When designing a service, especially in Java using Spring Boot or other frameworks, there are several key standards and best practices to follow. These ensure scalability, maintainability, security, and performance.

1. Naming Convention Standards

A naming convention is a set of rules and best practices for naming variables, functions, classes, files, and other programming elements in a consistent and readable manner. Following a standard naming convention makes code clean, maintainable, and understandable.

✅1.1 Variables

• Use camelCase for variable names (firstName, totalAmount).

• Should be descriptive and meaningful (avoid a, x1).

• Boolean variables should start with is, has, can, or should (isActive, hasPermission).

✅ Good Example:

string firstName = 'Phong';
boolean isFisrtLoggedIn = true;

❌ Bad Example:

int x = 100;
boolean logged = true;

✅1.2 Constants

• Use SCREAMING_SNAKE_CASE (MAX_SIZE, DEFAULT_TIMEOUT).

• Always declare constants as final in Java and const in JavaScript.

public static final int MAX_USERS = 500;

✅1.3 Functions & Methods

• Use camelCase (getUserName(), calculateSalary()).

• The method name should describe an action (get, calculate, find, update).

✅ Good Example:

public double calculateInterest(double amount, double rate) {
    return amount * rate / 100;
}

❌ Bad Example:

public double calc(double a, double r) {
    return a * r / 100;
}

✅1.4 Class & Interface Names

• Use PascalCase (CustomerAccount, ProductService).

• Interfaces should be adjectives or start with I (Runnable, IUserRepository).

public class UserManager { }
public interface IUserService { }

✅1.5 File & Folder Naming

• Class files should match the class name (UserService.java).

• Use lowercase for package names (com.example.service).

package com.company.customer;
public class CustomerService { }

2. Indentation Format Standards

Indentation refers to the practice of adding spaces or tabs at the beginning of lines in the source code to define code structure and readability. It helps differentiate blocks of code and makes the program more maintainable.

✅2.1 Language Indentation – Java(4 Spaces)

• Use 4 spaces per level (no tabs).

• Curly braces {} should be on the same line for methods and loops.

✅ Good Example

public class HelloWorld {
    public static void main(String[] args) {
        int x = 10;
        if (x > 5) {
            System.out.println("X is greater than 5");
        }
    }
}

❌ Bad Example (Inconsistent Indentation)

public class HelloWorld {
    public static void main(String[] args) {
        int x = 10;
        if (x > 5) {
            System.out.println("X is greater than 5");
        }
    }
}

✅2.2 Language Indentation – JavaScript & TypeScript (2 or 4 Spaces)

• JavaScript projects typically use 2 spaces.

• Functions and loops must be indented properly.

✅ Good Example

function add(a, b) {
  if (a > 0) {
    return a + b;
  } else {
    return b;
  }
}

❌ Bad Example

function add(a, b) {
  if (a > 0) {
    return a + b;
  } else {
    return b;
  }
}

✅2.3 Common Mistakes to Avoid 

❌ Mixing spaces and tabs (causes formatting issues).
❌ Inconsistent indentation across files.
❌ Over-indenting nested code (deep nesting makes code unreadable).

3. Coding Comment Standards

A comment is a piece of text in the source code that is ignored by the compiler/interpreter. It helps document the code, making it easier to understand and maintain.

Key Principles of Writing Comments:
✅ Explain why, not just what the code does.
✅ Use consistent format across the project.
✅ Avoid redundant or too many comments.

✅3.1 Commenting Standards by Language 

✅3.2 Commenting Standards Best Practices

🔹 Single-Line Comments (// or #)

• Used for brief explanations of logic or special cases.

• Placed above or beside the related line of code.

✅ Java Example:

// Get user input and validate
String name = scanner.nextLine();

❌ Bad Comment Example (Obvious Comment)

int count = 10; // Assign 10 to count (Unnecessary)

🔹 Multi-Line Comments (/* ... */ or """ ... """)

• Used for detailed explanations.

• Ideal for function descriptions and complex logic.

