 | Level: Introductory Nicholas Chase, President, Chase and Chase, Inc.
01 Jul 2003 Adding functionality such as JSP tag libraries to a portlet application is easy: simply include the appropriate files when creating the WAR file. But what if you need to use that tag library outside the portlet application? This tip follows the addition of the blogutil tag library to the MetroSphere portal's registration page.
You'll need to have a working installation of IBM WebSphere Portal Server Version 4.x to follow along with this tip.
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Editor's update
The Web site MetroSphere.com -- the online technical community discussed in this article -- is no longer live. However, the information and screen captures regarding the installation of IBM WebSphere Portal are still accurate and relevant.
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What we want to accomplish
The MetroSphere portal is a community weblog aimed at
technology professionals, and one of our team's major goals is the personalization of
content. As such, it's important that
we know what categories of information a particular user would like to
see. Although the personalization
engine that comes with portal provides all kinds of sophisticated ways to
figure that out through tracking and comparing a user's actions to those of
other users, there is one very simple way for us to know what topics interest a
user.
We can ask.
To do that, we're going to add a list of topics to the
registration page, as in Figure 1.
Figure 1. The completed page
This list is only temporary, of course. As we get closer to completion, we'll refine
it further, so it's natural to pull the topics from a database. And because this is just one of many places in which we're displaying a list of topics, it makes sense to use a tag library to do it.
Adding the tag library to the page
The body of the registration page is contained in the file:
<WebSphere Home>/PortalServer/app/wps.ear/wps.war/screens/html/UserProfileForm.jsp
In addition to changing the layout of the page slightly,
we added a reference to the tag library and the tags
themselves:
Listing 1. Adding the tags to the page
<%@ page session="false" buffer="none" %>
<%-- Licensed Materials - Property of IBM, 5724-B88, (C) Copyright IBM Corp. 2001, 2002 -
All Rights reserved. --%>
<%@ taglib uri="/WEB-INF/tld/engine.tld" prefix="wps" %>
<%@ taglib uri="/WEB-INF/tld/blogtaglib.tld" prefix="blogutil" %>
<%@ include file="BidiInclude.jsp" %>
<wps:constants />
<jsp:useBean id="userWrapper" class="com.ibm.wps.puma.UserWrapper" scope="request"/>
<jsp:useBean id="errorBean" class="com.ibm.wps.puma.UserState" scope="request"/>
<jsp:useBean id="reqAttributes" class="java.util.Vector" scope="request" />
<%@ page import="com.ibm.wps.datastore.LanguageDescriptor" %>
...
</td><td style="background-color: #ECECEC" valign="top">
<table>
<tr><td colspan="3"> </td></tr>
<tr>
<td align="<%= bidiAlignRight %>"><%=
reqAttributes.contains("FAVORITETOPICS")?"*":" " %></td>
<td align="<%= bidiAlignLeft %>" class="wpsEditText">
<b><label for="wps.FavoriteTopics"><wps:text key="metro.favTopics"
bundle="nls.metro">Preferred Topics</wps:text></label></b>
</td>
</tr>
<blogutil:topiclist selected="-1">
<jsp:useBean id="topicelement" class="com.metrosphere.util.TopicBean" />
<tr>
<td><input type="checkbox" name="topicChoice"
value="<jsp:getProperty name="topicelement" property="topicId" />"/>
</td>
<td><jsp:getProperty name="topicelement" property="topicName" /></td>
<td> </td>
</tr>
</blogutil:topiclist>
</table>
</td></tr>
</table>
<span class ="wpsEditSmText" ><wps:text key="requiredfield"
bundle="nls.registration" /></span>
</td></tr>
</td>
</tr>
</table>
<%-- start admin footer --%>
<table cellspacing="4" cellpadding="0" border="0" width="100%">
...
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In an upcoming article on using custom user attributes, we'll look at making sure that checkboxes
are preselected if the user is editing his or her profile rather than creating
a new one, but for now we're just thinking about getting the tag library in
place. Ultimately, we'll also have to
add the topics tags to the UserProfileConf.jsp page.
Adding the classes and tag library file
For any of this to work, we need to make sure
that the tag classes are available to the portal itself. When we were using the tags within a portlet
application, we didn't have to worry about it; we simply included the classes
in the application. Now we need to make
the classes available to the portal itself.
When using J2EE, there are typically two ways to make a
class available to the application. The
first, and most convenient, is to take the relevant class files and add them to
a JAR file, and then add the JAR
file to the /WEB-INF/lib directory.
In some cases, however, including some
versions of WebSphere Application Server included with WebSphere Portal, these
JAR files are not automatically added to the classpath, so you need to add the
individual classes to the /WEB-INF/classes directory of the overall application
server, taking into account the package hierarchy:
<WebSphere Home>/AppServer/classes/com/metrosphere/util/BlogConnection.class
<WebSphere Home>/AppServer/classes/com/metrosphere/util/TopicBean.class
<WebSphere Home>/AppServer/classes/com/metrosphere/util/TopicListTag.class
<WebSphere Home>/AppServer/classes/com/metrosphere/util/TopicTag.class
We also need to make the tag library definition file,
blogtaglib.tld, available to the portal
application. The trick is in
understanding that what we think of as the "portal" itself is
actually a J2EE application in the PortalServer
directory. So in order to add the blog
utility classes to the overall portal, we need to add the .tld
file to the following directory:
<WebSphere Home>/PortalServer/app/wps.ear/wps.war/WEB-INF/tld/
This is the directory referenced by the page directive:
<%@ taglib uri="/WEB-INF/tld/blogtaglib.tld" prefix="blogutil" %>
You can also use the web.xml
file to specify aliases for this tag library.
Using the web.xml file
In some cases, you may want to create an alias for the tag
library by adding it to the web.xml file.
This file is located in:
<WebSphere Home>/PortalServer/app/wps.ear/wps.war/WEB-INF/tld/
To add the tag library to the file, you can simply add a taglib
element:
Listing 1. Adding an alias to the web.xml file.
...
<servlet-mapping id="ServletMapping_tr_3">
<servlet-name>TranscodingUtilities</servlet-name>
<url-pattern>/TranscodingUtilities/*</url-pattern>
</servlet-mapping>
<taglib>
<taglib-uri>/WEB-INF/tld/blogtaglib.tld</taglib-uri>
<taglib-location>/WEB-INF/tld/blogtaglib.tld </taglib-location>
</taglib>
<taglib>
<taglib-uri>engine</taglib-uri>
<taglib-location>WEB-INF/tld/engine.tld</taglib-location>
</taglib>
...
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One reason to do this is for mantainability.
You can create an alias for the file, and
then if you decide to change it later, say, to create a new version, you won't
have to alter any of the actual JSP files.
Instead, you can just make one change to the web.xml
file.
Summary
By making the topic list tag library available to the
portal, you can greatly increase maintainability for pages that are not part of
a portlet application. To do that, you
add the classes to the classes directory
of the application server itself, and the tag library definition to the
WEB-INF/tld directory within the PortalServer
directory.
Resources
About the author | 
| | Nicholas Chase, a Studio B author,
has been involved in Web site development for companies such as Lucent
Technologies, Sun Microsystems, Oracle, and the Tampa Bay Buccaneers. Nick has
been a high school physics teacher, a low-level radioactive waste facility
manager, an online science fiction magazine editor, a multimedia engineer, and
an Oracle instructor. More recently, he was the Chief Technology Officer of an
interactive development firm in Clearwater, Florida, and is the author of four
books on Web development, including
XML
Primer Plus
(Sams). |
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