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| Using AADL to describe, validate, and verify system performance associated with the system in th | |
| Point of Contact |
Tom Hempler tom.hempler@ngc.com |
| Dates | June 2008 - October 2008 |
| Problem | Performance requirements, design, and implementation validation and verification when tasked by NASA programs, is currently accomplished manually on a limited basis. Like UML 2.0, Architecture Analysis and Design Language (AADL) is used to express, in graphical form, a model of the structure and behavior of the system. Unlike UML 2.0, AADL fills the performance analysis gap when modeling systems and extends the capability for the NASA IV&V facility to analyze system performance requirements and design within a model driven environment. Latencies in communications, timing allowances for system events, capacities, and bandwidths are critical validation points in the system specifications and design documentation that need to be evaluated using the System Reference Model (SRM) in conjunction with a Real-time Performance Model (RPM) as a facility for characterizing system performance. As an example, RPM written in AADL and SRM written in UML have a critical role in validating the real-time architecture concerns (end-to-end latency, jitter, execution flow) and time margins related to safely aborting launches within time intervals that vary with the position along the flight profile of the launch vehicle and spacecraft. These time intervals along with events that surround them and the processing time for managing them are requirements that need validation through the use of assertion test suites and performance analysis using AADL. As another example, using AADL to model performance in conjunction with the SRM test suite execution could have detected the priority inversion problem with the Mars pathfinder. System performance and capacities are modeled by the AADL tool and used with timing and loading parameters to evaluate real-time performance requirements. Events, states, and timing are executed during assertion testing within the SRM to validate requirements or find missing ones that would have mitigated the risk. |
| Objective | Using AADL, model non-functional requirements and verify system designs using SRM test scenarios to evaluate behavior with adjustable timing parameters. Specifically, use critical events, triggers, processing time, interface and end-to-end command/data latencies, and processing priorities to evaluate the correctness of timing requirements and audit the as-built design to ensure compliance. Where performance requirements are TBD or unknown, evaluate and recommend values for them. |
| Results | No results are available at this time. Please check back again. |
| Keywords | Schedulability, latency, throughput, processing time |
| Categories |
Design Analysis Dynamic Analysis Requirements Analysis Software Architecture Assessment |
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Curator: Josh Stonestreet NASA Official: Lisa Montgomery |
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