Here I describe the reasons for contract-first design.

Why contract-first design?

There has to be a standardized and decoupled contract of a service. In order to avoid an auto-generation of a contract, it has to be defined in advanced of the development of the service logic. The underlying logic is coupled to the contract (logic-to-contract coupling) and can optimize performance and reliability.

traditional:

1. using a component as the basis of the Web service
2. auto-generate the contract from the component’s interface

service oriented development process:

1. design the Web service contract
2. import the contract in the development environment
3. build the underlying solution logic