Abstract-Software is usually complex and always intangible. In practice, the development and maintenance processes are timeconsuming activities mainly because software complexity is difficult to manage. Graphical visualization of software has the potential to result in a better and faster understanding of its design and functionality, thus saving time and providing valuable information to improve its quality. However, visualizing software is not an easy task because of the huge amount of information comprised in the software. Furthermore, the information content increases significantly once the time dimension to visualize the evolution of the software is taken into account. Human perception of information and cognitive factors must thus be taken into account to improve the understandability of the visualization. In this paper, we survey visualization techniques, both 2D-and 3D-based, representing the static aspects of the software and its evolution. We categorize these techniques according to the issues they focus on, in order to help compare them and identify the most relevant techniques and tools for a given problem.

Software systems are often very complex because of their huge size and the tremendous number of interactions between their components. However, understanding relations between software elements is crucial to optimize the development and the maintenance process. A good way to ease this understanding of software relations is to use advanced visualization techniques to graphically see interactions between elements. Nevertheless representing those software relations is not an easy task and often leads to hard to understand clutter. We believe that combining both edge clustering techniques and real-world metaphors can help to address this issue, producing easierto-read visualizations that ease the cognitive process and thus significantly help understanding the underlying software. In this paper, we explain how we adapted the existing 2D Hierarchical Edge bundles technique to represent relations in a 3D space on top of city metaphors.

a b s t r a c tUnderstanding what happens during the runtime of a Java program is difficult. Tracking runtime flow can bring valuable information for program understanding and behavior analysis. Polymorphism, thread concurrency or even simple facts like the number of method invocations and the number of executed bytecodes are valuable information to track, but are difficult to compute outside the Java Virtual Machine (JVM) on running programs. In this paper, we present JBInsTrace, a new tool that instruments and traces Java bytecode. It produces static information about source code and a very fine grained trace of Java software execution, combining them to allow detailed analysis of the runtime. Our tool differs from others because it does not only trace program classes but also JRE classes, and does so at basic block level, without altering the JVM and without statically modifying class files. We explain JBInsTrace design, focused towards efficiency, which results in reasonable performance penalty.

Implementing a profiler to trace a program execution is nontrivial. One way to do this on running Java programs is through bytecode instrumentation. Nowadays, tools exist that ease the instrumentation process itself, but as far as we know, none offers an entirely dynamic implementation technique which is able to include the instrumentation of Java Runtime Environement (JRE) classes. In this paper we present the main principles of our technique, which performs such online bytecode instrumentation of both application and JRE classes, at basic block level.