Understanding the RESTful architecture

More and more people are beginning to realize that the website is software, and it is a new kind of software.

This "Internet Software" uses the client/server model, which is built on the distributed system and communicates with the Internet, which has the characteristics of high latency (hi latency) and high concurrency.

Website development, can adopt the model of software development completely. But traditionally, the software and the network are two different fields, seldom have the intersection, the software development is mainly for the single machine environment, the network mainly studies the communication between the system. The rise of the Internet has enabled these two areas to converge, and now we have to consider how to develop the software used in the Internet environment.

The restful architecture is one of the most popular Internet software architectures available. Its structure is clear, conforms to the standard, easy to understand, expands conveniently, therefore is getting more and more website adoption.

First, origin

The word rest is from Roy Thomas Fielding in his 2000 doctoral dissertation.

Second, the name

Fielding His architectural principles of Internet software, named REST, the abbreviation of representational state Transfer . My translation of this phrase is "presentation layer State transformation".

If a schema conforms to the REST principle, it is called a restful architecture.

III. Resource (resources)

The name of rest, "presentation Layer State Transformation", omits the subject. The "presentation layer" actually refers to the "presentation layer" of resources.

The so-called "resources", is an entity on the network, or is a specific information on the network. It can be a piece of text, a picture, a song, a service, in short, is a concrete reality. You can point to it with a URI (Uniform Resource Locator), and each resource corresponds to a specific URI. To get this resource, access its URI so that the URI becomes the address of each resource or a unique identifier.

The so-called "surfing the Internet" is to interact with a series of "resources" on the Internet and invoke its URI.

Iv. Presentation layer (representation)

A "resource" is an information entity that can have a variety of external representations. we take the form of "resources" specifically, called its "presentation Layer" (representation).

For example, text can be expressed in TXT format, can also be used in HTML format, XML format, JSON format, and even binary format can be used, images can be in JPG format, can also be used in PNG format.

The URI represents only the entity of the resource and does not represent its form. Strictly speaking, some URLs last ". html" suffix is unnecessary, because this suffix name represents the format, which belongs to the "presentation layer" category, and the URI should only represent the location of the "resource". Its specific representation should be specified in the header information of the HTTP request with the Accept and Content-type fields, which is the description of the "presentation layer".

V. State transformation (Transfer)

Accessing a Web site represents an interactive process between the client and the server. In this process, data and state changes are bound to be involved.

The Internet Communication Protocol HTTP protocol is a stateless protocol. This means that all States are saved on the server side. Therefore, if the client wants to operate the server, there must be some way to make the server side "state Transfer". And this transformation is based on the expression layer, so is the "Expression Layer state transformation."

The method that the client uses, can only be the HTTP protocol. Specifically, there are four verbs in the HTTP protocol that represent the mode of operation:GET, POST, PUT, DELETE. They correspond to four basic operations: get is used to get a resource, post is used to create a new resource (and can also be used to update resources), put is used to update resources, and delete is used to delete resources.

Vi. Summary of

Combining the above explanations, we summarize what a RESTful architecture is:

(1) Each URI represents a resource;

(2) between the client and the server, the transmission of such resources of some kind of performance layer;

(3) The client through four HTTP verbs, the server-side resources to operate, to achieve " performance Layer State transformation ."

Understanding the RESTful architecture