CK's Developer Blog

Below is an overview of implementation of RSS support for PrimeFaces. I have used YARFRAW.  The usage is as below.

<p:rss title="RSS feed title" link="http://www.karthikeyanc.com/feed.seam"
 tagLine="CKs Developer Notes.."
 xmlns:p="http://primefaces.prime.com.tr/ui"
 xmlns:f="http://java.sun.com/jsf/core"
 xmlns:ui="http://java.sun.com/jsf/facelets">
 <f:view contentType="application/atom+xml">
 <ui:repeat var="tut" value="#{rssfeed.feedTutorials}">
<p:rssEntry title="#{tut.topic}"
 link="http://localhost:8080/tutorial/#{tut.id}_#{tut.slug}"
 id="http://localhost:8080/tutorial/#{tut.id}_#{tut.slug}"
 author="karthikeyanC"
 published="#{tut.lastupdate}"
 updated="#{tut.lastupdate}"
 summary="#{tut.summary}"/>
 </ui:repeat>
  </f:view>
</p:rss>

The following changes were made for the same.

To begin with add the following dependency in pom.xml

<!--RSS Yarfraw-->
 <dependency>
 <groupId>net.sourceforge.yarfraw</groupId>
 <artifactId>yarfraw</artifactId>
 <version>0.92</version>
 <scope>provided</scope>
 </dependency>

I created two template files namely rss.xml and rssEntry.xml under primefaces/src/main/resources-maven-jsf/ui.

rss.xml content is as below.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE component SYSTEM "../misc/component.dtd" [
<!ENTITY standard_uicomponent_attributes        SYSTEM "../entities/standard_uicomponent_attributes.xml">
<!ENTITY widget_var_attribute                    SYSTEM "../entities/widget_var_attribute.xml">
<!ENTITY output_component_attributes            SYSTEM "../entities/output_component_attributes.xml">
]>
<component>
 <tag>rss</tag>
 <tagClass>org.primefaces.component.rss.RssTag</tagClass>
 <componentClass>org.primefaces.component.rss.Rss</componentClass>
 <componentType>org.primefaces.component.Rss</componentType>
 <componentFamily>org.primefaces.component</componentFamily>
 <rendererType>org.primefaces.component.RssRenderer</rendererType>
 <rendererClass>org.primefaces.component.rss.RssRenderer</rendererClass>
 <parent>javax.faces.component.UIComponentBase</parent>
 <attributes>
 &standard_uicomponent_attributes;
 <attribute>
 <name>title</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The title for RSS feed</description>
 </attribute>
 <attribute>
 <name>link</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The Link for RSS feed</description>
 </attribute>
 <attribute>
 <name>tagLine</name>
 <required>false</required>
 <type>java.lang.String</type>
 <description>The tag line for RSS feed</description>
 </attribute>
 </attributes>
 <resources/>
</component>

rssEntry.xml content is as below.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE component SYSTEM "../misc/component.dtd" [
<!ENTITY standard_uicomponent_attributes        SYSTEM "../entities/standard_uicomponent_attributes.xml">
<!ENTITY widget_var_attribute                    SYSTEM "../entities/widget_var_attribute.xml">
<!ENTITY output_component_attributes            SYSTEM "../entities/output_component_attributes.xml">
]>
<component>
 <tag>rssEntry</tag>
 <tagClass>org.primefaces.component.rss.RssEntryTag</tagClass>
 <componentClass>org.primefaces.component.rss.RssEntry</componentClass>
 <componentType>org.primefaces.component.RssEntry</componentType>
 <componentFamily>org.primefaces.component</componentFamily>
 <rendererType>org.primefaces.component.RssEntryRenderer</rendererType>
 <rendererClass>org.primefaces.component.rss.RssEntryRenderer</rendererClass>
 <parent>javax.faces.component.UIComponentBase</parent>
 <attributes>
 &standard_uicomponent_attributes;
 <attribute>
 <name>title</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The title for RSS entry</description>
 </attribute>
 <attribute>
 <name>link</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The Link for RSS entry</description>
 </attribute>
 <attribute>
 <name>id</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The id for RSS entry</description>
 </attribute>
 <attribute>
 <name>summary</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The summary text for RSS entry</description>
 </attribute>
 <attribute>
 <name>author</name>
 <required>true</required>
 <type>java.lang.String</type>
 <description>The author for RSS entry</description>
 </attribute>

