WSDL - Request-Response

1. What is Request-Response?

In WSDL and SOAP web services, a request-response operation is the most common communication pattern.

• The client (service consumer) sends a request to the service provider.

• The service provider processes the request.

• The provider sends a response back to the client.

Analogy:
It’s like asking a question and getting an answer.

2. Request-Response in WSDL

In a WSDL portType definition, a request-response operation includes both <input> and <output> messages.

Example WSDL (Request-Response Operation)

<portType name="AccountServicePortType">
  <operation name="GetBalance">
    <input message="tns:GetBalanceRequest"/>
    <output message="tns:GetBalanceResponse"/>
  </operation>
</portType>

• Input message: GetBalanceRequest → Sent by the client.

• Output message: GetBalanceResponse → Returned by the service.

3. SOAP Request & Response Example

SOAP Request (Client → Service Provider)

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                  xmlns:acc="http://bank.example.com/account">
   <soapenv:Header/>
   <soapenv:Body>
      <acc:GetBalanceRequest>
         <acc:accountID>101</acc:accountID>
      </acc:GetBalanceRequest>
   </soapenv:Body>
</soapenv:Envelope>

SOAP Response (Service Provider → Client)

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                  xmlns:acc="http://bank.example.com/account">
   <soapenv:Header/>
   <soapenv:Body>
      <acc:GetBalanceResponse>
         <acc:balance>2500.75</acc:balance>
      </acc:GetBalanceResponse>
   </soapenv:Body>
</soapenv:Envelope>

4. Request-Response Workflow

1. Client sends request → Based on WSDL definition.

2. Service provider receives request → Processes business logic.

3. Service provider sends response → In SOAP XML format.

4. Client processes response → Uses returned data.

5. Use Cases for Request-Response

Request-response is used when the client needs confirmation or data from the server.

Examples

• Banking services → Get account balance, transfer money.

• E-commerce → Place order, get order status.

• Weather services → Send location, receive forecast.

• Authentication services → Send credentials, receive authentication token.

6. Request-Response vs One-Way

7. Real-Life Analogy

• Request-Response:
  You call a customer support agent and ask about your bill → The agent gives you the answer.

• One-Way:
  You send a complaint letter but don’t expect a reply.

8. Summary

• Request-Response = Two-way communication.

• The client sends a request and receives a response.

• WSDL defines it with both <input> and <output>.

• Used when the client needs a confirmation or data.