Evolution of a Modular Software Network

"Evolution behaves like a tinkerer" (Francois Jacob, Science, 1977). Software systems provide a unique opportunity to understand biological processes using concepts from network theory. The Debian GNU/Linux operating system allows us to explore the evolution of a complex network in a novel way. The modular design detected during its growth is based on the reuse of existing code in order to minimize costs during programming. The increase of modularity experienced by the system over time has not counterbalanced the increase in incompatibilities between software packages within modules. This negative effect is far from being a failure of design. A random process of package installation shows that the higher the modularity the larger the fraction of packages working properly in a local computer. The decrease in the relative number of conflicts between packages from different modules avoids a failure in the functionality of one package spreading throughout the entire system. Some potential analogies with the evolutionary and ecological processes determining the structure of ecological networks of interacting species are discussed.Comment: To appear in PNA

An approach for measuring the software modularity based on the bursty evolution of functional dependencies

Modular Design of a software system is one of the parameters which defines the complexity of a software system. If the software is built as one whole module, then it makes testing a long process. Also, updating the software will make a significant impact on the whole system code because of the dependencies. We propose a methodology to study and visualize the evolution of the modular structure of a network of functional dependencies in a software system. We used the Understand C++ tool for analyzing the dependencies and Gephi to produce the network. Our method analyzes the modularity of the software and identifies specific periods of significant activities, which are known as the evolutionary hot spots in software systems. As a case study, we analyzed the modular structure of Octave during its life cycle beginning from 1993 to the present

LTE Spectrum Sharing Research Testbed: Integrated Hardware, Software, Network and Data

This paper presents Virginia Tech's wireless testbed supporting research on long-term evolution (LTE) signaling and radio frequency (RF) spectrum coexistence. LTE is continuously refined and new features released. As the communications contexts for LTE expand, new research problems arise and include operation in harsh RF signaling environments and coexistence with other radios. Our testbed provides an integrated research tool for investigating these and other research problems; it allows analyzing the severity of the problem, designing and rapidly prototyping solutions, and assessing them with standard-compliant equipment and test procedures. The modular testbed integrates general-purpose software-defined radio hardware, LTE-specific test equipment, RF components, free open-source and commercial LTE software, a configurable RF network and recorded radar waveform samples. It supports RF channel emulated and over-the-air radiated modes. The testbed can be remotely accessed and configured. An RF switching network allows for designing many different experiments that can involve a variety of real and virtual radios with support for multiple-input multiple-output (MIMO) antenna operation. We present the testbed, the research it has enabled and some valuable lessons that we learned and that may help designing, developing, and operating future wireless testbeds.Comment: In Proceeding of the 10th ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation & Characterization (WiNTECH), Snowbird, Utah, October 201

Network Operators Advice and Assistance (NOAA): a real-time traffic rerouting expert system

A real-time autonomous expert system has been developed to carry out traffic management in the Southern Californian telephone network. The system has been working on live data since September 1991 and generates rerouting advice that agrees with that generated by the present network management procedures. A modular software design was adopted to allow for evolution. A graphics interface allows the user to easily navigate through the display of exception conditions and advice. Exceptions are shown highlighted on a map of Southern California. A severity measure is calculated for each exception and is used to prioritize the display of information

A Dynamic Evolutionary Game Model of Modular Production Network

As a new organization mode of production in the 21st century, modular production network is deemed extensively to be a source of competitiveness for lead firms in manufacturing industries. However, despite the abundant studies on the modular production network, there are very few studies from a dynamic perspective to discuss the conditions on which a modular production network develops. Based on the dynamic evolutionary game theory, this paper constructs a model, which incorporates several main factors influencing the development of modular production network. By calculating the replicator dynamics equations and analyzing the evolutionary stable strategies, this paper discusses the evolution process of cooperation strategies of member enterprises in a modular production network. Furthermore, by using NetLogo software to simulate the model, this paper verifies the effectiveness of the model. From the model, we can find that the final stable equilibrium strategy is related to such factors as the initial cost, the extra payoff, the cooperation willingness of both parties, the cooperation efforts, and the proportion each party can get from the extra payoff. To encourage the cooperation of production integrator and modular supplier, some suggestions are also provided