CODEWITHSUNDEEP
signalrbroadcasting
Vipul Patel
Vipul Patel

Reputation: 69

How SignalR broadcast the messages?

Have started using SignalR. Would like to clear few queries regarding how SignalR have implemented broadcasting basically how server is able to initiate the Communication ?

1> In normal scenario whenever we request for a let say .aspx page, the server renders the page and returns the reponse back to the client and the things is done

But How SignalR is able to continously able to execute in Background/Async in case of Ticker demo available on the ASP.net site.

I googled little bit and found IRegisteredObject is one of the way where the the object which need to be excuted continously need to register with HostingEnvironment but for that the class have to implement the IRegisteredObject interface but in case of ticker demo none of the class implements the IRegisteredObject interface.

Am I mssing something over here or SignalR uses totally different technique ?

Upvotes: 1

Views: 508

Answers (1)

N. Taylor Mullen
N. Taylor Mullen

Reputation: 18301

SignalR utilizes 4 transports through which it handles data from the server. Only one transport is used at a time but SignalR has 4 to ensure server/client communication on a wide variety of devices/browsers. Here's the transports and a short technical description:

  1. Long Polling, to receive data it uses an ajax request whose response is not released until there is data available on the server, once the server returns data on the held onto response the client then creates another request and waits for the next batch of data. To send data it creates a second ajax request.
  2. Forever Frame, uses iframes through which the server pushes down javascript text which is then executed in the iframe, the iframe then propagates the execution up to the parent page which then handles the data. To send data SignalR uses ajax requests.
  3. Server Sent Events, uses the EventSource object. Supported in nearly everything but IE. The EventSource object opens up a one way pipe through which the server can pump data through, allowing the client to receive data in real time. To send data SignalR uses ajax requests.
  4. Web Sockets, uses the built-in browser WebSocket object which opens up a single, bi-directional channel through which data can be received and sent.

That's the essence of each of SignalR's transports, you can see an hour presentation in which David Fowler and Damian Edwards create a Lite version of SignalR here. It essentially highlights how SignalR works under the covers.

Upvotes: 3

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