What data format is Simple Object Access Protocol (SOAP) primarily based on?

Simple Object Access Protocol (SOAP) is primarily based on XML (eXtensible Markup Language). This is significant because XML provides a standardized way to encode information in a structured format, allowing for complex data types and nested data structures. SOAP utilizes XML for its messaging protocol, which means that SOAP messages are formatted as XML documents.

The use of XML allows SOAP to support advanced features such as namespaces, schema validation, and extensibility, which are crucial for interoperability between different systems and platforms. When a SOAP message is created, it consists of an envelope that defines the message structure, a header for any metadata, and a body for the actual payload. This structure leverages XML's strengths to ensure that the data can be easily interpreted and processed by different applications regardless of the underlying technology.

In contrast, data formats such as JSON (often used with REST APIs), plain text, and CSV do not possess the same level of complexity or standardization that XML provides for SOAP. For example, while JSON is commonly used for data interchange in web services, it lacks the rigorous structure that XML offers, which can be vital for certain applications.