Consumer-Driven Contracts: A Service Evolution Pattern

Overview: This paper discusses some of the challenges in evolving a community of service providers and consumers. It describes some of the coupling issues that arise when service providers change parts of their contract, particularly document schemas, and two well-understood strategies - adding schema extension points and performing "Just enough" validation of received messages - for mitigating such issues. Both strategies help protect consumers from changes to a provider contract, but neither give the provider any insight into the ways it is being used and the obligations it must maintain as it evolves.

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