HW18: Chapter 18

18.4. Define an interface specification for the Currency Converter and Check credit rating services shown in Figure 18.7

Currency Converter:

• utility service
• task-oriented
• not independent; relies on access to current exchange rates
• state not stored

Interface:

<interface name = “currency-converter” >
  <operation name = “get-conversion” pattern = “wsdlns: in-out”>
    <input messageLabel = “In” element = “c-conv:from-amt” />
    <input messageLabel = “In” element = “c-conv:from-curr” />
    <input messageLabel = “In” element = “c-conv:to-curr” />
    <output messageLabel = “Out” element = “c-conv:to-amt” />
    <outfault messageLabel = “Out” element = “c-conv:InDataFault” />
  </operation>
</interface>

REST:

• no security required, ease of access primary importance
• Example url-based REST implementation:
• baseurl/ ? amount= VALUE & from= CURRENCY & to= CURRENCY
• e.g. <www.example.com/currency-converter/?amount=123-45&from=USD&to=JPY> to convert 123.45 US Dollars to Japanese Yen

Credit Rating:

• more secure, autentication required(?)
• business service
• task-oriented
• not independent; relies on access to credit monitoring systems
• state not stored

Interface:

<interface name = “credit-retriever” >
  <operation name = “get-credit” pattern = “wsdlns: in-out”>
    <input messageLabel = “In” element = “c-conv:user-ID” />
    <input messageLabel = “In” element = “c-conv:password” />
    <input messageLabel = “In” element = “c-conv:target-ssn” />
    <output messageLabel = “Out” element = “c-conv:cred-score” />
    <outfault messageLabel = “Out” element = “c-conv:InDataFault” />
  </operation>
</interface>

SOAP:

• Should require authentication & more advanced user logging
• Shouldn’t be URL-based due to the inherent security required regarding usage of SSNs
• Must track users & permissions within the system