API Architecture
Purpose of this Document
This document defines the API architecture strategy for [System Name], including API design principles, patterns, governance, and implementation details.
API Strategy Overview
API Philosophy: [Approach to API design]
Primary Goals:
- [Goal 1, e.g., "Enable partner integration"]
- [Goal 2, e.g., "Support mobile applications"]
- [Goal 3, e.g., "Internal service communication"]
Key Principles:
- [Principle 1, e.g., "API-first design"]
- [Principle 2, e.g., "Contract-driven development"]
- [Principle 3, e.g., "Consistent error handling"]API Types and Usage
API Types:
REST:
Style: [REST/HAL/JSON-API/OData]
Version Strategy: [URI/Header/Content-Type]
Use Cases: [When to use REST]
Constraints: [Limitations or considerations]
GraphQL:
Schema Design: [Approach to schema design]
Federation: [Approach to federated schemas]
Use Cases: [When to use GraphQL]
Constraints: [Limitations or considerations]
gRPC:
Proto Design: [Approach to Proto definitions]
Streaming: [Strategy for streaming data]
Use Cases: [When to use gRPC]
Constraints: [Limitations or considerations]
Event-Based:
Protocol: [Webhook/SSE/WebSockets]
Format: [Message format]
Use Cases: [When to use events]
Constraints: [Limitations or considerations]API Governance
API Lifecycle:
Design: [Process for designing APIs]
Review: [Review process]
Versioning: [Approach to versioning]
Deprecation: [Process for deprecating APIs]
Retirement: [Process for retiring APIs]
Standards:
Naming: [Naming conventions]
Documentation: [Documentation requirements]
Security: [Security requirements]
Performance: [Performance requirements]
Monitoring:
Metrics: [Key metrics to track]
Alerting: [When to alert]
Reporting: [Required reports]API Gateway Architecture
graph TD
subgraph "API Consumers"
A[Mobile Apps]
B[Web Apps]
C[Partner Systems]
D[Internal Services]
end
subgraph "API Gateway Layer"
E[API Gateway]
F[Authentication]
G[Rate Limiting]
H[Request Routing]
I[Response Transformation]
J[Monitoring]
end
subgraph "Backend Services"
K[Service 1]
L[Service 2]
M[Service 3]
end
A --> E
B --> E
C --> E
D --> E
E --> F
E --> G
E --> H
E --> I
E --> J
H --> K
H --> L
H --> MAPI Gateway Components
@startuml
package "API Gateway" {
[Rate Limiting] as RL
[Authentication] as Auth
[Authorization] as Authz
[Routing] as Route
[Transformation] as Trans
[Caching] as Cache
[Monitoring] as Mon
}
cloud "Clients" {
[Mobile] as Mobile
[Web] as Web
[Partners] as Partners
}
cloud "Backend" {
[Microservices] as MS
[Legacy Systems] as Legacy
[External Services] as Ext
}
Mobile --> RL
Web --> RL
Partners --> RL
RL --> Auth
Auth --> Authz
Authz --> Route
Route --> Trans
Trans --> Cache
Route --> MS
Route --> Legacy
Route --> Ext
Auth ..> Mon
Route ..> Mon
Cache ..> Mon
@endumlAPI Design Standards
REST API Standards
- Resource Naming: Use plural nouns for collections (
/users), singular for specific resources (/users/{id}) - HTTP Methods:
- GET: Retrieve resources
- POST: Create resources
- PUT: Replace resources
- PATCH: Update resources partially
- DELETE: Remove resources
- Status Codes:
- 200: Success
- 201: Created
- 204: No Content
- 400: Bad Request
- 401: Unauthorized
- 403: Forbidden
- 404: Not Found
- 409: Conflict
- 422: Unprocessable Entity
- 429: Too Many Requests
- 500: Internal Server Error
- Query Parameters:
- Filtering:
?status=active - Sorting:
?sort=createdAt:desc - Pagination:
?page=2&limit=10 - Fields selection:
?fields=id,name,email
- Filtering:
- Response Format:
{
"data": {
"id": "123",
"type": "user",
"attributes": {
"name": "John Doe",
"email": "john@example.com"
},
"relationships": {
"orders": {
"links": {
"related": "/users/123/orders"
}
}
}
},
"meta": {
"requestId": "abc-123"
}
}GraphQL Standards
- Schema Design:
- Use descriptive type names
- Include descriptions for types and fields
- Use interfaces for common fields
- Implement connections for pagination
- Operations:
- Queries: For fetching data
- Mutations: For modifying data
- Subscriptions: For real-time updates
- Error Handling:
- Use standard GraphQL errors
- Include error codes
- Provide actionable error messages
- Example Schema:
"""
A user in the system
"""
type User {
id: ID!
name: String!
email: String!
createdAt: DateTime!
orders(first: Int, after: String): OrderConnection!
}
type OrderConnection {
edges: [OrderEdge!]!
pageInfo: PageInfo!
totalCount: Int!
}
type OrderEdge {
node: Order!
cursor: String!
