Restful

Simply speaking ： It is the process of interaction between client and server . In this interactive process , The client wants to access the resource Resources, Resource is a noun , There are many types . This involves the process of transferring resources to the server in some form

One ： Concept

REST The word , yes Roy Thomas Fielding In his 2000 Proposed in the doctoral thesis of .

Fielding Put his principles of Internet software architecture , Named REST, namely Representational State Transfer Abbreviation . Translated into Chinese is “ Represent layer state transformation ”.

that , What exactly is REST Well ？ Even if translated into Chinese “ Represent layer state transformation ”, It's still hard to understand .

First , It's hard to understand , Because the previous subject has been removed . The full name should be Resource Representational State Transfer, Translated into Chinese “ Resources in the network in some form of state transition ”.

Two ： characteristic

1. resources

every last URI Represents a resource

URI： Uniform resource locator 

URL： Uniform resource identifiers ,http

URL stay URI Inside 

So-called “ resources ”, It's an entity on the Internet , Or a specific information on the Internet . It can be a piece of text 、 A picture 、 A song 、 A service , In a word, it is a concrete reality . You can use a URI（ Uniform resource locator ） Pointing to it , Each resource corresponds to a specific URI. To get this resource , Visit its URI Can , therefore URI It becomes the address or unique identifier of each resource .

So-called “ surf the internet ”, With a series of Internet “ resources ” Interaction , Call it the URI.

2. The presentation layer

Between client and server , A layer of expression that conveys this resource

“ resources ” It's an information entity , It can have many external forms . We put “ resources ” In the form of , It's called it “ The presentation layer ”（Representation）.

such as , The text can be used txt Format representation , It can also be used. HTML Format 、XML Format 、JSON Format representation , It can even be in binary format . Pictures can be used JPG Format representation , It can also be used. PNG Format representation .

URI Entities that represent resources only , Does not represent its form . Strictly speaking , Some of the last ".html" Suffixes are unnecessary , Because this suffix means format , Belong to “ The presentation layer ” Category , and URI It should only represent “ resources ” The location of . Its concrete manifestation , belong HTTP The requested header information uses Accept and Content-Type Field assignment , These two fields are right “ The presentation layer ” Description of .

3. State shift

Client through four HTTP Verb , Operate on the server-side resources , Realization “ Represent layer state transformation ”.

Internet communication protocol HTTP agreement , It's a stateless protocol . It means , All States are saved on the server side . therefore , If the client wants to operate on the server , By some means , Let it happen on the server side “ State transformation ”（State Transfer）. And this transformation is based on the presentation layer , So is “ Represent layer state transformation ”.

The means used by the client , Can only be HTTP agreement . say concretely , Namely HTTP In the agreement ,4 A verb indicating the mode of operation ：GET、POST、PUT、DELETE. They correspond to each other 4 Basic operations ：GET Used to obtain resources ,POST Used to create a new resource （ Can also be used to update resources ）,PUT Used to update resources ,DELETE Used to delete resources .

3、 ... and ： give an example

1. Get student resources

   GET http://localhost:3000/students
   

2. Search students

   GET http://localhost:3000/students?type=name&value=" Zhang "
   

3. according to ID Get a student

   GET http://localhost:3000/sstudent/ Student id
   

4. Add students

   POST http:localhost:3000/students/ Student id
   

5. Revise students

   PUT http:localhost:3000/students/ Student id
   PATCH http:localhost:3000/students/ Student id
   

6. Delete students

   DELETE http:localhost:3000/students/ Student id
   

Four ：postman Tools

Except students

DELETE http:localhost:3000/students/ Student id

Four ：postman Tools