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Overview

This sample application demonstrates the basic Java batch processing in WildFly Jakarta EE and OpenShift cloud environment. This application follows the standard batch programming model as defined in JSR 352 (Batch Applications for the Java Platform). Project JBeret implements this specification and additional features to provide batch processing capability in Java SE, WildFly, and JBoss EAP.

Batch Job Definition

The batch job used in this application is defined in csv2db.xml. The batch job performs the following:

  • creates the output table (MOVIES) in Postgresql database, if not exist;
  • delete all rows from table MOVIES, to avoid any conflict between repeated runs;
  • reads movies data from online resource via csvItemReader, component from jberet-support library;
  • each movie is converted into java.util.Map object and returned from csvItemReader;
  • after 10 (default item-count in csv2db.xml) movie objects have been read, jdbcItemWriter (another component from jberet-support library) writes them to Postgresql database.

Reader Configuration

csvItemReader is configured with the following batch properties:

  • resource: the CSV resource to read
  • beanType: the java type of the object from reading a single row of data
  • nameMapping: the object field or map keys corresponding to each column of CSV data
  • cellProcessors: data formatting rules for when reading each column of CSV data

See csvItemReader for details.

Writer Configuration

jdbcItemWriter is configured with the following batch properties:

  • url: connection URL to connect to Postgresql database server

    • the host part defaults to postgresql
    • the database name part defaults to sampledb

  • user: Postgresql db user name, defaults to jberet

  • password: Postgresql db user password, defaults to jberet

  • sql: the sql statement to insert a single date item to Postgresql

  • parameterNames: parameter names used in the above insert sql statement

  • parameterTypes: parameter types for the above parameter names

  • beanType: java type of each data item passed to this writer class

See jdbcItemWriter javadoc for details.

Build and Run locally with WildFly or JBoss EAP

To clean, build and package the application into a WAR file intro-jberet.war

mvn clean install

And make sure WildFly and Postgresql database server are already running.

To deploy the application WAR file to WildFly:

$JBOSS_HOME/bin/jboss-cli.sh -c "deploy --force target/intro-jberet.war"

To undeploy the application from WildFly:

$JBOSS_HOME/bin/jboss-cli.sh -c "undeploy intro-jberet.war"

To test that the application has been deployed and ready, check the following URL:

curl http://localhost:8080/intro-jberet/

It should return the simple index.html file with the body content: Welcome to project JBeret!

To start running the csv2db.xml job:

If all Postgresql db connection params are the same as defaults used in csv2db.xml:

curl -X POST -H 'Content-Type:application/json' 'http://localhost:8080/intro-jberet/api/jobs/csv2db/start'

If db.host, db.name, db.user, or db.password is different from the defaults, then specify them as query params:

curl -X POST -H 'Content-Type:application/json' 'http://localhost:8080/intro-jberet/api/jobs/csv2db/start?db.host=localhost'

Sample output from starting a job execution:

{
   "startTime":null,
   "endTime":null,
   "batchStatus":"STARTING",
   "exitStatus":null,
   "executionId":4,
   "href":"http://localhost:8080/intro-jberet/api/jobexecutions/4",
   "createTime":1506284588752,
   "lastUpdatedTime":1506284588752,
   "jobParameters":null,
   "jobName":"csv2db",
   "jobInstanceId":4
}

The start operation is async, and returns while the submitted job is being processed.

To get details and status of a job execution, just follow the href link given above:

curl http://localhost:8080/intro-jberet/api/jobexecutions/4

To get all step executions belonging to a job execution:

curl http://localhost:8080/intro-jberet/api/jobexecutions/4/stepexecutions/

To get details for a step execution:

curl http://localhost:8080/intro-jberet/api/jobexecutions/4/stepexecutions/5

{
   "startTime":1506284589019,
   "endTime":1506284591953,
   "batchStatus":"COMPLETED",
   "exitStatus":"COMPLETED",
   "stepExecutionId":5,
   "stepName":"csv2db.step2",
   "metrics":[
      {
         "type":"WRITE_COUNT",
         "value":100
      },
      {
         "type":"ROLLBACK_COUNT",
         "value":0
      },
      {
         "type":"FILTER_COUNT",
         "value":0
      },
      {
         "type":"WRITE_SKIP_COUNT",
         "value":0
      },
      {
         "type":"PROCESS_SKIP_COUNT",
         "value":0
      },
      {
         "type":"COMMIT_COUNT",
         "value":11
      },
      {
         "type":"READ_SKIP_COUNT",
         "value":0
      },
      {
         "type":"READ_COUNT",
         "value":100
      }
   ]
}

To restart a failed job execution:

The following job execution will fail due to connection refused to Postgresql server, because db.host is not specified as query param:

curl -X POST -H 'Content-Type:application/json' 'http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobs/csv2db/start'

