Design of the JDM API - Java Data Mining: Strategy, Standard, and Practice - page 184

javax::datamining::resource
ConnectionFactory

javax::datamining::resource
Connection

Connection dmeConn =
getConnection(...)

getconnection (ConnectionSpec spec):
getconnection (Connection connection)
getconnection () : Connection

...

javax::naming
Referenceable

java::10
Serializable

com::xyz::resource
XYZConnectionFactory

getReference () : Reference

Creates

com::xyz::resource
XYZConnection

getconnection (ConnectionSpec spec):
getconnection (Connection connection)
getconnection () : Connection

...

Figure 8-14 XYZ vendors ConnectionFactory implementation details.

vendor-neutral way. Once the application gets access to the vendor-
specific ConnectionFactory , here the XYZConnectionFactory object, it
can instantiate a vendor-specific implementation of the Connection
object, that is, XYZConnection . This vendor-neutral DME connection
framework enables an application to interact with multiple DME
implementations.

8.4 Object Factories

In JDM, objects are defined as Java interfaces except for enumeration
and exception classes. A vendor must implement the JDM interfaces
to provide an implementation. All object factories inherit from a
common interface called Factory . Factory is defined as a marker inter-
face , that is an interface with no methods to distinguish the factory
objects from the other API objects. An application uses JDM object
factories, which are obtained through the Connection, to instantiate
mining objects. The Connection object serves as an abstract factory that
can create factory objects for any vendor-provided JDM interface
object. The getFactory method in Connection takes an object's class
name as input and creates an associated factory object. For example,
to create a PhysicalDataSetFactory instance, users invoke getFac-
tory(“javax.datamining.data.PhysicalDataSet”) . The abstract factory
pattern nicely hides the details of how the factory object is created by
the vendor-specific implementation.
Figure 8-15 depicts how a client application can create a
vendor-neutral object factory using the abstract factory pattern.