I am implement html5 player. It is similar to streaming, but it is not strictly streaming.
First I tried.
Using Media Source Extensions.
But I can not implement seeking. I do not know the byte offset.
So I thought.
If you can create an http server in your browser, I can only respond to range requests.
Can I create http server in browser using javascript?
It is support mobile/pc browser.
It is must support mobile/pc browser.
Can I create http server in browser using javascript?
No. Regular browser Javascript cannot create a web server. Browser Javascript was not given that capability and since you cannot create your own TCP server either, you cannot even build your own http server.
To do something like that, you'd have to have a browser extension that used some native code to set up an http server. But, even if you did that, you'd probably have firewall issues since most clients are not directly reachable by other clients unless they happen to be on the same sub-network as clients are usually behind a firewall.
Related
It is easy to create an AJAX request to obtain resources from an HTTP server. But I am trying to find a way to create a TCP connection to a server to obtain certain resources, in the browser.
HTTP works over TCP, so I think that the way AJAX creates an HTTP request, the modules they use can be used to do the same, since a TCP connection has to be established before creating an HTTP request.
So, I want to know how does the AJAX library create an HTTP request and what does it use so that I can do the same in my code.
Your browser will probably refuse to do this, for good security reasons.
When you visit a web page that contains javascript, that code gets pulled down and starts to run inside your browser (assuming you have allowed javascript). That's handy, because it allows the website to be dynamic and do useful things for you. But do you want to allow that javascript to read your hard drive? I can assure you, you do NOT want that. Do you want to allow it to make arbitrary TCP connections? I can assure you that you don't want that either. The browser WILL allow the code to go back to the same server and push and pull data - that's what the AJAX library is doing. Nowadays browsers also allow javascript to initiate WebSocket connections, which is a little risky, but perhaps not as wide open as arbitrary TCP connections.
I'm playing around trying to find a way to communicate between two browsers on the same network to establish WebRTC without a server roundtrip (no STUN/ICE/TURN). Basically an alternative to the approach found here, where the "handshake" is done via copy/mail/pasting.
After sifting through all the cross-browser-communication examples I could find (like via cookies or WebTCP) plus a bunch of questions on SO (like here), I'm back to wondering a simple thing:
Question:
If Alice and Bob visit the same page foo.html while on the same network and they know each others' internal assigned IP addresses, are there any ways they can communicate purely with what is available on the browser?
This excludes non-standard APIs like Mozilla TCP_Socket_API, but other than that all "tricks" are allowed (img tags, iframes, cookies, etc.).
I'm just curious if I can listen to someone on the same network "broadcasting" something via the browser at all.
Edit:
foo.html will be on static server, no logic, no ICE, no shortcut.
Edit:
Still not a solution but a websocket server as Chrome extension comes closer. Example here: almost pure browser serverless WebRTC
Yes, you can establish a direct connection between two browsers over the local network using WebRTC. It requires the use of ICE, but that does not mean that an outside STUN or TURN server is needed. If the browsers are on the same network, ICE will succeed with only the local candidates of each browser.
STUN/TURN is needed only in order to guarantee that two endpoints can establish a connection even when they are in different networks and behind NATs.
In fact, if you use most of the WebRTC example applications (such as apprtc) with two browsers connected in a local network, ICE is most likely to select and use the pair of local addresses. In this case a channel allocation on a TURN server will be made, but it will not get used.
In your WebRTC application, you can disable the use of STUN/TURN by passing empty iceServers when you create the PeerConnection.
While the MDN documentation lists WebSocketServer as a client API, I don't think this is accurate (maybe they wanted to document there how to write a server).
At the moment, I know no standard way to create a server socket on a web browser. I know a couple of attacks to scan the local network but most of them rely on an active server outside the network, that is you connect to a server and get JavaScript back which opens a WebSocket connection. Via that connection, I can take full control over the client and have it open more WebSockets with local IP addresses to scan the internal network.
If internal web sites don't implement CORS correctly (see here), I can access all internal web sites where the current user is currently logged in. That is a devious attack vector which allows external attackers to browser internal documents without cracking anything. This page has a demo of the attack.
Even Flash won't let you create a server socket.
If you allow a Java applet and the Java version on the client is very old or the user blindly clicked "OK", then you can create server sockets.
Related:
Socket Server in Javascript (in browsers)?
This could be explained easily. The answer is it's not possible. In order for alice and bob to communicate at all without a third-party, at least one of them needs to be listening for incoming connections. Not possible using a standard web browser alone.
