Sending Html5 SSE to specific clients

Question

1.00/5 (2 votes)

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ASP.NET

Javascript

HTML5

i want to send the server event(push notificaton) to specific users(based on their usernames) any idea how to do it?

Posted 16-Jun-12 8:19am

agha_ali22

Updated 16-Jun-12 21:46pm

v3

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bbirajdar 16-Jun-12 16:08pm

Not clear....

agha_ali22 17-Jun-12 3:13am

i have an aspx page which send notification to connected clients (connected by Html5 event source) and now i wanted to send notification to a specific username which i have saved in session or in some scenario i want to send notification to a group which is also saved in session as groupid(admin(1),manager(2),e.t.c)

2 solutions

Solution 1

HTTP works in disconnected mode. The server does not remember its clients.

You should implement server polling from client side scripting

http://api.jquery.com/category/ajax/[^]

http://stackoverflow.com/questions/3583203/server-polling-with-javascript[^]

http://stackoverflow.com/questions/1155245/javascript-poll-server-will-this-cause-a-stack-overflow[^]

Posted 17-Jun-12 20:36pm

bbirajdar

Comments

agha_ali22 18-Jun-12 5:24am

what i want is to notify a group of clients that something happened , now i can notify all the connected clients what i want is notify a group

Here is the Default.aspx file<script type="text/javascript">

window.onload = function () {
if (window.EventSource == undefined) {
document.getElementById('targetDiv').innerHTML = "Your browser doesn't support Server Side Events.";
}
var source = new EventSource('SSEHandler.aspx');

source.onopen = function (event) {
document.getElementById('targetDiv').innerHTML += 'Connection Opened.<br>';
};

source.onerror = function (event) {
if (event.eventPhase == EventSource.CLOSED) {
document.getElementById('targetDiv').innerHTML += 'Connection Closed.<br>';
}
};

source.onmessage = function (event) {
$("#targetDiv").append(event.data);
};
}
</script>

<div id="targetDiv">
</div>

and here is 'SSEHandler.aspx' cs

protected void Page_Load(object sender, EventArgs e)
{

Response.ContentType = "text/event-stream";

while (true)
{
if(checksomecondition())

{
Response.Write(string.Format("data: {0}\n\n","Hello"));
Response.Flush();
}
i++;
System.Threading.Thread.Sleep(3000);
}
}

now i want to send the response to the desired user. this can be done by long pooling but i want to do with html5 Server sent event any idea?

bbirajdar 18-Jun-12 6:02am

The reverse is not possible because of the stateless architecture of the HTTP. Polling is the only option as far as I know..

agha_ali22 18-Jun-12 6:40am

Server Side Events is a more basic way to send one way data from the server to the client. It works like a long request from the clients JavaScript function where data can is returned bit by bit during the response and each time a bit is returned a JavaScript event is triggered.

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D Hinterlang · Accepted Answer · 2013-04-03T23:19:00

SSE broadcasts to all open connections. Include your group in your JSON stream and do the group check in the javascript.

Note : This is not a secure method, do not use sensitive data this way, since everyone gets every single message, it'll only be handled by your javascript differently.

Example :

Server-Side C#

C#

string JSON = "data: {'IntendedFor' = 'AdminClerks', 'Message' = 'You\'ve got a server event'}";
Response.Write(JSON+'\n\n');
Response.Flush();

Client HTML

HTML

<input id='myGroup' type='hidden' value='AdminClerk' />

Client Javascript

JavaScript

var myGroup = document.GetElementById('myGroup').value;
var source = new EventSource('<insert url="" here="">');
source.onmessage = function (e) {
  var myJSONResponse = JSON.parse(e.data);
  if (myJSONResponse.IntendedFor == myGroup)
    alert("You've got a server event");
}