MX Release 3.2.1 (H06.26+, J06.15+)

successful user authentication, the Association Server assigns one of the available servers to the

user. If there are no more servers available, it returns an error.

• 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 requested data source

name, it assigns a server associated with the default data source.

3. The ODBC client application sends a connection request to the MXCS server, which is assigned

by the Association Server. If the user information is not valid, the connection is rejected.

4. When the ODBC client application disconnects, the MXCS server notifies the Association

Server that it is available for a new connection from other ODBC clients and returns to the

data source server pool.

An ODBC client application can connect to the default data source without creating an MXCS SQL

server data source.

16 ODBC/MX Client Overview