Hypertext Transfer Protocol, HTTP request process

Hypertext Transfer Protocol . 2.http Request procedure .

{

1> HTTP protocol : Hypertext Transfer Protocol (hypertext Transfer Protocol)

{

The HTTP protocol specifies the format of data transfer between the client and the server .

The HTTP protocol is the most commonly used protocol in web development . access to network resources often uses the HTTP protocol , Whether it is a mobile client or a PC-side.

HTTP Advantages :

<1> simple and fast :

HTTP protocol is simple and communication speed is very fast .

<2> flexibility :

the HTTP protocol allows the transfer of any type of data .

<3> HTTP protocol is a short connection ( non-persistent connection )

The HTTP protocol restricts each connection to only one request , and disconnects immediately after the server responds to the client's request . This way, the transmission time can be saved .

}

2> use of HTTP protocol ;

Complete http communication is divided into two steps :

<1> request : the client requests data from the server .

{

the HTTP protocol stipulates that a complete http request contains ' request line ',' request header ',' Three parts of the request body;

' request line ': contains the request method , request resource Path , HTTP protocol version .

"get/resources/images/http/1.1"

' request header ': contains information such as the client's environment description , the host address requested by the client .

The type of data that the accept:text/html//client can receive

ACCEPT-LANGUAGE:ZH-CN // Client language environment

Accept-encoding:gzip // client-supported data compression formats

host:m.baidu.com // the server host address that the client wants to access

user-agent:mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:37.0) gecko/20100101 firefox/37.0 // client type , Software Environment for c14> clients

' request body ': specific data that the client sends to the server, such as files / images .

}

<2> response : The server returns the data the client wants .

{

the HTTP protocol states that a complete http response contains a ' status line ',' response header ',' entity content ' ' three parts ;

' status line ': contains the HTTP protocol version , status , status English name .

"http/1.1 OK"

' response header ': contains a description of the server and a description of the returned data .

Content-encoding:gzip // server supported data compression format

Content-length: 1528 // length of returned data

content-type:application/xhtml+xml;charset=utf-8 // type of return data

Date:mon, June: £ º GMT // response time

Server:apache // server type

' entity content ': specific data returned by the server to the client ( image /html/ file ... ).

}

3> send http request :

{

in IOS development , there are a number of scenarios for sending HTTP requests, often in the following ways :

<1> Apple Native :

{

* Nsurlconnection: simple to use, a scheme of ancient classics .

* Nsurlsession:ios7 technology , features more powerful than nsurlconnection .

* the bottom of the Cfnetwork:nsurl , pure C language , generally not .

}

<2> Third-Party framework :

{

* Asihttprequest:http Terminator , the function is very powerful , Unfortunately the author has stopped updating .

* Afnetworking: simple to use, provides basic enough common functions , Maintenance and users more .

* Mknetworkkit: easy to use, produced from India , less maintenance and users .

}

in development , third-party frameworks are generally used .

}

}

Hypertext Transfer Protocol, HTTP request process