Node dives into HTTP modules

1. HTTP server #

HTTP is a hypertext transfer protocol built on TCP and belongs to the application layer protocol.

1.1 Creating an HTTP Server

let server  = http.createServer([requestListener]);
server.on('request',requestListener);
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• RequestListener A process that the server performs when it receives a connection from a client
  • HTTP.IncomingMessage Request object
  • HTTP.ServerResponse Object Server – side response object

1.2 Starting the HTTP Server

server.listen(port,[host],[backlog],[callback]);
server.on('listening',callback);
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• Port Indicates the listening port number
• Host Specifies the listening address
• Backlog specifies the number of client connections in the wait queue

let http = require('http');
let server = http.createServer(function(req,res){
}).listen(8080,'127.0.0.1'.function(){console.log('Server listening! ')});
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1.3 Shutting down the HTTP Server

server.close();
server.on('close'.function() {});Copy the code

let http = require('http');
let server = http.createServer(function(req,res){
});
server.on('close'.function(){
    console.log('Server down');
});
server.listen(8080,'127.0.0.1'.function(){
    console.log('Server listening! ')
    server.close();
});
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1.4 Listening server error

server.on('error'.function() {if(e.code == 'EADDRINUSE'){
         console.log('The port number is in use! ; }});Copy the code

1.5 the connection

let server = http.createServer(function(req,res){
});
server.on('connection'.function(){console.log(the client connection has been established); });Copy the code

1.6 setTimeout

If the timeout period is set, existing connections cannot be reused and requests must be sent to re-establish connections. The default timeout period is 2 minutes

server.setTimeout(msecs,callback);
server.on('timeout'.function(){
    console.log('Connection timed out');
});
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1.7 Obtaining Client Request Information

• request
  • Method Request method
  • Url Request path
  • Headers Request header object
  • HttpVersion HTTP version of the client
  • Socket The socket object that listens to client requests

    let http = require('http');
    let fs = require('fs');
    let server = http.createServer(function(req,res){
    if(req.url ! ='/favicon.ico') {let out = fs.createWriteStream(path.join(__dirname,'request.log'));
    out.write('method='+req.method);
    out.write('url='+req.url);
    out.write('headers='+JSON.stringify(req.headers));
    out.write('httpVersion='+req.httpVersion);
    }
    }).listen(8080,'127.0.0.1);
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let http = require('http');
let fs = require('fs');
let server = http.createServer(function(req,res){
  let body = [];
  req.on('data'.function(data){
    body.push(data);
  });
  req.on('end'.function() {let result = Buffer.concat(body);
      console.log(result.toString());
  });
}).listen(8080,'127.0.0.1);
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1.8 the querystring

The querystring module is used to convert the URL string to the querystring in the URL

The 1.8.1 parse method is used to convert strings into objects

querystring.parse(str,[sep],[eq],[options]);
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The 1.8.2 stringify method is used to convert an object to a string

querystring.stringify(obj,[sep],[eq]);
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1.9 the querystring

url.parse(urlStr,[parseQueryString]);
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• Href The original URL string converted
• Protocol used by the protocal client to send requests
• Slashes whether the // separator is used between the protocol and the path
• Host URL The complete address and port number in the string
• Auth The authentication part of the URL string
• Hostname URL Specifies the full address in the string
• Port Indicates the port number in the URL string
• Pathname Specifies the path of the URL string, excluding the query string
• Search query string containing?
• Path Path, which contains the query string
• Query A query string that does not contain a start string?
• Hash Hash character string containing#

1.10 Sending the Server Response Flow

The HTTP. ServerResponse object represents the response object

1.10.1 writeHead

response.writeHead(statusCode,[reasonPhrase],[headers]);
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• Content-type Indicates the content type
• Location redirects the client to another URL
• Content-disposition specifies a file name to download
• Content-length Specifies the bytes of the server response
• Set-cookie Creates a cookie on the client
• Content-encoding Specifies the encoding of the server response content
• Cache -cache Enables the cache mechanism
• Expires is used to set a cache expiration time
• Etag specifies that the data is not reloaded when the server responds that the content has not changed

1.10.2 Header

Set, get, and delete the Header

response.setHeader('Content-Type'.'text/html; charset=utf-8');
response.getHeader('Content-Type');
response.removeHeader('Content-Type'); Response. headersSent Checks whether the response header has been sentCopy the code

