Which term refers to any software that makes itself available over the Internet that uses a standardized XML messaging system?

• A. Secure Electronic Transaction (SET)
• B. Web Service
• C. 3-D
• D. Policy

Answer: (B)

Web services are software components that expose their functionality over the Internet and communicate using standardized XML formats. They typically send and receive XML messages (often via SOAP over HTTP), which lets different applications, built on different platforms or languages, interoperate smoothly. The service presents a defined interface (often described by WSDL) that clients can call to perform operations and get XML responses. This focus on XML-based messaging and interoperable interfaces is what makes a web service the best fit for the description.

Other options don’t describe software that is made available over the Internet using XML messaging: Secure Electronic Transaction is a payment protocol for card transactions, 3-D Secure is an online cardholder authentication protocol, and a policy is simply a rule set, not software service exposure.