RSC/MP Programming Manual

Introduction to Remote Server Call (RSC/MP) Unsolicited Message Service
If a TDP process that fails is running in persistent mode, a backup process takes over.
After re-establishing communications with a TDP, workstation applications can
reconnect and repeat the transaction.
See Monitoring Transaction Calls on page 6-6 for more information about using
RSC/MP with TMF. For information about TMF on the NonStop system, see the
TM/MP Introduction.
See Persistent Applications on page 6-15 for information about persistent applications.
Unsolicited Message Service
Any process running on the NonStop system can send unsolicited messages to
RSC/MP workstations. RSC/MP permits unsolicited messages to be sent to a session
on a workstation, to all workstations, or to a named group of workstations. See
Section 8, Unsolicited Message Service, for more information.
ACS Security
An access control server (ACS) is a user-written process that resides on a NonStop
system and that grants or denies workstation access to the RSC/MP services on a
NonStop system. The ACS can authenticate the user ID and password of the
workstation user each time an RSC/MP session is established, and optionally, each
time a Write or WriteRead occurs. An ACS can use either user-defined or Guardian
IDs and passwords.
When a workstation attempts to begin a session with the NonStop system (when the
application issues an RscBeginSession call), the TDP on the NonStop system
determines whether an ACS is configured for that workstation. If an ACS is configured,
the TDP sends a verification request to the ACS which uses the information contained
in the access verification request (the user ID and password) to grant or deny the
session.
An ACS can also grant or deny access to a particular server class or Pathmon. You
can use the ACS object in the TDP to configure an application-specific ACS. See
Section 9, Access Control Server, for information about configuring workstations to use
an ACS, descriptions of the ACS commands, and sample ACS code.
The use of an ACS process is optional. You can implement your own security
mechanisms, or yo u can choose to have no security checking. The sample ACS that is
supplied with RSC/MP host software authenticates Guardian user IDs and passwords.
You can modify this sample ACS to authenticate your own IDs and passwords.
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