39793092
Building Responsive and Scalable Web Applications
Responsiveness and scalability are important quality-of-service attributes for Web applications. Web sites that are slow, either because of poor responsiveness or lack of scalability, can produce customer dissatisfaction, loss of revenue and/or productivity, and potentially more serious consequences. To avoid these problems, it is important to know whether users will be able to access information in a timely fashion, whether the hardware will be able to handle the load, and whether the system will scale to meet projected demand before the system is deployed. This paper describes how to apply the techniques of Software Performance Engineering (SPE) to Web applications. We focus on using the SPE models to provide decision support during the software architectural design phase because the decisions made at that time have the largest effect on performance and scalability. A case study illustrates the application of these techniques to a typical Web application.
11071330
Performance Engineering of Software Systems
We may not be able to make you love reading, but performance engineering of software systems will lead you to love reading starting from now. Book is the window to open the new world. The world that you want is in the better stage and level. World will always guide you to even the prestige stage of the life. You know, this is some of how reading will give you the kindness. In this case, more books you read more knowledge you know, but it can mean also the bore is full.
192543
Performance Model Interchange Format: Semantic Validation
A Performance Model Interchange Format (PMIF) provides a mechanism whereby system model information may be transferred among queueing network model (QNM) based modeling tools. The PMIF allows diverse tools to exchange information and requires only that those tools provide importing/exporting mechanisms from/to the PMIF. The XML specification of the PMIF allows implementers to use widely available tools to parse the XML file, check the syntax, and simplify the translation to/from the XML format. Those tools, however, do not know the semantics of a QNM so they cannot check the XML to ensure that it contains a valid QNM. This paper presents the study of the validations needed to carry out such a semantic analysis, and the development of a semantic validation tool that can be used by any developer who wants to implement PMIF import/export mechanisms.
25855174
General Principles for Performance Oriented Design
28516165
Best Practices for Software Performance Engineering
Performance—responsiveness and scalability—is a make-or-break quality for software. Software Performance Engineering (SPE) provides a systematic, quantitative approach to constructing software systems that meet performance objectives.It prescribes ways to build performance into new systems rather than try to fix them later. Many companies suc- cessfully apply SPE and they attest to the financial, quality, customer satisfaction and other benefits of doing it right the first time. This paper describes 24 best practices for applying SPE to proactively managing the per- formance of new applications. They are vital for successful, proactive SPE efforts, and they are among the practices of world-class SPE organizations. They will help you to establish new SPE programs and fine tune existing efforts in line with practices used by the best software development projects.
2552665
From UML models to software performance results: an SPE process based on XML interchange formats
The SPE process uses multiple performance assessment tools depending on the state of the software and the amount of performance data available. This paper describes two XML based interchange formats that facilitate using a variety of performance tools in a plug-and-play manner thus enabling the use of the tool best suited to the analysis. The Software Performance Model Interchange Format (S-PMIF) is a common representation that is used to exchange information between (UML-based) software design tools and software performance engineering tools. On the other hand, the performance model interchange format (PMIF 2.0) is a common representation for system performance model data that can be used to move models among system performance modeling tools that use a queueing network model paradigm. This paper first defines an XML based S-PMIF based on an updated SPE meta-model Then it demonstrates the feasibility of using both the S-PMIF and the PMIF 2.0 to automatically translate an architecture description in UML into both a software performance model and a system performance model to study the performance characteristics of the architecture. This required the implementation of some extensions to the XPRIT software in order to export UML models into the S-PMIF and a new function in the SPEED software to import S-PMIF models, which are also described. The SPE process and an experimental proof of concept are presented.
42411588
Computer vision issues during eye-in-hand robotic tasks
Our previous work has introduced the framework of controlled active vision that provides a bridge between computer vision and control theory. This paper presents some of the computer vision techniques that were employed in order to detect targets, automatically select features, measure feature displacements, and evaluate measurements during the various applications of the controlled active vision framework. We experimented with a lot of different techniques, but the most robust proved to be the sum-of-squared differences (SSD) optical flow technique. Search optimizations and dynamic pyramiding are proposed in order to provide real-time performance. In addition, several techniques for the evaluation of the measurements are presented. One important characteristic of these techniques is that they can also be used for the selection of features for tracking in conjunction with several numerical criteria that guarantee the robustness of the servoing. These techniques are important aspects of our work since they can be implemented either on-line or off-line. The paper concludes with results from the application of these techniques to real images.
6341521
Rethinking classical internal forces for active contour models
The classical active contour model has two basic internal forces: tension and curvature. These forces are included to provide cohe sion, equal control point spacing, and locally smooth shape. These classical internal forces have undesirable attributes that are in conflict with these original desired characteristics. Tension evenly spaces the control points, but also causes the models to collapse in weak image gradients. Curvature produces locally smooth curvature, but it does so by forcing the model toward a straight line. The paper returns to the original active contour model motivations to reformulate these internal forces. The desired properties are achieved without the introduction of unwanted model behavior A new spacing force and a new constant change in curvature force are introduced and their performance characteristics are discussed. The paper includes experimental results that demonstrate the efficacy and performance of the proposed reformulations.
9601024
Using COTS to Construct a High Performance Robot Arm
In this paper we present a design study and technical specifications of a high performance robotic manipulator to be used for ball catching experiments using commercial off-the-shelf (COTS) components. Early evaluation shows that very good performance can be achieved using standardized PowerCube actuator modules from Amtec and a standard workstation using CAN bus communication. Implementation issues of low-level control and software platform are also described, as well as early experimental evaluation of the system.
17908956
Local Specification of Surface Subdivision Algorithms
Many polygon mesh algorithms operate in a local manner, yet are formally specified using global indexing schemes. This obscures the essence of these algorithms and makes their specification unnecessarily complex, especially if the mesh topology is modified dynamically. We address these problems by defining a set of local operations on polygon meshes represented by graph rotation systems. We also introduce the vv programming language, which makes it possible to express these operations in a machine-readable form. The usefulness of the vv language is illustrated by the application examples, in which we concentrate on subdivision algorithms for the geometric modeling of surfaces. The algorithms are specified as short, intuitive vv programs, directly executable by the corresponding modeling software.
41677043
Unknown object grasping using statistical pressure models
Grasping is one of the most fundamental and challenging tasks in robotics. Applications range from space missions (e.g., collection of rock samples) to industrial automation. In this work, we use a camera mounted on the end-effector of a manipulator to grasp an unknown object in the workspace. A novel deformable contour model is used to determine plausible grasp axes of the target object. Potential grasp point pairs are generated, ranked based upon measurements taken from the contour, and a vision-guided grasp of the object using the highest ranked grasp point pair is executed. Several experimental results are presented.