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Chapter 12. J2EE Connector Architecture scenario 403

Example 12-3 Data conversion (Unicode to EBCDIC)

rateRecord = new GenericRecord(account.getBytes(“IBM037”));

Example 12-4 shows how the entire output COMMAREA returned from the

enterprise tier is converted from EBCDIC to a String format using a String

constructor.

Example 12-4 Data conversion (EBCDIC to Unicode)

String commarea_rate = new String(rateRecord.getCommarea(),"IBM037");

12.3.3 Connection management

Once you have a mapping record structure in Java from COBOL or C code, you

are ready to make a connection and supply the required data. This section

describes the things that need to be done by the application program to connect

to CICS using a J2EE connector.

A connection can be

managed or nonmanaged. A managed connection is

managed by the application server. A non-managed connection is obtained

directly through the resource adapter.

The class diagram in Figure 12-4 on page 394 shows a managed connection.

The application program uses ConnectionFactory and Connection to manage the

connection. A reference to ConnectionFactory is obtained from the JNDI name

space using InitialContext, and an instance of Connection is obtained from

ConnectionFactory. The physical aspects of connection management are

handled by the following components:

򐂰 Application server and resource adapter

Connections from the application server to the CICS Transaction Gateway

through the ECI resource adapter can utilize the application server pool

manager to reuse free connections as they become available. This applies

both to network connections when using a remote Gateway daemon and to

local connections when using a local CICS Transaction Gateway. Similarly,

terminals in use with the EPI resource adapter are also pooled, although

connections are not pooled for the EPI resource adapter.

򐂰 Resource manager

Some resource managers have their own connection management functions.

The CICS Transaction Gateway internally manages the connections from the

Client daemon to the attached CICS regions. This is not visible to the

application server or resource adapter.

404 Patterns: Implementing Self-Service in an SOA Environment

Rational Software Architect generates another Java bean called a J2C Java

bean that implements connection management for us. The intializeBinding()

method handles the JNDI look up for managed connections. A resource

reference to the CICS ECI resource adapter connection factory, called

MartAccountCFRef, is defined in the deployment descriptor to map to the actual

JNDI name. The value of the JNDI reference can be changed at deployment

time.

JNDI lookup

The ITSOMart application looks up a connection factory instance with a

managed connection using the JNDI interface. Example 12-5 shows this lookup.

Example 12-5 Acquiring a connection factory using JNDI lookup

protected void initializeBinding() throws ResourceException {

ConnectionFactory cf = null;

String jndiName = "MartAccountCFRef";

javax.naming.Context ctx = null;

try {

ctx = new javax.naming.InitialContext();

if (ctx != null)

cf = (ConnectionFactory) ctx.lookup("java:comp/env/" + jndiName);

if (cf == null)

throw new javax.naming.NamingException();

} catch (javax.naming.NamingException exception) {

try {

if (ctx != null)

cf = (ConnectionFactory) ctx.lookup(jndiName);

} catch (javax.naming.NamingException exception1) {

}

}

For non-managed connections, the intializeBinding() method first creates a

managedConnectionFactory instance and sets the required values. Once the

connection properties are set, it creates the connection from the

managedConnectionFactory instance. Example 12-6 shows acquiring a

connection factory using managedConnectionFactory in a non-managed

environment.

Example 12-6 Acquiring a connection factory

com.ibm.connector2.cics.ECIManagedConnectionFactory mcf = new

com.ibm.connector2.cics.ECIManagedConnectionFactory();

mcf.setConnectionURL("sourcecode.rtp.raleigh.ibm.com");

mcf.setServerName("gifty");

mcf.setUserName("ANUPAG");

Chapter 12. J2EE Connector Architecture scenario 405

mcf.setPassword("anpag");

mcf.setTraceLevel(Integer.valueOf("1"));

cf = (ConnectionFactory) mcf.createConnectionFactory();

Once the connection is acquired, whether managed or non-managed, it is set

using setConnectionFactory:

setConnectionFactory(cf);

Dealing with a connection

The application component invokes the getConnection method on the

connection factory to get a CICS connection, as shown in Example 12-7. The

returned connection instance represents an application-level handle to an

underlying physical connection.

Example 12-7 Acquiring a connection

// use connection factory to get a connection handle

conn = cf.getConnection();

You can also specify a user ID and password in a connection spec, as shown in

Example 12-8.

Example 12-8 Acquiring a connection specifying user ID and password

// create a connection spec

ECIConnectionSpec connspec = new ECIConnectionSpec(userid, password);

// use connection factory to get a connection handle

conn = cf.getConnection(connspec);

The enterprise system uses the user ID and password for authentication and

authorization. A connection specification is unique to a resource adapter, so the

application needs to use the required connection specification, such as

ECIConnectionSpec. Creating ConnectionSpec is optional because the

authentication details can be specified when deploying the application.

After the component finishes with the connection, it closes the connection using

the close method, as shown in Example 12-9:

Example 12-9 Closing a connection

// close a connection

conn.close();

If an application component fails to close an allocated connection after its use,

that connection is considered an unused connection. The application server