Develop Web Services and Microservices with Java — Lesson 3: Microservice Boundaries, Persistence, Security, Resilience, and Messaging

Learning Objectives

• Explain the purpose and operating context of domain boundaries, data ownership, APIs, events, and service decomposition.
• Apply transactions, persistence, repositories, consistency, and saga awareness and tokens, OAuth awareness, TLS, secrets, authorization, and secure defaults in a controlled environment.
• Validate outcomes and troubleshoot risks involving timeouts, retries, circuit breakers, bulkheads, queues, and idempotent handling.

Detailed Topics

• domain boundaries, data ownership, APIs, events, and service decomposition
• transactions, persistence, repositories, consistency, and saga awareness
• tokens, OAuth awareness, TLS, secrets, authorization, and secure defaults
• timeouts, retries, circuit breakers, bulkheads, queues, and idempotent handling

Instructor Demonstration

Demonstrate domain boundaries, data ownership, APIs, events, and service decomposition for a customer and order integration exposed through REST, SOAP, and independently deployable Java services; capture the exact configuration, code, command, transaction, query, dashboard, model, schedule, or report evidence that proves the expected result.

Hands-On Exercise

Complete a controlled Develop Web Services and Microservices with Java exercise covering transactions, persistence, repositories, consistency, and saga awareness and tokens, OAuth awareness, TLS, secrets, authorization, and secure defaults; introduce an exception involving timeouts, retries, circuit breakers, bulkheads, queues, and idempotent handling, diagnose it from evidence, apply the smallest reversible correction, and rerun acceptance checks.

1. Confirm scope, prerequisites, identities, dependencies, data, risks, and expected outcome.
2. Perform the course-specific configuration, development, administration, analysis, or business-process workflow.
3. Capture commands, settings, records, logs, screenshots, reports, metrics, or test results.
4. Compare the observed result with acceptance criteria and document corrective or preventive action.

Scenario Analysis

• Identify the technical or business decision and the stakeholders affected by it.
• Compare security, performance, reliability, compliance, cost, usability, and support trade-offs.
• Define rollback, recovery, communication, evidence, ownership, and escalation requirements.

Troubleshooting Guidance

Diagnose issues involving domain boundaries, data ownership, APIs, events, and service decomposition, transactions, persistence, repositories, consistency, and saga awareness, tokens, OAuth awareness, TLS, secrets, authorization, and secure defaults, timeouts, retries, circuit breakers, bulkheads, queues, and idempotent handling without making an unverified production change. Separate symptoms from causes, gather time-correlated evidence, test a reversible hypothesis, validate the correction, and record recurrence controls.

Validation Checklist

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

Lesson Outcome

Learners can apply Microservice Boundaries, Persistence, Security, Resilience, and Messaging in a realistic Develop Web Services and Microservices with Java scenario and defend the result with documented evidence.