1.10.3 headersSent

Determines whether the response header has been sent

let http = require('http');
let server = http.createServer(function(req,res){
  console.log(resopnse.headersSent?"Response header has been sent":"Response header not sent!");
  res.writeHead(200,'ok); console.log(resopnse.headersSent?" Response header sent ":" Response header not sent!" ); });Copy the code

1.10.4 sendDate

Don’t send the Date

res.sendDate = false;
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1.10.5 write

You can use the write method to send the response content

response.write(chunk,[encoding]);
response.end([chunk],[encoding]);
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1.10.6 timeout

You can use the setTimeout method to set a timeout for a response, and if you do not respond within the specified time, the timeout event is emitted

response.setTimeout(msecs,[callback]);
response.on('timeout',callback);
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1.10.7 close

Before the end method of the response object is called, the close event of the HTTP. ServerResponse object is emitted if the connection is broken

response.on('close',callback);
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1.10.8 parser

.net onconnection _http_server. Js connect to monitor connectionListenerInternal socketOnData onParserExecuteCommon parserOnIncomingCopy the code

2. HTTP client

2.1 Request data from other websites

let req = http.request(options,callback);
req.on('request',callback);
request.write(chunk,[encoding]);
request.end([chunk],[encoding]);

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• Host Specifies the destination domain name or host name
• Hostname Specifies the destination domain name or hostname. If both hostname and host are specified, hostname is preferred
• Port Specifies the port number of the target server
• LocalAddress Indicates the local interface
• SocketPath Specifies the Unix domain port
• Method Specifies the HTTP request mode
• Path Specifies the request path and query string
• Headers specifies the client request header object
• Auth specifies the authentication part
• Agent is used to specify the HTTP proxy. In Node.js, the http. agent class represents an HTTP proxy. By default, keep-alive connections are used, and HTTP

let http = require('http');
let options = {
    hostname: 'localhost',
    port: 8080,
    path: '/',
    method: 'GET'
}
let req = http.request(options, function (res) {
    console.log('Status :' + res.statusCode);
    console.log('Response header :' + JSON.stringify(res.headers));
    res.setEncoding('utf8');
    res.on('data'.function (chunk) {
        console.log('Response content', chunk);
    });
});
req.end();
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2.2 Canceling a Request

You can use the abort method to terminate the request

req.abort();
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2.3 Listening for Error Events

An error event is raised if something goes wrong during the request

request.on('error'.function(err){});
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2.4 the socket

Description A socket event was triggered when a port was allocated to the connection during connection establishment

req.on('socket'.function(socket){
  socket.setTimeout(1000);
  socket.on('timeout'.function(){req.abort()});
});
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2.5 the get

You can use the GET method to send data to the server

http.get(options,callback);
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2.6 addTrailers

You can use the addTrailers method of the Response object to append a header to the end of the server response

let http = require('http');
let path = require('path');
let crypto = require('crypto');


let server = http.createServer(function (req, res) {
    res.writeHead(200, {
        'Transfer-Encoding': 'chunked'.'Trailer': 'Content-MD5'
    });
    let rs = require('fs').createReadStream(path.join(__dirname, 'msg.txt'), {
        highWaterMark: 2
    });
    let md5 = crypto.createHash('md5');
    rs.on('data'.function (data) {
        console.log(data);
        res.write(data);
        md5.update(data);
    });
    rs.on('end'.function () {
        res.addTrailers({
            'Content-MD5': md5.digest('hex')}); res.end(); }); }).listen(8080);Copy the code

let http = require('http');
let options = {
    hostname: 'localhost',
    port: 8080,
    path: '/',
    method: 'GET'
}
let req = http.request(options, function (res) {
    console.log('Status :' + res.statusCode);
    console.log('Response header :' + JSON.stringify(res.headers));
    res.setEncoding('utf8');
    res.on('data'.function (chunk) {
        console.log('Response content', chunk);
    });
    res.on('end'.function () {
        console.log('trailer', res.trailers);
    });
});
req.end();
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2.7 Creating a Proxy Server

let http = require('http');
let url = require('url');
let server = http.createServer(function (request, response) {
    let {
        path
    } = url.parse(request.url);
    let options = {
        host: 'localhost',
        port: 9090,
        path: path,
        headers: request.headers
    }
    let req = http.get(options, function (res) {
        console.log(res);
        response.writeHead(res.statusCode, res.headers);
        res.pipe(response);
    });
    req.on('error'.function (err) {
        console.log(err);
    });
    request.pipe(req);
}).listen(8080);Copy the code