How is the com.sap.runtime.logon.par implemented?

Question

Hi all
I want to make some changes to the logon.par file such that if the user authentication fails, I have to fire a custom RFC to check if the user exists in that backend system.
First of all, I have no clue about how I am going to implement this. Before jumping deep, I'd like to understand how the existing authentication works. Where does the logon get information about the user credentials?
Any information would be very helpful.
Thanks
J

Answer 1

Hi J,
The logon process is implemented through two layers, of which the one you have referred to is just representing the user interface, whereas the real logon process is implemented through login modules; for the latter see http://help.sap.com/saphelp_sm32/helpdata/de/46/3ce9402f3f8031e10000000a1550b0/frameset.htm
On both layers, you can determin if the logon worked or failed (to be concrete, the login module determins this by its own, whereas in the logon PAR you can determin the result of this process). So both layers could be used to implement this. As the login module is more generic, I would advise to use this, as this is also documented and supported, whereas in the login module you would have to modify the implemented logic (by decompiling or putting your logic into some existing JSP). The internal logic of the logon PAR is not documented (but not hard to understand when checking the JSPs and/or decompiling the code).
Hope it helps
Detlev