ASP.NET SignalR Hubs API Guide - Server (C#)
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When I sit down to talk to people about SignalR, a common discussion we have signalr options around transports and what the difference between them are. While SignalR gives signalr options the flexibility to choose your signalr options transport, it is often a better bet to simply allow the library to choose for you.
There are two pieces of the puzzle that need to be evaluated before a transport is chosen. The client and the server.
Anytime the server needs to send a message, the existing connection can be used. However, when a connection signalr options used, signalr options connection is closed. In order signalr options continue communicating with the server, a client will need signalr options reestablish the connection. In a best case scenario, the server is continuously sending data, so a connection is always reestablishing. Worse case, signalr options connection stands open for up to two minutes default timeout on most browsers.
The process of continuously opening and closing signalr options can be a bit of a strain on the server. Long polling works well on old browsers, including some browsers which should have died ten years ago. This is the final fallback position if no other acceptable transport can be used. When a connection is established with FF, a hidden Iframe is created on the page.
However, signalr options page loaded into the Iframe is special. Signalr options connection will never closed. Since the connection remains open forever, the server can use it to continuously send new script. These scripts are loaded and executed on the parent page.
SSE is a server to client communication protocol developed in the Netscape days. It creates an object called an EventSource, which is a pipe from the server to the client. Anytime the server needs signalr options send data, the EventSource pipe can be used.
Just as Forever Frame, if the client needs to communicate back with the server, a traditional AJAX call will need to be made. There is nothing better than WebSockets. When a WebSocket connection is made, there is a one-to-one connection between the client and server. Both are capable of communicating on the existing pipe. Of course, you are technically signalr options by the browser and server being used for a connection. Firefox, Chrome, and Safari generally have no problems.
IIS7 did not have support for WebSockets. As you look at the various transports available, you should start to appreciate what SignalR is doing for you underneath the scenes.
What would happen if you had to implement all these different scenarios yourself? I really appreciate you taking the time out of your schedule to read this post. I like to keep my friends updated on new articles and also spawn discussions here and there. If you'd like to keep in touch, please subscribe below. And I promise, no more than 1 email per week if even that. How does SignalR determine which transport to use?
A simple way signalr options explain the process is this: Long polling, for you. This works well IF: Try Forever Frame IE browsers. What are the pros and cons of each transport type? Long Polling Long polling is a game of hurry up and wait. Any client to server communication needs to be done the traditional way, via AJAX calls.
Pulling It All Together As you look at the various transports available, you should signalr options to appreciate what SignalR is doing for you underneath the scenes. Let's keep in touch I really appreciate you taking the time out of your schedule to read this post.