Internet Toolkit FAQ

G Web Server

• What is the difference between the G Web Server in the Internet Toolkit and the Web Server that ships with LabVIEW 6.1 and later?
  The G Web Server provides full Web Server functionality, including CGI scripting and access rights for files and directories. The G Web Server allows you to make VIs interactive on the Web, regardless of the availability of a client LabVIEW Run-Time Engine. The Web Server that ships with LabVIEW is designed primarily to show front panels and does not support CGI.
  
  Both servers allow you to publish VIs with the Web Publishing Tool. If you publish a VI as a remote front panel, you can interact with the VI across the Web without any additional programming, but you must install the LabVIEW Run-Time Engine on the client machine before you can view embedded remote front panels on Web pages. Refer to the Remote Front Panels Web pages (linked below) for more information about how to use remote front panels.

• Can the G Web Server use CGI scripts or executables written in languages other than LabVIEW (Perl, TCL, shell scripts, compiled code, and so on) to process client requests?
  No, not unless you modify the Server code to allow non-LabVIEW languages. LabVIEW and the G Web Server cannot pass the query string from a client's browser to any CGI routine other than those written in G. Also, the G Web Server cannot access the result of the non-LabVIEW script and pass this result back to the client. You encounter similar limitations when you use the System Exec VI in LabVIEW.

• Can other Web Servers (Apache, IIS, and so on) make use of CGI routines written in LabVIEW? Can these Web Servers make use of compiled CGI VIs?
  No, for reasons similar to those in the previous explanation. Native CGI VIs are unusable by other servers, and compiled CGI VIs present problems during argument-passing.

• Can I embed the G Web Server in an executable and then run this executable on a machine that does not have LabVIEW?
  Yes. In fact, in LabVIEW 5.1 and later, you do not need the Internet Toolkit to serve executables in Web pages. The Internet Toolkit, however, does make it easier to use LabVIEW to achieve CGI, SMTP, FTP, Telnet, and other behaviors.

• When I view a VI served by the G Web Server, can I make the controls interactive?
  You can make the VI interactive with remote front panels or with CGI.
  
  When you use remote front panels, you create a Web page with an embedded front panel that is updated live and can be controlled through the Web page. You do not need the Internet Toolkit to use remote front panels. To create a remote front panel page, choose Embedded in the Web Publishing Tool. Refer to the Remote Panels in LabVIEW Web page (linked below) for more information about how to configure and use remote front panels.
  
  When you use the Snapshot option to publish a front panel, you create an image of the remote front panel. You cannot enter information directly into this image. To provide interactive controls to a remote client who uses a Web browser, you can use a combination of the following elements when you develop the Web page:
  1. An HTML image map: Use this image map to bind elements of the front panel image to CGI VI links that change the corresponding front panel values via VI Server. An HTML image map allows you to control any LabVIEW Boolean or slider and many knob elements and numerics. You do not need to make any changes in the block diagram of the VI being controlled. You must, however, make some small changes to the image map and the callback CGI VI.
  2. HTML form elements: Use these elements in cases where simple clicks on the VI image do not provide the control you require. Examples are rings (which map to HTML form selection elements) and arbitrary numeric settings (which map to HTML form text entry boxes). As in the HTML image map, HTML form elements are processed by CGI VIs that change the values of the front panel elements via VI Server.
  
  Refer to Interacting with VIs on the Web (linked below) for more information about controlling VIs over the Web.

  Internet Protocols Resources
  

  • Where can I find more resources for getting started with the Internet Toolkit?
    Visit the G Server Homepage that installs with the Toolkit.
    1. From LabVIEW, select Tools»Internet Toolkit»Start G Web Server
    2. From your Web browser, browse to http://localhost:88.
  Refer to Getting Started with HTML (linked below) for more information about using HTML.