A message can also include optional header fields, called properties, specified as property name and property value pairs. Properties allow clients and providers to extend the message header and can contain any information that the client or the JMS provider finds useful to identify and process a message. Message properties allow a consuming client to ask that only those messages be delivered which fit a given criteria. For instance, a consuming client might indicate an interest for payroll messages concerning part-time employees located in New Jersey. The JMS provider will not deliver messages that do not meet the specified criteria.
The JMS specification defines nine standard properties. Some of these are set by the client and some by the JMS provider. Their names begin with the reserved characters “JMSX.” The client or the JMS provider can use these properties to determine who sent a message, the identity of the application sending a message, the state of the message, how often and when it was delivered, tansaction identification, and so forth. These properties are useful to the JMS provider in routing messages and in providing diagnostic information.
Message Queue defines a number of additional message properties. These properties are used to identify compressed messages and how messages should be handled if they cannot be delivered. For more information see Managing Message Size in Sun Java System Message Queue 4.3 Developer’s Guide for Java Clients.