IBM WebSphere Application Server V4.0 Extended Messaging Support in WebSphere EE

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1 IBM WebSphere Application Server V4.0 Extended Messaging Support in WebSphere EE Page 1 of 26

2 Agenda Messaging in an n-tier environment Messaging support in WebSphere JMS Listener in WebSphere Enterprise Extensions Programming model Configuration file Transaction support Connection pooling Prerequisites Further reading Page 2 of 26

3 Messaging in an n-tier environment Tier-1 Clients Message Exchange B2B Connections PvC Document Exchange JSP Servlet WAS Method Exchange Tier-1 Servers Presentation Logic EJB EJB EJB CTS Tier-2 Servers Business Logic Tier-3 Servers Data Logic Tier-0 Web Browsers Messaging is a method of communication between software components or applications. A messaging system is a peer-to-peer facility: a messaging client can send messages to, and receive messages from, any other client. Each client connects to a messaging agent that provides facilities for creating, sending, and receiving messages. Servlets and EJBs can send and receive messages to/from a messaging vendor. Messaging technologies provide an additional means of communicating with Server Side Components Page 3 of 26

4 Messaging in an n-tier environment Loose Coupling Enables application programs to communicate asynchronously with each other Application data sent as a message If the receiver, or the communication channel to it, is temporarily unavailable, the message can be forwarded at a later time. PUT Messaging Middleware (QUEUE) GET Messaging enables distributed communication that is loosely coupled. A component sends a message to a destination, and the recipient can retrieve it from the destination. However, the sender and receiver do not have to be available at the same time in order to communicate. In fact, the sender does not need to know anything about the receiver, nor does the receiver need to know anything about the sender; they only need to know what message format and what destination to use. In this respect, messaging differs from tightly coupled technologies such as Remote Method Invocation (RMI), which require an application to know a remote application's methods. Page 4 of 26

5 Messaging support in WebSphere Inbound Message PUT Message GET EJB Container EJB Client Program (Java, C++, VB etc.) Message GET Outbound Message PUT Servlet Container JNDI JSP JTA Servlet Java Mail JAF J2EE Server Core RMI/IIOP JDBC WebSphere 4.0 Application Server Applications running in WebSphere can create, send and receive messages using JMS Page 5 of 26

6 Inbound and Outbound messages Inbound Messages Inject work into WebSphere Application Server An EJB or Servlet programmatically receives messages from a JMS Destination (QUEUE)... or uses a JMS Listener Outbound messages Delegate work to application components outside WebSphere WebSphere sends messages to a JMS Destination A JMS Listener automates tasks that would otherwise be done by the application code. In JMS, a Message Queue is referred to as a JMS Destination. JMS Destinations can be of two types Queue: Used for Point-To-Point messaging Topic: Used for Publish/Subscribe messaging Page 6 of 26

7 Message Listener in an n-tier environment JMS Listener --> adds function to the server --> new source of inbound work --> target is EJBs Listener EJB Container Client Container Queue RMI/IIOP Message Bean Tier: Server-Side Data Logic Business Bean JNDI JTA Java Mail JAF J2EE Server Core Tier: Client-Side Presentation RMI/IIOP JDBC JNDI Servlet Container JSP JTA Servlet Java Mail JAF RMI/IIOP JDBC RMI / IIOP JNDI JTA Java Mail JAF RMI/IIOP J2EE Server Core JDBC Tier: Server-Side Business Logic J2EE Server Core Page 7 of 26

8 Benefits of JMS Listeners Automatic consumption of messages No polling needed in the application code Reduce application code Synchronous communication between Queue and Listener Leave resource management to the container Queue RMI/IIOP JNDI Listener EJB Container Message Bean JTA Business Bean Java Mail JAF RMI/IIOP J2EE Server Core JDBC Page 8 of 26

9 JMS Listener Send data to Queue Wait till WebSphere is ready Deliver data to WebSphere Listener EJB Container PUT Messaging Middleware (QUEUE) GET JNDI Message Bean JTA Business Bean Java Mail JAF RMI/IIOP JDBC J2EE Server Core Page 9 of 26

10 Message Bean "Application component that accepts INBOUND messages" A Message Bean is a Stateless Session Bean that follows certain guidelines Automatic synchronous delivery of messages Injects work into a WebSphere application Provides transactional support Follows direction for Message Driven Beans Message Driven Beans defined in J2EE 1.3 spec Supported in the next WebSphere release Built upon MQSeries and JMS Page 10 of 26

11 Message and Business Processing Provide separation between the Listener and Business logic By providing a clear separation between message and business processing, it is easier to implement the Message Beans as Message Driven Beans (J2EE 1.3) Page 11 of 26

12 onmessage() public void onmessage(javax.jms.message msg) { try { System.out.println("Input message = " + ((TextMessage) msg).gettext.()); Invoke the Business Bean MyEJBHome home = (MyEJBHome)PortableRemoteObject.narrow (ic.lookup("com/mycom/myejbhome"),myejbhome.class); MyEJBHome obj = home.create(); obj.mybusinessmethod(msg); // business method } } catch(exception err) { err.printstacktrace(); } An example of a Message Bean invoking a Business Bean Page 12 of 26