You can take a look at this
https://github.com/jed/browserver-client
I think that you can easily create an http server with javascript and send messages from one browser to another
With Nodejs you can achieve the same.
How can I make my javascript client application receive socket requests?
I mean not response on request, but request itself.
Javascript is running in browser without HTML5.
The thing is that I want my web page to reload changed content but without the need of making request to the server each several minutes.
I hope that a server can make some request to javascript on the page, making it refresh the page. If not what could you suggest instead javascript in this scope.
Many browsers that support HTML5 implement WebSocket interface. WebSocket allows two way communication, so browser and server can send requests. Check this post for more info What browsers support HTML5 WebSocket API?
If your browser doesn't support WebSockets you could try WebSocket emulation written in Flash/JS from this site https://github.com/gimite/web-socket-js
If this is also not suitable for you then the last option is "long polling". In this case browser ask server for some data and if server does not have any information available for the browser it doesn't send empty response. It holds the request and waits for new data to be available. Browser after receiving new data immediately ask server once again.
Check these links for more information:
http://en.wikipedia.org/wiki/Push_technology
http://en.wikipedia.org/wiki/Comet_(programming)
Yes and No.
No
Javascript running in a browser environment can't listen to sockets since it's running in a sandbox with limited capabilities.
Yes
However, JS is a full fledged programming language, so if you have it running in an environment where it is not crippled yes, it can do that and more.
A nice example is node.js - http://nodejs.org/
Wiki page - http://en.wikipedia.org/wiki/JavaScript#Uses_outside_web_pages
This question is for my curiosity only:
Is it possible to make a HTTP request from a backend server to a web browser, that is to say I have a HTTP server ON the web browser to listen for incoming HTTP requests?
Cause I want to use frontend <-> couchdb directly thus dumping the backend server .. but then i wondered how i would do normal processing when the database javascript is not sufficient.
That thought made me think of this question.
Generally speaking — no.
There are some exceptions, Opera has a feature called "Unite" which allows it to run a web server (this is not turned on by default!) as well as acting as a user agent. That wouldn't allow you to send a response to a request that hadn't been made though.
Most web browsers don't have a web server and they are unable to accept HTTP requests. Maybe there is an extension for Firefox, but that's not a typical use case.
Depending on what you are trying to achieve, using Comet or long polling could work for you.
I'm prototyping a realtime notification mechanism using http over port 80. The aim of the project is to allow a Flash application to respond to an event on a remote server quickly (specifically an inbound phone call being connected to a phone next to the computer.) Polling is one approach, but is too slow. Currently I use a socket connection to get low latency notification of the events on the server, which works well but isn't firewall friendly. I don't want to install anything except Flash, or Silverlight on the client. Cross compatibility of browsers isn't a concern - in this application I can specify what browser the client uses but IE is preferred.
I've made a server HttpHandler in .NET which never closes the connection and sends the "events" to the client by writing out bytes to the http response stream (ConnectedClientContext.Response.OutputStream.Write etc) and I have a .NET client application which can read these messages okay.
My Question:
Can I receive the bytes from the server over HTTP as they arrive using JavaScript, Flash or Silverlight? So far I can only find a way to get notified of the "download progress" and don't get the actual bytes until the response is closed - I want them as they arrive.
Best Regards,
Daniel
I don't know about Flash but in Javascript (by which you mean in browser) and Silverlight you are limited pretty much to the http protocol.
You can use the AJAX Http Streaming pattern. The basic ideas which is different from what you are trying is that as soon as data is available outstanding request ends and a new is immediately initiated asychronously, mean while your client process the newly arrived data.
Silverlight gives you more options since is HTTP stack is purely asynchronous but you can get your hands on the stream to you as soon as data starts to arive by setting the HttpWebRequest.AllowReadStreamBuffering to false. (Unlike XmlHttpRequest which always buffers).
it's very easy to use the Comet ideas for notifications. you don't even have to use a comet-specific framework. simply do an ajax request with a callback on answer, wrap this on a loop and you have an event loop, just like a GUI app. on the server side, don't bother answering the request until there's either an event, or a timeout (which is just a 'null' event).
Flex and Flash have several AMF/XML remoting libraries available that support data pushing. I would certainly look into that.
http://raghuonflex.wordpress.com/2008/04/17/data-push-in-flex-with-backend/
These libraries use a Comet - like implementation to achieve this.