Web Service

A web service is a server-side program that provides functionality that can be invoked and used at the programming level (interoperable architecture).

XML-RPC

Information.

Remote Procedure Call (RPC) protocol that uses XML (usually over HTTP) to invoke functionality. Composed of <methodCall>, <methodName> and <params>.

<!-- Content-Type: text/xml -->

<methodCall>
    <methodName>examples.getValue</methodName>
    <params>
       <param>
 	  <value>RandomValue</value>
       </param>
    </params>
 </methodCall>

JSON-RPC

Information.

Remote Procedure Call (RPC) protocol using JSON. Composed of method, params, id.

// Content-Type: application/json-rpc

{"method": "sum", "params": {"a":3, "b":4}, "id":0}

SOAP

Information.

Simple Object Access Protocol. Messaging protocol that uses XML and provides more functionality than XML-RPC. Composed of <soap:Envelope>, <soap:Header>, <soap:Body> and <soap:Fault>. Of which only Envelope and Body are mandatory.

WSDL (Web Services Definition Language) 1.1 2.0 SOAP can optionally also provide a WSDL declaration that specifies how services can be used. Look for them with ?.wsdl, .wsdl, ?.disk, .disk or on UDDI: directory service for Public Web Service.

<!-- 
Content-Type: text/xml; charset = utf-8
[ SOAPAction: "OperationName" ] 
-->

<?xml version="1.0"?> 
<soap:Envelope
 xmlns:soap="http://www.w3.org/2003/05/soap-envelope/"
 soap:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
   <soap:Header> ... </soap:Header>
   <soap:Body> 
        ... 
       <soap:Fault> ... </soap:Fault>
   </soap:Body>
</soap:Envelope>

RESTful

Information.

Representational State Transfer. It usually uses XML or JSON and relies on sets or principles to build a Web service. RESTful APIs are usually based on HTTP verbs to determine the actions to be taken.

POST /api/2.2/auth/signin HTTP/1.1

<!-- Content-Type:text/xml -->
<tsRequest>
  <credentials name="A" password="B"> … </credentials>
</tsRequest>

// Content-Type:application/json
{ "credentials": 
    { "name": "A", "password": "B",  …  }
}

Use Wsdler extension of BurpSuite.