Which technology was generalized into a standard protocol for sending messages of any type over various underlying protocols?

Introduction / Context:
As distributed systems grew, the need arose for a platform-neutral, extensible envelope for messages that could ride over multiple transport protocols. One widely adopted standard addressed exactly this need.

Given Data / Assumptions:

• The protocol should be transport-agnostic (HTTP, SMTP, etc.).
• It should carry arbitrary message types and structured data.
• It should be standardized and widely supported.

Concept / Approach:
SOAP (originally “Simple Object Access Protocol,” later just a name) specifies an XML-based envelope, header, and body for messages. It isn’t tied to any single transport, though HTTP is common. SOAP enables RPC-style and document-style exchanges with extensibility via headers and standardized fault handling.

Step-by-Step Solution:

Verification / Alternative check:
WS-* specifications build on SOAP for security, reliability, and transactions, demonstrating its role as a generalized messaging protocol.

Why Other Options Are Wrong:
SGML: Not a messaging protocol.
SQL: Database language, not transport protocol.
ADO: Library for data access, not a wire protocol.

Common Pitfalls:
Assuming SOAP implies HTTP only; in fact, SOAP can use many transports.

Final Answer:
SOAP