13 Listener Manager Every AppServer has a Listener Manager Enabled during AppServer initialization Creates JMSListeners for destinations Based upon a user provided XML configuration file Interfaces with JMS Application Server Facilities (ASF) Controls the cleanup of resources during server shutdown Page 13 of 26

14 Sample XML Configuration File <Config> <Pooling> <Timeout> timeoutmilliseconds </Timeout> <Threshold> 10 maxunusedconnections </Threshold> </Pooling> <Listener> <HomeJNDIName> homename </HomeJNDIName> <JMSConnectionFactory> factoryjndiname </JMSConnectionFactory> <JMSDestination> destinationjndiname </JMSDestination> <JMSDestinationType> javax.jms.queue javax.jms.topic </JMSDestinationType> <JMSSubscriptionDurability> nondurable durable </JMSSubscriptionDurability> <JMSSubscriptionName> name </JMSSubscriptionName> <JMSMessageSelector> selector </JMSMessageSelector> <JMSAcknowledgeMode> auto-acknowledge dups-ok-acknowledge </JMSAcknowledgeMode> <MaxRetries> 0 retrynumber </MaxRetries> <MaxSessions> 1 sessionnumber </MaxSessions> <Transactional> true false </Transactional> </Listener> <Listener>... </Listener> </Config> In order to enable Message Beans, the AppServer has to be provided a configuration file. This configuration file is read when the AppServer starts up. A sample configuration file is provided with WebSphere. In the config file, the underlined values are the defaults The config file can have multiple <Listener></Listener> tag pairs. The config file can have only one <Pooling></Pooling> tag pair. Page 14 of 26

15 JMS Listener Configuration in AEs Specifying the location of the XML config file in AEs Page 15 of 26

16 JMS Listener Configuration in AE Specifying the location of the XML config file in AE Page 16 of 26

17 Scaling A single Application Server can have multiple JMS Listeners Message Beans JMS Destinations EJB Module EJB2 EJB1 EJB3 Web Module JSP Servlet JNDI JTA Java Mail JAF RMI/IIOP JDBC Page 17 of 26

18 MQSeries configuration JMSAdmin.config in <MQ_JAVA_INSTALL> AEs INITIAL_CONTEXT_FACTORY=com.sun.jndi.fscontext.RefFSContextFactory PROVIDER_URL=file://C:/JNDI-Directory AE INITIAL_CONTEXT_FACTORY=com.ibm.ejs.ns.jndi.CNInitialContextFactory PROVIDER_URL=iiop://localhost/ JMSAdmin.bat is a configuration tool provided by MQSeries as part of the MA88 install. The tool uses a configuration file (default name JMSAdmin.config). The foil above shows the differences between AE and AEs when providing JNDI options in the config file. In AEs, we use a file system (C:\...) to configure the JMS administered objects. The reason being that AEs does not persist its JNDI namespace In AE however, we can rely on using WebSphere namespace (iiop://localhost/) Page 18 of 26

19 Listener Manager - One per AppServer a Listener Manager a Connection Queue A a Listener 01 a Listener 02 a Listener 03 a Connection sessions Queue B a Message Bean 01 a Message Bean 02 a Message Bean 03 One Listener Manager per App Server Many Listeners per Listener Manager One connection per Listener Many Sessions per connection Listener threads are managed by the Listener Manager Message Bean Session threads are managed by the Listener One Listener corresponding to a <Listener></listener> tag pair in the XML config file Message Bean has the onmessage() method Page 19 of 26

20 Filtering the message header a Listener Manager a Listener 01 a Listener 02 a Listener 03 a Connection Queue B sessions a Message Bean 01 a Message Bean 02 a Message Bean 03 Message headers can be read before pulling messages off a Queue. The filtering criteria is specified in the XML config file. Page 20 of 26

21 Message Flow Queues/Topics Destinations Q1 Q2 Q3 T1 T2 MessageBeans M1 M2 M3 M4 BusinessBeans B1 B2 B3 B4 Page 21 of 26

22 Transactional Support Allows JMS Listener participation in a 2-phase commit Configuration In XML configuration file: Transactional = true <Transactional> true false </Transactional> Use JMSAdmin to configure WebSphere JMS / XA connection factories The JMSAdmin tool is provided by MQSeries Detailed information on this tool can be found in the redbook "MQSeries Using Java" Page 22 of 26

23 Connection Pooling Enable MQSeries connection pooling Provides improved JMS system performance Maximum benefit when connections used for short time Enabled by Listener during initialization Configuration Values specified via configuration file Will use default values if not specified Timeout = milliseconds Threshold = 10 Connections Page 23 of 26

24 System Requirements WebSphere 4.0 (AE/AEs + EE) and it's pre-reqs MQSeries V5.2 Server MQSeries JMS support pack - MA88 MQSeries Pub/Sub support pack - MA0C Support pack ma0c needs to be installated in MQSeries to enable Publish/Subscribe. This is in addition to ma88 support pack. Page 24 of 26

25 Summary - JMS Listener Part of WebSphere 4.0 EE Provides ability to inject work into the system Provides transaction support Provides connection pooling with MQSeries Follows direction for Message Driven Beans in J2EE 1.3 Page 25 of 26

26 Documentation WebSphere EE 4.0 InfoCenter "MQSeries Using Java" SC White Paper- WebSphere 3.5 JMS/JTA support for MQSeries Page 26 of 26