public Task Add(string connectionId, string groupName) { if (connectionId == null) { throw new ArgumentNullException("connectionId"); } if (groupName == null) { throw new ArgumentNullException("groupName"); } var command = new Command { CommandType = CommandType.AddToGroup, Value = CreateQualifiedName(groupName), WaitForAck = true }; return _connection.Send(connectionId, command); }