Final answer:
The messaging protocol specification that defines how structured information can be exchanged between web applications is SOAP (Simple Object Access Protocol).
Step-by-step explanation:
SOAP is a messaging protocol that facilitates communication between web applications by defining a set of rules for structuring messages. It uses XML as its message format and typically relies on HTTP or SMTP as the transport protocol. WSDL (Web Services Description Language) is an XML-based language used to describe the functionalities offered by a web service. SOAP messages are often generated from WSDL files, which provide a standardized way to specify the operations, data types, and message formats supported by a web service.
SOAP serves as the messaging protocol for structured information exchange between web applications, and the information about these services can be defined and extracted from WSDL files. This combination provides a standardized approach to web services, enabling interoperability between different systems and platforms.