This is a quick tutorial on Consumer Defined Contract in Microservice architecture.

Consumer Defined Contract

• Consumer Defined Contracts is a pattern defined by Martin Fowler.
• In Consumer Defined Contracts, each consumer captures their expectations of the provider in a separate contract.All of these contracts are shared with the provider so they gain insight into the obligations they must fulfil for each individual client.

• Implementations:

  • Spring Cloud Contract - Spring Cloud Contract Reference Documentation
  • Found this java implementation few days back.
• CDC is a kind of test to ensure that constant changes in the microservices does not break the dependent microservices.
• We have a defined Provider API and a Consumer API to avoid ambiguity.
• The consumer has to write the test for that contract between the consumer and provider. In the pre-staging environment of deployment, consumer will run the tests. If the test fails to pass the contract then deployment is terminated.
• The provider also runs the consumer test on its side before the deployment and makes sure that its changes wont effect the consumers to whom it is providing the services.