Creating a JMS import to communicate with a JMS client

You may wish to connect your service-oriented architecture (SOA) application to an existing JMS client. In this task, we will take you step by step through the steps necessary to do this.

Prerequisite: The JMS administered objects are configured for the JMS Client and known. In addition, there should be a module that contains your service-oriented architecture application. The message format expected by the JMS client is also known

  1. In order for your SOA application to communicate to an existing JMS client, you will need to have created a business object and an interface that would represent your JMS client application in an SOA manner. Mapping a JMS, MQ or MQ JMS message to an SCA interface provides guidance on how to create such a business object and interface.
  2. You must create a component that will enable your existing SOA application to communicate to the existing JMS client application. To do this, you will create an import and add a binding type of JMS to it.

    There are two main types of information that need to be captured by the JMS binding. One set of information is needed by the Service Component Architecture (SCA). This includes information such as the interface, which we discussed earlier, and the serialization type, which we will discuss later. The other set of information is the configuration needed to communicate using JMS such as the specification of JMS destination objects, which we will also discuss later.

    Open the assembly editor of your module. From the import group on the palette, select an import and drag it on to the canvas. An import with no implementation and no interface is created. Right-click the component, select Add Interface from the contextual menu and add the interface created in step 1. Generate the JMS skeleton binding by selecting the import and from the contextual menu select Generate Binding > Messaging Binding > JMS Binding.


    Generating a JMS binding

  3. The JMS Import Binding dialog opens.

    You may select the JMS messaging domain as either Publish-Subscribe or Point-to-Point. The consequences of selecting publish-subscribe is that the values for the JMS Destination type will default to use javax.jms.Topic. Similarly, the consequences of selecting point-to-point is that the values for the JMS Destination type will be default to use javax.jms.Queue. You may change these defaults within the wizard. If your interface contains a request-response operation, the wizard will default the JMS messaging domain to point-to-point.

    You can also choose the serialization type that is expected by the JMS client application. The serialization type is used to map between the business object used in your SOA application and the message format expected by the JMS client application. There are several default serialization types provided. For serialization types beginning Simple JMS, you must have previously created the business objects required (see the Prerequisites section of Generating a JMS import binding for a quick way of creating these business objects).

    • Serialized Business Object using JMS ObjectMessage sends the business object whose underlying implementation is a service data object (SDO) in a JMS object message to and from the JMS client. This serialization type is preferred when dealing with other SOA components using JMS.
    • Business Object XML Using JMS TextMessage serializes the business object to and from XML and uses a JMS text message to communicate with the JMS client. To see how the business object is serialized to XML, see Business object XML using JMS text message serialization.
    • Simple JMS TextMessage Data Binding sends the JMSTextBody business object in a TextMessage message body to the client. The message body type is a String.
    • Simple JMS BytesMessage Data Binding sends the JMSBytesBody business object in a BytesMessage message body to the client. The message body type is a byte array.
    • Simple JMS MapMessage Data Binding sends the JMSMapBody business object in a MapMessage message body to the client. The message body type is a set of name/value pairs that can be addressed by name. The data type of the value is a Java primitive.
    • Simple JMS StreamMessage Data Binding sends the JMSStreamBody business object in a StreamMessage message body to the client. The message body type is a stream of Java primitives.
    • Simple JMS ObjectMessage Data Binding sends the JMSObjectBody business object in an ObjectMessage message body to the client. The message body type is a serialized Java Object.
    • Simple JMS Message Data Binding does not have a message body. It can be used to notify the JMS client of an event or to send some simple data in the message headers or properties.

    If the JMS client is expecting a different serialization style other than the two above, select User Defined and specify the appropriate data binding implementation. An example of this different serialization would be if the JMS client is expecting a JavaBean as the payload of a JMS object message, then a user-supplied data binding implementation would be used that would map between the SDO and the JavaBean. See Creating a user-defined JMS data binding for an illustration on how this would be done.

    For more information on JMS data bindings, see JMS and MQ JMS data bindings.

    Lastly, you must specify if you wish to generate the TargetFunctionName message header property for the default function selector class. Checking this box causes a header property to be generated, which is expected by the default function selector implementation. If this is the desired behavior, keep it checked, otherwise uncheck the box. See JMS and MQ JMS function selector for more information.

