[vistavrtoolkit-general] Fwd: Re: Problem with VistaMsgChannel - performing to slow

[Dominik R. <ra...@vr...>]

Hi

I forgot to reply to the lists, so here a Fwd of my reply.

Regards
   Dominik

-------- Original-Nachricht --------
Betreff: 	Re: [vistavrtoolkit-general] Problem with VistaMsgChannel - 
performing to slow
Datum: 	Wed, 07 Dec 2011 21:34:13 +0100
Von: 	Dominik Rausch <ra...@vr...>
An: 	Mat...@dl...



Hi

The concept you used is mostly suited for communication of external 
applications with the Vista application, as is done in the AliceBobDemo.
When trying to distribute events in cluster mode, there are better 
alternatives (especially since one usually only wants to send data to 
the slaves, but not receive answers).
Depending on your application, you have different options:

Directly use the MsgPort provided by the VistaSystem (as shown in the 
AliceBobDemo) to send external events to the Vista-App, which triggers 
an event on both master and slaves.
However, if I understand you correctly, you want to trigger the actions 
from within the main vista app.

You can emit your own VistaExternalMsgEvent, which is then not only 
Handled on the master, but also transmitted and processed on the clients.
Just create one and set a VistaMsg with a Custom MsgTicket, and do the 
processing in the VistaEventHandler::HandleEvent callback.
This is probably the easiest way to go, but has one drawback: there may 
be ordering issues when emitting the ExternalMsgEvent from a 
SystemEvent-callback, since on the master the event is emitted and 
handled immediately, but on the slaves this happens after the system 
event that is currently being processed. Keep that in mind, and try to 
emit the event right in the end of your custom SystemEvent-Handling

You could also use the DataTunnels and use DataLaVista to sync the data 
- however, this is probably a little overkill. Plus, I'm not too 
familiar with DLV, so I can't help you much here.

Another alternative was added with the recent merge-back of the 
CLUSTERMODE_TEST branch (not in 1.12, but in trunk).
It allows to request a VistaNetworkSync object from the ClusterMode, 
which allows syncing data (i.e. transmitting it to from master to 
slaves) in a way that you don't have to care about cluster layout etc.

Hope this helps :)
Regards
   Dominik


Dipl.-Inform. Dominik Rausch

Virtual Reality Group, RWTH Aachen University
Lehrstuhl für Informatik 12 (Hochleistungsrechnen)

   Rechen- und Kommunikationszentrum
   Seffenter Weg 23, 52074 Aachen
   Tel. +49 241 80 29732
   ra...@vr...
   www.vr.rwth-aachen.de


Am 07.12.2011 19:06, schrieb Mat...@dl...:
> Hi all,
>
> I encountered a Problem regarding the TCP connection.
>
> I am using Vista 1.12.0 from the tag.
>
> My intention is to create a master/slave setup where the Master is 
> sending data to the slave via TCP.
>
> The Master is establishing a TCP connection using the 
> "VistaConnectionIP" and using a "VistaMessageChannel" with this 
> connection to transfer the data to the slave.
> The Data is written in a "VistaPropertyList" and transfered using the 
> "WriteMsg (int iMethodToken, const VistaPropertyList 
> &rList,VistaPropertyList &rAnswer)" method.
> The order to send the Data is triggered by an InteractionEvent on the 
> Master's input devices (60+ events/second).
>
> The Slave on the other hand is using the MSGPORT to enable the master 
> to connect to him. The messages ( VistaCommandEvent's) are parsed by a 
> Class the is derived from the "VistaEventHandler".
>
> The communication struct is based on the VistaDemo 17 (Alice, Bob).
>
>
> The problem:
>
> The master is blocked by the "WriteMsg" method. Without this messaging 
> the master uses to have ~160 frames per second, but when the Messaging 
> is enabled this is reduced to 10 for 1 slave, 5 for 2 slaves and 3.3 
> for 3 slaves. Therefore the Slaves also receive the reduced amount of 
> events.
>
> I have already tried the following things:
>
> - Disable the blocking of the connection:
> This has lead to the slaves getting only 5 Events and then releasing 
> the port, so that the connection collapsed. The master went back to 
> ~160 frames/second, but the slave did not receive any more messages.
>
> - Disabled setting the answer of the slave
> Did not chance anything.
>
>
> Have you any suggestions to avoid this performance loss?
>
> Thanks for your help.
>
> Best regards
> Matthias
>
>
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