1. API Design

1.1. CRUD Operations

Basic operation of any data driven application

HTTP Example

• CREATE -> POST /api/products
• READ -> GET /api/products
• UPDATE -> PUT /api/products/:id
• DELETE -> DELETE /api/products/:id

1.2. Communication formats

JSON (JavaScript Object Notation)

• Characteristics:
  • Lightweight data-interchange format
  • Human-readable and easy to understand
  • Based on a subset of JavaScript
• Structure:
  • Uses key-value pairs and arrays
  • Supports nested structures
• Data Types:
  • String, Number, Boolean, Array, Object, null
• Pros:
  • Wide support across languages and platforms
  • Easy to parse and generate
  • Compact compared to XML
• Cons:
  • No support for comments
  • Limited data type support (e.g., no date type)
• Use Cases:
  • Web APIs, Configuration files, Data storage

XML (eXtensible Markup Language)

• Characteristics:
  • Markup language that defines a set of rules for encoding documents
  • Self-descriptive and flexible
• Structure:
  • Uses tags to define elements
  • Supports attributes within tags
• Features:
  • Namespaces for avoiding name conflicts
  • DTD and XML Schema for defining structure
• Pros:
  • Highly extensible
  • Strong support for metadata
  • Validation capabilities
• Cons:
  • More verbose than JSON or Protocol Buffers
  • Can be overly complex for simple data
• Use Cases:
  • SOAP web services, Configuration files, Data interchange in enterprise systems

Protocol Buffers (Protobuf)

• Characteristics:
  • Binary serialization format developed by Google
  • Language-neutral, platform-neutral, extensible
• Structure:
  • Defines message types in .proto files
  • Strongly typed fields
• Features:
  • Backward and forward compatibility
  • Code generation for multiple languages
• Pros:
  • Smaller size compared to JSON and XML
  • Faster parsing and serialization
  • Strict typing reduces errors
• Cons:
  • Not human-readable in binary form
  • Requires additional tooling for development
  • Less flexible than JSON or XML for dynamic structures
• Use Cases:
  • High-performance RPC systems (e.g., gRPC)
  • Inter-service communication in microservices
  • Data storage where space efficiency is crucial

Comparison

• JSON: Best for web applications and APIs where human readability is important
• XML: Suitable for complex data with metadata requirements and where extensive tooling support is beneficial
• Protocol Buffers: Ideal for high-performance scenarios and when working with strongly typed data in multiple languages

1.3. API Paradigms

REST (Representational State Transfer)

• Characteristics:
  • Stateless architecture
  • Uses standard HTTP methods (GET, POST, PUT, DELETE)
  • Typically uses JSON for data exchange
  • Resource-oriented design
• Pros:
  • Simple and widely adopted
  • Scalable and cacheable
  • Separation of client and server
• Cons:
  • Potential for over-fetching or under-fetching data
  • Multiple round trips for complex data requirements

GraphQL

• Characteristics:
  • Single endpoint for all operations
  • Strongly typed schema-based queries
  • Allows clients to request specific data
• Pros:
  • Avoids over-fetching and under-fetching
  • Flexible data retrieval
  • Strong typing and introspection
• Cons:
  • Complex queries can impact server performance
  • Only uses POST requests
  • Always responds with HTTP 200 (error handling complexity)
  • Steeper learning curve

gRPC (Google Remote Procedure Call)

• Characteristics:
  • Built on HTTP/2 protocol
  • Uses Protocol Buffers for serialization
  • Supports streaming (unary, server, client, bidirectional)
• Pros:
  • High performance and low latency
  • Efficient binary serialization
  • Strong typing with protocol buffers
  • Supports multiplexing and server push
• Cons:
  • Less human-readable (binary format)
  • Requires HTTP/2 support
  • Limited browser support
  • Steeper learning curve compared to REST

Use Cases

• REST: Good for public APIs and CRUD operations
• GraphQL: Ideal for complex data requirements and multiple client types
• gRPC: Excellent for microservices and high-performance inter-service communication

1.4. Backward Compatibility and Versioning

To ensure redesigns or changes don't break existing functionality, implement versioned URLs for different API versions.

REST API Versioning

• Current Version: /api/v2/products
  • Serves current clients
  • Latest features and improvements
• Legacy Version: /api/v1/products
  • Serves older clients
  • May be deprecated in future

GraphQL Versioning

• Current Version: products_v2
  • Serves current clients
  • Latest schema and resolvers
• Legacy Version: products
  • Serves older clients
  • Consider migration timeline

1.5. API Best Practices

Security Measures

1. Rate Limiter

• Purpose: Prevents DDOS attacks and excessive API usage
• Implementation:
  • Set request limits per user/IP
  • 429 Too Many Requests response when exceeded
  • Helps maintain API stability

2. CORS (Cross-Origin Resource Sharing)

• Purpose: Controls domain access to API
• Implementation:
  • Define allowed origins
  • Set appropriate headers
  • Prevents unauthorized cross-site interactions