    In this task, the JMS client is expecting XML in a JMS text message so we chose the appropriate serialization type Business Object XML using JMS TextMessage. In addition, because you are communicating with an existing JMS client, you will uncheck the Generate "TargetFunctionName" message header property for default JMS Function Selector because the JMS client would not know how to handle the custom JMS header tag that would have been generated if it were checked.


    Specifying the JMS import binding information

  4. The JMS binding is created and shown in the properties view when the Binding tab is selected. You need to specify the administered objects that were configured. The following chart provides some guidance in this area.
    Table 1. Relationship of usage, configuration, connection factory and destination information
    Usage and configuration Managed connection factory Send destination Receive destination Callback destination
    Usage A factory used to create the connection to the messaging provider. The destination where the message would be sent. The destination where the response message would be received. This value is specified in the JMSReplyTo field of the sent message. A destination used for internal purposes.
    Configuration If your administrator provided an administered connection factory object, use the JNDI name.

    If you do not use a JNDI name, a new connection factory will be created using the default settings when the SOA application is deployed. Your administrator should check that the connections resulting from this factory is appropriate to connect to the messaging provider.

    If your administrator provided an administered destination object where messages should be sent to the JMS client, use the JNDI name.

    If you do not use a JNDI name, a new destination would be created when the SOA application is deployed and this would be used as the destination for the sent message. Your administrator should then pass this JNDI name to the JMS client.

    If your administrator provided an administered destination object where messages should be received (if any), use the JNDI name.

    If you do not use a JNDI name, a new destination would be created when the SOA application is deployed and this would be used as the destination for the receive message (if any). Your administrator should then pass this JNDI name to the JMS client.

    Note: The SCA application will be listening to messages on the Receive Destination using a specific correlation scheme. The received message is expected to have the sent message's message id. That is, the receive message needs to have its message header property JMSCorrelationID to match the sent message header property JMSMessageID. The JMS client must ensure that response messages it sends to the SOA application have the message header property JMSCorrelationID specified correctly, otherwise the SOA application will not receive the message.
    You may specify a JNDI name of an existing administered destination object for performance reasons.

    If you do not specify a JNDI name, a new destination would be created each time the SOA application is deployed.

    To specify the administered objects, select the Endpoint configuration tab under the Binding tab. Under the Connection tab, you can specify a bound connection factory class to connect to the WebSphere Process Server default JMS provider. You could also accept the defaults, in which case the tools would create a connection factory when the application is deployed on the server. Because the connection factory that would be created with the default settings is sufficient for this task, you will accept the defaults.


    Endpoint configuration

    Under the JMS Destinations tab, you can specify the administered destination objects to send and receive messages or you can accept the defaults, in which case the tools would create them. Specify the appropriate settings to ensure your SOA application is able to communicate to the JMS client. For this task, the administrator provided JNDI names for the bound destination objects to send and receive a message to the existing JMS client and so you will specify the JNDI names for them. For the Send Destination Properties section, select the radio button Specify JNDI name for pre-configured messaging provider resource. Specify the JNDI name of the bound destination where you want to send your messages. Similarly, for the Receive Destination Properties section, select the radio button of Specify JNDI name for pre-configured messaging provider resource. Specify the JNDI name of the bound destination where you are to receive your messages.


    Specifying destination properties

  5. The existing JMS client may expect certain header properties to be configured. You may specify these under the Method bindings tab under the Binding tab. For each business method that represents a corresponding JMS client application method, you may specify unique JMS message header properties required. For example, if the existing JMS client application requires the message header JMSType to specify the application method name for which the JMS message is targeted, you will specify it here. Specify the application method name. Select Bound Methods for your business methods and specify the appropriate value in the JMS Type text field.


    Setting method level bindings

  6. The import that will communicate to the existing JMS client application is completed. You should test it before you attach it to your SOA application to ensure it is working as designed. To do this, you can use the test component feature of the integration test client. Once you are certain that it is correct, you can then connect your SOA application to the import you just created.
Related tasks
Creating a JMS export to communicate with a JMS client
Creating a JMS client to receive messages from a JMS import
Creating an import from an export using a JMS binding
Creating a user-defined JMS data binding

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