"Coming together is a beginning; keeping together is progress; working together is success."
- Henry Ford
One of the modes of interaction among microservices is direct messaging via APIs. REST APIs are one of the ways to make the direct messaging possible among microservices. REST APIs enable interoperability among microservices irrespective of the technology stack in which they are implemented. In this chapter, we will cover the following topics:
REST stands for representational state transfer, and defines an architectural style for distributed hypermedia systems. It focuses on creating independent component implementations that are stateless and scale well. Applications that support REST do not store any information about the client state on the server side. Such applications require clients to maintain the state themselves and use the REST-style implementations, such as HTTP APIs exposed by the application, to transfer the state between them and the server. Clients who use the REST API may query the server for the latest state and represent the same state at the client side, thus keeping the client and server in sync.
The state of an application is defined by the state of the entities of the system. Entities can be related to the concept of resources in REST architecture. A resource is a key abstraction of information in REST. It is a conceptual mapping to a set of entities that is defined by the resource identifier...
Web service APIs that conform to REST architecture is called RESTful APIs. Microservices mostly implement the HTTP-based RESTful APIs that are stateless and have a base URI and a media type (https://en.wikipedia.org/wiki/Media_type) for the representation of resources. It also supports predefined standard operations that are mapped to HTTP methods such as GET, POST, PUT, DELETE, and more.
For example, as shown in the following table, the Order service may define an API /orders to get access to the orders that it maintains. It can support a GET method to look up all the orders or get a specific order by specifying the order ID. It can also allow clients to create new orders by using the POST method or create an order with a specific ID by using the PUT method. Similarly, it can support the PUT method to update order details and the DELETE method to delete an order by specifying the order ID explicitly.
URI | HTTP method | Operation | Description |
|
| Read | Gets all the... |
URI | Method | Params | Description |
|---|---|---|---|
|
| Details (JSON) | Creates a new consumer and returns the consumer... |
