This paper presents a concept and tools for the detection and visualization of differences between versions of graphical software documents such as ER, class or object diagrams, state charts, etc. We first analyze the problems which occur when comparing graphical documents and displaying their similarities and differences. Our basic approach is to use a unified document which contains the common and specific parts of both base documents with the specific parts being highlighted. The central problem is how to reduce the amount of highlighted elements and enable the developer to have a certain amount of control over the changes be selectively highlighted. With regard to tool construction, we assume that software documents are modeled in a fine-grained way, that they are stored as syntax trees in XML (eXtensible Markup Language) files or a repository system and that a version management system is used. By using the features of the data model and the version model we are able to detect and visualize differences between diagram versions, including structural changes (e.g. shifting of a method from one class to another). We further exploit information about the version history delivered by the underlying version management system by highlighting only differences based on structural or logical changes.

This paper addresses the problem of how to detect and visualise differences between versions of UML documents such as class or object diagrams. Our basic approach for showing the differences between two documents is to use a unified document which contains the common and specific parts of both base documents; the specific parts are highlighted. The main problems are (a) how to abstract from modifications done to the layout and other (document type-specific) details which are considered irrelevant; (b) how to deal with structural changes such as the shifting of an operation from one class to another; (c) how to reduce the amount of highlighted information. Our approach is based on the assumption that software documents are modelled in a fine-grained way, i.e. they are stored as syntax trees in XML files or in a repository system, and that the version management system supports fine-grained data. Our difference computation algorithm detects structural changes and enables their appropriate visualisation. Highlighting can be restricted on the basis of the types of the elements and on the basis of the revision history, e.g. only changes which occurred during a particular editing session are highlighted.

In this paper we present a model of version and configuration management in the early phases of software development and an implementation of this model. We assume that software documents are modeled in a fine-grained way, that they are stored as syntax trees in XML files or a repository system, and that tools directly operate on these syntax trees. In contrast to file-based systems, structural changes in the document, e.g. the shifting of a method between two classes, can be identified in our model. Configurations allow us to manage groups of single modifications; such a group will mostly correspond to a specific design task or a similar activity. Configurations are thus a means to establish a connection to a change management system.