MX 3.x)

ODBC/MX Client Overview

HP NonStop Open System Services ODBC/MX Client Driver—640328-001

1-4

Connections

Meanwhile, the OSS ODBC/MX Client Driver waits for the reply from the Association

Server.

The following scenarios describe what steps the Association Server perform depending

on configuration and status of the data source.

If the data source is configured and is in a running state, the Association Server replies

to the OSS ODBC/MX Client Driver after authenticating the client driver credentials.

The OSS ODBC/MX Client Driver then connects to the MXOSRVR after receiving a

success reply from the Association Server. User authentication is performed in the

MXOSRVR as required for the SQL Executor. After successful user authentication, the

Association Server assigns one of the available servers to the user.

•

If the data source is configured, but is not in a running state, the Association Server

starts the MXOSRVR and replies to the OSS ODBC/MX Client Driver.

•

If the specified data source is not even configured in the ODBCDSN file, the

Association Server forwards the request to the default data source to connect to

the OSS ODBC/MX Client Driver.

The OSS ODBC/MX Client Driver resides on the NSK-OSS environment while the

server components are spread across NSK-Guardian and NSK-OSS environments.

The Association Server runs in the NSK-Guardian environment. The ODBC Server and

the Configuration Server run in NSK-OSS environment.

Connections

Connecting a Client to a Data Source

Figure 1-2 shows the flow of data among the ODBC/MX components. The OSS

ODBC/MX Client Driver routes the ODBC application requests to the ODBC server.

The communication between the OSS ODBC/MX Client Driver and the MXCS server is

done over TCP/IP sockets as a client/server paradigm. The client/server

implementation maintains an SQL Session context from the beginning of the

connection to the discontinuation of the connection. The messages from a SQL

Session context use the Socket paradigm as the client/server abstraction, which is

implemented using TCP/IP as the interconnect protocol. The IP address and the port

number on which the MXOAS server is running, is obtained from the ODBCDSN file.

The following scenario describes how an ODBC client application connects to an

MXCS server through the Association Server:

1. The ODBC client application sends a connection request to the MXCS service

using the client data source name. The client data source name specifies an IP

address and port number, or NonStop server DNS name that is defined when the

Association Server is started.

2. The Association Server assigns a connection request to an available MXOSRVR in

a process labeled as ‘association’. If the Association Server does not find the