To check the status (FAILED) of the above job execution:

curl http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/2

{
   "startTime":1506346579710,
   "endTime":1506346579755,
   "batchStatus":"FAILED",
   "exitStatus":"FAILED",
   "executionId":2,
   "href":"http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/2",
   "createTime":1506346579708,
   "lastUpdatedTime":1506346579755,
   "jobParameters":null,
   "jobName":"csv2db",
   "jobInstanceId":2
}

To restart the above failed job execution id 2, with correct db.host query param:

curl -X POST -H 'Content-Type:application/json' 'http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/2/restart?db.host=172.30.245.228'

# wait a bit for the job execution to complete

curl http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/3

{
   "startTime":1506346732383,
   "endTime":1506346733135,
   "batchStatus":"COMPLETED",
   "exitStatus":"COMPLETED",
   "executionId":3,
   "href":"http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/3",
   "createTime":1506346732381,
   "lastUpdatedTime":1506346733135,
   "jobParameters":{
      "db.host":"172.30.245.228"
   },
   "jobName":"csv2db",
   "jobInstanceId":2
}

Note that the previously failed job execution 2, and the successful restart job execution 3 both belong to the same job instance id 2.

To stop a running job execution:

curl -X POST -H 'Content-Type:application/json' 'http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/2/stop'

{
  "type":"javax.batch.operations.JobExecutionNotRunningException",
  "message":"JBERET000612: Job execution 2 has batch status FAILED, and is not running.",
  "stackTrace":"javax.batch.operations.JobExecutionNotRunningException: ..."
}

You can only stop a running job execution. Because job execution 2 has already completed, therefore the above stop operation failed.

To abandon a finished job execution:

curl -X POST -H 'Content-Type:application/json' 'http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobexecutions/2/abandon'

You can only abandon a finished job execution (not running job executions). Once it is abandoned, it may not be restarted.

To schedule a job execution

curl -X POST -H 'Content-Type:application/json' -d '{"jobName":"csv2db", "initialDelay":5, "jobParameters":{"db.host":"172.30.245.228"}}' 'http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/jobs/csv2db/schedule'

{
   "id":"1",
   "jobScheduleConfig":{
      "jobName":"csv2db",
      "jobExecutionId":0,
      "jobParameters":{
         "db.host":"172.30.245.228"
      },
      "scheduleExpression":null,
      "initialDelay":5,
      "afterDelay":0,
      "interval":0,
      "persistent":false
   },
   "createTime":1506349717648,
   "status":"SCHEDULED",
   "jobExecutionIds":[
   ]
}

The above command schedules to start running job csv2db after 5 minutes, with job parameter db.host = 172.30.245.228. More advanced scheduling are also supported by JBeret by customizing jobScheduleConfig field, such as repeated execution, interval between executions, and calendar-based cron-like schedules.

To check the status of the schedule:

curl http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/schedules

[
   {
      "id":"1",
      "jobScheduleConfig":{
         "jobName":"csv2db",
         "jobExecutionId":0,
         "jobParameters":{
            "db.host":"172.30.245.228"
         },
         "scheduleExpression":null,
         "initialDelay":5,
         "afterDelay":0,
         "interval":0,
         "persistent":false
      },
      "createTime":1506349717648,
      "status":"SCHEDULED",
      "jobExecutionIds":[

      ]
   }
]

# after the schedule execution is executed, the status of the schedule changes to `DONE`,
# and includes the job execution id

[
   {
      "id":"1",
      "jobScheduleConfig":{
         "jobName":"csv2db",
         "jobExecutionId":0,
         "jobParameters":{
            "db.host":"172.30.245.228"
         },
         "scheduleExpression":null,
         "initialDelay":5,
         "afterDelay":0,
         "interval":0,
         "persistent":false
      },
      "createTime":1506349717648,
      "status":"DONE",
      "jobExecutionIds":[
         4
      ]
   }
]

To cancel a scheduled job execution

curl http://intro-jberet-cfang-p1.1d35.starter-us-east-1.openshiftapps.com/intro-jberet/api/schedules/2/cancel

To query Postgresql MOVIES table to verify the output:

psql sampledb jberet --host=127.0.0.1 --port=5432

select * from MOVIES;

 rank |                        tit                        |      grs      |    opn
------+---------------------------------------------------+---------------+------------
    1 | Marvel's The Avengers                             | 623357910.000 | 2012-05-04
    2 | The Dark Knight Rises                             | 448139099.000 | 2012-07-20
    3 | The Hunger Games                                  | 408010692.000 | 2012-03-23
    4 | Skyfall                                           | 304360277.000 | 2012-11-09
    5 | The Hobbit: An Unexpected Journey                 | 303003568.000 | 2012-12-14
...

Build and Run in cloud with WildFly in OpenShift

What differs from local execution (on-premise) is how to provision WildFly, Postgresql and application. Once the application is ready for service, steps to run the batch application stay the same. For details, refer to OpenShift Tutorials.