Towards Integrated System and Software Modeling for Embedded Systems

Transcription

1 Towards Integrated System and Software Modeling for Embedded Systems Hassan Gomaa Dept. of Computer Science George Mason University Fairfax, Virginia International Workshop on Model-Based d Systems Engineering i (ACES11), MODELS Conference Wellington, New Zealand October

2 Introduction Integrate Systems Modeling Software Modeling Development of embedded systems Approach from software modeling perspective Extension of COMET method Software Modeling and Design with UML From Use Case Models to Software Architecture H. Gomaa, Designing Concurrent, Distributed, and Real-Time Applications with UML, Addison Wesley, 2000 H. Gomaa, Software Modeling and Design: UML, Use Cases, Patterns, and Software Architectures, Cambridge University Press, February

3 Overview Modeling languages SysML for system modeling Subset of UML 2 with extensions for system engineering Use subset compatible with UML 2 Block definition diagrams (static model) State machine diagrams Use case diagrams UML for software modeling Example of simple embedded system Microwave Oven System 3

4 Overview of System and Software Modeling System Modeling 1. Structural ral Modeling of the Problem Domain 2. System Context Modeling 3. Use Case Modeling 4. Dynamic State Machine Modeling Hardware/Software Boundary Modeling 1. Decompose system into hardware and software components. 2. Deployment modeling Software Modeling 1. Software Context Modeling 2. Software Component Structuring 3. UML-based Software Modeling and Design 4

5 Structural Modeling of Problem Domain Model real-world entities relevant to system under development Develop conceptual static model for system Use SysML block definition diagram Existing systems Users Physical entities Model as physical classes Have physical characteristics (can see, touch) Information entities Model as entity classes Data intensive classes, often persistent

6 Block Definition Diagram for Microwave Oven System 6

7 System Context Modeling Defines boundary between total system (hardware and software) and external environment Depicted on System Context Diagram SysML block definition diagram UML static modeling notation System Depicted as one aggregate «system» class External environment External classes that system interfaces to Categories of external classes Depicted using UML stereotypes «external user» «external system»

8 System Context Diagram for Microwave Oven System 8

9 Use Case Modeling Use Case model Define system functional requirements in terms of Actors and Use cases Use Case Describes sequence of interactions between user (actor) and system Actor models external entities of system Actor initiates actions in system Human user External system External device Timer U-9

10 Use Case Model for Microwave Oven System 10

11 Dynamic State Machine Modeling Many real-time embedded systems are state-dependent Action depends not only on input event Also depends on state of system State machine Precise notation for modeling state-dependent system Start from use case description Consider all state-dependent scenarios fsm- 11

12 Microwave Oven System State Machine 12

13 Hardware/Software Boundary Modeling 1. Decompose system into hardware and software components. 2. Deployment modeling Determine boundary between hardware and software components Start with structural model of problem domain Determine decomposition into hardware and software components Model physical hardware components Model software system as composite component 13

14 Hardware/Software Block Definition Diagram for Microwave Oven System 14

15 Deployment Modeling of Microwave Oven System Physically deploy hardware and software components to Hardware and software platforms 15

16 Software System Context Modeling Defines boundary between software system and external environment Depicted on Software System Context Class Diagram Software System Depicted as aggregate «software system» class Categories of external classes that system interfaces to Depicted using UML stereotypes «external I/O device» «external user» «external system» «external timer»

17 Software System Context Model for Microwave Oven System 17

18 Software Component Structuring Start from software system context class diagram Shows external classes Each external class must interface to Software boundary class Depicted using UML stereotypes Use UML static modeling notation External classes are outside the system Boundary classes are inside the system Input, Output, Input / Output classes Proxy, User Interaction, Timer Internal software classes State dependent control, entity

19 Hardware and Software Class Structuring in Microwave Oven System 19

20 Software Concurrent Task Design Characteristic of real-time embedded systems Concurrent processing Structure software system into concurrent tasks Design task interfaces Use of UML stereotypes: Categorization of task by role, e.g., input, control Categorization of task by concurrency criterion Event driven, periodic, demand driven 20

21 Concurrent Components for Microwave Oven Software System 21

22 Task Structuring Criteria Event driven I/O task Task for each event t(interrupt) t)di driven I/O device Event driven device generates interrupt Periodic I/O task Task for each polled I/O device I/O device (usually input) sampled at regular intervals State dependent control task Executes state machine Activated on demand 22

23 Event Driven Input Task and Demand Driven Control Task 23

24 Example of Periodic Input Task 24

25 Related Work Subsequent software modeling and design Single systems COMET/UML H. Gomaa, Designing Concurrent, Distributed, and Real-Time Applications with UML, Addison Wesley Object Technology Series, 2000 H. Gomaa, Software Modeling and Design, Cambridge University Press, February 2011 Product lines PLUS/UML H. Gomaa, Designing Software Product Lines with UML, Addison Wesley Object Technology Series,

26 Conclusions and Future Work Integration of system modeling and software modeling Use for modeling embedded systems Model hardware and software components SysML for system modeling UML for software modeling Emphasis on hardware/software boundary of system Decomposition into hardware and software components Designing interface between hardware and software components Future Work Model performance of embedded systems Model embedded system and software product lines 26