If you want the Delphi application to interface to c5, you may be able to code within the Delphi application to use an API, such as by Radiant Web in the last paragraph of:
http://www.concrete5.org/developers/open-source/...

Going the other way, for C5 to access the Delphi application, you would need to write an interface between php and the Delphi application, then a c5 block or single page to view use that interface.

If you don't need the Delpi data within c5, another route would be to pull data from it into a iframe on the web page. The user then sees its data within a c5 page, but c5 knows nothing about the actual data.

If the interface does not need to be real time, an alternate route may be by publishing and reading CSV files between c5 and the Delphi application.

Thank you,

I will study that!