[Lazarus] fpWeb long process progress

[Michael Schnell]

AFAIK, a web application uses the plain old standard mechanism, a web 
server uses to work with a CGI application. it start the application and 
when same ends, the web server retrieves its output and sends it to the 
browser. So the web application just does not live long to be able to 
wait for anything.

To create a longer living web enabled process it takes a lot more effort.

You can try several approaches:

  - purely propriety: Use a second process (a long living daemon) and 
have the web application communicate with same (e.g. via TCP/IP or Pipe)
  - fast CGI: here the (Apache) Web Server does exactly this 
communication on it's own account
  - ISAPI: here a (Microsoft) Web server communicates with a DLL

My colleagues do a combination of (1) and (3) with one of their (Delphi) 
project very successfully:

They created a very simple ISAPI DLL (using RemObjects to do the ISAPI 
communication)

They created a Windows service  and used RemObjects (using the "Windows 
Message" transport) to have the ISAPI DLL communicate with the service.

(RemObjects is a commercial product that is specified to work as well 
with Delphi as with FreePascal.)

-Michael