Page 1 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Chapter 16 Component based embedded systems

Page 2 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Overview  Introduction  Component technology in embedded systems  Case study – ABB’s Field Devices  Prerequisites for effective development of Component- based embedded systems  Summary

Page 3 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Where is the problem?  Huge market arises for embedded devices, and thus for software for them  Similar basic functionalities are repeated  New functionalities are added constantly  Shorter development time is required

Page 4 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Introduction

Page 5 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Embedded vs. Component-based  Monolithic approach requires re-implementing the functionalities  Component based SE provides a mean to reuse the functionalities Component based SE can provide a framework instead of technology Embedded devices are too small for component off-the- shelf technologies

Page 6 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Component technology in embedded world  Contractually specified interfaces  Component as a unit of composition and independent deployment  Explicit context dependencies  Component granularity  Reuse  Location transparency  Component wiring  Portability, platform independence

Page 7 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Contractually specified interfaces  State-of-the-art technologies approach: Interfaces as pure collection of methods. Embedded environment constraint: Non-functional specifications are equally important part of the contract

Page 8 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Interfaces II  Component interfaces support: Late binding, Polymorphism, Semantic specification  Pre conditions,  Post conditions,  Invariants

Page 9 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Unit of composition and independent deployment  Run-time composition Component model, Run-time environment, Dynamic communication,  Design-time composition Capable of generating monolithic firmware from component-based design, Optimization

Page 10 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Explicit context dependencies What is a context in embedded world?  Other components and interfaces  Run-time environment CPU, RTOS, Component implementation language, Resource constraints

Page 11 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Component granularity  Coarse-grained components, Too heavy bag of unnecessary functionality, Too much resources used,  Fine-grained components, Light, unneeded functionality reduced, Scarcer uses of resources, Greater communication overhead,

Page 12 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Reuse  Black-box reuse From component’s user point of view,  White-box reuse From composition environment point of view  Gray-box reuse (composition environment) If clear conventions for knowledge about implementation are introduced

Page 13 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Architecture and frameworks Defining components alone will not lead to reuse  Common architecture for family of embedded devices  Framework for development

Page 14 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Portability, Platform independence  Source level portability suffices, Design-time composition, Run-time environment restrictions  Source level portability requires: Agreement on implementation language, Agreement on available libraries, Providing proper abstractions (i.e. RTOS API)

Page 15 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Other issues  Location transparency For embedded devices there is a single location,  Component wiring Needed for flexible composition of software, Optimizes component interaction, Component ”glue code” should be in implementation language

Page 16 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Case study – ABB’s Field devices  Synchronous approach  Architecture of the field devices  Dynamic behavior  Inter-component communication

Page 17 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Synchronous approach Synchronous languages have been developed to simplify the programming of reactive systems  Provide the mean to handle concurrency, determinism, response time control  Based on synchrony hypothesis

Page 18 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Architecture of the field device

Page 19 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Dynamic behavior speed Tv,Tv,kp Setpoint error out setpoint a) Controller (2) manipulated variable (3) Controlled System actual value (1) b) Signalbus Sensors (1) PID (2) Actuator (3) out speed

Page 20 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Inter-component communication  Based on Signal Bus  Signal Bus communication is maintained by Object Manager  Communication itself is based on signals One source per signal

Page 21 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Types of Interfaces User Interface Real-time System Process Interface Communication Link Mass storage Interface (1) (2) (3) (4)

Page 22 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Prerequisites for effective development  Component model Additionally must address non functional properties, Allow for code generation, Allow for efficient functional interfaces, Allow for specification of architectural styles that describe component connections and containment relations,

Page 23 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Framework Component Repository Composition environment Run-time environment Component Model Component-based Architecture for field devices

Page 24 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Prerequisites II  Component-based architecture for field devices Framework, Compile time optimizations, Field-bus architecture,  Repository Storage and retrieval of components, Storage of non-functional properties, implementation, support and test scripts, Versioning

Page 25 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Prerequisites III  Composition environment Constraint verification, Component adaptation and code generation, Composition techniques, Definition of composition rules

Page 26 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Prerequisites IV  Run-time environment Provide efficient implementation model, Address embedded systems constraints, Allow for compilation to optimized firmware thus allowing for no extra run-time environment that RTOS Allow for hardware and RTOS independent implementation of components

Page 27 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Case study summary  Architecture of the field device  Prerequisites for effective development  Framework

Page 28 Building Reliable Component-based Systems Chapter 16 - Component based embedded systems Presentation summary  Introduction  Component technology in embedded systems  Case study – ABB’s Field Devices  Prerequisites for effective development of Component- based embedded systems  Summary