Installation

You need the Namespace.jar from the NamespacePlugin (I used the one from 26-Nov-2007 20:40).

To compile the sources I took the jspwiki 2.4.104 sources and imported them as a eclipse project.
I added namespace.jar to build path.

After building I moved the de-packages from the classes (eclipes output) to the classes dir of the 
jspwiki installation.

I changed the PageContent.jsp (templates/default) to the version as below (added taglib and two tags).

I put the namespace.tld file to the WEB-INF dir.

I changed the jspwiki.css to highlight the additions (as below)

I changed the jspwiki_print.css to suppress the additions (as below)

<** START: changed PageContent.jsp **>
<%@ taglib uri="/WEB-INF/jspwiki.tld" prefix="wiki" %>
<%@ taglib uri="/WEB-INF/namespace.tld" prefix="ns0" %>
<%-- Inserts page content. --%>

<div id="pagecontent">
  <%-- If the page is an older version, then offer a note and a possibility
       to restore this version as the latest one. --%>

  <wiki:CheckVersion mode="notlatest">
    <div class="warning">
      This is version <wiki:PageVersion/>.  
      It is not the current version, and thus it cannot be edited.<br />
      <wiki:LinkTo>[Back to current version]</wiki:LinkTo>&nbsp;&nbsp;
      <wiki:EditLink version="this">[Restore this version]</wiki:EditLink>
    </div>
  </wiki:CheckVersion>

  <ns0:InsertNamespace concat=">"/>
  <%-- Inserts no text if there is no page. --%>
  <wiki:InsertPage />
  <ns0:InsertNamespaceIndexPlugin />

  <wiki:NoSuchPage>
    <!-- FIXME: Should also note when a wrong version has been fetched. -->
    This page does not exist.  Why don't you go and
    <wiki:EditLink>create it</wiki:EditLink>?
  </wiki:NoSuchPage>

</div>

<wiki:HasAttachments>
  <div id="attachments">
    <h3>Attachments</h3>
    <div class="zebra-table">
      <table>
        <wiki:AttachmentsIterator id="att">
          <tr>
            <td><wiki:LinkTo><%=att.getFileName()%></wiki:LinkTo></td>
            <td><wiki:PageInfoLink><img src="<wiki:Link format="url" jsp="images/attachment_big.png"/>" border="0" alt="Info on <%=att.getFileName()%>" /></wiki:PageInfoLink></td>
            <td><%=att.getSize()%> bytes</td>
          </tr>
        </wiki:AttachmentsIterator>
      </table>
    </div>
  </div>
</wiki:HasAttachments>
<** END: changed PageContent.jsp **>

<** START: namespace.tld **>
<?xml version="1.0" encoding="ISO-8859-1" ?>

<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN"
   "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">

<taglib>
	<tlibversion>1.2</tlibversion>
	<jspversion>1.1</jspversion>
	<shortname>jspwikinamespace</shortname>

  <tag>
    <name>InsertNamespace</name>
    <tagclass>de.jplanets.jspwiki.tags.InsertNamespaceTag</tagclass>
    <bodycontent>empty</bodycontent>
    <attribute>
       <name>delimiter</name>
    </attribute>
    <attribute>
       <name>concat</name>
    </attribute>
    <attribute>
       <name>style</name>
    </attribute>
  </tag>  
  <tag>
    <name>InsertNamespaceIndexPlugin</name>
    <tagclass>de.jplanets.jspwiki.tags.InsertNamespaceIndexPluginTag</tagclass>
    <bodycontent>empty</bodycontent>
    <attribute>
       <name>delimiter</name>
    </attribute>
    <attribute>
       <name>items</name>
    </attribute>
    <attribute>
       <name>exclude</name>
    </attribute>
  </tag>  

</taglib>
<** END: namespace.tld **>


<** START: additions to jspwiki.css **>
/* Namespace Style */
.namespace {background-color: #f0f0f0; font-size: 10px; border: 1px solid gray;  }
.namespace strong{font-size: 12px;}
<** END: additions to jspwiki.css **>

<** START: additions to jspwiki_print.css **>
/* Namespace Style */
.namespace { display: none; }
<** END: additions to jspwiki_print.css **>

<** START: The Tag-Class to insert the namespaceplugin in a template page **>
package de.jplanets.jspwiki.tags;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.jsp.JspWriter;

import brushed.jspwiki.namespaceplugin.Namespace;
import brushed.jspwiki.namespaceplugin.NamespaceIndexPlugin;

import com.ecyrd.jspwiki.tags.WikiTagBase;

public class InsertNamespaceTag extends WikiTagBase
{
    
    protected Namespace m_namespace = new Namespace();
    protected Map m_params = new HashMap();
    public InsertNamespaceTag()
    {
        super.initTag();
        m_params.clear();
    }

    public int doWikiStartTag() throws Exception
    {
        JspWriter out = pageContext.getOut();
        out.print(m_namespace.execute(m_wikiContext, m_params));
        return SKIP_BODY;
    }
    public void setDelimiter(String d) {
        m_params.put(Namespace.PARAM_DELIMITER, d);
    }
    public String getDelimiter() {
        return (String)m_params.get(Namespace.PARAM_DELIMITER);
    }
    public void setConcat(String c) {
        m_params.put(Namespace.PARAM_CONCAT, c);
    }
    public String getConcat() {
        return (String)m_params.get(Namespace.PARAM_CONCAT);
    }
    public void setStyle(String s) {
        m_params.put(Namespace.PARAM_STYLE, s);
    }
    public String getStyle() {
        return (String)m_params.get(Namespace.PARAM_STYLE);
    }
}
<** END: The Tag-Class to insert the namespaceplugin in a template page **>
<** START: The Tag-Class to insert the namespaceindexplugin in a template page **>
package de.jplanets.jspwiki.tags;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.jsp.JspWriter;

import brushed.jspwiki.namespaceplugin.Namespace;
import brushed.jspwiki.namespaceplugin.NamespaceIndexPlugin;

import com.ecyrd.jspwiki.tags.WikiTagBase;

public class InsertNamespaceIndexPluginTag extends WikiTagBase
{
    
    private static final String ITEMS_PER_LINE = "itemsPerLine";
    private static final String EXCLUDE = "exclude";
    protected NamespaceIndexPlugin m_namespaceindexplugin = new NamespaceIndexPlugin();
    protected Map m_params = new HashMap();
    public InsertNamespaceIndexPluginTag()
    {
        super.initTag();
        m_params.clear();
    }

    public int doWikiStartTag() throws Exception
    {
        JspWriter out = pageContext.getOut();
        out.println("<div class='namespace'>");
        out.println("<strong>Children</strong>");
        out.println(m_namespaceindexplugin.execute(m_wikiContext, m_params));
        out.println("</div>");
        return SKIP_BODY;
    }
    public void setDelimiter(String d) {
        m_params.put(Namespace.PARAM_DELIMITER, d);
    }
    public String getDelimiter() {
        return (String)m_params.get(Namespace.PARAM_DELIMITER);
    }
    public void setItems(String s) {
        m_params.put(ITEMS_PER_LINE, s);
    }
    public String getItems() {
        return (String)m_params.get(ITEMS_PER_LINE);
    }
    public void setExclude(String s) {
        m_params.put(EXCLUDE, s);
    }
    public String getExclude() {
        return (String)m_params.get(EXCLUDE);
    }
}
<** END: The Tag-Class to insert the namespaceindexplugin in a template page **>