✅ Java Example:

/*
 * This function calculates the area of a rectangle
 * given its width and height.
 */
public int calculateArea(int width, int height) {
    return width * height;
}

🔹 Documentation Comments (Javadoc, Docstring, XML Comments)

• Used for documenting functions, classes, and APIs.

• Helps generate automatic documentation (e.g., Javadoc, Sphinx).

📌 Javadoc (Java, Kotlin, C# XML Comments)

/**
 * Adds two numbers and returns the result.
 * @param a First number
 * @param b Second number
 * @return Sum of a and b
 */
public int add(int a, int b) {
    return a + b;
}

3. Architectural Standards

✅ 3.1 Layered Architecture (or Hexagonal Architecture)

• Follow Layered Architecture:

  • Controller Layer → Handles HTTP requests.

  • Service Layer → Contains business logic.

  • Repository Layer → Manages database operations.

  • Database Layer → Stores data.

• Or use Hexagonal Architecture:

  • Core Business Logic should be independent of frameworks.

  • Use Ports & Adapters for flexibility.

4. API Design Standards

✅ 4.1 RESTful API Principles

• Use proper HTTP methods:

  • GET → Retrieve data.

  • POST → Create a new resource.

  • PUT → Update an existing resource.

  • PATCH → Partially update a resource.

  • DELETE → Remove a resource.

• Use meaningful URLs:

GET /users → Fetch all users
GET /users/{id} → Fetch user by ID
POST /users → Create a user
PUT /users/{id} → Update user
DELETE /users/{id} → Delete user

Use standard HTTP status codes:

✅ 4.2 Request & Response Standards

Request Standards

• Request Headers

POST /users HTTP/1.1
Host: user-management.itech.asia
Content-Type: application/json
Authorization: Bearer <JWT-TOKEN>

• Request Body (JSON)

{
  "firstName": "First",
  "lastName": "Last",
  "email": "email@gmail.com",
  "password": "P@ssw0rd!",
  "age": 30
}

Response Standards

• Response Headers

HTTP/1.1 201 Created
Content-Type: application/json

• Response Body (JSON) : 200 success payload

{
  "status": "success",
  "message": "User created successfully",
  "data": {
    "id": 1,
    "name": "name",
    "email": "email@gmail.com",
    "createdAt": "2025-01-01T12:12:12Z"
  }
}

• Response Body (JSON) : 400 error payload

{
  "status": "error",
  "message": "Validation failed",
  "errors": [
    {
      "field": "email",
      "message": "Invalid email format"
    },
    {
      "field": "password",
      "message": "Password must be at least 8 characters"
    }
  ]
}

• Use DTOs (Data Transfer Objects) to prevent exposing database entities directly.

• Use Pagination & Filtering for large datasets:

  GET /products?page=1&size=10&sort=price,desc

✅ 4.3 API Documentation

• Use Swagger (OpenAPI) for API documentation.

• Example with Spring Boot:

  @Operation(summary = "Get user by ID", description = "Returns a single user")
  @GetMapping("/{id}")
  public ResponseEntity<UserDTO> getUserById(@PathVariable Long id) {
      return ResponseEntity.ok(userService.getUserById(id));
  }

5. Security Standards

✅ 5.1 Authentication & Authorization

• Use JWT (JSON Web Token) or OAuth2 for authentication.

  • JWT tokens must be signed (such as RS256 or ES256, not HS256 for security reasons).

  • Access tokens must have an expiration time (short-lived, e.g., 15 minutes).

  • Refresh tokens should have a longer expiration (e.g., 7 days) and be securely stored.

• Example of JWT Token-based security:

  Authorization: Bearer <your-jwt-token>

• Implement Role-Based Access Control (RBAC).

  • Fine-grained roles should be used (Admin, User, Manager, Viewer).

• Avoid storing sensitive tokens in local storage (for web applications).

  • Use HttpOnly or secure cookies instead.

• Enforce Multi-Factor Authentication (MFA) for sensitive operations, automatically for all Admin roles.

