Chapter 14 Using the Java Message Service

This chapter describes how to use the Java™ Message Service (JMS) API. The Sun Java™ System Application Server has a fully integrated JMS provider: the Sun Java™ System Message Queue software.

For detailed information about JMS concepts and JMS support in Sun Java System Application Server, see the Sun Java System Application Server Administration Guide.

The JMS Provider

Sun Java System Application Server support for JMS messaging, in general, and for message-driven beans, in particular, requires messaging middleware that implements the JMS specification: a JMS provider. Sun Java System Application Server uses the Sun Java System Message Queue software as its native JMS provider. The Sun Java System Message Queue software is tightly integrated into Sun Java System Application Server, providing transparent JMS messaging support. This support (known within Sun Java System Application Server as the JMS Service) requires only minimal administration.

The relationship of the Sun Java System Message Queue software to the Sun Java System Application Server can be one of these types: LOCAL or REMOTE. The results of these choices and their interactions with clustering are as follows:

If the type is LOCAL (the default for a stand-alone Application Server instance), the Message Queue broker starts when the Application Server starts.

If the type is REMOTE, the Message Queue broker must be started separately. This is the default if clusters are defined in the Application Server. For information about starting the broker, see the Sun Java System Message Queue Administration Guide.

For more information about the Sun Java System Message Queue, refer to the following documentation:

Message Queue Resource Adapter

The Sun Java System Message Queue is integrated into the Sun Java System Application Server using a resource adapter that is compliant with the Connector 1.5 specification. The module name of this system resource adapter is jmsra. Every JMS resource is converted to a corresponding connector resource of this resource adapter as follows:

Connection Factory: A connector connection pool with a max-pool-size of 250 and a corresponding connector resource.

Destination (Topic or Queue): A connector administered object.

Administration of the JMS Service

To configure the JMS Service and prepare JMS resources for use in applications deployed to the Sun Java System Application Server, you must perform these tasks:

Configuring the JMS Service

The Default JMS Host

Creating JMS Hosts

Checking Whether the JMS Provider Is Running

Creating Physical Destinations

Creating JMS Resources: Destinations and Connection Factories

For more information about JMS administration tasks, see the Sun Java System Application Server Administration Guide and the Sun Java System Message Queue documentation at:

Configuring the JMS Service

The JMS Service configuration is available to all inbound and outbound connections pertaing to the Sun Java System Application Server cluster or instance. You can edit the JMS Service configuration in the following ways:

To edit the JMS Service configuration using the Administration Console, open the Java Message Service component under the relevant configuration. For details, see the Sun Java System Application Server Administration Guide.

To configure the JMS service, use the asadmin set command to set the following attributes:

server.jms-service.init-timeout-in-seconds = 60
server.jms-service.type = LOCAL
server.jms-service.start-args =
server.jms-service.default-jms-host = default_JMS_host
server.jms-service.reconnect-interval-in-seconds = 60
server.jms-service.reconnect-attempts = 3
server.jms-service.reconnect-enabled = true
server.jms-service.addresslist-behavior = random
server.jms-service.addresslist-iterations = 3
server.jms-service.mq-scheme = mq
server.jms-service.mq-service = jms

You can override the JMS Service configuration using JMS connection factory settings. For details, see the Sun Java System Application Server Administration Guide.

The Default JMS Host


Note	The Sun Java System Application Server instance must be restarted after configuration of the JMS Service.

A JMS host refers to a Sun Java System Message Queue broker. A default JMS host for the JMS service is provided, named default_JMS_host. This is the JMS host that the Application Server instance starts when the JMS Service type is configured as LOCAL.

If you have created a multi-broker cluster in the Sun Java System Message Queue software, delete the default JMS host, then add the Message Queue cluster’s brokers as JMS hosts. In this case, the default JMS host becomes the first JMS host in the AddressList. (For more information about the AddressList, see JMS Connection Features.) You can also explicitly set the default JMS host; see Configuring the JMS Service.

When the Application Server uses a Message Queue cluster, it executes Message Queue specific commands on the default JMS host. For example, when a physical destination is created for a Message Queue cluster of three brokers, the command to create the physical destination is executed on the default JMS host, but the physical destination is used by all three brokers in the cluster.

Creating JMS Hosts

Use the Administration Console. Open the Java Message Service component under the relevant configuration, then select the JMS Hosts component. For details, see the Sun Java System Application Server Administration Guide.

Use the asadmin create-jms-host command. For details, see the Sun Java System Application Server Reference Manual.

Checking Whether the JMS Provider Is Running

You can use the asadmin jms-ping command to check whether a Sun Java System Message Queue instance is running. For details, see the Sun Java System Application Server Reference Manual.

Creating Physical Destinations

Produced messages are delivered for routing and subsequent delivery to consumers using physical destinations in the JMS provider. A physical destination is identified and encapsulated by an administered object (a Topic or Queue destination resource) that an application component uses to specify the destination of messages it is producing and the source of messages it is consuming.

