Configure the WebSphere Application Server product so that it can
use both Version 8.1 clients. In cases where multiple Version
8.1 clients are installed on a WebSphere Application Server Version 5.x machine,
and you intend to use two or more clients in your Version 6.0.x Application
Servers, you can set DB2 environment variables within each application server,
instead of setting them globally as shown previously.
DB2 UDB Version
8 uses a new client and server communications mechanism that is based on distributed
relational database architecture. While the new communications mechanism provides
a number of advantages, it also introduces restrictions on the communications
capability between DB2 Version 7 and Version 8 products.
Because a
number of restrictions exist when using a Version 8 client to communicate
with a Version 7 server, this configuration is not recommended. However, a
Version 7 client can access a Version 8 server without difficulty.
If
you have a WebSphere Application Server application that accesses both a Version
7 server (on a WebSphere Application Server Version 5.x machine) and a Version
8 server (on a WebSphere Application Server Version 6.0.x machine), use the
DB2 Version 7 client on the WebSphere Application Server Version 5.x machine
to access both the Version 7 server and the Version 8 DB2 server.
WebSphere
Application Server Version 6.0.x supports DB2 Version 8.x but does not support
Version 7.
You can choose to use a Version 7 client to access a Version
7 server, and use a Version 8 client to access a Version 8 server. This choice
results in two versions of DB2 clients.
When you use a Version 7 client
(on a WebSphere Application Server Version 5.x machine) to access a Version
8 server, you must explicitly bind Version 7 packages to the Version 8 server.
To bind packages in the Version 7 client environment, make a connection to
the Version 8 server and bind both the
db2cli.lst and the
db2ubind.lst files.
For example:
cd /home/db2inst1/sqllib/bnd
db2 connect to v8server
db2 bind @db2cli.lst
db2 bind @db2ubind.lst
db2 terminate
One WebSphere Application Server node can support
multiple application server instances. Each application server is essentially
a single Java runtime environment, which is one Java virtual machine (JVM).
Each JVM can have its own set of environment variables that differ from other
application server instances.
You can set DB2 environment variables
per application server instance to let each application server instance communicate
with a single DB2 client instance. The client instance can have multiple databases
cataloged.
Such a configuration means that you cannot have one application
server instance communicating with both a Version 7 client and a Version 8.1
client. However, you can create another application server instance to communicate
with a different DB2 client.
Match the appropriate data source to the application component.
When mapping a data source to an application component, do not mismatch
data sources from different DB2 client instances.
For example, if you
set the server1 application server instance to run in the DB2 Version 7 client
instance, server1 application components can use only data sources defined
under the same Version 7 client JDBC driver.
WebSphere Application
Server Version 6.0.x supports defining a JDBC provider on different scopes:
cell, cluster, node (the default) and server. If you have different DB2 client
instances, consider defining them on the server level instead of on the node
or cluster level. Server level definitions avoid possible mismatches between
the data sources and different DB2 JDBC providers.