Pattern-Oriented Software Architecture, a System of Patterns by Frank Buschmann & Regine Meunier & Hans Rohnert & Peter Sommerlad & Michael Stal

Author:Frank Buschmann & Regine Meunier & Hans Rohnert & Peter Sommerlad & Michael Stal
Language: eng
Format: epub
ISBN: 9781118725269
Publisher: Wiley
Published: 2013-04-03T16:00:00+00:00

See Also

The Microkernel architectural pattern (171) supports adaptation and change by providing a mechanism for extending the software with additional or customer-specific functionality. The central component of this architecture—the microkernel—serves as a socket for plugging in such extensions and for coordinating their collaboration. Modifications can be made by exchanging these ‘pluggable’ parts.

An earlier version of this pattern appeared in [PLoP95].

Credits

One of the first works on reflection is the Ph.D. thesis by Brian Cantwell Smith [Smi82]. This describes reflection in the context of procedural languages. An overview of reflective concepts can be found in [Mae87].

We thank the members of PLoP’95 Working Group 1 for their valuable criticism and suggestions for improvement of an earlier version of this pattern, especially Douglas C. Schmidt and Aamod Sane. Special thanks also go to Linda Rising and David E. DeLano from AG Communication Systems, and Brian Foote and Ralph Johnson from the University of Illinois at Urbana Champaign. Their detailed review of an earlier version of this pattern helped to shape this description.

1. The Java bytecodes can be transformed into an ASCII representation that is a kind of object-oriented assembler code. This code can be read, but only with some pain!

2. Input/output buffering in higher layers is often intended to have the inverse effect—better performance than undisciplined direct use of lower-level system calls.

3. ATM (Asynchronous Transfer Mode) provides much higher data rates (ranging from 155Mbps to 2.4Gbps) and functionality (such as quality of service guarantees) than conventional low-speed networks such as Ethernet and Token Ring. In addition, ATM can emulate the behavior of Ethernet in a LAN, which allows it to be integrated seamlessly into existing networks. See [HHS94] for more information on ATM.

4. Any similarities in names, persons, or events are coincidental and unintended.

5. Note that all UNIX filters are active by this definition. Passive filters may be an unfamiliar concept. We introduce it to show that the Pipes and Filters pattern can be implemented without the overhead of context switches and data transfers and still remain a viable concept.

6. A ‘phone’ is the smallest unit of sound within a spoken language. This is distinct from ‘phoneme’, which is the smallest subdivision of a spoken language that conveys a distinct meaning. A phoneme can be represented by different phones. For example, the German hard ‘r’ sound and the English rolled ‘r’ sound are different phones, but belong to the same phoneme [Fel84].

7. We consider the problem of when to accept or reject top-level solutions in the Implementation section.

8. For more information on pipeline architectures, refer to the Pipes and Filters pattern (53) where we explain in more detail why building compilers according to Pipes and Filters is usually not a good idea.

9. The scheduling queue does not implicitly determine the sequence of elements to be removed, as a LIFO- or FIFO-queue does. Instead the Scheduler determines the sequence by repeatedly calculating priorities. Therefore, according to our terminology, the HEARSAY-II ‘scheduling queue’ is a container and not a queue.

10. In this pattern description servers are responsible for implementing services.

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