How to establish connection and send messages to remote WebSocket server from ASP.NET Core?
Is it possible now or I should wait for SignalR library to achieve this?
Sounds like you're looking for System.Net.WebSockets.Client. It's available, but not on all platforms (https://github.com/dotnet/corefx/issues/2486).
Related
I have created a dotnet core signalr project, and I want to allow other users to connect on the signalr web socket like I can do it when I connect on:
wss://echo.websocket.org
Currently, signalr generates ID when creating the negotiation, and when switching on wss it uses that id, but it is causing a problem when using external connections.
So, is it possible to tell SignalR not to generate the id when creating the websocket server, and also to accept external ws connections ?
try to use dotnet core websockets
https://learn.microsoft.com/en-us/aspnet/core/fundamentals/websockets?view=aspnetcore-2.2
SignalR for Xamarin doesn't have way to work through Websockets.
I have a web service with messaging by SygnalR by websockets.
Can i receive message in Xamarin without implementing SignalR to Xamarin?
Is it important to have SignalR on Xamarin client side?
If you have implemented a SignalR hub in your sever, you can use SignalR Client nuget in Xamarin. The transport will be SSE (Server Sent Events) by default, but it works pretty well.
Implementing a websocket in the client just to connect to a SignalR server makes no sense at all, unless you really need to use WebSockets instead of SSE.
SignalR uses transports to connect to the server. The portable version of SignalR client does not support the webSockets transport since there is no portable version of WebSocket client available. This is fine since there are two more transports - longPolling and serverSentEvents that can be used to talk to the server.
You can't connect to the SignalR 2.x server with bare webSockets. There is a protocol that needs to be followed and if a client does not follow this protocol its requests will be rejected.
If you absolutely need to use websockets you can implement your own websockets transport by implementing the IClientTransport interface and pass it to the Start method. This is how the webSockets transport is supported on UWP. Here is all the code I needed to write.
Assuming both browser & Server supports a web-socket connection.
If I've got 2 hubs on my SignalR server. and my SignalR client connects to both. does that mean that my signalR client will open up 2 separate web-socket connections to the server?
In SignalR v2+, hubs will share the same connection. I've had systems with connections to 4+ hubs without performance issue.
Question is a bit of a duplicate of: Multiple signalR connections/hubs on your website
I'm trying to get a better understanding of how the server-side architecture works for WebSockets with the goal of implementing it in an embedded application. It seems that there are 3 different server-side software components in play here: 1) the web server to serve static HTTP pages and handle upgrade request, 2) a WebSockets library such as libwebsockets to handle the "nuts and bolts" of WebSockets communications, and 3) my custom application to actually figure out what to do with incoming data. How do all these fit together? Is it common to have a separate web server and WebSocket handling piece, aka a WebSocket server/daemon?
How does my application communicate with the web server and/or WebSockets library to send/receive data? For example, with CGI, the web server uses environmental variables to send info to the custom application, and stdout to receive responses. What is the equivalent communication system here? Or do you typically link in a WebSocket library into the customer application? But then how would communication with the web server to the WebSocket library + custom application work? Or all 3 combined into a single component?
Here's why I am asking. I'm using the boa web server on a uClinux/no MMU platform on a Blackfin processor with limited memory. There is no native WebSocket support in boa, only CGI. I'm trying to figure out how I can add WebSockets support to that. I would prefer to use a compiled solution as opposed to something interpreted such as JavaScript, Python or PHP. My current application using long polling over CGI, which does not provide adequate performance for planned enhancements.
First off, it's important to understand how a webSocket connection is established because that plays into an important relationship between webSocket connections and your web server.
Every webSocket connection starts with an HTTP request. The browser sends an HTTP request to the host/port that the webSocket connection is requested on. That request might look something like this:
GET /chat HTTP/1.1
Host: example.com:8000
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Version: 13
What distinguishes this request from any other HTTP request to that server is the Upgrade: websocket header in the request. This tells the HTTP server that this particular request is actually a request to initiate a webSocket connection. This header also allows the web server to tell the difference between a regular HTTP request and a request to open a webSocket connection. This allows something very important in the architecture and it was done this way entirely on purpose. This allows the exact same server and port to be used for both serving your web requests and for webSocket connections. All that is needed is a component on your web server that looks for this Upgrade header on all incoming HTTP connections and, if found, it takes over the connection and turns it into a webSocket connection.
Once the server recognizes this upgrade header, it responds with a legal HTTP response, but one that signals the client that the upgrade to the webSocket protocol has been accepted that looks like this:
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
At that point, both client and server keep that socket from the original HTTP request open and both switch to the webSocket protocol.
Now, to your specific questions:
How does my application communicate with the web server and/or
WebSockets library to send/receive data?
Your application may use the built-in webSocket support in modern browsers and can initiate a webSocket connection like this:
var socket = new WebSocket("ws://www.example.com");
This will instruct the browser to initiate a webSocket connection to www.example.com use the same port that the current web page was connected with. Because of the built-in webSocket support in the browser, the above HTTP request and upgrade protocol is handled for you automatically from the client.
On the server-side of things, you need to make sure you are using a web server that has incoming webSocket support and that the support is enabled and configured. Because a webSocket connection is a continuous connection once established, it does not really follow the CGI model at all. There must be at least one long-running process handling live webSocket connections. In server models (like CGI), you would need some sort of webServer add-on that supports this long-running process for your webSocket connections. In a server environment like node.js which is already a long running process, the addition of webSockets is no change at all architecturally - but rather just an additional library to support the webSocket protocol.
I'd suggest you may find this article interesting as it discussions this transition from CGI-style single request handling to the continuous socket connections of webSocket:
Web Evolution: from CGI to Websockets (and how it will help you better monitor your cloud infrastructure)
If you really want to stick with the stdin/stdout model, there are libraries that model that for your for webSockets. Here's one such library. Their tagline is "It's like CGI, twenty years later, for WebSockets".
I'm trying to figure out how I can add WebSockets support to that. I
would prefer to use a compiled solution as opposed to something
interpreted such as JavaScript, Python or PHP.
Sorry, but I'm not familiar with that particular server environment. It will likely take some in-depth searching to find out what your options are. Since a webSocket connection is a continuous connection, then you will need a process that is running continuously that can be the server-side part of the webSocket connection. This can either be something built into your webServer or it can be an additional process that the webServer starts up and forwards incoming connections to.
FYI, I have a custom application at home here built on a Raspberry Pi that uses webSockets for real-time communication with browser web pages and it works just fine. I happen to be using node.js for the server environment and the socket.io library that runs on top of webSockets to give me a higher level interface on top of webSockets. My server code checks several hardware sensors on a regular interval and then whenever there is new/changed data to report, it sends messages down any open webSockets so the connected browsers get real-time updates on the sensor readings.
You would likely need some long-running application that incoming webSocket connections were passed from the web server to your long running process or you'd need to make the webSocket connections on a different port than your web server (so they could be fielded by a completely different server process) in which case you'd have a whole separate server to handle your webSocket requests and sockets (this server would also have to support CORS to enable browsers to connect to it since it would be a different port than your web pages).
I was wondering if Foxx/ArangoDB supports Socket.io ? Or would I have to fire a separate Express.js server if I want to use sockets.io ?
closing this QA, found threads below.
https://github.com/triAGENS/ArangoDB/issues/602 - Add support for websockets
https://groups.google.com/forum/#!topic/arangodb/F4geU6_KI8M - ArangoDB and Web Sockets