private async Task <Task> SetUpSource2()
        {
            source2 = client.GetGrain <IStreamSource>(Guid.NewGuid());
            await source2.InitDeaultOperators();

            var streamId = await source2.Join(userName);

            var stream = client.GetStreamProvider(Constants.FaultTolerantStreamProvider)
                         .GetStream <StreamMessage>(streamId, Constants.FaultTolerantStreamNameSpace);
            //subscribe to the stream to receiver furthur messages sent to the chatroom
            Mock <ILogger> mockLogger = new Mock <ILogger>();

            statefulStreamObserver = new StatefulStreamObserver(mockLogger.Object);
            await stream.SubscribeAsync(statefulStreamObserver);

            return(Task.CompletedTask);
        }
        private async Task <Task> SetUpSource()
        {
            await SetUpTopology();

            var streamId = await source.Join(userName);

            var stream = client.GetStreamProvider(Constants.FaultTolerantStreamProvider)
                         .GetStream <StreamMessage>(streamId, Constants.FaultTolerantStreamNameSpace);
            //subscribe to the stream to receiver furthur messages sent to the chatroom
            Mock <ILogger> mockLogger = new Mock <ILogger>();

            statefulStreamObserver = new StatefulStreamObserver(mockLogger.Object);
            await stream.SubscribeAsync(statefulStreamObserver);

            members = await source.GetMembers();

            return(Task.CompletedTask);
        }