Connecting to TCP Socket from browser using javascript

Question

I have a vb net application that opens a socket and listens on it    I need to communicate via this socket to that application using a javascript running on a browser  That is i need to send some data on this socket so that the app which is listening on this socket can take that data  do some stuff using some remote calls and get some more data and put it back on the socket that my javascript needs to read and print it in the browser   Ive tried  socket io  websockify but none have proved to be useful   Hence the question  is what i am trying even possible  Is there a way that a javascript running in a browser can connect to a tcp socket and send some data and listen on it for some more data response on the socket and print it to the browser   If this is possible can some one point me in the right direction as to which would help me establish the goal

User · Answer

As for your problem  currently you will have to depend on XHR or websockets for this   Currently no popular browser has implemented any such raw sockets api for javascript that lets you create and access raw sockets  but a draft for the implementation of raw sockets api in JavaScript is under-way  Have a look at these links   http   www w3 org TR raw-sockets   https   developer mozilla org en-US docs Web API TCPSocket  Chrome now has support for raw TCP and UDP sockets in its    experimental    APIs  These features are only available for extensions and  although documented  are hidden for the moment  Having said that  some developers are already creating interesting projects using it  such as this IRC client   To access this API  you   ll need to enable the experimental flag in your extension   s manifest  Using sockets is pretty straightforward  for example   chrome experimental socket create  tcp    127 0 0 1   8080  function socketInfo      chrome experimental socket connect socketInfo socketId  function  result            chrome experimental socket write socketInfo socketId   Hello  world

User · Answer

This will be possible via the navigator interface as shown below   navigator tcpPermission requestPermission  remoteAddress  127 0 0 1   remotePort 6789   then         gt           Permission was granted        Create a new TCP client socket and connect to remote host     var mySocket   new TCPSocket  127 0 0 1   6789           Send data to server     mySocket writeable write  Hello World   then               gt                    Data sent sucessfully  wait for response             console log  Data has been sent to server                mySocket readable getReader   read   then                     value  done      gt                        if   done                               Response received  log it                          console log  Data received from server     value                                                 Close the TCP connection                     mySocket close                                                        e   gt  console error  Sending error     e                  More details are outlined in the w3 org tcp-udp-sockets documentation   http   raw-sockets sysapps org  interface-tcpsocket  https   www w3 org TR tcp-udp-sockets   Another alternative is to use Chrome Sockets  Creating connections  chrome sockets tcp create     function createInfo      chrome sockets tcp connect createInfo socketId      IP  PORT  onConnectedCallback         Sending data  chrome sockets tcp send socketId  arrayBuffer  onSentCallback     Receiving data  chrome sockets tcp onReceive addListener function info      if  info socketId    socketId      return       info data is an arrayBuffer        You can use also attempt to use HTML5 Web Sockets  Although this is not direct TCP communication    var connection   new WebSocket  ws   IPAddress Port     connection onopen   function        connection send  Ping       Send the message  Ping  to the server      http   www html5rocks com en tutorials websockets basics   Your server must also be listening with a WebSocket server such as pywebsocket  alternatively you can write your own as outlined at Mozilla

User · Answer

In order to achieve what you want  you would have to write two applications  in either Java or Python  for example     Bridge app that sits on the client s machine and can deal with both TCP IP sockets and WebSockets  It will interact with the TCP IP socket in question  Server-side app  such as a JSP Servlet WAR  that can talk WebSockets   It includes at least one HTML page  including server-side processing code if need be  to be accessed by a browser    It should work like this   The Bridge will open a WS connection to the web app  because a server can t connect to a client   The Web app will ask the client to identify itself The bridge client sends some ID information to the server  which stores it in order to identify the bridge    The browser-viewable page connects to the WS server using JS  Repeat step 3  but for the JS-based page The JS-based page sends a command to the server  including to which bridge it must go  The server forwards the command to the bridge  The bridge opens a TCP IP socket and interacts with it  sends a message  gets a response   The Bridge sends a response to the server through the WS The WS forwards the response to the browser-viewable page The JS processes the response and reacts accordingly Repeat until either client disconnects unloads    Note 1  The above steps are a vast simplification and do not include information about error handling and keepAlive requests  in the event that either client disconnects prematurely or the server needs to inform clients that it is shutting down restarting   Note 2  Depending on your needs  it might be possible to merge these components into one if the TCP IP socket server in question  to which the bridge talks  is on the same machine as the server app

User · Answer

The solution you are really looking for is web sockets   However  the chromium project has developed some new technologies that are direct TCP connections TCP chromium

User · Answer

See jsocket  Haven t used it myself  Been more than 3 years since last update  as of 26 6 2014      Uses flash     From the documentation    lt script type  text javascript  gt         Host we are connecting to     var host    localhost           Port we are connecting on     var port   3000       var socket   new jSocket            When the socket is added the to document      socket onReady   function                socket connect host  port                              Connection attempt finished     socket onConnect   function success  msg               if success                          Send something to the socket                     socket write  Hello world                             else                      alert  Connection to the server could not be estabilished      msg                                              socket onData   function data               alert  Received from socket    data                    Setup our socket in the div with the id  socket      socket setup  mySocket            lt  script gt

User · Answer

ws2s project is aimed at bring socket to browser-side js  It is a websocket server which transform websocket to socket   ws2s schematic diagram    code sample   var socket   new WS2S  wss   ws2s feling io    newSocket    socket onReady        gt      socket connect  feling io   80    socket send  GET   HTTP 1 1 r nHost  feling io r nConnection  close r n r n      socket onRecv    data    gt      console log  onRecv   data

[javascript] Connecting to TCP Socket from browser using javascript

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