For a service that communicates over HTTP using XML, which protocol ensures proper data exchange?

Choosing SOAP (Simple Object Access Protocol) as the correct answer highlights its role in ensuring proper data exchange for services that communicate over HTTP using XML. SOAP is a protocol specifically designed for exchanging structured information in the context of web services. It uses XML as its message format and operates over various protocols, including HTTP.

By using SOAP, developers can define a standardized way for programs running on different operating systems or written in different programming languages to communicate with each other. It ensures that messages are sent in a formalized structure, which includes an envelope that encapsulates the message and provides information about how to process it, as well as a body that contains the actual data being exchanged.

The other options lack the specific capabilities necessary for enabling the structured communication that SOAP provides. Packet captures are used for network diagnostics and do not facilitate the structured information exchange needed for web services. NetFlow focuses on monitoring network traffic and flow rather than managing message formats. System logs are primarily for recording events and activities within a system and do not dictate how data is formatted and exchanged between services. Overall, SOAP's specifications provide the assurance of proper data structure and exchange in HTTP communications.