ODBC Server Reference Manual

Architecture Overview
HP NonStop ODBC Server Reference Manual—429151-002
2-5
Client-Side View
The function of a gateway is to translate all the objects in the SQL environment (SQL
syntax, data types, error codes, SQL catalog structures, and so on) between the two
sides.
The term “mapping” is used to mean the mechanism of translating an object on one
side (for example, ODBC) to the corresponding object on the other side (NonStop
SQL/MP). The NonStop ODBC Server employs several different types of mapping
schemes.
A HP SQL gateway has two main requirements:
•
The gateway should be transparent. The clients should not be aware of being
connected to a different type of database server. This allows client applications to
run unchanged.
•
The gateway must allow clients to take advantage of major HP product features
including high availability, scalability, and high performance.
These two requirements are sometimes in conflict when a special interface is needed
to use HP product features. For example, to invoke special DML query options in
NonStop SQL/MP, you must issue a NonStop SQL/MP CONTROL statement (which a
DBLIB client or ODBC client does not recognize).
Mapping tasks are not always well-defined and simple. Often, there is a choice of how
a client item is mapped to a NonStop SQL/MP item. An example is table naming, in
which ODBC uses ANSI SQL-like three-part names and NonStop SQL/MP uses
Enscribe file names. The NonStop ODBC Server chooses a fixed mapping scheme
when that is the best choice and provides a configurable scheme when there is no
single best choice.
Client-Side View
The description of the client-side view of the NonStop ODBC Server architecture
covers aspects visible to the client user and client administrator. This includes the SQL
API usage as well as configuration.
Figure 2-5. The NonStop ODBC Server as a SQL Gateway
HP Server
PC or Workstation
NonStop
ODBC
Server
O
D
B
C
Library
P
C
Program
ODBC SQL Environment
NonStop
SQL/MP EnvironmentSQL Gateway
NonStop SQL/MP
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