Answer
REST vs SOAP — Complete Comparison
| Feature | REST | SOAP |
|---|---|---|
| Type | Architectural style | Protocol |
| Format | JSON, XML, HTML, plain text | XML only |
| Transport | HTTP/HTTPS | HTTP, SMTP, TCP |
| Standards | No strict standard | Strict WSDL contract |
| Security | HTTPS, OAuth, JWT | WS-Security (built-in) |
| Performance | Faster (lightweight JSON) | Slower (verbose XML) |
| Error handling | HTTP status codes | SOAP fault elements |
| Browser support | Yes (native HTTP) | No |
| Stateless | Yes | Can be stateful or stateless |
| Learning curve | Easy | Steep |
REST — Representational State Transfer
- ✓Uses HTTP methods (GET, POST, PUT, DELETE)
- ✓Stateless — each request is independent
- ✓Returns JSON (lightweight, browser-friendly)
- ✓No strict standard — flexible implementation
- ✓Best for web APIs, mobile apps, microservices
CODE
GET /api/users/1
Response: { "id": 1, "name": "John" }
SOAP — Simple Object Access Protocol
- ✓Uses XML envelope structure for every message
- ✓Has WSDL (Web Service Description Language) contract
- ✓Built-in WS-Security for message-level encryption
- ✓Better for complex transactions requiring ACID compliance
XML
<soapenv:Envelope>
<soapenv:Body>
<GetUser>
<userId>1</userId>
</GetUser>
</soapenv:Body>
</soapenv:Envelope>
When to Use REST
- ✓Public APIs (Twitter, GitHub, Stripe)
- ✓Mobile and web applications
- ✓Microservices communication
- ✓When performance matters
When to Use SOAP
- ✓Banking and financial services (requires ACID transactions)
- ✓Legacy enterprise systems (ERP, SAP integrations)
- ✓When WS-Security is required
- ✓When strict contracts (WSDL) are needed
In Interviews
"REST is preferred for most modern APIs because it's lightweight, uses JSON, and is easy to consume from browsers. SOAP is still used in enterprise environments like banking where security contracts and formal WSDL definitions are required."