Analysis Of Trace Files Research Articles

Enhanced system for ns2 trace file analysis with network performance evaluation

One of the critical challenges facing operators around the world is how to ensure that everything is running smoothly as well as how to analyze the performance of the network. Nonetheless, the analytic system must be precise, user-friendly, and quick enough to depict network performance in real time. Network performance is essential for ensuring service quality. In this light, the Network Simulator NS-2 is generally employed for network research on the widely-used UNIX and Windows systems. Next, the network scenarios are generated using network simulation scripts, and upon completion of the simulation, trace files that record network events are generated. Information that might be utilized in a performance study could be recorded in trace files. This could include the total number of packets sent, their arrival times, any delays or losses, and so on. This trace file analysis problem arises mostly because NS-2 does not provide any visualization options for analyzing simulation results (trace files). A system is proposed to analyze the NS2 trace file and facilitate data extraction and evaluation. The main feature of this system is the Java language for network performance evaluation. And to prove the validity of the system, the system was compared with the Trace graph, where the speed of the new system was very high.

NsGTFA: A GUI Tool to Easily Measure Network Performance through the Ns2 Trace File

AbstractNs2 is an open-source communications network simulator primarily used in research and teaching. Ns2 provides substantial support for simulation of TCP, routing, and multicast protocols over wired and wireless networks. Although Ns2 is a widely used powerful simulator, it lacks a way to measure networks that are used to assess reliability and performance metrics (e.g., the number of packets transferred from source to destination, delay in packets, packet loss, etc.) and it does not analyse the trace files it produces. The data obtained from the simulations are not straightforward to analyse. Ns2 is still unable to provide any data analysis statistics or graphics as requested. Moreover, the analysis of the Ns2 trace file using any software scripts requires further steps by a developer to do data processing and then produce graphical outputs. Lack of standardisation of tools means that results from different users may not be strictly comparable. There are alternative tools; however, most of them are not standalone applications, requiring some additional libraries. Also, they lack a user-friendly interface. This article presents the architecture and development considerations for the NsGTFA (Ns2 GUI Trace File Analyser) tool, which intends to simplify the management and enable the statistical analysis of trace files generated during network simulations. NsGTFA runs under Windows and has a friendly graphical user interface. This tool is a very fast standalone application implemented in VC++, taking as input an Ns2 trace file. It can output two-dimensional (2D) and 3D graphs (points, lines, and bar charts) or data sets, whatever the trace file format (Tagged, Old, or New). It is also possible to specify the output of standard network performance metrics. NsGTFA satisfies most user needs. There is no complex installation process, and no external libraries are needed.

Software comprehension based on database relational algebra

Execution trace file analysis facilitates software comprehension which is a fundamental part of the software maintenance process. However, the scalability of large execution trace files limits understanding programmes and increases the complexity of the maintenance process. A programme interior representation which reflects the actual data structure is constructed from reduced execution traces. These reduced execution traces are extracted from a profiled run or logs of a programme. As a result, the generated output of these representations can then be easily analysed and visualised. This paper presents an approach to analyse execution trace files using relational database algebra methods to better comprehend and maintain softwares. Furthermore, this work can be helpful in evaluating the software's security using the logs trace files. The proposed approach was tested on real open source software. The results indicate that the proposed approach simplifies software comprehension, and may reduce the execution trace file size for up to 70% of its original size.

A web-based integrated environment for simulation and analysis with NS-2

The use of network simulators has not remained confined to the research community, but are increasingly being used for education purpose as well. Among the different network simulators available, Network Simulator version 2 (NS-2) is widely popular. However, installing NS-2, executing the simulations, and subsequently analyzing the generated trace files may not be an easy task, especially for novices. Although several tools have been developed to provide remote simulation facilities or to aid in the process of trace file analysis, often they have their own dependencies. Further, there is a lack of a single environment for simulation and post-processing. This paper presents ns2web, a Web application to address such issues and provide a single, integrated environment for simulation with NS-2, and analysis of trace files. Ns2web enables remote execution of simulations with NS-2 for both wired and wireless scenarios. The latter includes Wireless Sensor Networks (WSNs), Bluetooth, and WiMax modules, apart from the standard modules that ship with NS-2.34. The software also provides a toolkit to analyze trace files generated as a result of the simulation. Further, ns2web is publicly available and could be accessed by anyone over the Web. This application enables a user to focus on simulations with NS-2, rather than spend his time in installing (or patching) the simulator or writing custom scripts for analysis.

