Chapter 3: REST API & Web Layer

Building high-throughput, maintainable RESTful services requires mastering Spring MVC's front-controller pipeline, resource endpoint mapping, payload serialization, declarative validation, and standard HTTP response semantics.

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🧭 Subtopics & Curriculum

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Pipeline Architecture3.1

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3.1 Spring MVC Architecture & Request Flow

• End-to-End Request Processing Flow
• Core Architectural Components
• Filters vs HandlerInterceptors
• What is Statelessness in REST?
• Rest vs Soap

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Endpoint Design3.2

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3.2 REST Controllers & Endpoint Mapping

• @Controller vs @RestController
• HTTP Method Mappings & REST Semantics
• Indempotency

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Payload Ingestion3.3

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3.3 Request Parameters & Payloads

• 1. Parameter Extraction Annotations Matrix
• 2. Practical Endpoint Example
• 3. Best Practice: Java Records as Immutable DTOs

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HTTP Protocols3.4

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3.4 ResponseEntity & Content Negotiation

• 1. HTTP Status Code Conventions
• 2. Constructing Responses with Fluent API
• 3. Content Negotiation

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Data Integrity3.5

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3.5 Request Validation & Hibernate Validator

• Bean Validation
  • @NotNull vs @NotBlank vs @NotEmpty
• Core Validation Annotations
• What is @Valid
• What is @Validated
  • @Valid vs @Validated
• Triggering Validation in the Controller
• Custom Constraint Validator
  • 1. Define the Annotation
  • 2. Implement the ConstraintValidator

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