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Diego Liascovich
Diego Liascovich

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🔌 REST, GraphQL, Events, gRPC & More: API Types Explained with Use Cases

#api #rest #microservices #graphql

By Diego Liascovich

*Full-Stack Developer | Microservices | Api | Rest | GraphQL

APIs are the backbone of modern applications — but not all APIs are created equal. In this post, I’ll walk you through the most common types of APIs: REST, GraphQL, Event-Driven APIs, gRPC, and more — explaining how they work, their pros and cons, and when to use each.

🌐 1. REST (Representational State Transfer)

📌 Overview

REST APIs use standard HTTP verbs (GET, POST, PUT, DELETE) to access resources via URLs.

✅ Best For

  • CRUD applications
  • Simple and predictable data access
  • Public APIs

🧪 Example 

GET /api/users/42
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✔️ Pros

  • Easy to understand and implement
  • Widely supported by tools and frameworks
  • Can be cached via HTTP

❌ Cons

  • Overfetching/underfetching of data
  • Multiple requests needed to fetch related data

🧬 2. GraphQL

📌 Overview

GraphQL uses a single endpoint and a query language that lets clients request exactly the data they need.

✅ Best For

  • Complex UIs that need different data shapes
  • Frontend-heavy apps (like React/Angular)
  • Reducing number of API calls

🧪 Example 

query {
  user(id: "42") {
    name
    email
    orders {
      id
      total
    }
  }
}
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✔️ Pros

  • Precise data retrieval (no overfetching)
  • Strongly typed schema
  • One endpoint for all data

❌ Cons

  • Harder to cache with standard HTTP tools
  • Learning curve for query language
  • Complex server setup for some use cases

⚡ 3. Event-Driven APIs (EDA)

📌 Overview

Instead of calling APIs directly, services emit events (like order.placed) that other services subscribe to.

✅ Best For

  • Microservices architecture
  • Loose coupling between services
  • Asynchronous flows (notifications, logs, automation)

🧪 Example Event 

{
  "event": "user.created",
  "data": {
    "userId": "123",
    "email": "user@example.com"
  }
}
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✔️ Pros

  • Fully decoupled services
  • Highly scalable and resilient
  • Ideal for audit logs, triggers, and workflows

❌ Cons

  • Harder to debug and trace flow
  • Requires messaging infrastructure (e.g., RabbitMQ, Kafka)

🧠 4. gRPC (Google Remote Procedure Call)

📌 Overview

gRPC is a high-performance RPC framework using Protocol Buffers and HTTP/2.

✅ Best For

  • Microservices with high throughput needs
  • Internal service-to-service communication
  • Real-time streaming

🧪 Example (Proto) 

service UserService {
  rpc GetUser (UserRequest) returns (UserResponse);
}
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✔️ Pros

  • Extremely fast and lightweight
  • Language-neutral, auto-generates code
  • Built-in streaming support

❌ Cons

  • Not browser-friendly by default
  • Requires .proto file management
  • More complex debugging

📡 5. WebSockets

📌 Overview

WebSockets provide bi-directional communication between client and server, ideal for real-time applications.

✅ Best For

  • Chat apps
  • Live dashboards/notifications
  • Collaborative tools

✔️ Pros

  • Low latency, real-time data
  • Two-way persistent connection

❌ Cons

  • More complex server/client handling
  • Can’t use REST-style caching

🧓 6. SOAP (Simple Object Access Protocol)

📌 Overview

An older protocol using XML with a strict message format.

✅ Best For

  • Legacy systems (banks, governments)
  • Strong contract-based APIs

✔️ Pros

  • Rigid structure and strong typing
  • Works well in enterprise environments

❌ Cons

  • Verbose XML
  • Slower and more complex than REST/GraphQL

📊 Quick Comparison

API Type Style Best Use Cases Real-Time Complexity
REST HTTP CRUD, public APIs ❌ ⭐
GraphQL Query Lang Frontend data fetching, apps w/ UIs ❌ ⭐⭐
Events (EDA) Messaging Microservices, async workflows ✅ (indirect) ⭐⭐⭐
gRPC RPC Internal service comm, high perf ✅ ⭐⭐⭐⭐
WebSockets Socket-based Live apps, chats, dashboards ✅ ⭐⭐⭐
SOAP XML-based Enterprise systems, strong typing ❌ ⭐⭐⭐⭐

✅ Conclusion

There’s no “one size fits all” — choose your API type based on:

  • 🚀 Performance needs
  • 📦 System architecture
  • 🔄 Data patterns (real-time, on-demand, batch)
  • 🔧 Development environment

💬 What API style do you prefer and why? Share your experience below!

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