SignalR just terminate single long running task among many within a specific client - signalr

Question

I have been searching for right methodology to achieve this scenario without any luck.
This is regarding multiple long running tasks to a specific client, let's say there has been three tasks running in single client asynchronously at time t0, t1 and t2.
Clients.Client(TheConnectionID).Task1(GUID1) //at t0
Clients.Client(TheConnectionID).Task1(GUID2) //at t1
Clients.Client(TheConnectionID).Task1(GUID3) //at t2
Later, from server(Hub) user's request was sent to Task started running from t1.
Server know the GUID sent for the Task1 started at t1.
Clients.Client(TheConnectionID).Cancel(GUID2) //To cancel task started at t1
I tried to pair the GUID with CancellationToken and somehow throw operation cancelled exception with no luck. Somehow the thread where the exception thrown seems not the correct thread where t1 Task is running..
Please someone shed me light what I am doing wrong or if this is never possible with signalr invoke methods on client side.

Answer 1

Answering my own question seems awkward but I think this could be valuable to whom in similar situation. Also this solution with my observations could bring further discussion shedding some light.
Here is what I have found:
Based on the invoke of user request:
Clients.Client(TheConnectionID).Cancel(GUID)
You can do a handling of cancellation routine per the specific task in the client side:
try
{
concurrentCTSDictionary.TryGetValue(GUID, out CancellationTokenSource cts);
cts.Cancel();
}
The actual event handler, which was running task and token fed:
async Task SomeMethodUserWantCancel([]args, CancellationToken ct)
{
// Option #1 or #2
}
Now here is what gets a little strange,
When I used option #1, the thread containing throwing exception was not running on the same thread where actual task was running and task kept running even when exception thrown. That's why I posted question to stackoverflow.
Option #1:
using (var ctr = ct.Register(async () =>
{
ct.ThrowIfCancellationRequested();
}))
{
while (longtaskrunning)
{
await longTask();
}
}
Option #2 worked and solved my issue:
while (longtaskrunning)
{
ct.ThrowIfCancellationRequested();
await longTask();
}