One of the aims of the JCA CCI support is to provide convenient facilities for manipulating CCI records. The developer can specify the strategy to create records and extract datas from records, for use with Spring's CciTemplate. The following interfaces will configure the strategy to use input and output records if you don't want to work with records directly in your application.

In order to create an input Record, the developer can use a dedicated implementation of the RecordCreator interface.

public interface RecordCreator {

  Record createRecord(RecordFactory recordFactory) throws ResourceException, DataAccessException;
}

As you can see, the createRecord(..) method receives a RecordFactory instance as parameter, which corresponds to the RecordFactory of the ConnectionFactory used. This reference can be used to create IndexedRecord or MappedRecord instances. The following sample shows how to use the RecordCreator interface and indexed/mapped records.

public class MyRecordCreator implements RecordCreator {

  public Record createRecord(RecordFactory recordFactory) throws ResourceException {
    IndexedRecord input = recordFactory.createIndexedRecord("input");
    input.add(new Integer(id));
    return input;
  }
}

An output Record can be used to receive data back from the EIS. Hence, a specific implementation of the RecordExtractor interface can be passed to Spring's CciTemplate for extracting data from the output Record.

public interface RecordExtractor {

  Object extractData(Record record) throws ResourceException, SQLException, DataAccessException;
}

The following sample shows how to use the RecordExtractor interface.

public class MyRecordExtractor implements RecordExtractor {

  public Object extractData(Record record) throws ResourceException {
    CommAreaRecord commAreaRecord = (CommAreaRecord) record;
    String str = new String(commAreaRecord.toByteArray());
    String field1 = string.substring(0,6);
    String field2 = string.substring(6,1);
    return new OutputObject(Long.parseLong(field1), field2);
  }
}

The CciTemplate is the central class of the core CCI support package (org.springframework.jca.cci.core). It simplifies the use of CCI since it handles the creation and release of resources. This helps to avoid common errors like forgetting to always close the connection. It cares for the lifecycle of connection and interaction objects, letting application code focus on generating input records from application data and extracting application data from output records.

The JCA CCI specification defines two distinct methods to call operations on an EIS. The CCI Interaction interface provides two execute method signatures:

public interface javax.resource.cci.Interaction {
  ...
  boolean execute(InteractionSpec spec, Record input, Record output) throws ResourceException;

  Record execute(InteractionSpec spec, Record input) throws ResourceException;
  ...
}

Depending on the template method called, CciTemplate will know which execute method to call on the interaction. In any case, a correctly initialized InteractionSpec instance is mandatory.

CciTemplate.execute(..) can be used in two ways:

With the first approach, the following methods of the template will be used. These methods directly correspond to those on the Interaction interface.

public class CciTemplate implements CciOperations {

  public Record execute(InteractionSpec spec, Record inputRecord)
      throws DataAccessException { ... }

  public void execute(InteractionSpec spec, Record inputRecord, Record outputRecord)
      throws DataAccessException { ... }

}

With the second approach, we need to specify the record creation and record extraction strategies as arguments. The interfaces used are those describe in the previous section on record conversion. The corresponding CciTemplate methods are the following:

public class CciTemplate implements CciOperations {

  public Record execute(InteractionSpec spec, RecordCreator inputCreator)
      throws DataAccessException { ... }

  public Object execute(InteractionSpec spec, Record inputRecord, RecordExtractor outputExtractor)
      throws DataAccessException { ... }

  public Object execute(InteractionSpec spec, RecordCreator creator, RecordExtractor extractor)
      throws DataAccessException { ... }

}

Unless the outputRecordCreator property is set on the template (see the following section), every method will call the corresponding execute method of the CCI Interaction with two parameters: InteractionSpec and input Record, receiving an output Record as return value.

CciTemplate also provides methods to create IndexRecord and MappedRecord outside a RecordCreator implementation, through its createIndexRecord(..) and createMappedRecord(..) methods. This can be used within DAO implementations to create Record instances to pass into corresponding CciTemplate.execute(..) methods.

public class CciTemplate implements CciOperations {

  public IndexedRecord createIndexedRecord(String name) throws DataAccessException { ... }

  public MappedRecord createMappedRecord(String name) throws DataAccessException { ... }

}

Spring's CCI support provides a abstract class for DAOs, supporting injection of a ConnectionFactory or a CciTemplate instances. The name of the class is CciDaoSupport: It provides simple setConnectionFactory and setCciTemplate methods. Internally, this class will create a CciTemplate instance for a passed-in ConnectionFactory, exposing it to concrete data access implementations in subclasses.

public abstract class CciDaoSupport {

  public void setConnectionFactory(ConnectionFactory connectionFactory) { ... }
  public ConnectionFactory getConnectionFactory() { ... }

  public void setCciTemplate(CciTemplate cciTemplate) { ... }
  public CciTemplate getCciTemplate() { ... }

}

If the connector used only supports the Interaction.execute(..) method with input and output records as parameters (that is, it requires the desired output record to be passed in instead of returning an appropriate output record), you can set the outputRecordCreator property of the CciTemplate to automatically generate an output record to be filled by the JCA connector when the response is received. This record will be then returned to the caller of the template.

