In software engineering the comparison of graph-based models is a well-known problem. Although different comparison metrics have been proposed, there are situations in which automatic or pre-configured approaches do not provide reasonable results. Especially when models contain semantic similarities or differences, additional human knowledge is often required. However, only few approaches tackle the problem of how to support humans when comparing models.

Visual comparison of hierarchies such as directory structures is often considered a passive analysis task. Thus, insights gained from the visualization need to be recorded and applied afterwards. In contrast in this paper, we propose and explore an active visual analytics approach focusing on the manipulation of directory structures in the context of comparison. Two directories including subdirectories and files are presented side by side while links between the two representations connect matching files. Embedded into an elaborate interaction concept, drag-and-drop operations allow the users for interactively modifying the directories. We explored different application scenarios of the approach in a qualitative user study.

Nowadays file browsers represent a common means to organize hierarchically structured data provided by a file system. However, when it comes to comparing and merging different directory structures, file browsers often do not explicitly support users to accomplish such a task. In this paper, we present a special-purpose approach focusing on the manipulation of directory structures in the context of comparison. To this end, two directory structures including subdirectories and files are displayed side by side while links between them indicate similar files. Drag-and-drop operations allow the users for interactively manipulating or merging both directory structures.

Object-orientation is one of the essential parts of every software engineering course. However, according to literature, it often lacks the following: First, modeling on a conceptual level independent from a particular programming language is often neglected. Moreover, the actual process of designing or implementing a piece of software seems to be less important than providing an optimal solution. Finally, students often follow the slides of the teacher passively without thinking about or even questioning the material. But, in order to actively apply a proper form of object-orientation, it is essential that one understands the concepts of this programming paradigm and is able to deal with problems and communicate ideas rather than handling a specific programming language. In this paper we introduce CREWSpace-a tool for co-located collaboration that implements a digital version of the CRC method. To this end, students actively participate in so called CRC sessions, which fosters communication and problem solving skills. In particular, they design a software system on a conceptual level and use our tool to analyze and adjust the proposed design through role play. Moreover, CREWSpace records these analyses for a later replay such that the students are able to reflect on their decisions.

In requirements engineering, CRC modeling and use case analysis are established techniques and are often performed as a group work activity. In particular, role play is used to involve different stakeholders into the use case analysis. To support this kind of co-located collaboration we developed CREW-Space, which allows several users to simultaneously interact through Android-enabled mobile devices with the same model displayed on a shared screen. Furthermore, it keeps track of the current state of the role play and, in addition, each mobile device serves as a private workspace; it actually turns into a tangible digital CRC card.

So far, research on model merging has mostly focused on algorithmic problems. But, there are various situations when software engineers have to compare and merge different models manually or at least make important decisions. In this paper, we provide insights into the process of how users compare and merge visual models. To this end, we observed people's activities when manually merging UML class diagrams and analyzed the recorded data following the Grounded Theory approach. To illustrate the usefulness of our results we derived some guidelines for tool design.

In this paper, we present CREWW, a tool for co-located, collaborative CRC modeling and use case analysis. In CRC sessions role play is used to involve all stakeholders when determining whether the current software model completely and consistently captures the modeled use case. In this activity it quickly becomes difficult to keep track of which class is currently active or along which path the current state was reached. CREWW was designed to alleviate these and other weaknesses of the traditional approach.