A Model-Driven Framework for Architectural Evaluation of Mobile Software Systems George Edwards Dr. Nenad Medvidovic Center for Software Engineering University of Southern California

Project Overview Motivation –Provide a “tailorable infrastructure” for evaluating, refining, and validating software architectures for mobile software systems. Investigate the consequences of architectural decisions. Weigh architectural trade-offs. Validate the achievement of quality attributes. Approach –Develop a software architecture modeling and simulation tool chain that leverages the Model-Driven Engineering (MDE) approach to system design. Focus on concerns of particular relevance to mobile software systems. –Implement a mapping between architectural constructs and simulation constructs. Modeling language based on xADL, an extensible architecture description language. Simulators based on adevs, a discrete event simulation engine.

The Extensible Modeling and Simulation Toolchain xADL extensions are implemented as GME metamodels. –Define domain-specific modeling concepts, including elements, relationships, views, and constraints. Software architecture models are created in GME. –Provides an intuitive mechanism for building complex models. –Automatically enforces the language rules. Plug-ins interpret, transform and analyze architecture models. –Generate discrete-event simulations that provide data about a system’s run- time characteristics.

xADL Extensions D ATA –Includes data types and sizes. B EHAVIOR –Includes tasks and states. P OWER –Includes computational and communication energy costs. R ELIABILITY –Includes failure probabilities and recovery times. PowerxADL Metamodel (includes Structure, Data, and Power extensions)

Example Model

The xADL-to-adevs Transformation Transforming architecture models into discrete event simulations allows run-time properties to be observed and quantified. –Achieved via xADL-to-adevs mapping. –GME plug-ins implement the mapping and instrument the generated code to record the appropriate measurements. xADL Typeadevs Type Architecture, SubarchitectureStatic digraph Component, ConnectorAtomic model InterfacePort Link, Interface MappingCouple DatumObject

Discrete Event Simulators Latency –Requires Structure and Types, Data, and Behavior extensions. –Provides, for each required interface, the response time for each invocation. Reliability –Requires Structure and Types, Data, Behavior, and Reliability extensions. –Provides the time and type of failures and the recovery time. Power Consumption –Requires Structure and Types, Data, Behavior, and Power extensions. –Provides the energy consumption of each host (i.e., remaining battery power) over time.

Ongoing and Future Work Improve accuracy of simulation measurements. –e.g., overlay software models on a high-fidelity wireless network simulator. Enhance the D ATA modeling extension. –e.g., provide support for A/V streams. Enhance the B EHAVIOR modeling extension. –e.g., provide support for threading and queuing. Validate simulation results through comparison to a real system. Create integrated simulations consisting of both simulated and real (operational) components. –e.g., “test harnesses” for implemented components. Implement automatic conversion between xADL XML schemas and GME metamodels.