ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-15
Major Components
This subsystem handles all communication with the client workstation and
manages the NonStop ODBC servers. To avoid costly process start-ups, SCS
maintains server classes of previously started NonStop ODBC servers in an
available list. Each client connection results in the creation of an association
between the client network ID and an assigned available NonStop ODBC server.
SCS passes the connection message to this server for authentication and
subsequently passes all messages in both directions until the connection is
terminated. SCS uses SCF for reporting run time performance data and EMS to
report internal state changes as well as diagnostics.
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NOSUTIL
This utility process performs several services. It is a server process initiated by any
of the processes, NOSCOM, SCS or NonStop ODBC server, to customize NonStop
SQL/MP catalogs for NonStop ODBC Server use and to manage NonStop ODBC
Server mapping and configuration tables. NOSUTIL can also be called by a
NonStop ODBC server to support create database and drop database commands.
NOSUTIL is also called by SCS to acquire initial server class definitions and
periodic updates to server class configurations. Additionally, NOSUTIL provides
name-mapping service to SCS at connection time to determine which server class
is to be used.
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NOSCOM
HP client interface used to issue NonStop ODBC utility commands. It starts a
NOSUTIL process and sends utility commands and receives result data or error
messages. NOSCOM also provides the common CI commands of HELP, FC,
HISTORY and LOG.
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SPELIB
This call library is provided by the NonStop ODBC Server for Pathway server class
programs that implement stored procedures. The functions in SPELIB are used to
decode the stored procedure calls and to encode results to be returned.
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Mapping and configuration data
This data is stored in several NonStop ODBC catalog SQL tables. The NonStop
ODBC Server maintains SQL tables to map client names to NonStop SQL/MP
names and to help provide SQL catalog tables for ODBC and DBLIB clients. There
are also SQL tables to hold server-side attributes of users. SCS is also driven by a
SQL table that defines the server classes.
Each SCS is identified by a network address (such as an IP address) to clients. The
client’s ODBC.INI file or DBLIB configuration file is configured with the appropriate
address (for DBLIB, SCS is like a SQL Server). You can think of one SCS, together
with the components in Figure 2-15, as one NonStop ODBC server system.
A NonStop server might contain multiple SCS processes. Each is free to access any of
the customized catalogs registered in its designated system catalog mapping table,
ZNSDB. Figure 2-16 shows three clients connecting to NonStop ODBC Server
databases through two SCS processes. Clients 1 and 2 use the top SCS and are