A tool for automating network simulation and processing tracing data files

One of the most highly regarded discrete event simulators used for network simulation is NS-2 (Network Simulator). NS-2 executes simulation scenarios producing various data of which trace files are considered the most beneficial for evaluating a simulation. In this paper we present the design considerations and implementation of a new tool that can be used both in TRAce FILe analysis and execution of simulations using NS-2. Although TRAFIL is primarily based on NS-2 trace files it can be extended to support a number of different other simulation trace file formats. It aims to make the execution of a great number of network simulations quicker, and the extraction of results from a large amount of data more flexible and productive. In order to accomplish the above tasks TRAFIL presents a novel way of interpreting, parsing, reading and eventually using NS-2 trace files. It introduces the notion of “metafiles” and “sub metafiles” throughout the procedures of trace file recognition and parsing, making the overall analysis operation substantially efficient and faster than alternative approaches. Metafiles and sub metafiles are used to encode NS-2 trace file structures enabling a more abstract approach to the trace file processing operation. Furthermore, TRAFIL facilitates the overall trace file analysis task by offering the opportunity to store each trace file as well as every Quality of Service (QoS) measurement produced for each trace file. Following the trace file recognition and processing operations, the information contained in a trace file is presented through a Graphical User Interface (GUI) offered by TRAFIL along with a variety of data, metrics and statistics related to simulation results. Finally, the tool offers the opportunity to execute custom Structured Query Language (SQL) queries to the local database and to completely automate the simulation procedure by enabling the user to execute NS-2 scripts as well as perform a simulation of a video transmission using the Evalvid-RA framework.

SNPmplexViewer--toward a cost-effective traceability system

BackgroundBeef traceability has become mandatory in many regions of the world and is typically achieved through the use of unique numerical codes on ear tags and animal passports. DNA-based traceability uses the animal's own DNA code to identify it and the products derived from it. Using SNaPshot, a primer-extension-based method, a multiplex of 25 SNPs in a single reaction has been practiced for reducing the expense of genotyping a panel of SNPs useful for identity control.FindingsTo further decrease SNaPshot's cost, we introduced the Perl script SNPmplexViewer, which facilitates the analysis of trace files for reactions performed without the use of fluorescent size standards. SNPmplexViewer automatically aligns reference and target trace electropherograms, run with and without fluorescent size standards, respectively. SNPmplexViewer produces a modified target trace file containing a normalised trace in which the reference size standards are embedded. SNPmplexViewer also outputs aligned images of the two electropherograms together with a difference profile.ConclusionsModified trace files generated by SNPmplexViewer enable genotyping of SnaPshot reactions performed without fluorescent size standards, using common fragment-sizing software packages. SNPmplexViewer's normalised output may also improve the genotyping software's performance. Thus, SNPmplexViewer is a general free tool enabling the reduction of SNaPshot's cost as well as the fast viewing and comparing of trace electropherograms for fragment analysis. SNPmplexViewer is available at http://cowry.agri.huji.ac.il/cgi-bin/SNPmplexViewer.cgi.

Express barcodes: racing from specimen to identification

Although devices combining microfluidic and advanced sequencing technologies promise a future where one can generate a DNA barcode in minutes, current analytical regimes typically involve workflows that extend over 2 days. Here we describe simple protocols enabling the advance from a specimen to barcode-based identification in less than 2 h. The protocols use frozen or lyophilized reagents that can be prepackaged into 'kits' and support barcode analysis across the animal kingdom. The analytical procedure allows 5min for DNA extraction, 25min for polymerase chain reaction amplification of the barcode region, 25min for cycle-sequencing, 10min for cleanup, 45min for capillary sequencing and 5min for trace file analysis to complete DNA-based identification. This study involved the comparison of varied DNA preservation and extraction methods, and evaluated Taq polymerases with high processivity and resistance to inhibitors.

Parallel Software Performance Metrics as Continuous Functions of Event Times

In software development, a metric is the measurement of some characteristic of a program's performance. When developing software for parallel architectures, metrics can play a very useful role in tuning properties such as task granularity and load balancing. A current approach to parallel software development is the use of analysis or visualisation tools to reveal important aspects of the parallel execution, often by post-execution analysis of trace files. For example, it may be useful to detect the creation of a large number of fine-grained tasks, which cause significant runtime overheads. A simple metric to estimate this danger is the number of parallel tasks created per second. This may be computed by dividing the trace into time slots, and counting the number of created tasks in each slot. Such metrics require parallel events like task creation and completion to be assigned time stamps. However, precise times are hard to obtain in asynchronous parallel systems. The difficulty is exacerbated by the well-known “probe effect” whereby the act of monitoring performance affects the performance itself. This inaccuracy may render a metric meaningless if it relies on the order in which events occur, or on the precise duration of tasks. Another danger is that the choice of time slot length may create artifacts, which becomes obvious if a visualisation tool allows the user to zoom in on parts of the trace file. The designer of parallel performance metrics must therefore take great care to ensure that they are meaningful.This paper argues that small inaccuracies in event times should not produce large effects on metrics, and hence on numbers, graphs, pictures or animations produced by analysis or visualisation tools. This is not sufficient to guarantee good metrics but it is a useful necessary condition. The requirement that small changes have small effects is characteristic of continuous functions, and it is therefore proposed that metrics be defined as continuous functions of event times. To bridge the gap between discrete events and continuous functions, metrics can be defined as integrals (over time slots) of simpler functions called trace abstractions. A trace abstraction need not be continuous in time: it may be a simple step functions that changes value when an event occurs. Such functions can easily be integrated over time slots, and a trace abstraction obeying certain conditions yields a metric that is insensitive to event time inaccuracy. Practical sufficient conditions are provided for such trace abstractions, and rules provided for the composition of complex trace abstractions from simple ones. As a bonus, continuous metrics are shown to be insensitive to time slot length and hence to be well-behaved under changes in time scale.