Although SOAP and RESTful Web Services – both serve the same purpose i.e. building applications based on SOA (Service-Oriented Architecture), yet they are pretty much different in the way how they help in achieving the final output. Let’s note down the most noticeable differences between SOAP and REST based APIs:
| SOAP | REST |
|---|---|
| SOAP is a XML based messaging protocol | REST is not a protocol but an architectural style |
| SOAP has specifications for stateful implementation | REST follows only stateless model |
| Minimal tooling/middleware is necessary. Only HTTP (mostly it’s HTTP based) support is required | URL typically references the resource being accessed/deleted/updated |
| Well defined mechanism for describing the interface e.g. WSDL+XSD, WS-Policy | Formal description standards not in widespread use. Everybody interprets on his own |
| Payload must comply with the SOAP schema | No constraints on the payload |
| Built-in error handling | No error handling though you can use HTTP error codes |
| Both SMTP and HTTP are valid application layer protocols used as Transport for SOAP | Tied to the HTTP transport model |
| SOAP web services totally ignore web caching mechanism | RESTful web service take full advantage of web caching mechanism because they are basically URL based |
| Hard to learn | Easy to learn because everybody understand HTTP |
| SOAP security is well standardized through WS-SECURITY | Security is provided on the HTTP protocol layer such as basic authentication and communication encryption through TLS |
| When you’re publishing an API to the outside world that is either complex or likely to change, SOAP will be more useful | Other than that, REST is usually the better option |
Feel free to add more differences if you know them. It will help others as well.
Happy Learning !!
Himansu
1. SOAP Envelop makes it heavier.
2. SOAP Support stateless/statefull conversation.
3. SOAP Support ACI transaction – WS-AT
4. SOAP Support Reliable Messaging – WS-RM
5. With reliable messaging async messaging is possible.