![17
Group Exercise : Introduction to ERT
system
Given the three computer systems
categorized: batch, interactive and real-time.
Answer the following questions.
1.What are the differences between the
categorizes?
2.Give an application example for each
category.
[5 marks]](https://image.slidesharecdn.com/1-250707193101-ad641b90/85/1-2-Topic-1-Introduction-Details-pdf-Real-time-Software-Engineering-RTSE-17-320.jpg)
![18
Group Exercise : Introduction to ERT
system
Classify the following applications to non-real-time systems, hard
real-time systems or soft real-time systems. Give your reason for
each answer. For the application of real-time systems, state a
timing requirement example (soft, hard or firm).
•An automatic teller machine
•Cruise control
•A computer-controlled routing switch used at a local telephone
company branch exchange
•Bioinformatics software to compute protein-protein interaction
•ECG systems
•A police database that provides information on stolen
automobiles
•A coin-operated video game
•A university grade-processing system
[16 marks]](https://image.slidesharecdn.com/1-250707193101-ad641b90/85/1-2-Topic-1-Introduction-Details-pdf-Real-time-Software-Engineering-RTSE-18-320.jpg)
1.2-Topic 1-Introduction (Details).pdf | Real-time Software Engineering (RTSE)
- 1. Dayang Norhayati Abang Jawawi Universiti Teknologi Malaysia email : dayang@utm.my
- 2. 2 The Structure of Presentation 1. Introduction 2. Characteristics and Challenges 3. Conclusion Software Engineering for Real-Time Systems
- 3. 3 v Batch – the results can arrive any time, typically minutes, hours or days. v Interactive – results within a fairly short time, typically a few seconds, v Real-Time – results within definite timescales, otherwise the systems just won’t work properly. Introduction Computer Systems Category
- 4. 4 v Real-time system is a system, which the correctness of the system depends not only on the logical results , but also on the time at which the results are produce. v The measurement of system time is related to events in the real external environment. v A real-time system can be classified as either hard or soft. The distinction, however, is somewhat fuzzy. Introduction Real-Time Systems The real-time spectrum (Stewart, 2001)
- 5. 5 v Hard real time system ü Response time to incoming events must be guaranteed even under extreme conditions ü Missed deadlines lead to severe consequences, eg flight control systems may cause loss of human life, ü Correctness is critical. v Soft real system ü Can miss events’ deadline and still function within parameters ü Here, overall performance is central concern but individual activity deadlines are not critical ü Failure may still be tolerable. Introduction Real-Time Systems
- 6. 6 Introduction Category of timing requirements in RTS vSoft real time - Utility degrades with distance from deadline. Missed deadline - still produce useful result vHard real time - System fails if deadline window is missed. Missed deadline – damaging effect. vFirm real time - Result has no utility outside deadline window, but system can withstand a few missed results. Missed deadline – wasteful but no harmful. Value of response Time deadline hard firm soft
- 7. 7 v Real-time systems come in many types and sizes. v Example of largest real-time system – telemetry control system . v Example of small real-time system – missile systems. v In industrial scene many installation on real-time systems use computer-based stand-alone controller or called dedicated systems or embedded systems. Introduction Real-Time Systems
- 8. 8 EMBEDDED SYSTEMS transportation home appliances advances equipment communication equipment office equipment Introduction Embedded Systems v Embedded system is a system, which contains microcomputer as a component, but the user does not see the system as a computer. Most embedded systems are real-time systems => Embedded Real-Time (ERT) systems
- 9. v Embedded System provides the major part of necessary technology for new trends of computing in: • Ubiquitous/ pervasive computing - “information anytime, anywhere” • ambient intelligence - utilizes communication technology in future homes and smart buildings v Embedded System frequently connects to environ- ment through sensors & actuators. Thus, has an immediate impact on the environment. For safety critical embedded systems h/w & s/w must be dependable. Introduction Embedded Systems
- 10. v Some examples of embedded systems & their real-time requirements. Krasner J., “Optimizing Technology Choices For Device Software”, Embedded Market Forecasters, May 2005 Introduction Embedded Real-Time Systems
- 11. 11 Introduction The market for ERT systems v Survey by Tennenhouse, 2000 shows rate of CPU shipments in year 2000: general purpose computing / Interactive embedded computers Rate 2% 80% % 150 million 8 billion parts/year such as personal computing, office automation, e-commerce and their associated networking Emb. Computers 80% Robots 6% Interactive 2% Vehicles 12%
- 12. 12 v The annual growth rate for microcontrollers, which are used in embedded systems is higher as compare to for the general- purpose processors (Gupta, 1998). Introduction The market for ERT systems
- 15. 15 Introduction Why RTS are Different with non-RTS? v Have deadlines attached to some or all tasks v Faults in the system may lead to catastrophic v Must have the ability to deal with exceptions v Must be fast, predictable reliable, adaptive
- 16. 16 Introduction Why ERTs are Different with Desktop PC? v ERTs are dedicated to specific tasks, whereas PCs are generic computing platforms. v ERTs are supported by a wide array of processors and processor architectures. v ERTs are usually cost sensitive. v Implementation constraints in ERTs are real-time, resources and size. v If an ERTs is using an OS at all, it is most likely using a real- time operating system (RTOS). v The implications of software failure is much more severe in ERT than in desktop systems and run continuously. v ERT require specialized tools and methods to be efficiently designed.
