Extended stored procedures are implemented by an Open Server application called XP Server, which runs on the same machine as Adaptive Server. Adaptive Server and XP Server communicate through remote procedure calls (RPCs). Running ESPs in a separate process protects Adaptive Server from a failure resulting from faulty ESP code. The advantage of using ESPs instead of RPCs is that the ESP runs in Adaptive Server the same way a stored procedure runs; you do not need to have Open Server to run the ESP.
XP Server is automatically installed when Adaptive Server is installed.
XP Server must be running for Adaptive Server to execute an ESP. Adaptive Server starts XP Server the first time an ESP is invoked and shuts down XP Server when Adaptive Server itself exits.
On Windows NT, if the start mail session configuration parameter is set to 1, XP Server automatically starts when Adaptive Server starts.