This property simply holds an implementation of the RecordCreator interface, used for that purpose. The RecordCreator interface has already been discussed in Section 23.3.1, “Record conversion”. The outputRecordCreator property must be directly specified on the CciTemplate. This could be done in the application code like so:

cciTemplate.setOutputRecordCreator(new EciOutputRecordCreator());

Or (recommended) in the Spring configuration, if the CciTemplate is configured as a dedicated bean instance:

<bean id="eciOutputRecordCreator" class="eci.EciOutputRecordCreator"/>

<bean id="cciTemplate" class="org.springframework.jca.cci.core.CciTemplate">
  <property name="connectionFactory" ref="eciConnectionFactory"/>
  <property name="outputRecordCreator" ref="eciOutputRecordCreator"/>
</bean>

	Note
	As the CciTemplate class is thread-safe, it will usually be configured as a shared instance.

The following table summarizes the mechanisms of the CciTemplate class and the corresponding methods called on the CCI Interaction interface:

CciTemplate also offers the possibility to work directly with CCI connections and interactions, in the same manner as JdbcTemplate and JmsTemplate. This is useful when you want to perform multiple operations on a CCI connection or interaction, for example.

The interface ConnectionCallback provides a CCI Connection as argument, in order to perform custom operations on it, plus the CCI ConnectionFactory which the Connection was created with. The latter can be useful for example to get an associated RecordFactory instance and create indexed/mapped records, for example.

public interface ConnectionCallback {

  Object doInConnection(Connection connection, ConnectionFactory connectionFactory)
      throws ResourceException, SQLException, DataAccessException;
}

The interface InteractionCallback provides the CCI Interaction, in order to perform custom operations on it, plus the corresponding CCI ConnectionFactory.

public interface InteractionCallback {

  Object doInInteraction(Interaction interaction, ConnectionFactory connectionFactory)
      throws ResourceException, SQLException, DataAccessException;
}

	Note
	InteractionSpec objects can either be shared across multiple template calls or newly created inside every callback method. This is completely up to the DAO implementation.

In this section, the usage of the CciTemplate will be shown to acces to a CICS with ECI mode, with the IBM CICS ECI connector.

Firstly, some initializations on the CCI InteractionSpec must be done to specify which CICS program to access and how to interact with it.

ECIInteractionSpec interactionSpec = new ECIInteractionSpec();
interactionSpec.setFunctionName("MYPROG");
interactionSpec.setInteractionVerb(ECIInteractionSpec.SYNC_SEND_RECEIVE);

Then the program can use CCI via Spring's template and specify mappings between custom objects and CCI Records.

public class MyDaoImpl extends CciDaoSupport implements MyDao {

  public OutputObject getData(InputObject input) {
    ECIInteractionSpec interactionSpec = ...;

    OutputObject output = (ObjectOutput) getCciTemplate().execute(interactionSpec,
        new RecordCreator() {
          public Record createRecord(RecordFactory recordFactory) throws ResourceException {
            return new CommAreaRecord(input.toString().getBytes());
          }
        },
        new RecordExtractor() {
          public Object extractData(Record record) throws ResourceException {
            CommAreaRecord commAreaRecord = (CommAreaRecord)record;
            String str = new String(commAreaRecord.toByteArray());
            String field1 = string.substring(0,6);
            String field2 = string.substring(6,1);
            return new OutputObject(Long.parseLong(field1), field2);
          }
        });

    return output;
  }
}

As discussed previously, callbacks can be used to work directly on CCI connections or interactions.

public class MyDaoImpl extends CciDaoSupport implements MyDao {

  public OutputObject getData(InputObject input) {
    ObjectOutput output = (ObjectOutput) getCciTemplate().execute(
        new ConnectionCallback() {
          public Object doInConnection(Connection connection, ConnectionFactory factory)
              throws ResourceException {
              
            // do something...
          }
        });
    }
    return output;
  }
}

	Note
	With a ConnectionCallback, the Connection used will be managed and closed by the CciTemplate, but any interactions created on the connection must be managed by the callback implementation.

For a more specific callback, you can implement an InteractionCallback. The passed-in Interaction will be managed and closed by the CciTemplate in this case.

public class MyDaoImpl extends CciDaoSupport implements MyDao {

  public String getData(String input) {
    ECIInteractionSpec interactionSpec = ...;

    String output = (String) getCciTemplate().execute(interactionSpec,
        new InteractionCallback() {
          public Object doInInteraction(Interaction interaction, ConnectionFactory factory)
              throws ResourceException {
            Record input = new CommAreaRecord(inputString.getBytes());
            Record output = new CommAreaRecord();
            interaction.execute(holder.getInteractionSpec(), input, output);
            return new String(output.toByteArray());
          }
        });

    return output;
  }
}

For the examples above, the corresponding configuration of the involved Spring beans could look like this in non-managed mode:

<bean id="managedConnectionFactory" class="com.ibm.connector2.cics.ECIManagedConnectionFactory">
  <property name="serverName" value="TXSERIES"/>
  <property name="connectionURL" value="local:"/>
  <property name="userName" value="CICSUSER"/>
  <property name="password" value="CICS"/>
</bean>

<bean id="connectionFactory" class="org.springframework.jca.support.LocalConnectionFactoryBean">
  <property name="managedConnectionFactory" ref="managedConnectionFactory"/>
</bean>

<bean id="component" class="mypackage.MyDaoImpl">
  <property name="connectionFactory" ref="connectionFactory"/>
</bean>

In managed mode (that is, in a Java EE environment), the configuration could look as follows:

<jee:jndi-lookup id="connectionFactory" jndi-name="eis/cicseci"/>

<bean id="component" class="MyDaoImpl">
  <property name="connectionFactory" ref="connectionFactory"/>
</bean>