API Protocols and Standards

Recently while discussing with high school students ( I volunteer at High School) one of the students asked about API and comparison of contemporary standards and protocols.

I am sharing the same document here with wider audience, hopefully useful for budding software engineers.

A.     Major Types of API Protocols / Standards

a.      REST (Representational State Transfer) API

Type: Architectural style (not a protocol)
Data Format: Usually JSON (some time XML as well)
Transport: HTTP/HTTPS

Key Traits:

• Resource-based (/users, /orders).
• Stateless; each request contains all needed info.
• Widely used in web and mobile apps.
• Easy to develop, cache, and scale.

Best Use Cases:

• Public APIs
• CRUD-style services
• Simple, broadly compatible integration

 

b.     SOAP (Simple Object Access Protocol) API

Type: Protocol
Data Format: XML
Transport: Typically, HTTP + XML envelopes

Key Traits:

• Strict rules, strong standards (WSDL, XSD).
• Built-in error handling and security standards (WS-Security).
• Contracts strongly enforced.

Best Use-Cases:

• Enterprise systems (banking, telco, healthcare).
• High-security, ACID-like transactions.
• Legacy but still heavily used in regulated industries.

 

 

c.       gRPC (Google Remote Procedure Call)

Type: Protocol
Data Format: Protobuf (binary)
Transport: HTTP / HTTPS 2

Key Traits:

• High performance, low latency.
• Strongly typed schemas (protobuf).
• Supports streaming (client, server, and bidirectional).
• Autogenerates client SDKs.

Best Use-Cases:

• Microservices communication
• Real-time internal systems
• High-throughput, low-latency services
• Audio / Video Streaming

 

 

d.     GraphQL

Type: Query language + runtime
Data Format: JSON
Transport: Usually HTTP

Key Traits:

• Client defines exactly what data it wants.
• Single endpoint (/graphql) instead of multiple REST endpoints.
• Reduces over-fetching/under-fetching.
• Strong type system.

Best Use-Cases:

• Complex UIs needing customized data
• Mobile apps where bandwidth matters
• Aggregating multiple back-end sources

 

 

e.      Webhooks

Type: Event-driven callback mechanism
Transport: HTTP

Key Traits:

• Server sends data to your endpoint when an event occurs.
• “Push” model — you don’t poll.

Best Use-Cases:

• Notifications (payments, deployments, Git events)
• Integrations between SaaS platforms
• Automation workflows

 

 

f.       WebSockets

Type: Full duplex communication protocol
Transport: WebSocket over TCP

Key Traits:

• Persistent connection between client and server.
• Real-time, bidirectional messaging.

Best Use-Cases:

• Chat apps
• Online gaming
• Live dashboards
• Collaborative editing

 

 

g.      WebRTC (Web Real-Time Communication)

Type: Protocol suite for peer-to-peer media/data
Transport: SRTP, SCTP, ICE/STUN/TURN

Key Traits:

• Real-time audio/video streaming.
• Peer-to-peer communication.
• Built into browsers without add-ons.
• Supports data channels.

Best Use-Cases:

• Video conferencing (Zoom, Meet)
• Live audio streaming
• Peer-to-peer file transfer 
  

B.     Quick Comparison Table

Technology	Paradigm	Strength	Weakness	Best Fit
REST	Resource-based	Simple, universal	Over/under-fetching	Web APIs
SOAP	Strict protocol	Security, reliability	Heavy, XML	Enterprise transactions
gRPC	RPC-based	High speed, streaming	Harder for browsers	Microservices
GraphQL	Query-based	Flexible data retrieval	Overcomplex if simple	Modern UIs
Webhooks	Event push	Simple automation	Delivery failures	SaaS integration
WebSockets	Bidirectional	Real-time updates	Persistent connection overhead	Chat, live apps
WebRTC	Peer-to-peer	Real-time media	Complex NAT traversal	Video/voice apps