Listener create SERVICE with name xxxx.
and When u try to check listener using:

tnsping xxx

where sid name = xxx, and real database for this sid doesn't exists,
then listener say to u --> OK! SERVICE (NOT SID) for sid xxx ESTABLISH !!!
(this isn't the same thing as EXISTS)
<--- THIS IS STATIC REGISTRATION OF SEVICES (NOT SIDs)

listener will try to create server process (or connect to dispatcher) ONLY
if u execute usual CONNECT command from a client mashine.

Another thing :
Doesn't matter u declared REAL INSTANCE in listener.ora file or not,
listener will use DYNAMIC REGISTRATION procedure for ESTABLISH this
instance in service list.


[Edited by Shestakov on 08-20-2002 at 12:12 PM]