Passing information from smaller to larger services
Information and data need to be passed from elementary services to composite services or process services. The following list names different mechanisms that can be applied for this:
Request/reply: In this message exchange, a service consumer invokes a service by sending a request message; for example, a composite service that invokes an elementary service. The invoked service responds by sending a reply message that can contain information for the service consumer to act upon. In this case, the data can be used by the composite service. This type of invocation is synchronous, meaning the consumer is blocked between the time the request was made and the time the reply was received. The following figure shows a request/reply message exchange:
Callbacks: Next to synchronous request/reply messages, services can also define callback operations in their interface. When using callbacks, the consumer sends the request and can continue with other...