- 17. 17 Group Exercise : Introduction to ERT system Given the three computer systems categorized: batch, interactive and real-time. Answer the following questions. 1.What are the differences between the categorizes? 2.Give an application example for each category. [5 marks]
- 18. 18 Group Exercise : Introduction to ERT system Classify the following applications to non-real-time systems, hard real-time systems or soft real-time systems. Give your reason for each answer. For the application of real-time systems, state a timing requirement example (soft, hard or firm). •An automatic teller machine •Cruise control •A computer-controlled routing switch used at a local telephone company branch exchange •Bioinformatics software to compute protein-protein interaction •ECG systems •A police database that provides information on stolen automobiles •A coin-operated video game •A university grade-processing system [16 marks]
- 19. Actuators Embedded Real- Time Software Environment Sensors input output determine the status of environment control the system according to the environment status Human operator input output 19 v The key difference of ERT software is due to the need for the system to respond to real-world environment. v The software is tightly integrate with physical process (sensor and actuator ). Characteristics and Challenges Respond to real-world environment Unique characteristics of ERT systems & each characteristic will contribute toward the challenges in developing the ERT software.
- 20. 20 Characteristics and Challenges Respond to real-world environment v The sensor-system-actuator model of RTS consists of 3 parts: 1. sensors provide inputs (stimuli), 2. computational units elaborate responses, and 3. actuators convey outputs (responses) v RTS receive stimuli (both external and internal) and provide responses to these stimuli v Stimuli: 1. Periodic: occur at preset intervals of time (e.g., every 20 ms) 2. Aperiodic: have irregular occurrences
- 21. 21 General model of an RTS Real-time control system Actuator Actuator Actuator Actuator Sensor Sensor Sensor Sensor Sensor Sensor Characteristics and Challenges Respond to real-world environment
- 22. 22 Sensor/actuator processes Data processor Actuator control Actuator Sensor control Sensor Stimulus Response Characteristics and Challenges Respond to real-world environment
- 23. 23 Characteristics and Challenges v Timeliness ü Reaction to stimuli “on time” (deadlines must be met) ü Relative and absolute timing constraints v Reliability ü Many errors have roots in incorrect specification ü Formal techniques needed for safety-critical systems v Intensive dynamics ü Models to describe behavior are necessary (based on finite state machines). ü Systems can adapt to situation changes v Exception handling ü Priorities should be assigned to stimuli/events ü Mechanisms for handling interrupts need be developed
- 24. 24 Characteristics and Challenges v Concurrency ü Parallel tasks are inherent in RTS ü The environment is also “concurrent” in nature v Distribution & resource allocation ü Distribution is not necessarily a characteristic of RTS, but should be taken into consideration in larger applications v Communication and synchronization ü Synchronous and asynchronous communication mechanisms should be designed v Size ü In larger applications, there are numerous processes and threads ü Size is associated with continuous change ü Decomposition in smaller units is needed, as are mechanisms for modeling hierarchical structures
- 25. 25 v The ERT systems need to respond to real-world environment or external events that are frequently not predictable. v Characteristic : The responses toward these events must be tightly bounded in time, especially for hard ERT systems. v In ERT software the logical correctness is not enough, but the time at which the response are produced is an importance concerns. v Challenge : Software technologies on non-ERT software are not enough for ERT software, because issues of time are not address specifically. According to Lee, 2002, currently more work is done to use some software technologies in ERT software but the attempts are far from satisfactory. Characteristics and Challenges 1. Timeliness
- 26. 26 Characteristics and Challenges 2. Concurrency v To respond to real-world environment, systems response in ERT software can occur in 3 styles: 1. reactive systems – react continuously to their environment at the speed of environment; 2. interactive systems – react with the environment at their own speed and 3. transformational systems – simply take a body of input data and transform it into a body of output data. v Characteristic : To handle these two styles of event real-time systems need to be concurrent and multitasking. v Challenge : The presence of multitasking and concurrency in real-time software is making them more difficult to design than non-real-time software. Issues to provide multitasking in ERT systems are RTOS and RT scheduling.
