NEWS AT SEI
This library item is related to the following area(s) of work:Predictability by Construction
This article was originally published in News at SEI on: May 1, 2008
Many software systems have stringent quality attribute requirements. For example, industrial robots must perform tasks with strict deadlines, medical devices must comply with safety requirements, and most software must minimize security vulnerabilities. Although analysis theories and techniques to satisfy these requirements have existed for many years, they are not widely used because of the resources and expertise required to create, maintain, and evaluate analysis models. Even when such theories are used, doubts often remain about the accuracy of the results because of uncertainty of the correspondence between the models that are analyzed and the code that will be executed.
The PACC Starter Kit (PSK) is an integrated set of software development tools that demonstrates how existing technologies can be integrated to provide objective confidence in predictions of system behavior. “Our primary intent is to provide working examples and building blocks that help organizations get started with integrating such technologies in their own development environments,” says James Ivers, a researcher at the SEI and one of the developers of the PSK.
“The PSK is an Eclipse-based development environment for Windows that combines a model-driven development approach with reasoning frameworks that apply analyses to predict runtime behavior based on specifications of component behavior and are accompanied by some measure of confidence,” says Ivers.
Often, quality attribute requirements in areas such as performance, security, or safety are some of the most difficult system behaviors to get right. Effective techniques to provide early confidence in the ability to satisfy such requirements usually include some form of architectural or design analysis that exploits knowledge of the relevant quality attributes.
Unfortunately, there often remains a gap between architectural concepts and the implementations that will actually be deployed. And that gap leads to uncertainty as to whether the qualities designed into an architecture will ultimately be realized in the executing software.
The PSK shows how a collection of today’s technologies can be integrated to mitigate this risk. Key features of the concepts integrated in the PSK include
The PSK includes online tutorials that guide a user through its use on a number of examples. According to Ivers, the most interesting example is the audio-mixing application, which is built from components that include a signal generator, WAV decoder, splitter, adder, inverter, and graphical display. Ivers explains that “the audio example has some of the same quality attribute requirements as larger, more complex systems, but is a small application that is easy to understand. Problems tend to be readily observable, either audibly or by using the included graphical display.”
The tutorial demonstrates how the behavior of individual components is specified and how the architecture of the mixer is depicted in the PSK. It shows how code for the included component technology is generated from component specifications and how that code is deployed and executed. It also shows how the included reasoning frameworks are applied to provide quality attribute analyses; two of the analyses that are demonstrated for this example are
This view is the result of information extracted from the specification of the audio application; this form is more suitable for analysis by the various performance evaluation procedures found in the PSK.
This is one example of the type of evidence supplied to give users a reason to believe analysis results.
Ivers explains how these examples are used: “You can use them to see how problems can be detected early, modify the architecture or the details of individual components to correct problems, re-analyze the results to confirm fixes, and confirm that the executing system exhibits the qualities indicated by the analyses.”The PSK is intended as a vehicle for demonstrating how these concepts can be integrated in practice. The PSK, now available for download integrates a collection of technologies that include
To learn more, visit the PSK pages or contact us using the link in the For More Information box at the bottom of this page.
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