# Overview An [[XML]]-based protocol for making [[Request-Response]] requests via [[APIs]]. It has a sprawling and complex list of standards, that results in bulky, text-based messages. # Key Considerations Uses a XML-based language called the [[Web Services Description Language (WSDL)]]. # Pros - Strong legal contracts and authentication # Cons - Slow - Messages are complicated and difficult to construct manually, thus requires tool support, code generation, and IDEs. # Use Cases - High-security data transmission - Billing operations - Booking - Payment systems # Related Topics