What are data contracts?

While building multi-tiered applications that integrate with multiple other external systems, the most common mode of communication is the application programming interface (API). These APIs are interfaces to the functionality of the application. APIs have the following elements bundled into a contract:

• The protocol used
• The URL of the API
• The request format
• The response format
• Any special security information

Various standards for APIs exist. Simple Object Access Protocol (SOAP), representational state transfer (REST), GraphQL, and WebSocket are some of the examples.

Once these APIs are built, they keep changing over time. New functionality, new data elements, and several other reasons can force teams to change, deprecate, and build new APIs.

In a small project, these changes are easy to manage. It’s a small team that communicates very effectively because the API builder and consumer are probably sitting across the...