}
type PageInfo {
hasNextPage: Boolean!
hasPreviousPage: Boolean!
startCursor: String
endCursor: String
}gRPC Standards
- Proto Design:
- Use descriptive service and message names
- Version proto files
- Include field comments
- Use appropriate field types
- Service Types:
- Unary: Simple request/response
- Server streaming: One request, multiple responses
- Client streaming: Multiple requests, one response
- Bidirectional streaming: Multiple requests and responses
- Example Proto:
syntax = "proto3";
package example.v1;
service UserService {
// GetUser returns a single user by ID
rpc GetUser(GetUserRequest) returns (GetUserResponse);
// ListUsers returns a paginated list of users
rpc ListUsers(ListUsersRequest) returns (ListUsersResponse);
// CreateUser creates a new user
rpc CreateUser(CreateUserRequest) returns (CreateUserResponse);
// WatchUserUpdates streams user updates in real-time
rpc WatchUserUpdates(WatchUserUpdatesRequest) returns (stream UserUpdate);
}
message GetUserRequest {
string user_id = 1;
}
message GetUserResponse {
User user = 1;
}
message User {
string id = 1;
string name = 2;
string email = 3;
google.protobuf.Timestamp created_at = 4;
}API Security
Security Controls:
Authentication:
- OAuth 2.0:
Grant Types: [Authorization Code, Client Credentials, etc.]
Token Format: [JWT]
Token Lifetime: [Access token and refresh token lifetime]
- API Keys:
Usage: [When to use API keys]
Distribution: [How API keys are distributed]
Rotation: [Key rotation policy]
- mTLS:
Usage: [When to use mTLS]
Certificate Management: [Process for managing certificates]
Authorization:
- RBAC:
Roles: [Key roles]
Permissions: [How permissions are managed]
- Scopes:
Definition: [How OAuth scopes are defined]
Validation: [How scopes are validated]
- Rate Limits:
Default: [Default limits]
Tiers: [Rate limit tiers]
Enforcement: [How limits are enforced]
Headers: [Response headers]
Transport Security:
- TLS Version: [Minimum TLS version]
- Cipher Suites: [Allowed cipher suites]
- HSTS: [HSTS configuration]
- Certificate Management: [Process for managing certificates]API Management
Developer Experience:
Documentation:
- API Reference: [Format and location]
- Tutorials: [How-to guides]
- Code Examples: [Example code in key languages]
- SDKs: [Available SDKs]
Developer Portal:
- Self-service: [Registration and API key management]
- Analytics: [Usage reporting]
- Support: [How to get support]
Sandbox Environment:
- Access: [How to access]
- Data: [Sample data]
- Limitations: [Differences from production]
API Gateway Features:
Request Processing:
- Validation: [Schema validation]
- Transformation: [Request transformation]
- Enrichment: [Request enrichment]
Response Processing:
- Transformation: [Response transformation]
- Compression: [Compression settings]
- Caching: [Caching strategy]
Operational:
- Logging: [Logging configuration]
- Monitoring: [Metrics collected]
- Alerting: [Alert conditions]API Operations
Monitoring:
Metrics:
- Availability: [SLA targets]
- Response Time: [Performance targets]
- Error Rate: [Error rate targets]
- Usage: [Usage tracking]
Logging:
- Request Logs: [What is logged]
- Error Logs: [Error details]
- Audit Logs: [Audited events]
- Retention: [Log retention period]
Alerts:
- SLA Breaches: [Alert conditions]
- Error Spikes: [Alert conditions]
- Usage Anomalies: [Alert conditions]
- Security Events: [Alert conditions]
Troubleshooting:
Tools:
- Request Tracing: [Tracing tools]
- Log Analysis: [Log analysis tools]
- API Testing: [Testing tools]
Common Issues:
- Authentication Failures: [Troubleshooting steps]
- Rate Limiting: [Troubleshooting steps]
- Performance Issues: [Troubleshooting steps]
- Integration Errors: [Troubleshooting steps]API Analytics
Usage Analytics:
Metrics:
- Calls by API: [Tracking API usage]
- Calls by Consumer: [Tracking consumer usage]
- Calls by Endpoint: [Tracking endpoint usage]
- Error Rates: [Tracking errors]
- Performance: [Tracking performance]
Reporting:
- Dashboards: [Available dashboards]
- Alerts: [Alert thresholds]
- Exports: [Data export options]
Insights:
- Trend Analysis: [Usage trends]
- Anomaly Detection: [Unusual patterns]
- Consumer Behavior: [Usage patterns]API Deployment
Deployment Strategy:
- CI/CD Pipeline: [Approach to automated deployment]
- Environment Promotion: [Dev → Test → Prod flow]
- Canary Releases: [Approach to gradual rollout]
- Feature Flags: [Runtime configuration]
API Versioning:
- Strategy: [URI/Header/Content-Type]
- Compatibility: [Backward compatibility policy]
- Deprecation: [Process for deprecating versions]
- Sunsetting: [Process for retiring versions]Example Implementation
REST API Endpoint
@RestController
@RequestMapping("/api/v1/users")
public class UserController {
@GetMapping("/{id}")
public ResponseEntity<UserResponse> getUser(@PathVariable String id) {
// Authorization check
// Fetch user
// Transform to response
return ResponseEntity.ok(userResponse);
}
@PostMapping
public ResponseEntity<UserResponse> createUser(@RequestBody @Valid UserRequest request) {
// Validation
// Create user
// Return response with location header
return ResponseEntity
.created(URI.create("/api/v1/users/" + userId))
.body(userResponse);
}
}GraphQL Resolver
const resolvers = {
Query: {
user: async (_, { id }, context) => {
// Authorization check
const user = await context.dataSources.users.getUserById(id);
return user;
},
users: async (_, { filter, page, limit }, context) => {
// Filter and paginate users
const result = await context.dataSources.users.listUsers(filter, page, limit);
return {
edges: result.items.map(user => ({
node: user,
cursor: encodeCursor(user.id)
})),
pageInfo: {
hasNextPage: result.hasMore,
endCursor: result.items.length ? encodeCursor(result.items[result.items.length - 1].id) : null
},
totalCount: result.totalCount
};
}
},
Mutation: {
createUser: async (_, { input }, context) => {
// Create user
const user = await context.dataSources.users.createUser(input);
return { user };
}
}
};