'
            xmlns:pr='http://www.alfresco.org/pr'
            xmlns:fmt='http://java.sun.com/jsp/jstl/fmt'>

The fourth line (in bold) says 'import the tag lib URI named http://www.alfresco.org/pr and associate it with the XML namespace prefix  pr.  Recall that we defined this tag lib URI earlier in web.xml (see above).

Around line 90, you'll see a JSP statement like this:

 <c:forEach items='${pr:getPressReleases(pageContext)}' var='pressRelease'>

That means 'loop over all items returned by the function call ${pr:getPressReleases(pageContext)} using a temporary variable for the 'current' item called pressRelease.  Recall that:

•   ${ ... } is interpreted as a statement in the JSP expression language
  
•   pr: is an alias for the http://www.alfresco.org/pr tag lib namespace
  
•   getPressReleases(pageContext) returns a list of PressReleaseBean objects.
  

Thus the following expression invokes the press release listing convenience function within our index.jsp:

 ${pr:getPressReleases(pageContext)}

On around line 91, you can see this loop variable being used:

 <jsp:attribute name='href'><c:out value='${pressRelease.href}'/></jsp:attribute>

Note, within PressReleaseBean.java, the PressReleaseBean class has the following getter:

 public String getHref()
 {
     return this.href;
 }

Thus, in JSP expression language the following statement in your index.jsp:

 ${pressRelease.href}

is translated into a call to that getter.