I'm writing a JavaScript Application that has to receive a huge amount of data from other users. It is not important if some of this data gets lost. Is there some way of using JavaScript WebSockets with UDP instead of TCP?
It sounds like what you're waiting for is WebRTC which is working it's way through the standards process. WebSockets, as other people have pointed out, run over TCP as a result of initiating with an HTTP Upgrade.
No, it's not possible to have UDP communication within JavaScript. Sorry.
Sounds like the question is meant for client-side UDP, but since I ended up here...
You can do UDP in JavaScript on the server using the node.js dgram package.
The WebSockets protocol is over TCP only as currently defined.
You could do UDP with Flash if you are willing to use a RTMFP (Real Time Messaging Flow Protocol) server.
If this question is still pending:
I found a project called JNEXT and there is an example using UDP.
The project itself seems to be paused but at least in Firefox it works (it doesn't work with Chrome and Opera).
May be it is worth to look for it.
I think you can leverage Silverliht 4 technology. You can create a Silverlight 4 application to communicate with server and then enbamdded it to html page. Then your JavaScript can build TCP connections via Silverlight 4 application!
You could write a WebSocket server to serve as proxy/bridge between TCP/UDP.
Related
I know there are already similar questions in forum, but I didn't really find a direct answer for my question there.
What I'm trying to do:
I have a pub/sub middleware that uses UDP multicast to send data to other hosts and I want to be able to visualise that data with JavaScript im Browser. Best case scenario for me would be to receive the UDP packets directly in JavaScript (like just "rewriting my subscriber code in JS"), but I understand this is not possible for security reasons. So what other way is there to somehow get to these UDP packets from the browser?
I read that, under specific conditions, it's possible to communicate with the browser over UDP using WebRTC, but I don't understand what these conditions are. If this would be your suggestion, it would be very nice if you could explain that. I'm kinda new to the whole real-time-data-transfer-to-browser topic.
Thank you in advance! :)
WebRTC provides Datachannels, this allows a browser to send/receieve datagrams. These datagrams will be carried over UDP, but also use SCTP and DTLS.
To get your packets into the browser you will need to write a UDP -> WebRTC bridge. This will not run in the browser, but the browser will connect to it. You have lots of choices when writing this bridge Python, C/C++, Go, node.js, Rust and more.
Since you are writing a bridge you could also use Websockets or even HTTP poll. But today there is no way to directly get UDP into the browser. A Raw Sockets API was proposed, but AFAIK is not going to happen.
Not for raw-UDP, but for coap(s), there are http-coap-cross-proxies, which may help.
Request out:
Browser -- HTTP -> http2coap-cross-proxy -- coap -> coap-server
Response back:
Browser <- HTTP -- http2coap-cross-proxy <- coap -- coap-server
Anyway, that keeps the request/response scheme, so I'm not sure, if that matches your requirements/expectations.
I have a c# tcp server, I want to connect to the server via a html client page.
The problem: There is no simple way to create TCP sockets in Javascript on a browser side. Although solutions like Websockets allow to create something that resemble sockets, you can use them to connect only to servers that support Websockets. Not to any random servers that know nothing about HTTP.
so is there a solution to connect to my srver.
No. There just isn't. The browser is a tightly locked down environment. The only socket connection that you can open from JavaScript is WebSocket. Since it's your server, adding WebSocket support shouldn't be too complicated, and there are WebSocket libraries available for C#.
Maybe someone else will have an idea for you, but...
The best solution I can think of is for your server to support websockets.
The situation you described - along with connectivity issues for traffic passing through proxies and routers - is one of the reasons Websockets were introduced in the first place.
Bare in mind that Websockets can send and receive binary data. It's just that javascript make it more comfortable to write text based messages.
Also, many NAT routers, Proxies and firewalls will block raw TCP/IP communication while allowing Http communication to pass through. This is why you have a better chance at connection establishment and retention when implementing the Websocket protocol.
I am interested to know if anyone has built a javascript websocket listener for a browser. Basically the server side of a websocket that runs in a client. This would allow messages to be sent to the client directly. Why? Because instead of having a Node.js, python, java, etc, server process sitting on or near the client/browser, I can just use a thread in the browser as a listening server thread. I don't think that any browsers support this currently.
I've run across answers like this: https://news.ycombinator.com/item?id=2316132
Just curious if anyone has done this. I believe that the current Websockets spec does not support listeners on the browser. It would make the deployment of various peer-to-peer applications a bit easier to deploy.
WebRTC allows for peer-to-peer connections to be made between browsers.
You would still need a server in order for individual users to discover each other but then they could connect directly to each other rather than having to pass all their traffic via a central server.
The idea.
You can use a simple echo server written in any language. Your script can send the data to the server then get it back, handle it on the same page with different functions/classes emulating the real server.
An example: http://www.websocket.org/echo.html
Then, you can think about different formats of packets to/from server to diffirentiate them inside one script.
I have a c# tcp server, I want to connect to the server via a html client page.
The problem: There is no simple way to create TCP sockets in Javascript on a browser side. Although solutions like Websockets allow to create something that resemble sockets, you can use them to connect only to servers that support Websockets. Not to any random servers that know nothing about HTTP.
so is there a solution to connect to my srver.
No. There just isn't. The browser is a tightly locked down environment. The only socket connection that you can open from JavaScript is WebSocket. Since it's your server, adding WebSocket support shouldn't be too complicated, and there are WebSocket libraries available for C#.
Maybe someone else will have an idea for you, but...
The best solution I can think of is for your server to support websockets.
The situation you described - along with connectivity issues for traffic passing through proxies and routers - is one of the reasons Websockets were introduced in the first place.
Bare in mind that Websockets can send and receive binary data. It's just that javascript make it more comfortable to write text based messages.
Also, many NAT routers, Proxies and firewalls will block raw TCP/IP communication while allowing Http communication to pass through. This is why you have a better chance at connection establishment and retention when implementing the Websocket protocol.
Is the following possible? There are 2 persons working on 2 different computers. Both are connected to the Internet. These users can communicate with each other using a JavaScript program run in a browser.
I do not want to use a server. I want to use a P2P approach and I am wandering if it is possible to do it with the JavaScript?
No.
The same origin policy prevents JavaScript (in a webpage) from opening a connection to a host other than the one on which the page was served from.
You will need to use a server in any case. Even if you could specify an IP address and tweak JavaScript into establishing a connection to a computer using AJAX / JSON / JSONP, the other computer would have to have some serving capabilities to answer the call, something which neither your browser nor JavaScript are equipped to handle.
For direct computer-to-computer communication, you will need to delve into serious client side programming, for example using Java, C++/C#, the .NET platform or something similar.
No this is a violation of the same origin policy.
You cannot do that with pure javascript without using the server, I think. Javascript can communicate with network only with ajax requests so the other computer would have to run http server.
The opera unite service allows you to do this. Of course this is limited to Opera browsers only.
Take a look here for a fantastic introduction to the system
Maybe consider using Java instead? You still need a server though so clients can find eachother.
A server in the middle is definitely required. Absolutely no way around that.
I am curious what you would want to do this for though?