IBM BPM, V8.0.1, All platforms > Authoring services in Integration Designer > Services and service-related functions > Access external services with messaging systems > Java Message Service (JMS) > JMS, MQ JMS and generic JMS bindings > JMS function selectors > Overview of JMS function selectors
JMS function selector
The JMS function selector for the JMS standard of defining a message class with subclasses for the payload is discussed.
Standard JMS message function selector
A second function selector is available that follows the JMS standard of defining a message class with five subclasses of the message class for the body or payload which contains the message itself. Each subclass has a different body type. This function selector uses the JMSType property of the message to select the operation name.
The function selector is com.ibm.websphere.jms.data.bindings.JMSFunctionSelector.
To simplify working with this function selector, a function has been added to generate the appropriate business objects for the body types. In the dependencies editor of a module beneath the Predefined Resources heading, selecting Native Body schema for Native Body DataHandler and saving the dependencies generates the business objects for these body types. You can then use these business objects to represent the message from the JMS client.
These data bindings could be used for routing messages.
For example, using a mediation module between an export and two imports, a message filter primitive examines the values in the message properties and routes high priority messages to one destination and lower priority messages to another destination. Another possible use could be to add an mapping transformation or database lookup mediation primitive between an export and import to modify the message.
The following table shows the relationship of the predefined resource, the body type, the business object created for it, and the data type for standard JMS messages.
Relationship of predefined resource, body type, business object and data type for standard JMS messages Predefined resource Body type Business object Data type Native Body schema for Native Body DataHandler BytesMessage BytesBody Byte array Same as first row MapMessage MapBody Set of name/value pairs addressed by name. Value is a simple Java™ type. Same as first row Message BaseBody None (empty) Same as first row ObjectMessage ObjectBody Serialized Java object Same as first row StreamMessage StreamBody Stream of simple Java types Same as first row TextMessage TextBody Java String If that if the operation name is not set, it will be derived from the type of incoming message as determined by this table:
Default behavior if an operation name is not set Message type Operation name BytesMessage handleBytes MapMessage handleMap ObjectMessage handleObject StreamMessage handleStream TextMessage handleText Message handleBase If the operation name returned by the function selector has not been configured for the export, an exception will be thrown.