web server - Borland Technical Publications

Chapter
21
21Connecting to Resources with BES:
Chapter
using the Definitions Archive (DAR)
Note
J2EE specifies a uniform mechanism for establishing connections to resources using
Java standard interfaces. A resource related object containing resource manager
location details and connection attributes is bound under a JNDI service provider, and
can be retrieved by your application as a resource connection factory in a JNDI lookup.
Sample resource connection factories include JDBC datasources and JMS connection
factories. Once a resource connection factory is obtained from JNDI, a connection to
the desired resource manager can then be established. A connection to a relational
database is obtained through a JDBC datasource, a connection to a message broker is
obtained through a JMS connection factory, and general Enterprise Information
Systems (EIS) connections are obtained through JCA resource adapters.
Use the Borland Management Console and Borland Deployment Descriptor Editor
(DDEditor) to create, edit, and deploy resource connection factories and other resource
related JNDI objects, such as JMS destinations. An XML descriptor file (jndidefinitions.xml),
generally called the JNDI Definitions module, captures the properties
representing resource related objects. This file is packaged in a Data ARchive (DAR)
module.
In BES, a partition hosted Naming Service represents the default JNDI service provider
- its an implementation of a CosNaming service provider. Resource related objects are
bound in the Naming Service of a BES partition through deployment of DAR or RAR
module using standard BES deployment procedures. At that time, only properties
required to create an instance of a resource connection factory, or JMS destination, are
stored in the JNDI bound object. During JNDI lookup for a resource related object, an
instance of the desired resource object is created using the stored property values from
the object retrieved. The newly created instance is then passed back to the caller of
JNDI lookup() method. In this way, DARs can be successfully deployed to a BES
partition without having to load classes for vendor specific resource objects. Class
libraries for resource vendors are only required by application processes that actually
perform JNDI lookup of resource related objects.
In prior versions of BES, a file-system service provider called the Serial Provider was
the default JNDI service provider for deployment of DARs and JNDI Definitions
modules. Resource related objects bound to this provider involved creation of the
resource objects during deployment, and hence required vendor class libraries to be
deployed in advance. In addition, JNDI names for resource related objects required a
Chapter 21: Connecting to Resources with BES: using the Definitions Archive (DAR) 191