LabVIEW Toolkit to acces data using Web Browser

[JCNT]

Hi smercurio,

Does it mean that I don't have to be worried about runtimes or licences in the computer client? Great! However, I could get data using the CGI tools but how should I display the data in a waveform graph? Should I make a Web appl?

Thanks so much and I will be waiting for you reply

JC

[smercurio_fc]

As I've stated before, if you don't use an embedded object then the only thing that a browser understands is HTML. For the example you provided this means you need a web page that has the following things on it:

• textbox for entering a start date
• textbox for entering an end date
• an image that is the graph
• a "Submit" button

Note that these would all be standard "web" elements, not LabVIEW elements.

Clicking the "Submit" sends an HTTP GET request to the server. The server needs to handle the GET request and send HTML back to the client. One way to accomplish this is to essentially create a LabVIEW app that the web server can call with the start/end dates and the LabVIEW app simply writes the graph image to disk. The server returns an HTML page to the client that includes an <IMG> element pointing to the image that the LabVIEW app created. The LabVIEW app can be an executable or a DLL. Your call. In fact, for this you would not need the Internet Toolkit. The web server would, however, require the LabVIEW Run-Time Engine in order to actually run the LabVIEW code.

The advantage of the above suggestion is that you don't need to have an additional web server (the LabVIEW web server). You already seem to have a web server in your configuration so you just need to create the web page using your favorite server-side scripting language. The content is actually not complicated.

A completely different suggestion: If all you want to do is to display data in a graph then you can implement a non-LabVIEW solution for the web. According to your configuration the data is stored in a database. Well, you can create web pages that get data from databases based on user inputs pretty easily, and you don't need LabVIEW to do that. If you want to display data in a graph then you can probably use a server-side control to create the graph and generate an image from it. For example, for .NET there's ZedGraph.

[JCNT]

Due to I don't know anything about scrip languages, would you please tell me where I could find information about that? Another question is which function I should use in LabVIEW to receive the request of the Web page and how to send the information to it?

The figure that I provided was just a basic example because the original have tab controls, trees, and some buttons which determines which data are going to display.

JC 

[smercurio_fc]

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"Due to I don't know anything about scrip languages, would you please tell me where I could find information about that?"

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I can't point you to a specific place for web scripting languages because it's dependent on what kind of web server you're running and on what platform. There are several available, including ASP, ASP.NET, PHP.

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"Another question is which function I should use in LabVIEW to receive the request of the Web page and how to send the information to it?"

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You misunderstood what I was saying. There is no function used in LabVIEW. Using the method I described the LabVIEW app/DLL doesn't know anything about being called from a web page. It has nothing to do with receiving HTTP. It's just being called with the values of the controls being set by the caller. If you build an EXE it can be command-line arguments. If you build a DLL then it would be function arguments.

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"The figure that I provided was just a basic example because the original have tab controls, trees, and some buttons which determines which data are going to display.

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Well, that's definitely more complicated, and while you can create a web page to do that at some point you really need to ask whether it's worth it, considering you have no experience in designing or writing a script-based web page. What you want to do can be easily accomplished with the embedded control, but as has been noted that requires the Run-Time Engine. You will need to determine the cost-benefit ratio of going down the path of creating your own web interface for calling your LabVIEW app as opposed to just using the embedded control. I can't provide that analysis for you.

[JCNT]

Hi smercurio,

With all the information that you provided me I have a better understanding about my problem. I have just to make a decision  which depend on the cost-benefit as you said.

Thank you very much for all your support.

Best regards,

JC