If a message-driven bean is deployed and the physical destination it listens to doesn’t exist, the Application Server automatically creates the physical destination and sets the value of the property maxNumActiveConsumers to -1 (see Load-Balanced Message Inflow). However, it is good practice to create the physical destination beforehand.

Use the Administration Console. Open the Resources component, open the JMS Resources component, then select Physical Destinations. For details, see the Sun Java System Application Server Administration Guide.

Use the asadmin create-jmsdest command. This command acts on the default JMS host of its target. For details, see the Sun Java System Application Server Reference Manual.

Creating JMS Resources: Destinations and Connection Factories

You can create two kinds of JMS resources in Sun Java System Application Server:

Connection Factories: administered objects that implement the ConnectionFactory, QueueConnectionFactory, or TopicConnectionFactory interfaces.

Destination Resources: administered objects that implement the Queue or Topic interfaces.

In either case, the steps for creating a JMS resource are the same. You can create a JMS resource in the following ways:

To create a JMS resource using the Administration Console, open the Resources component, then open the JMS Resources component. Click Connection Factories to create a connection factory, or click Destination Resources to create a queue or topic. For details, see the Sun Java System Application Server Administration Guide.

To create a JMS resource, use the asadmin create-jms-resource command. For details, see the Sun Java System Application Server Reference Manual.



Note	When a Queue is automatically created for a message-driven bean deployed to an Application Server cluster, the value of the property maxNumActiveConsumers is set to -1 so that multiple consumers can access the Queue at the same time. For more information, see Load-Balanced Message Inflow. All JMS resource properties that used to work with version 7 of the Application Server are supported for backward compatibility.

Restarting the JMS Client After JMS Configuration

When a JMS client accesses a JMS administered object for the first time, the client JVM retrieves the JMS service configuration from the Sun Java System Application Server. Further changes to the configuration are not available to the client JVM until the client is restarted.

JMS Connection Features

The Sun Java System Message Queue software supports the following JMS connection features:

Connection Pooling

Connection Failover

Both these features use the AddressList configuration, which is populated with the hosts and ports of the JMS hosts defined in the Sun Java System Application Server. The AddressList is updated whenever a JMS host configuration changes. The AddressList is inherited by any JMS resource when it is created and by any MDB when it is deployed.

Connection Pooling


Note	In the Sun Java System Message Queue software, the AddressList property is called imqAddressList.

The addresslist-behavior JMS service attribute is set to random by default. This means that each ManagedConnection (physical connection) created from the ManagedConnectionFactory selects its primary broker in a random way from the AddressList.

When a JMS connection pool is created, there is one ManagedConnectionFactory instance associated with it. If you configure the AddressList as a ManagedConnectionFactory property, the AddressList configuration in the ManagedConnectionFactory takes precedence over the one defined in the Sun Java System Application Server.

Connection Failover

To specify whether the Application Server tries to reconnect to the primary broker if the connection is lost, set the reconnect-enabled attribute in the JMS service. To specify the number of retries and the time between retries, set the reconnect-attempts and reconnect-interval-in-seconds attributes, respectively.

If reconnection is enabled and the primary broker goes down, the Sun Java System Application Server tries to reconnect to another broker in the AddressList. The AddressList is updated whenever a JMS host configuration changes. The logic for scanning is decided by two JMS service attributes, addresslist-behavior and addresslist-iterations.

You can override these settings using JMS connection factory settings. For details, see the Sun Java System Application Server Administration Guide.

The Sun Java System Message Queue software transparently transfers the load to another broker when the failover occurs. JMS semantics are maintained during failover.

Load-Balanced Message Inflow

You can configure ActivationSpec properties of the jmsra resource adapter in the sun-ejb-jar.xml file for a message-driven bean using activation-config-property elements. Whenever a message-driven bean (EndPointFactory) is deployed, the connector runtime engine finds these properties and configures them accordingly in the resource adapter.

The Sun Java System Application Server transparently enables messages to be delivered in random fashion to message-driven beans having same ClientID. The ClientID is required for durable subscribers.

For non-durable subscribers in which the ClientID is not configured, all instances of a specific message-driven bean that subscribe to same topic are considered equal. When a message-driven bean is deployed to multiple instances of the Application Server, only one of the message-driven beans receives the message. If multiple distinct message-driven beans subscribe to same topic, one instance of each message-driven bean receives a copy of the message.

To support multiple consumers using the same queue, set the maxNumActiveConsumers property of the physical destination to a large value. If this property is set, the Sun Java System Message Queue software allows multiple message-driven beans to consume messages from same queue. The message is delivered randomly to the message-driven beans. If maxNumActiveConsumers is set to -1, there is no limit to the number of consumers.

Transactions and Non-Persistent Messages

During transaction recovery, non-persistent messages might be lost. If the broker fails between the transaction manager’s prepare and commit operations, any non-persistent message in the transaction is lost and cannot be delivered. A message that is not saved to a persistent store is not available for transaction recovery.