 </attributes>
 <resources/>
 </component>

The related renderer classes are as below.

package org.primefaces.component.rss;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.context.ResponseWriter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.primefaces.renderkit.CoreRenderer;
import yarfraw.core.datamodel.ChannelFeed;
import yarfraw.core.datamodel.FeedFormat;
import yarfraw.io.FeedWriter;

public class RssRenderer extends CoreRenderer {

 static final String CHANNELFEED_KEY = "CHANNELFEED_KEY";
 private static final String MIME_TYPE = "text/xml";

 public void encodeBegin(FacesContext facesContext, UIComponent component) throws IOException {

 Rss rss = (Rss) component;

 ChannelFeed feed = new ChannelFeed();
 feed.setUid(String.valueOf(System.nanoTime()));
 feed.setTitle(rss.getTitle());
 feed.setDescriptionOrSubtitle(rss.getTagLine());

 feed.addLink(rss.getLink());
 HttpServletRequest request = (HttpServletRequest) facesContext.getExternalContext().getRequest();
 request.setAttribute(RssRenderer.CHANNELFEED_KEY, feed);
 }

 public void encodeEnd(FacesContext facesContext, UIComponent component) throws IOException {

 HttpServletRequest request = (HttpServletRequest) facesContext.getExternalContext().getRequest();

 ChannelFeed feed = (ChannelFeed) request.getAttribute(RssRenderer.CHANNELFEED_KEY);
 request.removeAttribute(RssRenderer.CHANNELFEED_KEY);

 ResponseWriter writer = facesContext.getResponseWriter();

 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 try {
 FeedWriter.writeChannel(FeedFormat.ATOM10, feed, baos);
 } catch (Exception e) {
 throw new RuntimeException("Cannot create RSS feed", e);
 }

 HttpServletResponse response = (HttpServletResponse) facesContext.getExternalContext().getResponse();
 response.setContentType(MIME_TYPE);
 response.setContentLength(baos.size());
 writer.write(baos.toString());
 writer.flush();
 facesContext.responseComplete();

 }
}

and RssEntryRenderer.java is as below.

package org.primefaces.component.rss;

import java.io.IOException;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;

import javax.servlet.http.HttpServletRequest;
import org.primefaces.renderkit.CoreRenderer;
import yarfraw.core.datamodel.ChannelFeed;
import yarfraw.core.datamodel.ItemEntry;
import yarfraw.core.datamodel.Person;

public class RssEntryRenderer extends CoreRenderer {

 public void encodeBegin(FacesContext facesContext, UIComponent component) throws IOException {
 HttpServletRequest request = (HttpServletRequest) facesContext.getExternalContext().getRequest();

 RssEntry rssEntry = (RssEntry) component;

 ChannelFeed feed = (ChannelFeed) request.getAttribute(RssRenderer.CHANNELFEED_KEY);
 ItemEntry entry = new ItemEntry();
 entry.setUid(rssEntry.getId());
 entry.setTitle(rssEntry.getTitle());
 entry.addLink(rssEntry.getLink());

 //author is a mandatory attribute
 Person person = new Person();
 person.setName(rssEntry.getAuthor());
 entry.addAuthorOrCreator(person);

 entry.setDescriptionOrSummary(rssEntry.getSummary());

 feed.addItem(entry);

 }
}

To use this component in their application one has to add the YARFRAW jar as a dependency in their application pom.xml or in the classpath (if they dont use Maven for build)