Point to point integrations

Some products publish their own interfaces, and routing their data through the API gateway is not always practical because the product itself provides its own access management/statistics/self-service, or its data traffic is very heavy.

However, if these APIs are public and generally useful, their Swagger/OpenAPI description should be published in the API gateway catalog, and a link to the actual service should be provided on the descriptive page (landing page). This way, all APIs can be found in a common catalog without unnecessarily complicating their data traffic. Even the OpenAPI/Swagger description is not strictly necessary; the API gateway can publish an API whose only content is a markdown page indicating that further details about the API can be found via this web link.

Some system product families do not genuinely produce open APIs, and the data traffic between their family members is optimized by the manufacturer to be done as direct integrations between the members (without a centralized platform like an API gateway or ESB). In such cases, usually for cost reasons, these manufacturer-specific direct integrations have been made, foregoing the benefits offered by the API gateway. Typically, their own APIs are not intended for wider use.