You can create and set properties for messages if you need values in addition to those provided by the header fields. You can use properties to provide compatibility with other messaging systems, or you can use them to create message selectors (see JMS Message Selectors). For an example of setting a property to be used as a message selector, see An Application That Uses the JMS API with a Session Bean.
The JMS API provides some predefined property names that a provider can support. The use either of these predefined properties or of user-defined properties is optional.