Running Labview 8.2 on Win XP in multi-session mode.

[Sytze]

Good day

Our client is has been evaluating a multisession (or terminal) solution on a single PC. ASome undesired behaviour is experienced when the client tested LV 8.2 on this solution. When user 1 runs LV first, and opens an example in the NI Example Finder, the example opens on user 1's screen. When user 2 runs LV and opens the an example, it will open on user2's screen. This is all normal behaviour. However, while these 2 sessions are running, and user1 now opens another example, the example will open on user2's screen.

My understanding of what the problem is, is that there is an activeX Server fired up when the user opens the example to handle the instantiation of VI's. I am not sure if it is done by the DLL or EXE located in:
    C:\Program Files\National Instruments\Shared\Session Manager\NISessionServer.dll
    C:\Program Files\National Instruments\Shared\Session Manager\NIExternalSessionServer.dll
I have derived this from the programming examples that installs with the solution.

We are trying to help our customer to make savings on PC hardware, and all software seems to run fine, except LabView.My question therefore are:
    1. Does Labview.exe's ExampleFinder fire up NISessionServer.dll/NIExternalSessionServer.dll or something else?
    2. Would the session manager be able to change behaviour? Not sure if the "c:\windows\system32\nisvcloc.exe" windows service has anything to do with this. It has a "-s" parameter (s="server" or "single instance"?).
    3. Can the PC be set up to act as a server to dish up VI's? Would this possibly solve the problem?

The National Instruments Labview version is 8.2.0.4002. The client has an educational license. The multisession solution details can be found here.

I would appreciate any help to get around this problem without a hack if at all possible.

Best regards
Sytze Visser
SoftXpand Representative
South Africa

[griffindore]

Hi Sytze,

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Not sure if the "c:\windows\system32\nisvcloc.exe" windows service has anything to do with this

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nisvcloc.exe is the NI Service Locator. The NI Service Locator "facilitates communication between National Instruments support programs and services, such as the NI Example Finder. These programs and services use local dynamic TCP ports to communicate with each other. NI Services Locator manages these dynamic ports." How does the multisession software handle the TCP ports on the computer? Does it generate simulated TCP/IP for each terminal? It's very possible that this is the root of the problem. Some more information on the NI Service Locator is found below.

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Can the PC be set up to act as a server to dish up VI's? Would this possibly solve the problem?

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You can set up VI Server, but I don't know how the capabilities of VI server could help correct the issue of opening VIs from the NI Example Finder. You can take a look at some information on VI Server below.

Have you see any other peculiar behavior with opening VIs from the LabVIEW Getting Started screen or through the File menu? You can always open examples from the directory labview\examples.

Information on NI Service Locator and NI Example Finder:
What Is The NI Service Locator And How Do I Troubleshoot?
Error when opening NI Example Finder: The NI HelpServer could not be found
NI HelpServer Could Not Be Found When Opening a LabVIEW VI from the Example Finder 
Error: NI Service Locator is Not Running

Information on VI Server:
What Is the VI Server?
Capabilities of the VI Server
Serving Up Powerful Solutions: LabVIEW VI Server Examples 
Programmatically Controlling LabVIEW 
Distributed Computing Using VI Server 

[griffindore]

One more question.

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When user 1 runs LV first, and opens an example in the NI Example Finder, the example opens on user 1's screen. When user 2 runs LV and opens the an example, it will open on user2's screen.

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What happens if you open NI Example Finder on user1's screen (don't open an example), then open NI Example Finder on user2's screen, and then open an example in NI Example Finder on user1's screen? Does the VI load on user2's screen? Basically I'm asking if the VI always opens on the user's screen who opened NI Example Finder most recently. Thanks Sytze.

[Sytze]

Hi Mike

Apologies for answering you so long after the initial question. To answer your question: What you are stating is exactly correct.

In the mean time we have been able to devise a work-around. The client stated that they will hardley ever use the Example Finder. When browsing for an example file by any of the users, this seems not to be a problem at all, or when you make one of the examples a Favourite, then there is not problem when picking the example from the favourites list.

the problem seems to be located at the example finder application. In my yesteryears of programming I remember that ActiveX servers behave in the same fashion. The ActiveXServer keeps a reference count (number of people connected, or requesting an object), and when the last reference(connection) is terminated, then the ActiveX Server (exe) will terminate. So the ActiveX server instance will be resident on the user session that last invoked the ActiveX exe.

I hope this helps, and maybe this can be considered in future releases, not to make the Example Finder behave in this way. But OK, if the example finder is not being used, there is no problem. I will assist in any other questions that you may have.

The multisession application that we tested is called SoftXpand. You can download an evaluation version from here (http://www.miniframe.com/Files/LinksFiles/SoftXpandTrial.exe) and check it out your'self. It runs for 80 hours and should be enough for you to test NI.

The principle behind the solution is to help educational institutions (and others) to cut down on hardware cost, power consumption and maintenance by using one PC with multiple screens, keyboards and mice to run independent workstations from one box. In South Africa especially, this is an excellent solution, and obviously beneficial in this case for NI to get more students to access your product without the loss of license revenue. Win-win for all.

I know a bit about electronics, but boy, your software seems to be an engineers' Utopia!

Best regards
Sytze Visser
sytze@thinsolv.com
Let your one PC work for multiple users without compomising performance.
4 users, 4 screens, 4 keyboards, 4 mice, ONE PC - doing more with less...with SoftXpand.
No politics here: "One PC, four employees...where'd the cost go?"

[griffindore]

Hi Sytze,

I think it would be very beneficial to track down the cause of this problem. In order to do so I think it is important to know how the multisession software handles TCP ports on the computer? If this is something that you'd not like to discuss on a public forum, then I'd suggest calling into support by calling 1-866-ASK-MYNI.

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To answer your question: What you are stating is exactly correct.

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I assume that this means that the VI always opens on the user's screen who opened NI Example Finder most recently.

It sounds as if the NI Example Finder is only maintaining the TCP connection to the most recent connection since we are always going over the same TCP port to establish that connection. That makes sense from our standpoint, but the multisession application would have to somehow handle that single TCP port and service to act as if it were individual for each session. I think it would be great to get this issue resolved because NI Example Finder is not the only application of ours that is communicated with via TCP. Thanks Sytze.

[Sytze]

Hi Mike

I  will contact Technical Support for SoftXpand. I think that you may be on to something regarding TCPIP and ports. We have not yet tried to load a proxy server with the solution to ensure IP uniqueness per user.

Will be incontact soon.

Best regards
Sytze Visser
sytze@thinsolv.com
Let your one PC work for multiple users without compomising performance.
4 users, 4 screens, 4 keyboards, 4 mice, ONE PC - doing more with less...with SoftXpand.
No politics here: "One PC, four employees...where'd the cost go?"

Message Edited by Sytze on 04-25-2008 11:09 AM