Network Deployment (Distributed operating systems), v8.0 > Develop and deploying applications > Develop batch applications > Develop batch applications

Develop a simple transactional batch application

We can write a simple batch application using a batch job controller and EJB data stream, the command line, or the Apache ANT tool. If the batch step uses a batch data stream (BDS) whose data is local to the file system of the application server to which the batch application is deployed, then certain steps must be followed to support job restart scenarios. If such a batch application is deployed to application servers that can run on multiple machines, then there is no guarantee that the restart request is accepted by the machine on which the batch job originally ran. This occurs when the batch application is deployed to a cluster, and if a batch job that runs against such an application is canceled and then restarted. In this scenario, the deployment might send the restart request to an application server that runs on a different machine. Therefore, in cases where file-based affinity is required, you can apply the following solutions to support the job restart scenario:

• Ensure that the data is equally available to every machine on which the batch application can be started. Use a network file system for this example. This action might reduce performance of application.
• Deploy the application on application servers that can only run on the machine where the local data exists. Complete this action by deploying the application to a cluster that exists in a node group that has only one member node.

The batch application developer must ensure that transactional work done in the batch step callback methods inherits the global transaction started by the grid endpoints. This action ensures that work performed under a batch step only gets committed at every checkpoint and rolls back if the step fails.

Some commands are split on multiple lines for printing purposes.

Procedure

• Create batch jobs using a batch job controller and an EJB data stream.

  1. Create batch job steps.

     1. Create a Java class that implements the com.ibm.websphere.BatchJobStepInterface interface.
     2. Implement business logic.

        If your step has one input and one output stream you can alternatively use the Generic batch step of GenericXDBatchStep.

  2. Create batch data streams.

     1. Create a Java Class that implements the interface com.ibm.websphere.batch.BatchDataStream.

        Batch data streams are accessed from the business logic, for example, from the batch job steps by calling BatchDataStreamMgr with jobID and stepID. JobID and stepID are retrieved from the step bean properties list using keys BatchConstants.JOB_ID and BatchConstants.STEP_ID.

     2. Map BatchConstants.JOB_ID to com.ibm.websphere.batch.JobID and map BatchConstants.STEP_ID to com.ibm.websphere.batch.StepID.

        You should already have access to the BatchConstants class.

        The batch datastream framework provides several ready-to-use patterns to work with different types of datastreams such as file and database.

        To use the batch datastream framework, complete the following steps.

        1. Identify the data stream type with which to operate, such as TextFile, ByteFile, JDBC, or z/OS stream.

        2. Identify whether you would read from the stream or write to the stream.
        3. See the table in the batch data stream framework and patterns. Select the class from the supporting classes column that matches your data stream type and operation. For example, to read data from a text file, then select TextFileReader.
        4. Implement the interface listed in the pattern name column that corresponds to the supporting class you selected in the previous step. The supporting class handles all the book keeping activities related to the stream and the batch programming model. The implementation class focuses on the stream processing logic.
        5. Declare the supporting class and your implementation class in the xJCL.
        6. Repeat this procedure for each datastream required in your step.

  3. Define batch data streams in xJCL.

     <batch-data-streams>
     
     <bds>
     
     <logical-name>inputStream
     </logical-name>
     
     <props>
     
     <prop name="PATTERN_IMPL_CLASS" value="MyBDSStreamImplementationClass"/>
     <prop name="file.encoding" value="8859_1"/>      
     
     <prop name="FILENAME" value="${inputDataStream}" />
     <prop name="PROCESS_HEADER" value="true"/>      
     
     <prop name="AppendJobIdToFileName" value="true"/>
     </props>
     
     <impl-class>com.ibm.websphere.batch.devframework.datastreams.patterns.FileByteReader
     
     </impl-class>
     
     </bds> 

     The PATTERN_IMPL_CLASS class denotes the user implementation of the BDS framework pattern and the impl-class property denotes the supporting class.
  4. Declare a batch job controller.

     1. Add a stateless session bean to your deployment descriptor and point to the implementation class that the product provides. Do so by specifying com.ibm.ws.batch.BatchJobControllerBean as the bean class. Do this specification only once per batch application.

     2. Use com.ibm.ws.batch.BatchJobControllerHome for the remote home interface class and com.ibm.ws.batch.BatchJobController for the remote interface class.

  5. Configure the EJB deployment descriptor.

     1. Configure a resource reference on the Controller bean to the default WorkManager wm/BatchWorkManager of the type commonj.work.WorkManager.
     We must declare the deployment descriptor of the batch controller bean in the EJB deployment descriptor of a batch application. Only one controller bean can be defined per batch application.

• Create batch jobs using the command line.

  1. Create batch job steps.

     1. Create a Java class that implements the com.ibm.websphere.BatchJobStepInterface interface.
     2. Implement business logic.

        If your step has exactly one input and one output stream you could alternatively use the Generic batch step of GenericXDBatchStep.

