Message Patterns and Asynchronous Messaging
The W3C WSDL Specification identifies four message patterns:
*request-response, the usual pattern for Web services, with a request sent by the client and a server response.
*one-way, sent by the client with no response from the server
*solicit-response, sent by the server with a client response
*notification, sent by the server but with no client response
HydraExpress supports all patterns listed above, and generates the appropriate code automatically. HydraExpress determines the correct pattern for a given service operation by analyzing the definition of input and output messages for the operation in the WSDL file.
HydraExpress also supports asynchronous messaging. The request-response and solicit-response patterns are typically synchronous, but in practice there may be good business logic reasons for making the responses asynchronous, particularly in complex, orchestrated services. The one-way and notification patterns are inherently asynchronous at the service level, since there is no response to synchronize to, but they can be used together to create something very close to a synchronous interaction. For more information on asynchronous messaging, see Chapter 13, Asynchronous Messaging.