MessageContext is the super interface for all JAX-WS message contexts. It extends Map<String,Object> with additional methods and constants to manage a set of properties that enable handlers in a handler chain to share processing related state. For example, a handler may use the put method to insert a property in the message context that one or more other handlers in the handler chain may subsequently obtain via the get method.

Properties are scoped as either APPLICATION or HANDLER. All properties are available to all handlers for an instance of an MEP on a particular endpoint. E.g., if a logical handler puts a property in the message context, that property will also be available to any protocol handlers in the chain during the execution of an MEP instance. APPLICATION scoped properties are also made available to client applications (see section 4.2.1) and service endpoint implementations. The defaultscope for a property is HANDLER.