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Sun GlassFish Enterprise Server 2.1 Developer's Guide

Chapter 18 Using the Java Message Service

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

For general information about the JMS API, see “Chapter 31: The Java Message Service API” in the Java EE 5 Tutorial.

For detailed information about JMS concepts and JMS support in the Enterprise Server, see Chapter 4, Configuring Java Message Service Resources, in Sun GlassFish Enterprise Server 2.1 Administration Guide.

This chapter contains the following sections:

The JMS Provider

The Enterprise 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. The Enterprise Server uses the Sun GlassFish Message Queue software as its native JMS provider. The Message Queue software is tightly integrated into theEnterprise Server, providing transparent JMS messaging support. This support is known within Enterprise Server as the JMS Service. The JMS Service requires only minimal administration.

The relationship of the Message Queue software to the Enterprise Server can be one of these types: EMBEDDED, LOCAL, or REMOTE. The effects of these choices on the Message Queue broker life cycle are as follows:

For more information about setting the type and the default JMS host, see Configuring the JMS Service.

For more information about the Message Queue software, refer to the documentation at http://docs.sun.com/coll/1343.8.

For general information about the JMS API, see the JMS web page at http://java.sun.com/products/jms/index.html.

Note –

Some topics in the documentation pertain to features that are available only in domains that are configured to support clusters. Examples of domains that support clusters are domains that are created with the cluster profile or the enterprise profile. For information about profiles, see Usage Profiles in Sun GlassFish Enterprise Server 2.1 Administration Guide.

Message Queue Resource Adapter

The Sun GlassFish Message Queue software is integrated into the Enterprise Server using a resource adapter that is compliant with the Connector 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:

You use connector configuration tools to manage JMS resources. For more information, see Chapter 12, Developing Connectors.

Generic Resource Adapter

The Enterprise Server provides a generic resource adapter for JMS, for those who want to use a JMS provider other than Sun GlassFish Message Queue. For details, see http://genericjmsra.dev.java.net/ and Configuring the Generic Resource Adapter for JMS in Sun GlassFish Enterprise Server 2.1 Administration Guide.

Administration of the JMS Service

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

For more information about JMS administration tasks, see Chapter 4, Configuring Java Message Service Resources, in Sun GlassFish Enterprise Server 2.1 Administration Guide and the Sun Java System Message Queue 4.3 Administration Guide.

Configuring the JMS Service

The JMS Service configuration is available to all inbound and outbound connections pertaining to the Enterprise Server cluster or instance. You can edit the JMS Service configuration in the following ways:

You can override the JMS Service configuration using JMS connection factory settings. For details, see Chapter 4, Configuring Java Message Service Resources, in Sun GlassFish Enterprise Server 2.1 Administration Guide.

Note –

The Enterprise Server instance must be restarted after configuration of the JMS Service.

The Default JMS Host

A JMS host refers to a Sun GlassFish Message Queue broker. A default JMS host for the JMS service is provided, named default_JMS_host. This is the JMS host that the Enterprise Server uses for performing all Message Queue broker administrative operations, such as creating and deleting JMS destinations.

If you have created a multi-broker cluster in the 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 Enterprise 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

You can create additional JMS hosts in the following ways:

For machines having more than one host, use the Host field in the Admin Console or the -–mqhost option of create-jms-host to specify the address to which the broker binds.

Checking Whether the JMS Provider Is Running

You can use the asadmin jms-ping command to check whether a Sun GlassFish Message Queue instance is running. For details, see the Sun GlassFish Enterprise Server 2.1 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 Queue physical destination it listens to doesn’t exist, the Enterprise 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 Queue physical destination beforehand.

You can create a JMS physical destination in the following ways:

To purge all messages currently queued at a physical destination, use the asadmin flush-jmsdest command. This deletes the messages before they reach any message consumers. For details, see the Sun GlassFish Enterprise Server 2.1 Reference Manual.

To create a destination resource, see Creating JMS Resources: Destinations and Connection Factories.

Creating JMS Resources: Destinations and Connection Factories

You can create two kinds of JMS resources in the Enterprise Server:

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

Note –

All JMS resource properties that used to work with version 7 of the Enterprise 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 Enterprise Server. Further changes to the configuration are not available to the client JVM until the client is restarted.

JMS Connection Features

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

Both these features use the AddressList configuration, which is populated with the hosts and ports of the JMS hosts defined in the Enterprise 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.

Note –

In the Sun GlassFish Message Queue software, the AddressList property is called imqAddressList.

Connection Pooling

The Enterprise Server pools JMS connections automatically.

To dynamically modify connection pool properties using the Admin Console, go to either the Connection Factories page (see Creating JMS Resources: Destinations and Connection Factories) or the Connector Connection Pools page (see Deploying and Configuring a Stand-Alone Connector Module).