ConnectionFactory Authentication

If your web, EJB, or client module has res-auth set to Container, but you use the ConnectionFactory.createConnection("user","password") method to get a connection, the Sun Java System Application Server searches the container for authentication information before using the supplied user and password. Version 7 of the Application Server threw an exception in this situation.

Message Queue varhome Directory

Sun Java System Message Queue uses a default directory for storing data such as persistent messages and its log file. This directory is called varhome. Sun Java System Application server uses domain_dir/imq as the varhome directory. Thus, for the default Application Server domain, Message Queue data is stored in the following location:

When executing Sun Java System Message Queue scripts such as install_dir/imq/bin/imqusermgr, use the -varhome option. For example:

imqusermgr -varhome $AS_INSTALL/domains/domain1/imq add -u testuser -p testpassword

Delivering SOAP Messages Using the JMS API

Web service clients use the Simple Object Access Protocol (SOAP) to communicate with web services. SOAP uses a combination of XML-based data structuring and Hyper Text Transfer Protocol (HTTP) to define a standardized way of invoking methods in objects distributed in diverse operating environments across the Internet.

You can take advantage of the JMS provider’s reliable messaging when delivering SOAP messages. You can convert a SOAP message into a JMS message, send the JMS message, then convert the JMS message back into a SOAP message. The following sections explain how to do these conversions:

Sending SOAP Messages Using the JMS API

Receiving SOAP Messages Using the JMS API

Sending SOAP Messages Using the JMS API

Use the MessageTransformer utility to convert a SOAP message into a JMS message. Then send the JMS message containing the SOAP payload as if it were a normal JMS message.

Import the library com.sun.messaging.xml.MessageTransformer. This is the utility whose methods you use to convert SOAP messages to JMS messages and the reverse.

import com.sun.messaging.xml.MessageTransformer;

Initialize the TopicConnectionFactory, TopicConnection, TopicSession, and publisher.

tcf = new TopicConnectionFactory();
tc = tcf.createTopicConnection();
session = tc.createTopicSession(false,Session.AUTO_ACKNOWLEDGE);
topic = session.createTopic(topicName);
publisher = session.createPublisher(topic);

Construct a SOAP message using the SOAP with Attachments API for Java (SAAJ). For more information on constructing a SOAP message, see the Sun Java System Message Queue Developer’s Guide.

*construct a default soap MessageFactory */
MessageFactory mf = MessageFactory.newInstance();

* Create a SOAP message object.*/
SOAPMessage soapMessage = mf.createMessage();

/** Get SOAP part.*/
SOAPPart soapPart = soapMessage.getSOAPPart();

/* Get SOAP envelope. */
SOAPEnvelope soapEnvelope = soapPart.getEnvelope();

/* Get SOAP body.*/
SOAPBody soapBody = soapEnvelope.getBody();

/* Create a name object. with name space */
/* http://www.sun.com/imq. */
Name name = soapEnvelope.createName("HelloWorld", "hw",
"http://www.sun.com/imq");

* Add child element with the above name. */
SOAPElement element = soapBody.addChildElement(name)

/* Add another child element.*/
element.addTextNode( "Welcome to Sun Java System Web Services." );

/* Create an atachment with activation API.*/
URL url = new URL ("http://java.sun.com/webservices/");
DataHandler dh = new DataHandler (url);
AttachmentPart ap = soapMessage.createAttachmentPart(dh);

/*set content type/ID. */
ap.setContentType("text/html");
ap.setContentId("cid-001");

/** add the attachment to the SOAP message.*/
soapMessage.addAttachmentPart(ap);
soapMessage.saveChanges();

Convert the SOAP message to a JMS message by calling the MessageTransformer.SOAPMessageintoJMSMessage() method.

Message m = MessageTransformer.SOAPMessageIntoJMSMessage (soapMessage, session );

Publish the JMS message.

publisher.publish(m);

Close the JMS connection.

tc.close();

Receiving SOAP Messages Using the JMS API

The JMS message containing the SOAP payload is received as if it were a normal JMS message. Use the MessageTransformer utility to convert the JMS message back into a SOAP message.

Import the library com.sun.messaging.xml.MessageTransformer. This is the utility whose methods you use to convert SOAP messages to JMS messages and the reverse.

import com.sun.messaging.xml.MessageTransformer;

Initialize the TopicConnectionFactory, TopicConnection, TopicSession, TopicSubscriber, and Topic.

messageFactory = MessageFactory.newInstance();
tcf = new com.sun.messaging.TopicConnectionFactory();
tc = tcf.createTopicConnection();

session = tc.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);

topic = session.createTopic(topicName);
subscriber = session.createSubscriber(topic);
subscriber.setMessageListener(this);
tc.start();

Use the OnMessage method to receive the message. Use the SOAPMessageFromJMSMessage method to convert the JMS message to a SOAP message.

public void onMessage (Message message) {
  SOAPMessage soapMessage =
  MessageTransformer.SOAPMessageFromJMSMessage( message,
  messageFactory ); }

Retrieve the content of the SOAP message.

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