turning labview applications into web applications

[David_Lieberman]

This is just a general query.

I have a significant collection of labview applications.  I would like to "web-ize" some of them, i.e., run the front panel in a browser and the block diagram logic in a server.  There are a lot of articles on the NI web site about this but I find them confusing and often self contradictory.  Many of the articles are quite old and may be out of date.

I have the following specific questions:

1.  I am running Labview 7.1 on a Windows XP machine.  Do all the features I need exist in 7.1 or must I upgrade?

2.  Is it possible to do this simply through configuration options or do I need to modify code or restructure the application?

3.  Can anyone point me to an article or a book with current step-by-step instructions for doing what I want to do?

4.  Are there anything I should be wary of, specific labview features which are problematical?  Performance issues?  etc.

[James_R]

You should be able to enable the webserver in the build specifications of your executable and rebuild all of your .exes and then it should just work

[James_R]

You should be able to enable the activex server in the build specifications of your executable and rebuild all of your .exes

use the web publishing tool to create the webpage for your user to use

note that your user must have the runtime engine installed one any machine that is going to use the webpage

labview has a smaller runtime engine that is for web only and it is only 24mb instead of the 100mb one

on your server make sure the labview webserver is turned on  (tools -> options -> webserver configuration)

[Ben_S]

David,

Hello!

Here is the Documentation from the LabVIEW 7.1 help. It should show you all the steps you need to know in creating Remote Front Panels in LabVIEW 7.1.

• Viewing a Front Panel Remotely Using a Browser
• Creating HTML Documents and Embedding VI Front Panel Images

[David_Lieberman]

Thanks for your help.  I was indeed able to get simple labview apps running remotely in a browser.

However, more complicated applications have problems.  

1.  If an applications generate sounds, the sounds play on the server computer, not the browser computer.  Is there anyway around this?  I thought that using SO Config to choose an appropriate "device" might help but the documentation does not indicate how this might be done.

2.  If you give control to the remote user then you can only have one user dealing with the application.  I suppose you have to have multiple copies of the program running on the server and manage the incoming requests in some way.  And it appears that if you just want the remote user to input variables you have to give him control.  Is that right?

3.  If you have to update front panel graphs often (say, more than two or three times per second) you run into severe performance isssues.  

Is it possible that browser access is not appropriate for my kind of applications and that we have to take a different approach?  Is there any information about creating a browser plug in?  Or must I do cooperating client server labview applications without a browser?  

Any thoughts?

david

[waldemar.hersacher]

Hello David,

1: The VI is running on the server. Just the front panel  is displayed in the browser. All access to devices including files are done on the server. There is no way around that.

2: The standard single licence will give only one user access to the front panel. You can buy and install additional licences. Then more users will have access to the application at the same time.

3: Yes there may be performance problems that the updates will be delayed. I don't know how much optimization was done by NI but in LV 5.1 we made a solution by transfering only the data from the application to the browser and a web page including an Java applet. The Java applet was conneting to the LV application and doing all the data exchange via TCP/IP. The Java applet was also responsible for drawing all in the browser.

[David_Lieberman · Accepted solution]

Just as I feared, but thanks a lot for some straight answers and useful advice.

David