Reliability in Systems Development

Integration and web services

So the systems already talking to yours do not have to change: today’s contract is answered as is, with its modern equivalent alongside.

An integration contract is a promise made to somebody who is not in the room. When we modernise, the first rule is that the existing consumer keeps reading exactly the same XML — quirks included — while the new consumer gets an API that does not hurt.

What it includes

  • SOAP services compatible with the existing contract, WSDL and Fault included
  • REST API with typed codes and idempotency
  • Queues and batch processes
  • Tests using the real consumer’s parser as the oracle
  • Traffic observation to document undocumented contracts