WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

378 WebSphere Application Server V8.5 Administration and Configuration Guide for the Full Profile

 Advanced DB2 features:

– Optimize for get/use/close/connection pattern with heterogeneous pooling

If you check this property, the heterogeneous pooling feature allows you to extend the

data source definition.

– DB2 automatic client reroute options

Client reroute for DB2 allows you to provide an alternate server location in case the

connection to the database server fails. If you decide to use client reroute with the

persistence option, the alternate server information persists across Java Virtual

Machines (JVMs). In the event of an application server crash, the alternate server

information is not lost when the application server is restored and attempts to connect

to the database.You can specify the retry interval for client reroute, how often to retry,

alternate server name or names for the DB2 server, port number, and JNDI name.

9.9 Shared and unshared connections

The WebSphere Application Server V8.5 connection manager supports both unshareable

and shareable connections. It also provides local transaction containment (LTC) in an

unspecified transaction context:

 An unshareable connection cannot be shared with other components in an application.

The component using this connection has full control over it. Access to a resource marked

as unshareable means that there is a one-to-one relationship between the connection

handle that a component is using and the physical connection with which the handle is

associated. This access implies that every call to the getConnection() method returns a

connection handle solely for the requesting user.

 The use of a shareable connection means that, if conditions allow it, different

getConnection() requests by an application actually receive a handle for the same physical

connection to the resource. The physical connection is shared through multiple connection

handles instead of retrieving a new physical connection from the connection pool for every

getConnection() invocation.

More information about shared and unshared connections are in the information center at the

following website:

http://pic.dhe.ibm.com/infocenter/wasinfo/v8r5/index.jsp?topic=/com.ibm.websphere.

base.doc/ae/welcome_base.html

9.9.1 Factors that determine sharing

This section explains the factors that determine sharing, and the listing here is not an

exhaustive one. The product might or might not share connections under different

circumstances. The factors are:

 Each getConnection() request must have the same connection properties.

 Each getConnection() request must be made within the same sharing scope.

Connection sharing conditions are such that a connection can be shared only within a sharing

scope. The most common sharing scope is a transaction scope, where multiple active

connections share the same physical connection.