8,879 research outputs found
An Introduction to Slice-Based Cohesion and Coupling Metrics
This report provides an overview of slice-based software metrics. It brings together information about the development of the metrics from Weiser’s original idea that program slices may be used in the measurement of program complexity, with alternative slice-based measures proposed by other researchers. In particular, it details two aspects of slice-based metric calculation not covered elsewhere in the literature: output variables and worked examples of the calculations. First, output variables are explained, their use explored and standard reference terms and usage proposed. Calculating slice-based metrics requires a clear understanding of ‘output variables’ because they form the basis for extracting the program slices on which the calculations depend. This report includes a survey of the variation in the definition of output variables used by different research groups and suggests standard terms of reference for these variables. Our study identifies four elements which are combined in the definition of output variables. These are the function return value, modified global variables, modified reference parameters and variables printed or otherwise output by the module. Second, slice-based metric calculations are explained with the aid of worked examples, to assist newcomers to the field. Step-by-step calculations of slice-based cohesion and coupling metrics based on the vertices output by the static analysis tool CodeSurfer (R) are presented and compared with line-based calculations
Architecture, design and source code comparison of ns-2 and ns-3 network simulators
Ns-2 and its successor ns-3 are discrete-event simulators. Ns-
3 is still under development, but offers some interesting characteristics
for developers while ns-2 still has a big user base.
This paper remarks current differences between both tools
from developers point of view. Leaving performance and resources
consumption aside, technical issues described in the
present paper might help to choose one or another alternative
depending of simulation and project management requirements.Ministerio de Educación y Ciencia TIN2006-15617-C03-03Junta de Andalucía P06-TIC-229
A Practical Attack on the MIFARE Classic
The MIFARE Classic is the most widely used contactless smart card in the
market. Its design and implementation details are kept secret by its
manufacturer. This paper studies the architecture of the card and the
communication protocol between card and reader. Then it gives a practical,
low-cost, attack that recovers secret information from the memory of the card.
Due to a weakness in the pseudo-random generator, we are able to recover the
keystream generated by the CRYPTO1 stream cipher. We exploit the malleability
of the stream cipher to read all memory blocks of the first sector of the card.
Moreover, we are able to read any sector of the memory of the card, provided
that we know one memory block within this sector. Finally, and perhaps more
damaging, the same holds for modifying memory blocks
Analysis of methods
Information is one of an organization's most important assets. For this reason the development and maintenance of an integrated information system environment is one of the most important functions within a large organization. The Integrated Information Systems Evolution Environment (IISEE) project has as one of its primary goals a computerized solution to the difficulties involved in the development of integrated information systems. To develop such an environment a thorough understanding of the enterprise's information needs and requirements is of paramount importance. This document is the current release of the research performed by the Integrated Development Support Environment (IDSE) Research Team in support of the IISEE project. Research indicates that an integral part of any information system environment would be multiple modeling methods to support the management of the organization's information. Automated tool support for these methods is necessary to facilitate their use in an integrated environment. An integrated environment makes it necessary to maintain an integrated database which contains the different kinds of models developed under the various methodologies. In addition, to speed the process of development of models, a procedure or technique is needed to allow automatic translation from one methodology's representation to another while maintaining the integrity of both. The purpose for the analysis of the modeling methods included in this document is to examine these methods with the goal being to include them in an integrated development support environment. To accomplish this and to develop a method for allowing intra-methodology and inter-methodology model element reuse, a thorough understanding of multiple modeling methodologies is necessary. Currently the IDSE Research Team is investigating the family of Integrated Computer Aided Manufacturing (ICAM) DEFinition (IDEF) languages IDEF(0), IDEF(1), and IDEF(1x), as well as ENALIM, Entity Relationship, Data Flow Diagrams, and Structure Charts, for inclusion in an integrated development support environment
Geometric combinatorics and computational molecular biology: branching polytopes for RNA sequences
Questions in computational molecular biology generate various discrete
optimization problems, such as DNA sequence alignment and RNA secondary
structure prediction. However, the optimal solutions are fundamentally
dependent on the parameters used in the objective functions. The goal of a
parametric analysis is to elucidate such dependencies, especially as they
pertain to the accuracy and robustness of the optimal solutions. Techniques
from geometric combinatorics, including polytopes and their normal fans, have
been used previously to give parametric analyses of simple models for DNA
sequence alignment and RNA branching configurations. Here, we present a new
computational framework, and proof-of-principle results, which give the first
complete parametric analysis of the branching portion of the nearest neighbor
thermodynamic model for secondary structure prediction for real RNA sequences.Comment: 17 pages, 8 figure
Analysis of source code metrics from ns-2 and ns-3 network simulators
Ns-2 and its successor ns-3 are discrete-event simulators which are closely related to each
other as they share common background, concepts and similar aims. Ns-3 is still under
development, but it offers some interesting characteristics for developers while ns-2 still
has a large user base. While other studies have compared different network simulators,
focusing on performance measurements, in this paper we adopted a different approach
by focusing on technical characteristics and using software metrics to obtain useful conclusions.
We chose ns-2 and ns-3 for our case study because of the popularity of the former in
research and the increasing use of the latter. This reflects the current situation where ns-3
has emerged as a viable alternative to ns-2 due to its features and design. The paper
assesses the current state of both projects and their respective evolution supported by
the measurements obtained from a broad set of software metrics. By considering other
qualitative characteristics we obtained a summary of technical features of both simulators
including, architectural design, software dependencies or documentation policies.Ministerio de Ciencia e Innovación TEC2009-10639-C04-0
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