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

Client Data Sources

Client data sources are used for ODBC/MX connections and reside on a client workstation. Each

client data source is a logical name that identifies the attribute values used to connect to the MXCS

service and defines some local behavior for the connection. Use the Microsoft ODBC Data Source

Administrator to add, configure, and remove ODBC/MX client data sources.

Connections

Connecting a Client to a Data Source

Figure 2 (page 14) shows the flow of data among the client and server components.

The MXCS association server starts and manages the MXCS SQL servers associated with MXCS

data sources in the NonStop system. When a client requests a connection to a data source, the

association server also associates the client with an available MXCS SQL server. The following

scenario describes how a client application connects to an MXCS SQL server through the association

server:

1. The client application sends, via an API call, a connection request to the MXCS service. The

client specifies an IP address or the NonStop server Domain Naming Service (DNS) name

and port number that is defined when the association server is started up. ODBC Clients

connect to MXCS by connecting via a client data source, which contains the connection-specific

information. JDBC clients specify the name of the Server Data source and other connection

details as part of the connect API call.

2. The association server grants the connection request and associates the client application with

an available MXCS SQL server for the data source. (If the association server does not find the

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

all available MXCS servers already have a connection, the request is denied.

NOTE: If a client tries to connect to a server data source that is stopped, MXCS rejects the

connection.

3. The client application sends a connection request to the MXCS SQL server that was assigned

by the association server. If the user information is not valid, the connection is rejected.

NOTE: Starting with SQL/MX Release 3.2 or later, connecting to a data source takes less

time.

4. When the client application disconnects, the MXCS SQL server notifies the association server

that it is available for connections from other clients and returns to the server data source pool.

Connections 13