To use the command line, use the asadmin create-connector-connection-pool command to manage the pool (see Deploying and Configuring a Stand-Alone Connector Module.

For the developer profile, 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.

For the cluster and enterprise profiles, the addresslist-behavior JMS service attribute is set to priority by default. This means that the first broker in the AddressList is selected first. This first broker is the local colocated Message Queue broker. If this broker is unavailable, connection attempts are made to brokers in the order in which they are listed in the AddressList. This ensures colocated production and consumption of messages and equitable load distribution across the Message Queue broker cluster.

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 Enterprise Server.

Connection Failover

To specify whether the Enterprise 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 Enterprise 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 Chapter 4, Configuring Java Message Service Resources, in Sun GlassFish Enterprise Server 2.1 Administration Guide.

The Sun GlassFish 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. See activation-config-property in Sun GlassFish Enterprise Server 2.1 Application Deployment Guide.

The Enterprise 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 nondurable 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 Enterprise 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 GlassFish 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.

To ensure that local delivery is preferred, set addresslist-behavior to priority. This setting specifies that the first broker in the AddressList is selected first. This first broker is the local colocated Message Queue instance. If this broker is unavailable, connection attempts are made to brokers in the order in which they are listed in the AddressList. This setting is the default for Enterprise Server instances that belong to a cluster.

Note –

Some topics in the documentation pertain to features that are available only in domains that are configured to support clusters. Examples of domains that support clusters are domains that are created with the cluster profile or the enterprise profile. For information about profiles, see Usage Profiles in Sun GlassFish Enterprise Server 2.1 Administration Guide.

JMS Service High Availability

There are two levels of availability for JMS components:

You can enable data availability in the Sun GlassFish Message Queue cluster that comprises the Java Message Service (JMS). Messages are saved to the high-availability database (HADB) if HADB is installed, data availability is enabled, and the enterprise profile is selected. For information about profiles, see Usage Profiles in Sun GlassFish Enterprise Server 2.1 Administration Guide. You must enable availability for the Enterprise Server instances before you can enable data availability for the corresponding brokers.

Note –

Individual applications and modules cannot control or override JMS availability.

To enable data availability, select the Availability Service component under the relevant configuration in the Admin Console. Check the Availability Service box. To enable availability for the JMS service, select the JMS Availability tab, then check the Availability Service box. All instances in an Enterprise Server cluster should have the same instance availability and JMS availability settings to ensure consistent behavior. For details, see the Sun GlassFish Enterprise Server 2.1 High Availability Administration Guide.

Note –

Some topics in the documentation pertain to features that are available only in domains that are configured to support clusters. Examples of domains that support clusters are domains that are created with the cluster profile or the enterprise profile. For information about profiles, see Usage Profiles in Sun GlassFish Enterprise Server 2.1 Administration Guide.

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.

Authentication With ConnectionFactory

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 Enterprise Server searches the container for authentication information before using the supplied user and password. Version 7 of the Enterprise Server threw an exception in this situation.

Message Queue varhome Directory

The Sun GlassFish Message Queue software uses a default directory for storing data such as persistent messages and its log file. This directory is called varhome. The Enterprise Server uses domain-dir/imq as the varhome directory if the type of relationship between the Enterprise Server and the Message Queue software is LOCAL or EMBEDDED. If the relationship type is REMOTE, the Message Queue software determines the varhome location. For more information about the types of relationships between the Enterprise Server and Message Queue, see The JMS Provider.

When executing Message Queue scripts such as as-install/imq/bin/imqusermgr, use the -varhome option to point the scripts to the Message Queue data if the relationship type is LOCAL or EMBEDDED. For example:

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

For more information about the Message Queue software, refer to the documentation at http://docs.sun.com/coll/1343.8.

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.

For more information about SOAP, see the Apache SOAP web site at http://xml.apache.org/soap/index.html.

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:

ProcedureTo Send SOAP Messages Using the JMS API

  1. Import the MessageTransformer library.

    import com.sun.messaging.xml.MessageTransformer;

    This is the utility whose methods you use to convert SOAP messages to JMS messages and the reverse. You can then send a JMS message containing a SOAP payload as if it were a normal JMS message.

  2. 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);

  3. Construct a SOAP message using the SOAP with Attachments API for Java (SAAJ). 

    /*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();

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

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

  5. Publish the JMS message.

    publisher.publish(m);

  6. Close the JMS connection.

    tc.close();

ProcedureTo Receive SOAP Messages Using the JMS API

  1. Import the MessageTransformer library.

    import com.sun.messaging.xml.MessageTransformer;

    This is the utility whose methods you use to convert SOAP messages to JMS messages and the reverse. The JMS message containing the SOAP payload is received as if it were a normal JMS message.

  2. 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();

  3. 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 ); }

  4. Retrieve the content of the SOAP message.