When using web sockets all the tutorials I can find talk about the code for the client side. But the server side is just left out. What does the connection url here actually point too? Do I need to also be using PHP, Ruby, node.js or any server side language?
var connection = new WebSocket('ws://html5rocks.websocket.org/echo', ['soap', 'xmpp']);
Tutorial referenced:
http://www.html5rocks.com/en/tutorials/websockets/basics/
There are some server side languages that have Websockets support, I personally recommend using:
Socket.io
Who works over node.js, it's very easy to setup and a good starting point. Later you can have an Websockets endpoint in any language. Java and C# solutions are a bit complicated by the time.
Yes, you need a server that handles websockets. Many do including Apache HTTPD, Apache Tomcat, Play framework, and nodejs.
Here is an example:
http://www.tomcatexpert.com/blog/2012/05/01/how-apache-tomcat-implemented-websocket
Have you seen the great (and simple) echo sample on websocket.org?
Also, Kaazing has a hosted WebSocket server, and a browser-based tutorial that walks you through a simple pub-sub example.
Check out:
Tutorial Home Page with screencast of completed app
Seven-part blog post about with step-by-step instructions
Completed demo in JSFiddle (with HTML and JavaScript source code)
Hint: Open this link in two browser windows an interact with the slider above the image
Hope this helps!
Related
I am trying to develop a flutter chat app using nodejs and socketio.i'm just getting started with the socketio i have surf several examples in which every front end or client side having a set of socketio script. Can i develop my code purely server side? so that i can integrate with any type of front end.
You can do that. Socket.io is a web socket implementation in node js. It enables real-time, bidirectional and event-based communication between client and server.
Server and client can send and receive the events. If you don't want write any script in client side then you don't have any use of sockets.
Edit:
socket.io given nice example for chat application with explanation. https://socket.io/get-started/chat/
Socket.io has two distinct parts - the server and the client. The docs make this clear. There is nothing preventing you from just writing the server part, and leaving the client implementation out of the equation, for someone else to implement.
Although the main point of Socket.io is to implement the WebSocket protocol, it does so by wrapping it in its own interface, so to speak. So a socket.io server can only talk to socket.io clients, not clients that implement WebSocket in other ways. That being said, there are socket.io client libraries for pretty much every major language out there:
Javascript (main client)
Java
C++
Dart/Flutter
You also asked about React and Angular, but both of those are web front-ends, so there should be no reason why they can't use the standard Javascript client library with those frameworks.
I am working on chat server so I want to create a server and I have been said to use express and socket.io module. Would someone explain me about these modules and help me making chat server?
When you post questions on Stackoverflow, it is expected that you provide some code that you have experimented with so far. Please refer here for details about how to ask a question.
However, from the looks of it, you seem to be someone who is just starting off with Socket.io and NodeJS. So I'm answering here so that someone else who might also be at your stage can get an idea where to start.
A good starting point for learning how to build Chat applications with Socket.io and NodeJS using Express can be found here on Socket.io's official website
Scotch.io also provides a good tutorial on this here
In a chat application, Socket.io provides an abstraction over the HTML5 WebSockets API on the client side, and implements WebSockets on the server side, where your server is running on NodeJS.
ExpressJS is a Web Framework built on top of Node, that provides you an easier API for building servers, and dealing with requests.
Using a browser, is it possible using client only technologies (like JS, HTML ...) to send data to another browser without going through the server that servers the HTML page?? I mean if both ends are already synchronized (one has open a port, and the other one sends the data), is it possible to do that?
With only javascript and HTML, the answer is clearly no : you can't establish a direct P2P connection.
There are solutions involving a plugin, for example java (in the case of java, the user has to relax security, usually through signing).
But note that with websockets you connect and exchange through a server but it's efficient enough for most uses (provided your users will accept not to use IE9-). WebSocket programming is easy enough those days (here's an example of a complete chat client/server, googling would give an example for your favorite language) so I really recommend not to try using a plugin.