✅ 5.2 Secure API Endpoints

• Use HTTPS for all communications.

  • TLS 1.2 or 1.3 must be enforced.

  • Disable insecure ciphers and protocols (e.g., TLS 1.0, 1.1).

• Validate and sanitize user input to prevent SQL Injection & XSS.

  • Use parameterized queries in SQL.

  • Implement input validation on both the front-end and back-end.

  • Escape and encode output properly.

• Implement Rate Limiting to prevent abuse

  • Use tools like Spring Cloud Gateway, Nginx, or API Gateway.

  • Use tools like Anti-DDOS, and WAF features in both the Test and Production environments.

• Implement Content Security Policy (CSP) for web apps.

✅ 5.3 Secure Data Handling

• Use AES-256 encryption for sensitive data at rest.

• Use bcrypt, Argon2, or PBKDF2 for password hashing.

• Disable data exposure through verbose error messages.

• Do not store PII or sensitive data in logs.

✅ 5.4 Secure Logging & Monitoring

• Use structured logging formats (JSON preferred).

• Log failed authentication attempts and suspicious access patterns.

• Mask sensitive data in logs (e.g., passwords, credit card numbers).

• Integrate centralized logging (e.g., ELK Stack, Loki, or Splunk).

✅ 5.5 Secure Logging & Monitoring

• Use tools to detect vulnerable dependencies (e.g., Snyk, OWASP Dependency Check).

• Keep dependencies updated regularly.

• Avoid using unverified third-party packages.

✅ 5.6 Secure Software Development Lifecycle (SDLC)

• Enforce static code analysis (SAST).

• Perform dynamic security testing (DAST).

• Use Infrastructure-as-Code security scanning (e.g., Checkov, Terraform Validator).

• Implement security peer reviews in code review processes.

✅ 5.7 Secure CI/CD Pipeline

• Ensure secrets are not hardcoded in repositories.

• Use environment variables or a secrets manager (e.g., AWS Secrets Manager, HashiCorp Vault).

• Use automated security scanning tools in CI/CD.

6. Performance & Scalability

✅ 6.1 Caching

• Use Redis or Ehcache to cache frequently accessed data.

• Example:

  @Cacheable(value = "users", key = "#id")
  public UserDTO getUserById(Long id) { ... }

✅ 6.2 Asynchronous Processing

• Use @Async for background tasks.

  @Async
  public void sendEmail(String email) { ... }

• Use Message Queues (RabbitMQ, Kafka) for event-driven processing.

✅ 6.3 Database Optimization

• Use Indexes on frequently queried columns.

• Use Connection Pooling (HikariCP).

• Avoid N+1 Query Problem by using @EntityGraph or JOIN FETCH.

7. Testing Standards

✅ 7.1 Unit Testing (JUnit & Mockito)

• Use JUnit & Mockito for unit tests.

  @Test
  public void testGetUserById() {
    when(userRepository.findById(1L)).thenReturn(Optional.of(new User(1L, "Phong")));
    assertEquals("Phong",userService.getUserById(1L).getName());
  }

  ✅ 7.2 Integration Testing

• Use Spring Boot Test for full application testing.

  @SpringBootTest
  @WebMvcTest(UserController.class)
  public class UserControllerTest { ... }

  ✅ 7.3 API Testing

• Use Postman, RestAssured, or Karate for API validation.

8. Version Control & Code Review Standards

✅ 8.1 Version Control Standard

Version control is a system that tracks changes to files, allowing multiple developers to collaborate efficiently. The most common version control system is Git.

To maintain a structured workflow, teams follow version control standards to ensure consistency, traceability, and efficiency in managing code changes.

8.1.1 Branching Strategy – Version Control

• Use branches to separate development, features, and bug fixes.

• Common branch strategies:

  • Main Branches:

    • main (or master): Stable, production-ready code.

    • develop: Active development branch.

  • Feature Branches: feature/feature-name (for new features).

  • Bugfix Branches: bugfix/fix-description (for bug fixes).

