Let’s imagine the problem: Your company creates a B2B product that provides a service for some other companies. This service helps client-company to resolve very specific problems of their customers. This customer can communicate with our company web app and do some operations. The results of these operations should be reported to the other company side. 

Times go on, and now you have a few more clients that work by the same scheme. At first, you connect small companies one by one, but when you get to much bigger client companies, you discover that they use third-party API service providers and delegate all the integration problems to them. These API service providers act as a proxy for this toil of service reverse integration, which unifies the logic of cross-company communication on both sides. Due to the structure of presented business relationships, our company almost inevitably start to use a set of similar actions to communicate with dozens of different APIs for hundreds of clients in the future.