- 27. 27 v Unlike the non-ERT systems, ERT systems interact minimally with the user but more interactions with its environments through the hardware interfaces. v Characteristic : ERT systems is reactive to its physical or external environment, reactive systems have real-time constraints, and are frequently safety-critical and must be robust. v Challenge : Milojicic, 2002, suggested that the major challenge of ERT software design and development has to do with tools and process. The tools associated with ERT are not very strong. Characteristics and Challenges 3. Dependability and Robustness
- 28. 28 v Most RTS undergo at least some degree of evolutionary change e.g. telecommunication system. v Characteristic : In ERT, software evolution change means software needs to be changed in ways that were not considered when the system was built originally. v These evolution change of the system requirement need to be captured properly because for ERT systems, changes of functional requirements often have the impact on non- functional requirements such as timing. v Challenge : The evolving specifications of ERT systems has forced designers to look at implementations that are intrinsically flexible, i.e., that can be changed rapidly. ERTs are usually constructed with the least powerful computers that can meet the evolving system requirement which are functional and performance requirements. Characteristics and Challenges 4. Evolving Systems Requirements with implementation constraints
- 29. 29 v They mix computational styles and implementation technologies. The systems are often a mixture of hardware and software designs. v Characteristic : ERT systems requires the application of different types of models in the designed process. v Challenge : What model to use whether use a grand-unified theory and a common model that subsumes everything as a special case or different modeling language for different design? Characteristics and Challenges 5. Heterogeneity
- 30. 30 Conclusion v RT systems is an enabling technology for many current and future applications that affect public safety, competitiveness, the economy, and life-style. v SE disciplines are essential for Embedded & RT software development but require considerable adaptation for ERT software.
- 31. 31 Forming Heterogeneous Groups 1. Name 2. Age 3. Level of academic achievement v CGPA v Selection of this subject? A. Interest. B. No other subject to select 4. Ethnic or racial background v Race v State origin 5. Gender
- 32. 32 Create a Feeling of Group Identity 1. Ice-breaking 2. Choose name, create motto & team goal 3. Set ground rules (agree all members)
- 33. 33 1. Refer to Past Year Question 2. Answer question 1a & 1b 3. Submit at the end of this class in group Problem solving 1 Group Exercise
- 34. 34 References 1. Stewart, D. B., “Introduction to Real Time”, Embedded Systems Programming, Jan. 2001. 2. David Tennenhouse, “Proactive Computing”, Communication of the ACM, Volume 43, no.5, pp 43-50, May 2000. 3. Gupta, R. K. (1998). “Introduction to Embedded Systems.” Lecture note ICS212. University of California. 4. Edward A. Lee, “Embedded Software”, Advances in Computers, Vol. 56, Academic Press, September 2002. 5. Dejean Milojicic, 2002, “Trends War – Embedded Systems”, IEEE Concurrency, Vol.8, Issue 4, Oct-Dec 2000. 6. Arnold S. Berger “Embedded Systems Design: An Introduction to Processes, Tools, and Techniques”, CMP Books, 2002. 7. Calvez, J. P., Pasquier, O. and Peckol, J. (1997). “Software Implementation Techniques for Hw/Sw Embedded Systems.” Proceedings of the 5th International Workshop on Hw and Sw Codesign (CODES/CASHE’97). 49-53. 8. John A. Stankovic et al. “Strategic Directions in Real-time and Embedded Systems”, ACM Computing Survey, Vol. 28, No. 4, December 1996. 9. Gerrit Muller, “Opportunities and challenges in embedded systems”, Technical Paper logo TBG, Embedded Systems Institute, May 22, 2010. 10. Sheetal Patil and Laxman Kapaleshwari, “Embedded Software - Issues and Challenges”, SAEInternational, Dec 2010.
- 35. 35 Thank You.