  2. Create batch data streams.

     1. Create a Java Class that implements the interface com.ibm.websphere.batch.BatchDataStream.

        Batch data streams are accessed from the business logic, for example, from the batch job steps by calling BatchDataStreamMgr with jobID and stepID. JobID and stepID are retrieved from the step bean properties list using keys BatchConstants.JOB_ID and BatchConstants.STEP_ID.

     2. Map BatchConstants.JOB_ID to com.ibm.websphere.batch.JobID and map BatchConstants.STEP_ID to com.ibm.websphere.batch.StepID.

        You should already have access to the BatchConstants class.

        The batch datastream framework provides several ready-to-use patterns to work with different types of datastreams such as file and database.

        To use the batch datastream framework, complete the following steps.

        1. Identify the data stream type with which to operate, such as TextFile, ByteFile, JDBC, or z/OS stream.

        2. Identify whether you would read from the stream or write to the stream.
        3. See the table in the batch data stream framework and patterns. Select the class from the supporting classes column that matches your data stream type and operation. For example, to read data from a text file, then choose TextFileReader.
        4. Implement the interface listed in the pattern name column that corresponds to the supporting class you selected in the previous step. The supporting class handles all the book keeping activities related to the stream and the batch programming model. The implementation class focuses on the stream processing logic.
        5. Declare the supporting class and your implementation class in the xJCL.
        6. Repeat this procedure for each datastream required in your step.

  3. New feature: Open a command prompt and ensure that Java is on the path.
  4. New feature: Issue the following command, all on a single line.

     New feature:

     java -cp ${WAS_INSTALL_ROOT}/plugins/com.ibm.ws.batch.runtime.jar
     com.ibm.ws.batch.packager.WSBatchPackager
       -appname=
     <Application_Name>   -jarfile=
     <jarfile containing the POJO batch steps>   -earfile=
     <name of the output EAR file without the .ear extension>   [-utilityjars=
     <semicolon separated list of utility jars>]
       [-debug]
       [-gridJob]
     

     For example, for batch jobs, issue

     java -cp ${WAS_INSTALL_ROOT}/plugins/com.ibm.ws.batch.runtime.jar
     com.ibm.ws.batch.packager.WSBatchPackager
       -appname=XDCGIVT
       -jarfile=XDCGIVTEJBs.jar
       -earfile=XDCGIVT
     

• Create batch jobs using ANT.

  1. Create batch job steps.

     1. Create a Java class that implements the com.ibm.websphere.BatchJobStepInterface interface.
     2. Implement business logic.

        If your step has exactly one input and one output stream you could alternatively use the Generic batch step of GenericXDBatchStep.

  2. Create batch data streams.

     1. Create a Java Class that implements the interface com.ibm.websphere.batch.BatchDataStream.

        Batch data streams are accessed from the business logic, for example, from the batch job steps by calling BatchDataStreamMgr with jobID and stepID. JobID and stepID are retrieved from the step bean properties list using keys BatchConstants.JOB_ID and BatchConstants.STEP_ID.

     2. Map BatchConstants.JOB_ID to com.ibm.websphere.batch.JobID and map BatchConstants.STEP_ID to com.ibm.websphere.batch.StepID.

        You should already have access to the BatchConstants class.

        The batch datastream framework provides several ready-to-use patterns to work with different types of datastreams such as file and database.

        To use the batch datastream framework, complete the following steps.

        1. Identify the data stream type with which to operate, such as TextFile, ByteFile, JDBC, or z/OS stream.

        2. Identify whether you would read from the stream or write to the stream.
        3. See the table in the batch data stream framework and patterns. Select the class from the supporting classes column that matches your data stream type and operation. For example, to read data from a text file, then select TextFileReader.
        4. Implement the interface listed in the pattern name column that corresponds to the supporting class you selected in the previous step. The supporting class handles all the book keeping activities related to the stream and the batch programming model. The implementation class focuses on the stream processing logic.
        5. Declare the supporting class and your implementation class in the xJCL.
        6. Repeat this procedure for each datastream required in your step.

  3. For a batch job, ensure the com.ibm.ws.batch.runtime.jar file is on the class path.
  4. Declare the task.

     Use the following command to declare the task:

     <taskdef name="pgcpackager" classname="com.ibm.ws.batch.packager.PGCPackager"
       classpath="${WAS_INSTALL_ROOT}/plugins/com.ibm.ws.batch.runtime.jar" /> 

  5. After compiling the Java files in the application, invoke the WSBatchPackager task.

     <WSBatchPackager appname="
     <appname>" earFile="
     <location name of EAR file to generate>"
     jarfile="location of the POJO jar file"/>
     

Results

You have developed a simple transactional batch application using a batch job controller and EJB data stream, the command line, or the ANT tool.

What to do next

Install the compute-intensive application and configure WebSphere grid endpoints.
Batch job steps
The batch programming model
Batch controller bean
Batch data stream framework and patterns
xJCL elements
Configure WebSphere grid endpoints
Install the batch application
Deploy batch applications

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