AD183 Red Hat Application Development I: Programming in Java EE — Lesson 2: REST Services, JSON, Validation, Persistence, JPA, and Transactions

Learning Objectives

• Configure the main services, objects, and controls involved in REST services, JSON, and validation.
• Apply JPA persistence and transactions while preserving reviewable technical evidence.
• Recognize and correct the risk where a valid command creates the wrong outcome because variables, identity, or sequencing are incorrect.

Detailed Topics

• REST services: apply the concept to a Java team building and deploying a maintainable enterprise application on Red Hat JBoss EAP, record the relevant settings or decisions, and explain the operational consequence.
• JSON: apply the concept to a Java team building and deploying a maintainable enterprise application on Red Hat JBoss EAP, record the relevant settings or decisions, and explain the operational consequence.
• validation: apply the concept to a Java team building and deploying a maintainable enterprise application on Red Hat JBoss EAP, record the relevant settings or decisions, and explain the operational consequence.
• JPA persistence: apply the concept to a Java team building and deploying a maintainable enterprise application on Red Hat JBoss EAP, record the relevant settings or decisions, and explain the operational consequence.
• transactions: apply the concept to a Java team building and deploying a maintainable enterprise application on Red Hat JBoss EAP, record the relevant settings or decisions, and explain the operational consequence.

Instructor Demonstration

The instructor demonstrates rest services, json, validation, persistence, jpa, and transactions by tracing the relevant architecture, commands, configuration, messages, and evidence. The walkthrough highlights how a valid command creates the wrong outcome because variables, identity, or sequencing are incorrect and shows how to isolate the cause without masking dependent issues.

Hands-On Exercise

Implement the core workflow and compare expected versus observed behavior for REST Services, JSON, Validation, Persistence, JPA, and Transactions. Add verified outcomes to the Java EE application repository, integration tests, deployment package, and developer handover guide.

1. Confirm the scope, versions, access, dependencies, and success criteria.
2. Perform the workflow while recording commands, settings, output, and platform events.
3. Test one expected case and one controlled exception specific to this lesson.
4. Retest the correction and document ownership, rollback, and follow-up actions.

Scenario Analysis

• Identify which dependency most strongly influences REST services in the stated scenario.
• Compare two approaches for JPA persistence and explain the security, reliability, and support trade-offs.
• Decide what evidence must be retained in the Java EE application repository, integration tests, deployment package, and developer handover guide before operational acceptance.

Troubleshooting Guidance

Begin with the first observable difference from the expected result. Check configuration, permissions, sequencing, and functional behavior separately, then correlate logs, events, commands, and configuration history. Do not accept the initial assumption that a valid command creates the wrong outcome because variables, identity, or sequencing are incorrect; confirm the cause with a reproducible retest.

Validation Checklist

• The required configuration, permissions, sequencing, and functional behavior were checked and recorded.
• The normal path and a course-specific exception were tested.
• The Java EE application repository, integration tests, deployment package, and developer handover guide links conclusions to commands, configuration, logs, or other objective evidence.
• Corrective actions, rollback steps, ownership, and handover notes are complete.

Lesson Outcome

Learners can apply REST Services, JSON, Validation, Persistence, JPA, and Transactions, explain the observed Red Hat platform behavior, and support the result with a reviewable Java EE application repository, integration tests, deployment package, and developer handover guide.