The architecture of software it not tangible; but in different situations it is preferable to have it tangible. For example, while reviewing it against the intended design, introducing the software to others, or starting to develop on a new part. Basic aspects of a software architecture are the modules the software is constructed of and the dependencies between them. To comprehend these aspects is important especially for software using a technology such as OSGi, which key concept is modularization. In this paper, we describe interactive visualization tools that we developed to comprehend OSGi-based applications with their modules and dependencies. We focus on concepts to treat large number of modules and dependencies: navigation, filtering, and selection. We applied our solution for OSGi-based applications with hundreds of modules containing multiple submodules each. With the resulting visualizations, we can explore the modularization of the software architecture.

In large software projects, it can be hard to understand the actual architecture of the implemented software systems if current design documents are outdated or do not exist at all. For systems based on the OSGi component specification, which are used to build quite large applications with back-end and front-end services, tools for visualizing the actual architecture can help to understand the system. We provide an interactive tool that visualizes OSGi-based systems with their components, packages, services, and dependencies in 3D using Virtual Reality headsets. It uses the metaphor of modular electronic systems. The tool allows software engineers, project managers, or clients to explore the architecture and get a first impression about component sizes and their dependencies.