Push can be controlled by a programmatic API. However a durable topic still needs to be created and registered in both RichFaces and the Java Messaging Service.
The programmatic API consists of a TopicKey which addresses the topic, and a TopicsContext which is used for publishing messages.
For the purpose of observing events from the server, the client creates a permanent connection to the server either by using a WebSocket connection or the long-polling method. Permanent connections are managed by the Atmosphere Framework.
In this example, the message doesn't contain any data - it instructs the client to re-render part of the page. In this case it forces the client to load new unique ID.
<!DOCTYPE html> <ui:composition xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:a4j="http://richfaces.org/a4j"> <h:form id="form"> <a4j:push id="pushTopics" address="pushTopicsContext"> <a4j:ajax event="dataavailable" render="uuid" /> </a4j:push> <h:panelGrid columns="2"> <h:outputLabel value="New UUID:" /> <a4j:outputPanel id="uuid" layout="block"> #{pushBean.UUID} </a4j:outputPanel> </h:panelGrid> </h:form> </ui:composition>
package org.richfaces.demo.push; import org.richfaces.application.push.TopicKey; import org.richfaces.application.push.TopicsContext; import org.richfaces.log.Logger; import org.richfaces.log.RichfacesLogger; /** * Sends message to topic using TopicsContext. * * @author <a href="http://community.jboss.org/people/lfryc">Lukas Fryc</a> */ public class TopicsContextMessageProducer implements MessageProducer { public static final String PUSH_TOPICS_CONTEXT_TOPIC = "pushTopicsContext"; private Logger log = RichfacesLogger.WEBAPP.getLogger(); /* * (non-Javadoc) * * @see org.richfaces.demo.push.MessageProducer#sendMessage() */ public void sendMessage() throws Exception { try { TopicKey topicKey = new TopicKey(PUSH_TOPICS_CONTEXT_TOPIC); TopicsContext topicsContext = TopicsContext.lookup(); topicsContext.publish(topicKey, "message"); } catch (Exception e) { log.info("Sending push message using TopicContext failed (" + e.getMessage() + ") - operation will be repeated in few seconds"); if (log.isDebugEnabled()) { log.debug(e); } } } /* * (non-Javadoc) * * @see org.richfaces.demo.push.MessageProducer#getInterval() */ public int getInterval() { return 5000; } /* * (non-Javadoc) * * @see org.richfaces.demo.push.MessageProducer#finalizeProducer() */ public void finalizeProducer() { } }
