how to interact with client so from webapp??

hi, is there a system to interact with client so from a webapp (if in client browser i can reduce restriction to minimal for my webapp).
like as manage a POST for bancomat, credit card or other.
or like manage serial port of client ??
for example i know that powerbuilder + appeon can make a webapp that when it is launched install an activex that can interact with
client so like as power user

If what you are asking for is SSL, then yes, CGI apps inherit the SSL capabilities of the web server they are running under, and Standalone web apps can be told to listen securely.

That being said, there is no built-in capability for accessing end-user hardware, except for cases where the browser makes it available through javascript. If you wish to create a control like this, you should look at the WebSDK located in the Extras folder next to the IDE.