Java Web Services — Lesson 2: JSON Binding, Validation, Error Handling, Security, and Transactions

Learning Objectives

• Explain the architecture, workflow, or business purpose behind JSON binding, DTO boundaries, dates, enums, and null handling.
• Apply bean validation, business rules, and consistent error models and authentication, authorization, tokens, TLS, and secret handling in a controlled scenario.
• Validate outcomes and troubleshoot risks involving service transactions, retries, duplicate requests, and data consistency.

Detailed Topics

• JSON binding, DTO boundaries, dates, enums, and null handling
• bean validation, business rules, and consistent error models
• authentication, authorization, tokens, TLS, and secret handling
• service transactions, retries, duplicate requests, and data consistency

Instructor Demonstration

Demonstrate JSON binding, DTO boundaries, dates, enums, and null handling within an order-and-shipping integration exposing REST APIs while supporting a contract-driven SOAP partner, then capture the exact configuration, command, transaction, report, model, query, code, or process evidence that proves the result for lesson 2.

Hands-On Exercise

Implement a controlled exercise covering bean validation, business rules, and consistent error models and authentication, authorization, tokens, TLS, and secret handling, then introduce and resolve an exception involving service transactions, retries, duplicate requests, and data consistency while preserving before-and-after evidence.

1. Confirm the environment, identities, inputs, dependencies, risks, and expected outcome.
2. Complete the course-specific configuration, development, analysis, or process workflow.
3. Capture settings, commands, data, outputs, logs, reports, screenshots, calculations, or test results.
4. Compare the observed result with acceptance criteria and document corrective action.

Scenario Analysis

• Identify the technical or business decision that must be made.
• Compare valid approaches and their security, performance, reliability, cost, compliance, and support trade-offs.
• Define rollback, recovery, ownership, communication, and evidence requirements.

Troubleshooting Guidance

Diagnose issues across JSON binding, DTO boundaries, dates, enums, and null handling, bean validation, business rules, and consistent error models, authentication, authorization, tokens, TLS, and secret handling, service transactions, retries, duplicate requests, and data consistency without making an unverified production change. Separate symptoms from causes, gather evidence, test the smallest reversible correction, rerun validation, and record preventive action.

Validation Checklist

• The requirement, scope, inputs, dependencies, and expected result are documented.
• The result is reproducible and supported by course-specific evidence.
• Normal, boundary, failure, security, performance, and operational conditions are reviewed.
• Exceptions, rollback, ownership, and the next improvement priority are recorded.

Lesson Outcome

Learners can apply JSON Binding, Validation, Error Handling, Security, and Transactions in a realistic Java Web Services scenario and validate the result with documented evidence.