Sending Html5 SSE to specific clients

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?