ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-28
NonStop ODBC Server
When SCS creates the NonStop ODBC server, the server initializes itself then waits
until client A connects. When A disconnects, the server holds its cached information.
Client B then connects for a session. Finally, SCS stops the server, perhaps because
there are too many idle servers in the server class.
The NonStop ODBC server handles each SQL request fully before processing the next
one. Processing a request involves reading the entire input message (perhaps several
packets), performing all the actions required, and returning the results to the client
(again, perhaps several packets). This is illustrated in Figure 2-23.
Figure 2-22. Life Cycle of an NonStop ODBC Server Process
Figure 2-23. Processing an SQL Request
SQL Activity
Timeline
SCS
creates
server.
SCS stops
server.
Client B
disconnects.
Client B
connects
.
Client A
disconnects.
Client A
connects
.
SQL Activity
Initialize and
add to free pool
of servers.
NonStop ODBC server retains
cache of configuration
information and SQL
statements.
Connection is extra
fast if Client B uses
same configuration
as Client A.
IdleBusyIdleIdle Busy
VST026.vsd
Timeline
Next SQL
request
arrives
Last message
sent to client.
First message
with results
sent to client.
NonStop
ODBC Server
processes request.
SQL request arrives
from client (via SCS).
Waiting
Processing Request
Waiting
VST027.vsd