ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-29
NonStop ODBC Server
As the NonStop ODBC server obtains results (such as rows fetched for a cursor), it
starts sending the results to the client. Based on this behavior, the client library can do
a variety of things: it could wait for all results before returning to the application, it could
return results as available, it could even support asynchronous calls. The NonStop
ODBC/MP driver returns a result row as soon as it receives it from the NonStop ODBC
server.
When a request arrives, the NonStop ODBC server uses one or more READ
operations on the interprocess communication (IPC) with SCS to receive the entire
request, which is then decoded. A SQL request can be one SQL statement or several
(called a batch in TSQL; batches are supported for DBLIB clients only).
Each statement is parsed, translated, and placed in a list of statement objects. There
are actually two parsers, one for Transact-SQL and one for CORE SQL; the choice is
based on the mode in which the NonStop ODBC server is running. The parser builds a
parse tree in memory; the translator traverses the tree and makes changes.
Figure 2-24. Inside the NonStop ODBC Server
IPC with SCS
EncodeDecode
Name
Mapping
Parse
Translate
SPE
Execution
NonStop
SQL/MP
NOSUTIL
(Create Database)
Pathway
Servers
Result data
Return status
VST028.vsd