This chapter is dedicated to advanced JOnAS users concerned by EAI (Enterprise Application Integration). The Java Connector Architecture (Connectors) defines a way for enterprise applications (based on EJB, servlet, JSP or J2EE clients) to communicate with external existing Enterprise Information Systems (EIS). This requires the use of a third party software component called "Resource Adapter", provided for a kind of EIS, and which should be previously deployed on the application server. In the case of JOnAS as application server, this chapter describes the way such a Resource Adapter should be deployed, and how an EJB application may use it. As JOnAS currently provides only an EJB container, only the EJB components of an enterprise application may access an EIS through a Connectors Resource Adapter; JSP, Servlets or EJB clients are currently not concerned.
The Java Connector Architecture allows the connection of different Enterprise Information Systems (EIS) to an application server such as JOnAS. It is based on the Resource Adapter (RA), an architecture component comparable to a software driver, connecting the EIS, the application server, and the enterprise application (EJB components in the case of JOnAS as application server). The RA is generally provided by an EIS vendor, and provides an interface (the Common Client Interface or CCI) to the enterprise application (EJBs) for accessing the EIS. The RA also provides standard interfaces for being plugged to the application server, so that they can collaborate to keep all system-level mechanisms (transactions, security, and connection management) transparent from the application components.
The resource adapter plugs into JOnAS and provides connectivity between the EIS, JOnAS, and the EJB application. The application performs "business logic" operations on the EIS data using the RA client API (CCI), while transactions, connections (including pooling) and security on the EIS is managed by JOnAS through the RA (system contract).
The following steps are involved for using a Connector Resource Adapter with JOnAS
<resource-ref> <res-ref-name>eis/MyEIS</res-ref-name> <res-type>javax.resource.cci.ConnectionFactory</res-type> <res-auth>Container</res-auth> </resource-ref>The mapping to the actual JNDI name of the connection factory (here
adapt_1
) will be done
in the JOnAS specific deployment descriptor with the following element:
<jonas-resource> <res-ref-name>eis/MyEIS</res-ref-name> <jndi-name>adapt_1</jndi-name> </jonas-resource>
This means that the bean programmer will have access to a connection factory instance using the JNDI interface via the java:comp/env/eis/MyEIS name:
// obtain the initial JNDI naming context Context inictx = new InitialContext(); // perform JNDI lookup to obtain the connection factory javax.resource.cci.ConnectionFactory cxf = (javax.resource.cci.ConnectionFactory) inictx .lookup("java:comp/env/eis/MyEIS<");The bean programmer can then get a connection by calling the method
getConnection
on the connection factory.
javax.resource.cci.Connection cx = cxf.getConnection();The returned connection instance represents an application-level handle to a physical connection for accessing the underlying EIS.
close
method on the Connection
interface:
cx.close();
build a jonas specific resource adapter configuration file
that will be included in the resource adapter.
This jonas-ra xml file is used to configure the resource adapter in the operational
environment and reflects the values of all properties declared
in the deployment descriptor for the resource adapter.
JOnAS provides a deployment tool RAConfig
that is capable to build
this xml file from a Resource adapter deployment descriptor inside an rar file.
example:
RAConfig -j adap_1 ra
managedConnectionFactory
class. It is important for JOnAS that this class
provides getter and setter method for each of its supported properties
(as it is required in the Connector Architecture specification).
.jar
files that are part of the resource adapter archive file
(.rar
file) in a location that can be seen by the server at launching time
via the classpath.
In jonas.properties
file:
resource
must be inserted in thejonas.services
property,
jonas.service.resource.resources
rarfile. If the '.rar' suffix is not used on the property, it will be used when trying to allocate the
specified Resource Adapter.jonas.service.resource.resources MyEIS.rar, MyEIS1