Which application programming interface provides online web services to client-side applications for retrieving and updating data from multiple sources?

• A. SOAPAction
• B. Web API
• C. WS-Attacker
• D. XMLSpy

Answer: (B)

Web APIs provide online web services that client-side applications can call to retrieve and update data from multiple sources. They expose endpoints over the web, typically using HTTP, and data is commonly exchanged in JSON or XML. This allows a single application to pull together information from various systems and update them as needed, often in a RESTful or SOAP-based manner.

The other options don’t fit that role: SOAPAction is a header used with SOAP messaging, not a general interface for web services; WS-Attacker is a security-testing tool for web services; XMLSpy is an XML editor/development environment, not an API.