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<document> <header> <title>BAM Queue</title> <description> <p>Using BAM to implement a queuing service.</p> </description> <type>tutorial</type> <tutorial-startpage>demo.jsp</tutorial-startpage> </header><body><summary/><s1 title="Files in this tutorial"><deftable><tr> <th>file</th> <th>description</th></tr><tr> <td><viewfile-link file="WEB-INF/resin-web.xml"/></td> <td>Configures the BamService.</td></tr><tr> <td><viewfile-link file="WEB-INF/classes/example/ExampleService.java"/></td> <td>The Java message listener.</td></tr><tr> <td><viewfile-link file="WEB-INF/php/bam_queue.php"/></td> <td>The PHP message listener.</td></tr><tr> <td><viewfile-link file="WEB-INF/classes/example/ExampleMessage.java"/></td> <td>The custom message model.</td></tr><tr> <td><viewfile-link file="demo.jsp"/></td> <td>The JSP demo</td></tr><tr> <td><viewfile-link file="demo.php"/></td> <td>The PHP demo</td></tr></deftable></s1><s1 title="Overview"><p>Messaging lets a servlet delegate processing to a batch process eitheron the same machine or on a separate machine. The servlet creates a messageand sends it to a queue. The servlet immediately completes and when thebatch process is ready, it processes the message.</p><p>Messaging is therefore comprised of three main components:</p><ul><li>A <var>Producer</var> creates messages and sends them toa <var>Consumer</var>, continuing processing. The Producer couldbe a Servlet or PHP page that sends a request to a backend consumerand continues the web response without waiting for the task to complete.</li><li>A <var>Consumer</var> processes messages as they becomeavailable. In BAM, the <var>Consumer</var> extends<var>SimpleBamService</var> to receive the messages.</li><li>The <var>Queue</var> buffers messages from the Produces and providesthem to a Consumer when the Consumer is ready. The Queue is part of the BAMmessaging system.</li></ul></s1><s1 title="Producer"><p>In this example, the Producer is a Servlet which sends a simple message.The Producer creates a <code>BamClient</code> to send the message.</p><example title="Example: MessageServlet using BamClient">import com.caucho.bam.BamClient;public void send(){ BamClient client = new BamClient(); ExampleMessage message = new ExampleMessage("sample message"); client.message("consumer@", message); client.close();}</example><example title="Example: PHP using bam_send_message"><?php$msg = java("example.ExampleMessage", "sample message");bam_send_message("consumer@", $msg);?></example></s1><s1 title="Consumer"><p>The Queue delivers message to the Consumer one by one. When theConsumer finishes processing a message the Queue will deliver the nextavailable message. The Consumerimplements <code>com.caucho.bam.BamService</code>.</p><p>In this example, the Consumer just logs the message.</p><example title="Example: ExampleService">package example;import com.caucho.bam.SimpleBamService;import com.caucho.bam.annotation.Message;public class ExampleService extends SimpleBamService{ @Message public void onMessage(String to, String from, ExampleMessage message) { System.out.println("Message: " + message + " from=" + from); }}</example><p>The PHP version of the service implements a <code>bam_message</code>method to handle the message and calls <code>bam_dispatch()</code> todispatch the message. The PHP service will call the bam_queue.php whenit receives a message.</p><example title="Example: bam_queue.php"><?phpfunction bam_message($to, $from, $value){ resin_debug($value);}bam_dispatch();?></example></s1><s1 title="Configuration"><example title="Example: resin-web.xml"><web-app xmlns="http://caucho.com/ns/resin"> <bam-service name="java-consumer" class="example.ExampleService"/> <bam-service name="php-consumer" uri="caucho.php:"> <init script="WEB-INF/php/bam_queue.php"/> </bam-service></web-app></example></s1></body></document>⌨️ 快捷键说明
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