How to send data from C# to JavaScript/AJAX webpage

Question

Basically, I have a need for a c# server to be able to send data back to an HTML5 webpage which has previously send data to the server. The server is retrieving data from another application and this data then needs to be send to the webpage to be displayed.

This c# server is running on .NET CF 3.5 so websockets are not an option (not supported).

I have seen some suggestions elsewhere but nothing which fits the necessary criteria for this particular situation. Most other implementations seem to work on the basis that the webpage will only be waiting for this data to be sent over.

Any and all suggestions welcome!

How long does it take for the web server to get the data from the other application? — Jason P, Sep 20 '13 at 13:07
Why not just return a JSON response. Easy and flexible. JSON.NET makes this easy to do well. — Gary Walker, Sep 20 '13 at 13:14

score 1 · Accepted Answer · answered Sep 20 '13 at 13:37

1

If websockets are not an option then you are left with Comet.

Client-side you could do something like this :

(function poll(){
    $.ajax({ 
        url: "url",
        success: function(data) { /*display data*/ },
        complete: poll, 
        timeout: 30000 });
})();

Which means an ajax request will be sent every 30 seconds.

This is not as performant as websockets but it works quite well.

answered Sep 20 '13 at 13:37

Romain Meresse

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Thanks for this, seems like the most viable given what I'm able to do. I do have one question though, how would I specify what data to provide to this request on the server side? – Patrick_92 Sep 23 '13 at 08:07

score 0 · Answer 2 · answered Sep 20 '13 at 13:14

Create an .aspx page and remove all the HTML from it. Call it GetData.aspx
In the code behind of GetData.aspx.cs you can receive the POST data from the HTML5 page.
Do work.
Use jquery.
$.post("GetData.aspx",{name: value},function(json){ // put processing instructions here. });

score 0 · Answer 3 · answered Sep 20 '13 at 13:25

There are two ways to do this :

Using a ASP.NET web-page

Create HTML element that calls a javascript function
Inside of the javascript function, use ajax to make a POST to a ASP.NET Web Page (that uses C# as back-end)
Get the returned value in the ajax "success" block.
Use as you wish...

Using a jSON string return

Create HTML element that calls a javascript function
Inside of the javascript function, use ajax to make a POST to a Web Service (that uses C# as back-end), that returns a jSON string.
Use the returned jSON data in which ever way needed.

I personally prefer jSON, as it emulates a data set, and works well with HTML and ajax.

How to send data from C# to JavaScript/AJAX webpage

3 Answers3

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