Network programming of Nodejs Learning notes

Learn about the OSI seven layer model

osi layer	features	TCP/IP protocol
Application layer	file transfer, e-mail, file service, virtual terminal	tftp,http,snmp,ftp,smtp, Dns,telnet
presentation layer	data formatting, transcoding, data encryption	-
Session layer	data formatting, transcoding, data encryption	-
Transport layer		tcp,udp
Network layer	Select route for packet	ip,icmp,rip,ospf,bgp,igmp
Data link layer	transmit address frames and error detection	slip,cslip,ppp,arp,rarp, MTU
Physical layer	transfer data on physical media as binary data	ISO2 110,ieee802,ieee802.2

Main content

• TCP (Transmission Control Protocol)
• UDP (User Packet protocol)
• HTTP (Hyper-Text Transfer Protocol)
• Websocket
• Network services and Security (Cryto TLS HTTPS)

TCP Features

• Connection-oriented protocols
• Need three handshake

TCP Service Practice (i)  To create a service side:

var net = require (' net '); var server = Net.createserver (socket) {    ///New Connection    Socket.on (' Data ', function (data) {        Console.log (' The server receives a message from the client: ' + data.tostring ());        Socket.write (' Service-side response: Hello ');    });    Socket.on (' End ', function () {        console.log (' Server Disconnect ');})    ; Server.listen (8124, function () {    console.log (' TCP service Creation ');});

TCP Service Practice (ii)  To create a client:

var net = require (' net '); var client = Net.connect ({port:8124}, function () {    console.log (' Client connection succeeded ');    Client.write (' Client initiates greetings: Hello ');}); Client.on (' Data ', function (data) {    Console.log (' Client receives service-side message: ' + data.tostring ());    Client.end ();}); Client.on (' End ', function () {    console.log (' client disconnects ');});

Events for TCP Services (i)

• Server events
• Listening:server.listen ()
• Connection:net.createServer ()
• Close:server.close ()
• Error

the practice of TCP Services (ii)

• Connection Events
• Data: One end executes write () and the other end triggers the event
• End: Disconnect at either end to trigger the event
• Connect: This event is used by the client to trigger when the socket server connection succeeds
• Drain: When the Write () is triggered at either end, the event is triggered by the current end
• Error: This event is triggered when an exception occurs
• Close: This event is triggered when the socket ends
• Timeout: Triggers the event when the connection is no longer active after a certain amount of time

TCP Summary

• Connection oriented (establish communication lines: build, use, release)
• Three-time handshake (the process of establishing the connection)
• Nodejs implementation (NET module)

UDP features

• No connection
• Unreliable information Services
• In the case of poor network, packet loss is serious
• You can send a message to the client and receive a message from the server.
• Usage scenarios: scenarios where packet loss is not required (audio, video, DNS service)

UDP Service Practice (i)To create a service side:

var Dgram = require (' Dgram '); var server = dgram.createsocket (' udp4 '); Server.on (' message ', function (msg, rinfo) {    console.log (' Server access information: ' +msg+ ' from: ' +rinfo.address+ ': ' +rinfo.port ');}); Server.on (' Listening ', function () {    var address = server.address ();    Console.log (' Decent service in listening: ' +address.address+ ': ' +address.port);}); Server.bind (41234);

UDP Service Practice (ii)To create a client:

var Dgram = require (' Dgram '); var client = Dgram.createsocket (' udp4 '); var message = new Buffer (' I am the client's message '); Client.send (msg, 0, Message.length, 41234, ' 10.16.15.155 ', function (err, bytes) {    Console.log (' Client send complete, close client ');    Client.close ();});

UDP Socket Events

• Message: When a UDP socket listens for a NIC port, the event is triggered when the message is received, carrying the buffer object and the remote address information
• Listening: This event is triggered when UDP starts to listen
• Close: This event is triggered when the close () method is called
• Error: When an exception occurs, the event is triggered and, if not processed, causes the process to exit

UDP Summary

• For no connection (no need to establish a communication line, send the packet with the destination address to the line)
• Usage scenarios (Low packet loss requirements, IP, UDP protocol are not connected)
• Nodejs implementation (Dgram module)

HTTP Features

• Application layer protocol based on TCP
• Classic mode: b/S
• Well-known HTTP standard: RFC2616 (both the and IETF)

HTTP Service Practice (i)

Create server: var http = require (' http '); Http.createserver (function (req, res) {    Res.writehead ($, {' Content-type ': ' Text/plain '});    Res.end (' Hello world!\n ');}). Listen (8000); Console.log (' Server enabled ');

HTTP Messages

• Part I: Classic TCP three-time handshake

• Part Two: Client (curl) Sending request message

• Part III: Server response (includes response header and response body)

• Part IV: Ending a session

HTTP Service Practice (ii)To create a client:

var http = require (' http '); var options = {    hostname: ' 10.16.15.155 ',    port:8000,    method: ' GET ',    path: '/'}, var req = Http.request (o ptions, Function (res) {    console.log (' Status: ' +res.statuscode);    Console.log (' Headers: ' +json.stringify (res.headers));    Res.setencoding (' Utf-8 ');    Res.on (' Data ', function (chunk) {        console.log (chunk);    });}); Req.end ();

HTTP Service event (i)

• Server-side events
• Connection
• Request
• Close
• Checkcontinue
• Connect
• Upgrade
• Clienterror

HTTP Service Events (ii)

• Client Events
• Response
• Socket
• Connect
• Upgrade
• Continue

HTTP Summary

• HTTP protocol based on TCP
• Client requests can be done via impersonation (curl, http_client.js, browser, etc.)
• Nodejs implementation (HTTP module)

WebSocket features

• Built on top of HTTP service
• After the connection is established, it is upgrade to the data frame protocol, which realizes the interaction between the server and the client.
• Full Duplex communication

WebSocket Instances (socketio)Socketio Document Socketio Example WebSocket Summary

• Full Duplex communication
• The protocol is switched after the HTTP service is created
• Nodejs implementation (WS, Socket.io module)

Network services and securityThe process of a secure connection:

• Certification based on digital certificates
• For encrypted transmissions
• Exchanging public keys
• Client encrypts using the public key of the service side
• The server uses the server-side private key to decrypt it.
• The server uses the client's public key for encryption
• Client uses the client's private key to decrypt

Network Programming Summary

• Understanding the OSI seven layer model
• Nodejs implementation of the Key Learning Transport layer (TCP, UDP) and Application layer (HTTP, Websocket) protocol
• Preliminary understanding of network transport security

Reference: "Nodejs in layman's language"--the seventh Chapter network programming

Network programming of Nodejs Learning notes