Messages Between Processes in HTTP

The process requesting a CRUD action (i.e. an action of creating, reading, updating, and/or deleting) a World Wide Web hypermedia resource, called a client, sends a request message to a separate process, called a server, which responds with a response message.

The process which typically requests a CRUD action is a user agent such as a web browser on the basis of user interactions with that browser. Other user agents include mobile apps, voice browsers, and web crawlers.

A request message includes:

• URL, which stands for Uniform Resource Locator,

• method,

• headers, and

• optional body.

A response message includes:

• status,

• headers, and

• optional body