Java Web Services — Lesson 1: HTTP, REST Constraints, JAX-RS Resources, and API Contracts

Learning Objectives

• Explain the architecture, workflow, or business purpose behind HTTP methods, status codes, headers, idempotency, and caching.
• Apply resource modeling, URI design, JAX-RS annotations, and routing and request and response representations, media types, and content negotiation in a controlled scenario.
• Validate outcomes and troubleshoot risks involving OpenAPI awareness, contract examples, and compatibility decisions.

Detailed Topics

• HTTP methods, status codes, headers, idempotency, and caching
• resource modeling, URI design, JAX-RS annotations, and routing
• request and response representations, media types, and content negotiation
• OpenAPI awareness, contract examples, and compatibility decisions

Instructor Demonstration

Demonstrate HTTP methods, status codes, headers, idempotency, and caching 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 1.

Hands-On Exercise

Implement a controlled exercise covering resource modeling, URI design, JAX-RS annotations, and routing and request and response representations, media types, and content negotiation, then introduce and resolve an exception involving OpenAPI awareness, contract examples, and compatibility decisions 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 HTTP methods, status codes, headers, idempotency, and caching, resource modeling, URI design, JAX-RS annotations, and routing, request and response representations, media types, and content negotiation, OpenAPI awareness, contract examples, and compatibility decisions 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 HTTP, REST Constraints, JAX-RS Resources, and API Contracts in a realistic Java Web Services scenario and validate the result with documented evidence.