The "Relay API Gateway" is a framework for creating a REST API server for building applications and workflows on top of it. It abstracts away various backend systems, provides user management, authentication, caching, locking, authorization and a modular system for composing an API with so called API bundles. Various bundles are readily available and can be configured to your needs, or you can write your own bundles to extend the system/API.
The framework consists of a core bundle which provides functionality that's useful in a multitude of API use cases, authentication, caching, logging, automatic API documentation, integration with the Symfony and API Platform frameworks etc.
All other functionality is implemented in extra bundles which can add new endpoints to the API and, in turn, can depend on other bundles and their endpoints. For example a bundle providing a library management API can add new endpoints for working with books by talking to an external library system. It can depend on the core bundle for user management and authentication.
External apps, like browser or mobile applications can be written easily to access data via the API. The user authentication is done via an OIDC server like Keycloak.
An example for a web application would be the Library application.
External services like server applications that don't act on behalf of a user can access the API via "Client Credential" grants, also available in Keycloak for example.
Extending and Customizing
The API gateway can be easily extended by simply installing an existing bundle, changing exiting bundle behavior via event hooks, or writing your very own bundle.
If you write your own bundle you can create completely new APIs, or connect an existing API to a new external system. If you then share your bundle with the world everyone can install it and profit 😊
For how to write your own bundle please see our Developer Guide.