I am trying to understand the purpose of websocket multiplexing extension, the main purpose what the document states is to use a single same origin physical websocket connection to the server while each browser tab uses a logical connection multiplexed on top of physical connection. I see another alternative using which we can accomplish this behavior today, the approach is to launch a shared web worker which opens the websocket connection and let each browser tab send and receive message to/from this worker. i have not tried this yet and i wonder will this work at all.
Your question reflects a misunderstanding of the problem the WebSocket Multiplexing Extension is trying to solve.
The base WebSocket spec (RFC 6455) defines a protocol for bi-directional exchange of data over TCP/IP. A WebSocket starts as a normal HTTP request / response. In this exchange, the client and server negotiate to switch to the WebSocket protocol. After the switch, the client and server exchange data frames over the TCP/IP connection. This creates a bi-directional data stream between client and server.
A drawback of the base protocol is that it supports only a single stream of data flowing in each direction. The multiplexing extension augments the base protocol, by allowing the client and server to create multiple "channels" over the same TCP/IP connection.
So the purpose of the multiplexing extension is to allow multiple WebSocket channels to run over the same TCP/IP connection. That's all.
Having multiple browser tabs (or web workers) share a single TCP/IP connection is just an example of how multiplexed websockets might be used. In standards terminology, it's just "informative" (descriptive), not "normative" (a required part of the spec).
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I built the server into Java,The server sends (image)data to the web browser through a web socket.So far it works fine.
and I wand that The web browser send data from the server to another web browser (client) using webRTC, So I looked for the webrtc...
I noticed that there are occasions when you need to use webSocket with webRTC
What is the role of websocket in webRTC?
In order to establish a WebRTC connection between two browsers, these browsers will have to negotiate a connection first. To negotiate a connection they need to be able to talk to each other. But they cannot talk to each other because they have not established a connection yet.
That's where a signalling server comes in. That's a server that both peers are already connected to and which can relay messages between them until they have established a connection. Using a websocket connection for this purpose is the most useful way, since it's a (soft) realtime bi-direction communication channel, exactly what you want when relaying messages as quickly as possible.
It doesn't have to be a websocket though; AJAX and/or long-polling will do too, but they have more overhead and are slower, which means it will take longer to negotiate the WebRTC connection.
Assume I have a simple ASP.NET MVC application with an Index view that just shows some static data.
Considering the fact that the web is stateless, when a browser requests for this index.cshtml, a HTTP Get request is made and the server sends the contents of the page to the client.
In Such case is there an entity called connection? If so when can we say that connection is established?
Hope my question is clear.
A connection is established between the client (browser) and the underlying web server (IIS) prior to any invocation of your MVC application.
If you get a request in your web application, then a TCP connection has already been established and an HTTP request has been sent to the server over TCP. With keep-alive semantics, multiple requests may use the same connection, and of course multiple actions could even be called for the same request.
So basically, the establishment of a connection is not something that is particularly useful for a web application to indicate or track, if that is what you are trying to do.
The connection is estabished to the IIS Server/Process and then forwarded to .NET, so the moment IIS receives it, it's 'established'
The HTTP protocol is based on the TCP protocol. Before the GET request is made, a TCP connection must be made.
"The connection is closed" happens when the TCP connection is closed, usually after a single request/response interaction.
The connection may be kept open by using Keep-Alive.
I have this project for my classes i'm currently workin' on. here it is:
WebPage client for Telnet not on standard ports, with ability to choose a port and connect
I have machines with telnet servers on them, just waiting for connection.
So my idea was to set up a nodeJS with express server on a dedicated machine. This would handle connections through telnet and host a page for clients, that would use socket.io to exchange information with server side.
But as i'm new to such technologies (telecommunications student) i wonder if it is possible. I spotted something like this - jsterm.com by Peter Nitsch, but i see there are some massive gaps in code and the demo does not really work so i don't know if it actually works. Did anyone try this?
My other problem is - when i send information to nodeJS server through websockets, which seems achievable for me, what do i do with this information? Do i just set up another websocket to pass the same data i got from client websocket directly to the telnet port?
Can sockets connect directly to specific port, without any websocket waiting on the other side?
If my idea is wrong, could anyone help me - maybe there exists some nice solution - i was thinking about Anyterm for example but i see that it requires an apache server and runs completely different technologies...
Just to be clear, WebSocket connections are not raw TCP socket connections. They have extra header information in each packet, browser to server data is masked using a running XOR, etc.
In order for the browser to communicate with a normal TCP server (e.g. a telnet server) you will need some sort of bridge service. It just so happens that such a thing already exists. websockify is a server that accepts WebSocket connections and bridges them to a raw TCP server.
In fact, the websockify project already includes a working telnet client as an example application. However, note that one limitation of websockify (for security reasons) is that the client cannot pick an arbitrary server address/port to connect to. The target address(es) must be predefined, either as a single target specified on the command line for websockify, or as multiple targets specified in a configuration file (and selected via a token in the WebSocket connect string).
There are multiple implementations of websockify in different languages (python, C, node, ruby, Clojure) however, only the python version currently supports multiple targets via a configuration file.
Disclaimer: I created websockify.
I am would like to create a websocket server. I understand that the client will make a request and that a partially encrypted response needs to be sent back to the client. My question is does that connection need to stay open to handle the websocket messages after the connection is made. Or does the client establish a new connection after receiving the response from the server?
Thanks,
-ren
Here's an article on the websockets handshake.
And, a sample implementation of a websockets server in PHP.
The socket stays open.
The whole protocol is described in RFC 6455.
I already have a server with port and want to write a web app to get the information form the port. Will this be possible with WebPorts?
The Client doesn't even need to talk back to the server, which is the whole point of websockets I would imagine, but since I already have the ports setup, I might be easier and cleaner to just connect and get the info without having to refresh.
WebSockets are not intended as clear TCP channels over which other existing protocols can be implemented.
WebSockets are designed to allow messages to be sent between a client and server, where an event is raised each time a message is received.
Hence a WebSocket client cannot simply connect to an existing TCP server - that server also has to speak the WebSocket protocol.
You could of course write a WebSocket-based server that does nothing but act as a proxy to existing network services.
I think you want websockify which is a WebSocket to plain TCP socket bridge/proxy. It also allows sending and receiving of binary data with the older version of the WebSocket protocol which hadn't yet added direct binary data support.
Disclaimer: I created websockify.