Why signalr

If you have multiple types of messages that you want to send between a server and a client then it is recommended to use Hubs so you don't need to do your own dispatching. You can create an application either using Hubs or a Persistent connection; the only concern is, with Hubs it will be easy to implement. So now we have an idea of what SignalR is so now it's time to proceed to "why". For examle, a dashboard, games and chat applications.

It also provides an API for server-to-client Remote Procedure Calls RPC call, it may be something new for you because most of the time we use a request and response model.

SignalR includes automatic connection management, it provides the facility to broadcast messages to all connected clients or to a specific client. The connection between the client and server is persistent while in HTTP it isn't persistent. So now where to use SignalR:. MyServerFunction " and suppose we have a JavaScript function named "myClientFunction " and we want to call that method from the server so we can call that using "Client. Client id. I know many of you are thinking, what are this connection, hub and server keywords.

So please be patient, very shortly I will explain all these when I will explain both modes persistent and hubs in details. See the following diagram for a better understanding. As you can see, during the RPC using SignalR the hub will be at the server side and the client will have a hub proxy. When the proxy object wants to call a real method of the server, the object implements Ajax style calls to the real method.

Whereas when the server wants to invoke the client method , it is resolved using dynamic types and a special protocol that packages these calls to the server. When an application has a SignalR connection and it wants to send some data to the server, the data is not sent in a raw form, SignalR wraps that data in JSON with other information and wraps it all on the JOSON payload before sending to the server.

I think we have explained many concepts about SignalR. With SignalR, none of these will matter. The code is so simple that it looks almost like you can directly call methods on the server from a client and vice versa. Yes, SignalR works with any types of client and not necessarily web pages. We will cover more of this later. Of course, remote method calling is not what actually happens under the hood.

But all complex implementation details have been abstracted away, so this is not something you, as a developer, will have to worry about. Likewise, the code will be exactly the same regardless of which transport mechanisms you use.

But the code will still look the same regardless. Back in the days, AJAX was a standard way of making partial updates to a web page by asynchronously retrieving some data chunks from the server. This was especially popular when jQuery was used everywhere. AJAX was completely fine when all you needed was to retrieve data from the server when some user-initiated action happened on the web page. But what if you needed to retrieve new data as soon as it becomes available?

With AJAX, you would have to implement some sort of logic that queries the server at regular intervals. This would make real-time applications, such as chat, fairly inefficient and not necessarily fully synchronized in time.

Your client will automatically receive the update as soon as the data is available. In a chat scenario, which is often used as a SignalR example, all participants will receive the message as soon as someone posts it. This uses quite a bit of network bandwidth. Browser-based clients are a common use case for SignalR. However, in real world, not all the clients are browser-based. For example, you may have some IoT devices that communicate with the centralized hub on the server.

SignalR provides an official support for. And, on top of that, any client that supports WebSocket, Server-sent Events or long polling in their pure form can be made compatible with SignalR server. For instance, this online course provides an example of how to use a pure WebSocket client with your SignalR hub. As these transport mechanisms can be implemented in any programming language on any platform, your SignalR client can be written in any programming language on any platform.

SignalR has a number of in-built ways of scaling your application out. This would be extremely difficult if you would have to do it on your own for applications with persistent real-time connection.

For example, if you want to send a message from a particular client to all clients in a particular group, how would you identify all required clients, if they are connected to different nodes in a load-balanced cluster? Learn more.

How SignalR works internally? Ask Question. Asked 10 years ago. Active 3 years, 8 months ago. Viewed 42k times. Can anyone let me know how SignalR works internally in a high level way?

Improve this question. Matheus Lacerda 5, 11 11 gold badges 28 28 silver badges 43 43 bronze badges. Good article about signal r architecture and how it works lostechies. I know its a long time ago but microsoftvirtualacademy. It's very informative. It's pre 2. Add a comment. Active Oldest Votes. SignalR has a few built in transports: WebSockets Server Sent Events Forever Frame Long polling SignalR tries to choose the "best" connection supported by server and client you can also force it to use a specific transport.

JS If you're asking about how the long polling transport works in particular: It sends an ajax request to the server that's waiting asynchronously for a signal to respond. I left some details out about how the client it keeps track of what it saw so it doesn't miss messages Hopefully that answers most of your question. Improve this answer. Regarding how many connections the Signalr is going to support depends on the request limit of the IIS.