  • Release Branches: release/version-number (for releases).

  • Hotfix Branches: hotfix/urgent-fix (for critical production fixes).

  • ✅ Example Git Flow

    main
     ├── develop
     │   ├── feature/login
     │   ├── feature/cart
     │   ├── bugfix/payment-issue
     │   └── release/v1.0
     └── hotfix/security-fix
    

8.1.2 Commit Message – Version Control

• A commit message should be clear, concise, and meaningful.

• Use imperative tense (e.g., “Fix bug”, not “Fixed bug”).

• Follow a structured format, such as:

✅ Good Commit Message Format

<type>: <short description>
[Optional] Longer description explaining *what* and *why*.
[Optional] Issue reference (e.g., Closes #123).

✅ Good Commit Messages

feat: Add JWT authentication
- Implement JWT-based login
- Secure API routes with middleware
- Closes #45

❌ Bad Commit Messages

"Fixed bug"
"Updated code"
"asdfghjkl"

8.1.3 Tagging & Versioning (Semantic Versioning)

• Use Semantic Versioning: MAJOR.MINOR.PATCH (v1.2.3).

  • MAJOR: Breaking changes (v2.0.0).

  • MINOR: New features, backward-compatible (v1.1.0).

  • PATCH: Bug fixes (v1.0.1).

✅ Example Git Tagging

git tag -a v1.0.0 -m "Initial release"
git push origin v1.0.0

✅ 8.2 Code Review Standard 

• Use Pull Requests (PRs) for merging changes.

• Follow naming conventions for PRs (e.g., [FEATURE] Implement user profile).

• PR must be reviewed before merging.

• Use a checklist before merging: ✅ Code follows style guide.
  ✅ No console logs or debug prints.
  ✅ Tests have been written and pass.
  ✅ Code is reviewed and approved.

✅ Example PR Title & Description

[FEATURE] Implement User Profile API
## Description
- Added endpoints for user profile retrieval and update.
- Integrated JWT authentication.
- Closes #56.
## Checklist
- [x] Code follows project conventions.
- [x] Tests added and passing.
- [x] Peer-reviewed.

• Codebase Hygiene

  • Regularly delete merged branches.

  • Avoid committing large files (Use .gitignore for logs, builds).

  • Use rebase instead of merge to keep history clean:

    git pull --rebase origin develop

9. Logging & Monitoring Standards

✅ 9.1 Standard structured for Message Logging

• Essential Fields in a Log Message

Sample in JSON Format

{
  "timestamp": "2024-02-06T12:34:56.789Z",
  "level": "ERROR",
  "service": "user-service",
  "traceId": "abc123-trace",
  "userId": "user-5678",
  "source": "UserService.createUser()",
  "message": "User creation failed: Email already exists",
  "metadata": {
    "email": "user@example.com"
  }
}

• Standardized Log Levels

✅ 9.2 Centralized Logging

• Use SLF4J + Logback for structured logs.

  private static final Logger logger = LoggerFactory.getLogger(UserService.class);
  logger.info("User retrieved: {}", userId);

• Use ELK Stack (Elasticsearch, Logstash, Kibana) or Grafana or Loki for log analysis.

✅ 9.3 Metrics & Monitoring

• Use Spring Boot Actuator for health checks:

  GET /actuator/health

• Use Prometheus + Grafana for performance monitoring.

10. Deployment & DevOps Standards

✅ 10.1 CI/CD Pipeline

• Use GitHub Actions, Jenkins, or GitLab CI/CD for automated builds and deployments.

• Example GitHub Actions workflow:

  jobs:
    build:
      runs-on: ubuntu-latest
      steps:
        - uses: actions/checkout@v2
        - name: Set up JDK
          uses: actions/setup-java@v2
          with:
            java-version: '17'
        - name: Build with Maven
          run: mvn clean install

✅ 10.2 Containerization

• Use Docker for consistent deployments.

