XMLenn

XMLenn is a fictional open specification for XML data modeling and transformation that combines an XML-based language with a runtime processing engine. Intended for use in data interchange and document workflows, XMLenn aims to simplify the creation, validation, and transformation of XML documents through declarative rules and modular components.

Core concept: XMLenn defines schemas, transformation rules, and processing pipelines expressed as XML constructs. The language supports strong typing, namespaces, and annotations, and integrates with established XML standards such as XML Schema, XPath, and XSLT. A key design goal is to enable streaming processing and incremental validation for large documents.

Transformations in XMLenn are declared as reusable rules that map input structures to output structures. Pipelines compose multiple rules into end-to-end workflows. The runtime compiles these declarations into executable pipelines and supports error reporting, logging, and transactional execution. The system is extensible through plugins that provide custom functions or data adapters.

Tooling and ecosystem: A reference implementation is available in Java and Python, along with a lightweight command-line toolkit and an integrated editor known as XMLenn Studio. Interoperability features include round-tripping with XSLT and XQuery, and adapters to load and save documents from common formats and databases.

History and reception: XMLenn was introduced in the early 2020s as an attempt to unify XML transformation practices under a single declarative model. While it attracted interest in enterprise data exchange and government document programs, adoption remained modest due to competing standards and the learning curve associated with its domain-specific language. Critics have noted complexity and performance considerations for streaming large XML streams.