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A Procedure for Designing Abstract Interfaces for Device Interface Modules. Presented By: Andy Mroczkowski Dan Talaber Tracy Xie Joshua Wetzel. David Parnas. Overview. Definitions Examples of Device Interface: Car JINI Embedded Real-Time Controller Summary Questions?.
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A Procedure for Designing Abstract Interfaces for Device Interface Modules Presented By: Andy Mroczkowski Dan Talaber Tracy Xie Joshua Wetzel David Parnas
Overview • Definitions • Examples of Device Interface: Car JINI Embedded Real-Time Controller • Summary • Questions?
Definitions User Program Device 1 Abstract Interface Device Interface Modules 1 Hardware Interface Device 1 Abstract Interface Device Interface Modules 1 Hardware Interface Legend: : hardware : software : interface
Car Example Driving Brakes OperateCar Brake Pedal BrakeController Brake Line Engine Accelerator ThrottleController Fuel WheelAngle Steering Wheel Steering system SteeringColumn
Car Example • Braking Disc Brakes OperateCar BrakePedal Brake Controller Brake Line Disc Brakes Brake Pedal ABS Controller BrakeLine
Car Example • Braking Disc Brakes OperateCar BrakePedal Brake Controller Brake Line Perform- ance Brakes Brake Pedal Brake Controller BrakeLine
Car Example • Design Approach • Assumption List Characterizing the Virtual Device • “The device provides a mechanism which slows the car at variable rates.” • Programming Constructs Embodying the Assumptions • INCREASE_BRAKING • DECREASE_BRAKING
Jini • What is Jini? • A dynamic distributed computing architecture that provides spontaneous networking between clients and services. • Effective use of abstract interfaces and device interface modules.
Jini Architecture in a Nutshell Clients Lookup Service Proxies Services
Service and Lookup Service Service Lookup Service Proxy, Interface Legend: Repository Java Object Communication HW/SW/Both
Client and Lookup Service Interface Client Lookup Service Proxy Legend: Repository Java Object Java Interface Communication SW w/ JVM
Client and Service Client Service request Proxy Legend: HW/SW/Both Java Software Communication
Client with JVM Common Service Interface Proxy Object Network Service Printer Proxy Object Office Tool Printer Interface LAN Printer Legend: Software Interface Service Provider How Jini Relates to Parnas’ Model Proxy objects implement an interface and encapsulate differences (e.g. protocols) among various service providers.
Intro of Embedded Software System An embedded software system is a single component of a significantly larger hardware or software system.
Embedded Software Design with Abstract Interface User Interface Client Control Builder Station BigBlue Data Access Interface Firmware_Ver1 FIM DeviceA (I/O) Firmware_Ver2 IOLIM DeviceB (IOP) Different Vendor Image Version Interface Module DeviceC Legend: :Group : software : interface : hardware Note: FIM (Fieldbus Interface Module) IOLIM(I/O Link Interface Module) IOP (I/O Processor)
High Alarm Low Alarm Comm. Err. Embedded Software Architecture Ethernet Data Access Interface User Interface Control Net Pressure Device Interface Module Temperature I/O Control Net Flow Data bus Valves
Embedded Software • Features: • Redundant Hardware Interface • Primary, Secondary (OPM) • Flexible Hardware Interface • Sub-Interface Module • Relation between Virtual Device and Hardware Device • Configuration-time/Load-time/Run-time
References • Ilango S. Kumaran, Jini Technology: An Overview, ISBN 0-13-033385-9 • Jim Waldo and The Jini Techology, The Jini Specifications, Second Edition, edited by Ken Arnold, ISBN 0-201-72617-3 • Picture of Parnas: http://www.martinfowler.com/articles/xp2002.html