What are the main differences between SOAP and REST protocols in the context of web services?

SOAP (Simple Object Access Protocol) and REST (Representational State Transfer) are two different approaches to creating web services.

• SOAP is a protocol based on XML, with a strictly defined message exchange standard. It supports advanced features such as security (WS-Security), transactions, and reliable message delivery. SOAP only uses POST requests and requires complex parsing.

• REST is an architectural style that uses standard HTTP methods (GET, POST, PUT, DELETE). REST services typically use JSON or XML for data transfer, are simpler and easier to implement. REST is more flexible and scalable.

Main differences:

Characteristic	SOAP	REST
Protocol	Strict, based on XML	Architectural style, HTTP
Message format	XML	JSON, XML, others
HTTP methods	Only POST	GET, POST, PUT, DELETE, etc.
Security standards	WS-Security	HTTPS, OAuth, etc.
Complexity	High	Low

Example REST request to get a user:

GET /users/123 HTTP/1.1
Host: example.com
Accept: application/json

Example SOAP request (fragment):

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ex="http://example.com/">
   <soapenv:Header/>
   <soapenv:Body>
      <ex:GetUser>
         <ex:UserId>123</ex:UserId>
      </ex:GetUser>
   </soapenv:Body>
</soapenv:Envelope>