What is REST and what is SOAP?

REST (Representational State Transfer) is an architectural style for building web services based on the use of standard HTTP methods (GET, POST, PUT, DELETE, etc.) and resources represented as URLs. REST services typically use JSON or XML for data transfer and focus on simplicity, scalability, and independence of client and server.

SOAP (Simple Object Access Protocol) is a protocol for exchanging structured messages in XML format, which defines strict standards for message exchange, including operation descriptions, data types, and security rules. SOAP is more formal and complex, supporting advanced features such as transactions, security, and reliable delivery.

Key differences:

• REST is simpler and lighter, uses HTTP directly, while SOAP is a separate protocol over HTTP (or other transports).
• REST usually uses JSON, SOAP uses XML.
• SOAP supports WS-* standards for security, transactions, etc., REST is more lightweight.

Example REST request:

GET /users/123 HTTP/1.1
Host: example.com

Example SOAP message (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>