JAVA-BASED REAL-TIME PROGRAMMING

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2. Fundamentals as expressed in the source code should result in the same correct result independent of the underlying scheduler or operating system. • Correctness from a real-time point of view; the timing requirements are considered so that control output is computed in time. • Proper object oriented design and implementation; we use the established principles of object orientation to improve structure, readability, maintainability, etc. of embedded software. • Appropriate trade-off between active and passive objects; the thread class should be used where appropriate but not too excessive for efficiency and readability reasons. • Proper protection of shared resources; the concepts of semaphores, synchronized methods, and messages (events) should be used appropriately. Since software development tends to take a bigger and bigger part of system development resources, it is very important that we are able to handle the above items. In a wider perspective, there are different approaches to development of embedded systems. The focus could be on hardware, control theory, and/or software issues. All of these focuses are important for industrial development of control systems. Here we approach the development of embedded software from a programming point of view, leaving the rest (like selection of computing and IO hardware, discretizing control algorithms, etc.) for other books. 40 2012-08-29 16:05
Chapter 3 Multi-Threaded Programming Goal: To know concurrent object-oriented programming using standard Java. With understanding of application demands and concepts presented in previous chapters, we will in this chapter look into the issue of handling concurrency within one program, utilizing the features of the Java-platform. Acquaintance with both (sequential programming in) Java and object oriented programming (OOP) is assumed. The following properties and restrictions should be clear to the reader: • One program means one executable unit in which different objects (possibly concurrently) can address data in a common memory space. The program is run either as one process using an Operating System (OS) or as an embedded application linked together with a so called real-time kernel (or RTOS). • As should be clear from the application examples, the software needs to respond to concurrently occurring external events. Sequential computing and handling of sequences of such events, expressed as ordinary sequential programs, then has to be executed concurrently. • By simply using the concept of thread objects, we assume that the underlying OS/kernel (which includes a scheduler) schedules the concurrent threads (normally many) for execution on the available CPUs (normally one). Hence, the system interleaves the code at run-time based on system calls which have been programmed according to this chapter. • For the software to be correct, it should produce the correct result regardless of the actual interleaving. That is, the correct result should be obtained for any interleaving (for given input sequences) that comply 41
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Page 4 and 5: • Each piece of software must be
Page 7 and 8: Contents I Concurrent programming i
Page 9: Part I Concurrent programming in Ja
Page 12 and 13: 1. Introduction pany depends on the
Page 14 and 15: 1. Introduction control may be dela
Page 17 and 18: Chapter 2 Fundamentals Goal: Review
Page 19 and 20: 2.2. Our physical world is parallel
Page 21 and 22: 2.4. Concurrency a trend that the p
Page 23 and 24: 2.4. Concurrency Behind the term co
Page 25 and 26: 2.4. Concurrency in functions like
Page 27 and 28: 2.5. Interrupts, pre-emption, and r
Page 29 and 30: 2.5. Interrupts, pre-emption, and r
Page 31 and 32: 2.6. Models of concurrent execution
Page 33 and 34: Object properties Implicit mutual e
Page 35 and 36: 2.6. Models of concurrent execution
Page 37 and 38: 2.7 Multi-process programming 2.7.
Page 39: 2.9. Software issues In this chapte
Page 43 and 44: 3.1.1 Thread creation At start of a
Page 45 and 46: to foresee the value actually retur
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Page 49 and 50: the run-time system (that is, the s
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3.4. Message-based communication -
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RTEvent post(RTEvent e) final void
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4. Exercises and Labs 4. In the pro
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4. Exercises and Labs /** * The buf
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4. Exercises and Labs object and gi
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4. Exercises and Labs Excerpt from
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4. Exercises and Labs 4.3 Lab 1 - A
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4. Exercises and Labs Some advice o
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4. Exercises and Labs 4.4 Exercise
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4. Exercises and Labs • CustomerH
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4. Exercises and Labs 4.5 Exercise
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4. Exercises and Labs Lab 2 prepara
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4. Exercises and Labs } /** Draws a
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4. Exercises and Labs public static
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4. Exercises and Labs Specification
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4. Exercises and Labs /** * Turns t
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4. Exercises and Labs your washing
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4. Exercises and Labs } } super(mac
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4. Exercises and Labs } /** * @retu
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4. Exercises and Labs PeriodicThrea
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4. Exercises and Labs Miscellaneous
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4. Exercises and Labs Scheduling wi
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4. Exercises and Labs Getting appro
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5. Solutions 2. With some additiona
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5. Solutions 5.2 Solution to exerci
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5. Solutions class YourMonitor { pr
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5. Solutions 5.4 Solution to exerci
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5. Solutions b) After the rewriting
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