Appendix H MQ Implementation of Optional JMS Functionality

The JMS specification indicates certain items that are optional-- each JMS provider (vendor) chooses whether or not to implement them. The MQ product handling of each of these optional items is indicated below:

Table H-1 Optional JMS Functionality
Section in JMS Specification	Description and MQ Handling
3.4.3 JMSMessageID	“Since message ID’s take some effort to create and increase a message’s size, some JMS providers may be able to optimize message overhead if they are given a hint that message ID is not used by an application. JMS Message Producer provides a hint to disable message ID.” MQ implementation: Product does not disable Message ID generation (any setDisableMessageID() call in MessageProducer is ignored). All messages will contain a valid MessageID value.
3.4.12 Overriding Message Header Fields	“JMS does not define specifically how an administrator overrides these header field values. A JMS provider is not required to support this administrative option.” MQ implementation: The MQ product supports administrative override of the values in message header fields through configuration of connection factory administered objects (see Table 7-3).
3.5.9 JMS Defined Properties	“JMS Reserves the ’JMSX’ Property name prefix for JMS defined properties.” “Unless noted otherwise, support for these properties is optional.” MQ implementation: The JMSX properties defined by the JMS 1.1 specification are supported in the MQ product (see Table 7-3).
3.5.10 Provider-specific Properties	“JMS reserves the ’JMS_<vendor_name>’ property name prefix for provider-specific properties.” MQ implementation: The purpose of the provider-specific properties is to provide special features needed to support JMS use with provider-native clients. They should not be used for JMS to JMS messaging. MQ 3.5 does not use provider-specific properties.
4.4.8 Distributed Transactions	“JMS does not require that a provider support distributed transactions.” MQ implementation: Distributed transactions are supported in this release of the MQ product (see "Distributed Transactions").
4.4.9 Multiple Sessions	“For PTP <point-to-point distribution model>, JMS does not specify the semantics of concurrent QueueReceivers for the same queue; however, JMS does not prohibit a provider from supporting this.” See section 5.8 of the JMS specification for more information. MQ implementation: The MQ implementation supports queue delivery to multiple consumers. For more information, see "Queue Delivery to Multiple Consumers".