HTTP requires a server. For personal projects you can try the web server plug-in for Firefox:
https://addons.mozilla.org/en-us/firefox/addon/pow-plain-old-webserver/
You can't do a direct client-to-client transaction with JS, HTML yet, but if you check red5 to uses Java frame work, it provides RTMP(Real Time Media Protocol) which for P2P connection.
There is a server I need to talk to that publishes a protocol over TCP/IP for querying data from a database and listening on a socket to receive notifications when data is updated. The sever guys provide a Java API which uses this TCP protocol. This means I could easily write a Swing App to talk to this server.
I would like a browser based solution. As the protocol is known to me, could I do this in JavaScript? My app will have to display the data in a table. I have heard of Web Sockets but I'm not sure if it will allow this two way communication. Is it feasible? Is there a better way that is cross platform and will work in most browsers? Should I be considering a Java Swing based solution that runs inside a browser?
EDIT: What about changing the code in my C++ server to add an additional interface that my Javascript code can communicate directly with it?
The WebSocket protocol differs from TCP/IP sockets. You will have to write something to link them together.
You can do this perfectly well in JavaScript: use Node.js. There's enough tutorials to be found on the subject. The best way to link it to your in-browser JS is through Socket.IO.
Create a Node.js server that connects to the api
Make the server talk to your web app
Use it :)
This will work cross-platform and cross-browser (Socket.IO can use/emulate websockets even on IE6(!!)). You'll have to run a server-app (the Node.js app) though.
My personal opinion is that if you want a web/browser based solution, you should use native technology, and not Java.
Hope this helps :)
We have a network camera. It has an HTTP server to provides the current image. There is also a Telnet interface for controlling the camera (i.e. trigger, focus, etc.). I would like to add an HTML page to the camera that would provide a simple interface (we already have client software we write). I can "GET" the image and display that, but I would also like to have controls that use the Telnet interface to control the camera. So a button might have JavaScript code behind it that connects to the camera via Telnet (logs in) and issues the command to trigger the camera.
I know that JavaScript/browsers support connecting to the same host via XMLHttpRequest. In this case I would be looking to open a socket on port 23 and send text. I also know that I can do this through Flash, Java, or some other technology, but I would prefer to use JavaScript only. If that is possible.
Thomaschaaf is correct, while HTML5 introduces websockets you'll find they still require special server support as they post HTTP style information upon opening the socket:
JS/HTML5 WebSocket: Connect without HTTP call
The best way, currently, to have true sockets is to either
use a flash or Java component on the webpage that does the actual socket work.
use a proxy server with websockets that can handle the additional protocol overhead of websockets and connect to the real tcp/ip port with plain sockets.
The jsterm example Matt linked does the latter, and if your webcans are behind a firewall it will not work in your situation without also implementing another server.
There are libraries that implement the first method, two are linked here for convenience, many others can be found using a search engine:
http://stephengware.com/proj/javasocketbridge/ (Java)
http://matthaynes.net/blog/2008/07/17/socketbridge-flash-javascript-socket-bridge/ (Flash)
jsTerm is an HTML5 implementation of a Telnet client.
You'll need a browser that supports HTML5 WebSockets. WebSockets is the only method of doing non-HTTP requests with pure JavaScript.
Currently there is no way to do socket connections with JavaScript only.
But what you are searching for is a socket connection ;)
https://developer.mozilla.org/en/XML_Extras
If I interpret the question liberally as "is there a remote connectivity library for Javascript", then the answer is yes (quoting from https://xtermjs.org/):
A web based SSH2 client using xterm.js, socket.io, and ssh2: https://github.com/billchurch/WebSSH2
HTML5 Based SSHv2 Web Client with E2E encryption utilising xterm.js, SJCL & websockets: https://github.com/stuicey/SSHy
I've tried WebSSH2 with node.js briefly, it worked for me - I managed to connect to a Linux-based server with it.
(I know this probably doesn't help the OP but this is a 7-year old question anyway. Maybe it helps others who are needing an answer to a similar problem.)