How can a service sync up asynchronously with its consumers?:
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Problem |
When a service needs to respond to a consumer request for the issuance of multiple messages or when service message processing requires a large amount of time, it is often not possible to communicate synchronously. |
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Solution |
A service can require that consumers communicate with it asynchronously and provide a callback address to which the service can send response messages. |
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Impacts |
Asynchronous communication can introduce reliability concerns and can further require that surrounding infrastructure be upgraded to fully support the necessary callback correlation. |
Problem: When service logic requires that a consumer request is responded to with multiple messages, a standard request-response messaging exchange is not appropriate. Similarly, when a given consumer request requires that the service perform prolonged processing before being able to respond, synchronous communication is not possible without jeopardizing scalability and reliability of the service and its surrounding architecture.
Solution: Services are designed in such a manner that consumers provide them with a callback address at which they can be contacted by the service at some point after the service receives the initial consumer request message. Consumers are furthermore asked to supply correlation details that allow the service to send an identifier within future messages so that consumers can associate them with the original task.