Java on OCI: Develop a REST-Based Microservice — Lesson 2: Persistence, Transactions, Configuration, Secrets, and OCI Service Access

Learning Objectives

• Explain the purpose and operating context of database access patterns, connection pools, repositories, and transactions.
• Apply configuration profiles, environment variables, feature flags, and portability and Vault secrets, resource principals, policies, and least privilege in a controlled environment.
• Validate outcomes and troubleshoot risks involving retry, timeout, duplicate request, consistency, and failure tests.

Detailed Topics

• database access patterns, connection pools, repositories, and transactions
• configuration profiles, environment variables, feature flags, and portability
• Vault secrets, resource principals, policies, and least privilege
• retry, timeout, duplicate request, consistency, and failure tests

Instructor Demonstration

Demonstrate database access patterns, connection pools, repositories, and transactions for a small inventory microservice packaged, deployed, secured, and monitored on OCI; 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 Java on OCI: Develop a REST-Based Microservice exercise covering configuration profiles, environment variables, feature flags, and portability and Vault secrets, resource principals, policies, and least privilege; introduce an exception involving retry, timeout, duplicate request, consistency, and failure tests, 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 database access patterns, connection pools, repositories, and transactions, configuration profiles, environment variables, feature flags, and portability, Vault secrets, resource principals, policies, and least privilege, retry, timeout, duplicate request, consistency, and failure tests 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 Persistence, Transactions, Configuration, Secrets, and OCI Service Access in a realistic Java on OCI: Develop a REST-Based Microservice scenario and defend the result with documented evidence.