XCC: change control of XML documents An Efficient and Reliable Framework for XML Diff, Patch, and Merge

XML-based documents play a major role in modern information architectures and their corresponding workflows. In this context, the ability to identify and represent differences between two versions of a document is essential, as well as the merging of document versions resulting from parallel editing processes. Different approaches try to meet these challenges using operational transformation or document annotation. In both approaches, the changes are tracked during editing, which requires corresponding editing applications. In the context of software development, however, a state-based approach is common. Here, versions are compared and merged using external tools, called diff and patch. This allows the users for editing documents without being tightened to editing tools. Approaches exist that are able to compare XML documents, but lack a corresponding merge capability. In this article, we present a comprehensive framework that allows for comparing and merging of XML documents using a state-based approach. Its design is based on an analysis of XML documents and their modification patterns. The framework is built on top of a context-oriented delta model. We present a diff algorithm that appears to be highly efficient in terms of speed and delta quality. The patch algorithm is able to merge document versions efficiently and reliably. The efficiency and the reliability of our approach are verified using a competitive test scenario.