• Example Dockerfile for a Spring Boot app:

  FROM openjdk:1-jdk
  COPY target/app.jar app.jar
  ENTRYPOINT ["java", "-jar", "app.jar"]

✅ 10.3 Scalability

• Use Kubernetes or Docker Compose for container orchestration.

• Implement Load Balancing with Nginx or AWS ALB.

11. Code Quality & Static Analysis Tools

Ensuring code quality, security, and maintainability in a Java Spring Boot project requires integrating static analysis tools. These tools help detect vulnerabilities, enforce coding standards, and improve overall software quality. Below are the best options:

✅ 11.1 SonarQube

• Purpose: Code quality, bug detection, security vulnerability analysis.

• Integration: Can be integrated with Maven, Gradle, GitHub Actions, Jenkins.

• Key Features:

  • Detects code smells, bugs, vulnerabilities.

  • Supports OWASP, SAST, and dependency scanning.

  • Generates detailed reports on code maintainability.

Setup with Maven:

<plugin>
    <groupId>org.sonarsource.scanner.maven</groupId>
    <artifactId>sonar-maven-plugin</artifactId>
    <version>3.9.1.2184</version>
</plugin>

Run Analysis:

mvn clean verify sonar:sonar -Dsonar.projectKey=-itech-user-management

✅ 11.2 SpotBugs

• Purpose: Finds bugs in Java code (successor of FindBugs).

• Integration: Maven, Gradle, Jenkins.

• Key Features:

  • Detects null pointer exceptions, resource leaks, and concurrency issues.

  • Provides an HTML report.

Setup with Maven:

<plugin>
    <groupId>com.github.spotbugs</groupId>
    <artifactId>spotbugs-maven-plugin</artifactId>
    <version>4.7.3.4</version>
    <executions>
        <execution>
            <goals>
                <goal>check</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Run Analysis:

mvn spotbugs:check

✅ 11.3 PMD

• Purpose: Detects programming flaws and enforces coding standards.

• Integration: Maven, Gradle.

• Key Features:

  • Identifies unused variables, empty catch blocks, inefficient loops.

  • Supports custom rule configuration.

Setup with Maven:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-pmd-plugin</artifactId>
    <version>3.18.0</version>
    <executions>
        <execution>
            <goals>
                <goal>check</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Run Analysis:

mvn pmd:check

Feature Comparison :

12. Security Analysis Tools

Security scanning and vulnerability detection are crucial for maintaining secure and high-quality code. Below is a detailed comparison of SonarQube, Snyk, and WhiteSource (Mend.io) based on key security features, capabilities, and best use cases.

✅ 12.1 SonarQube:

SonarQube performs static code analysis (SAST) to detect security vulnerabilities, code smells, and bugs in source code.
✔ Detects OWASP Top 10, CWE (Common Weakness Enumeration), and Security Hotspots.
✔ Best for preventing vulnerabilities before deployment in custom code.
✔ Supports CI/CD pipelines for automated security checks.

🔹 Best for: Developers and security teams focusing on code security within applications.

🔗 Website: SonarQube

✅ 12.2 Snyk

Snyk specializes in dependency security and open-source package vulnerability scanning (SCA).
✔ Detects vulnerabilities in third-party libraries, Docker containers, and Kubernetes clusters.
✔ Provides real-time monitoring and integrates with GitHub, GitLab, Bitbucket, Azure DevOps.
✔ Identifies zero-day vulnerabilities and applies automated security fixes.

🔹 Best for: DevOps teams, organizations using open-source dependencies, containers, and cloud-native applications.

🔗 Website: Snyk

✅12.3 WhiteSource (Mend.io)

WhiteSource (Mend.io) focuses on open-source security, software composition analysis (SCA), and compliance.
✔ Scans third-party components for security issues and license risks (GPL, MIT, Apache, etc.).
✔ Tracks and mitigates open-source vulnerabilities using CVE databases.
✔ Supports real-time dependency monitoring for license risk management.

🔹 Best for: Enterprises that need license compliance & dependency security management.

🔗 Website: Mend.io

Feature Comparison

Summary: Key Requirements for a Service