xmi

XMI, or XML Metadata Interchange, is a standard developed by the Object Management Group (OMG) for exchanging metadata information in XML. It provides a way to serialize metadata about models, particularly those created with the Unified Modeling Language (UML), so that tools, repositories, and code generators can share model information in a tool‑ and vendor‑neutral form. XMI defines a family of XML schemas and a mapping from the Meta-Object Facility (MOF) modeling framework to XML, allowing elements such as classes, attributes, associations, and diagrams to be represented with unique identifiers and interelement references.

The primary purpose of XMI is to enable interoperability in model-driven engineering and model exchange within the OMG ecosystem, including Model Driven Architecture (MDA) workflows. In practice, an XMI document captures the structure and metadata of a model, using an XMI namespace and attributes such as xmi:id and xmi:type to preserve identity and type information across tools. While each tool may implement the standard differently, XMI is intended to provide a common format for tool-to-tool exchange of UML models and related metadata.

Usage and limitations: XMI remains widely used for model interchange, but its practical adoption can be uneven across vendors and tool versions. Files can be large and complex, and vendor-specific extensions or profiles may appear, complicating round‑tripping between tools. Profiles, stereotypes, and custom metadata can add further complexity to exchanges. Despite these challenges, XMI remains a formal OMG standard and a foundational option for sharing UML models, with ongoing relevance in model-driven engineering, even as other formats and approaches evolve.