On a pure Web approach, there are two ways of architecturing a LabVIEW
application: the server-push approach and the client-pull approach.
1- Server push approach
The server-push approach is based on a CGI process (CGI means common
gateway interface) that runs under the webserver. This CGI process
dynamically builds a GIF file (or is it a JPEG, anyway, an image) that
is sent into a HTML page to the browser. Since this image is constanltly
(re)built, the image is seen as the VI.
My questions are: how is the CGI process linked to the data? Can this
data should be in an ASCII format? Can it be in a database format? Can
this CGI process be linked with another machine (the acquisition
machine) via datasockets? Can t
his CGI process be ran under HTTP server
than the BridgeVIEW server (i.e. Netscape Entreprise server or IIS for
exemple)?
2- Client pull approach
The client-pull approach is based on a JAVA applet that is sent to the
browser. The applet then opens a connection with the server and the data
is sent to the applet. Finally, the JAVA controls (AWT) are updated in
real-time.
My question are: what is the process is listening (and speaking) on a
dedicated port to the applet? Is it a servlet? A CGI process? Something
else? And once again, what is the connection between the server process
and the data?
TIA
Jacques Brisson
Hydro-Quebec
Montreal
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