How can you use HTTP to implement RESTful communication protocol for microservices?

1 What is HTTP?

HTTP stands for Hypertext Transfer Protocol, and it is the foundation of the web. It is a simple and stateless protocol that defines how clients and servers exchange messages over a network. HTTP messages consist of a request line, headers, and an optional body. The request line contains the method, the URI, and the version of the protocol. The headers provide additional information about the message, such as the content type, the authorization, or the cache control. The body contains the actual data of the message, such as a HTML document, a JSON object, or a binary file.

2 What is REST?

REST, which stands for Representational State Transfer, is an architectural style for designing web services that makes them more scalable, uniform, and interoperable. It is not a standard or a protocol, but rather a set of constraints and best practices. REST is resource-oriented; each service exposes a set of resources that can be identified by a unique URI. Additionally, it has a uniform interface with methods corresponding to the HTTP verbs: GET, POST, PUT, PATCH, DELETE etc. REST is also stateless; each request contains all the information necessary to process it and the server does not store any client state. Finally, it is hypermedia-driven; each response contains not only the data of the resource but also links to other related resources or actions. This allows the client to discover and navigate the service dynamically.

3 How to use HTTP and REST for microservices?

Using HTTP and REST for microservices requires designing each service as a web service that follows the RESTful principles. This includes having a well-defined interface that exposes resources and methods using HTTP URIs and verbs, as well as communicating with other services using HTTP messages that contain the data and the links of the resources. For instance, a microservice managing orders may have an interface such as GET /orders: Returns a list of orders, POST /orders: Creates a new order, GET /orders/{id}: Returns a specific order, PUT /orders/{id}: Replaces an existing order, PATCH /orders/{id}: Updates an existing order, and DELETE /orders/{id}: Deletes an existing order. A response from the GET /orders/{id} method may look like this: { "id": 123, "customer": "Alice", "items": [ { "product": "Book", "quantity": 2, "price": 10 }, { "product": "Pen", "quantity": 5, "price": 1 } ], "total": 25, "status": "Pending", "links": [ { "rel": "self", "href": "/orders/123" }, { "rel": "cancel", "href": "/orders/123/cancel" }, { "rel": "pay", "href": "/orders/123/pay" } ] }. All of these details are essential for informing and reassuring stakeholders, as well as providing valuable insights for improving cloud security posture.

4 What are the benefits of using HTTP and REST for microservices?

Using HTTP and REST for microservices offers several advantages, such as simplicity, scalability, interoperability, and evolvability. HTTP and REST are widely used and understood by developers and tools, making them easy to test and debug. They also don't require any special libraries or frameworks to implement or consume. Furthermore, HTTP and REST are stateless and resource-oriented, which makes them suitable for distributed and load-balanced systems. They also support caching and compression to reduce network bandwidth and latency. Additionally, HTTP and REST are based on open and standard protocols and formats, allowing cross-platform and cross-language communication. Moreover, they support content negotiation and versioning so that different clients and servers can exchange data in different formats and versions. Finally, they are hypermedia-driven, decoupling the clients from the servers so that changes or new features can be added without breaking the clients as long as the same interface is maintained.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?