Dr. Ivar Jacobson,Vice President of Business Engineering, is the inventor of the OOSE method, and he is also the founder of Objectory AB in Sweden, which recently merged with
A short history and acknowledgments
The work presented in this book was initiated in 1967 when I proposed a set of new modeling concepts (notation with associated semantics) for the development of large telecommunication switching systems. The main concepts were signals and blocks. A real-time system is an open system communicating with its environment by signals alone. A signal models the physical stimulus/response communication which a concrete system has when interacting with the outside world. Given a signal as input, a system performs internal actions such as executing algorithms, accessing internal information, storing results and sending output signals to the environment. This view presents the system in a very abstract way - as a black box. A less abstract view on a lower level models the system as a set of interconnected blocks. Blocks are modules which can be implemented in hardware or software or any combination of both. A block communicates with its environment only through signals. Signals between two blocks are internal, whereas signals modeling physical communication, that is, signals between a block and the environment of the system, are external. Internal signals are messengers conveying data from one block to another within the same system. All entries of a block were labelled and constituted the signal interface of that block, to be specified in a separate interface document. Hence the system can now be viewed as a set of interconnected blocks jointly offeringthe functions of the system. Each block has a program which it obeys on a receipt of an input signal, performing internal actions, that is, executing algorithms, storing and accessing block internal information, and sending internal and external signals to the environment.
The proposal can be summarized as an attempt to unify long experience of systems design with the possibilities offered by dramatically new computer technology. Since the two technologies were so different, this was not a self-evident method, neither within Ericsson nor within computer science. There was a rather strong belief that the two represented unrelated technological universes: the new one was so different that it would be meaningless and only a burden to make any attempt to learn from the old one. However, the two techniques were joined and a set of modeling concepts evolved.
The modeling constructs were soon followed by the skeleton of a new design method, the use of which was first demonstrated in the development of the AKE system put into service in Rotterdam in 1971, and more completely demonstrated in the AKE system put into service in Fredhall, Sweden, in 1974. Naturally this experience has guided subsequent work on the development of the successor to AKE, the AXE system, which is now in use in more than 80 countries worldwide. The modeling constructs were very important and, for the AXE system, a new programming language and a new computer system were developed in accordance to these early ideas.
Although it is a neighbouring country, the early development of object-oriented programming and Simula in the 1960s in Norway was done independently and in parallel with our work. It was not until 1979 that we "discovered" object-oriented programming and then it was in terms of Smalltalk. Although object-oriented ideas have influenced our recent work, basically two separate problems are being solved: "large-scale" and "small-scale".
The modeling constructs introduced during the 1960s were further formalized in research taking place between 1978 and 1985. The research resulted in a formally described language which offered support for object-orientation with two types of object and two types of communication mechanism, send/wait and send/no-wait semantics. The language supported concurrency with atomic transactions and a special semantic construction for the handling of events similar to the use case construct presented later. This work, reported in a PhD thesis in 1985, resulted in a number of new language constructs, initially developed from experience, being refined and formalized. This was a sound basis from which to continue and, taking a new approach, develop the method. The principles of Objectory were developed in 1985-7. I then further refined and simplified the ideas, generalized the technique used in the telecom applications, extended it with the inheritance concept and other important constructs like extensions, and coupled to it an analysis technique and object-oriented programming.
Today these concepts have been further redefined. The Objectory process, of which this book describes some fundamental ideas, is the result of work by many individuals, most of whom today work at Objective Systems SF AB, Sweden. Gunnar Overgaard and Patrik Jonsson did much of the writing of the first process description of Objectory analysis and design, respectively. Magnus Christerson did much to condense and rewrite the material into the form of this book. They have all contributed to Objectory; especially the formalization of the concepts. Magnus has also related the ideas of Objectory to other areas as presented in this book. Fredrik Lindstrom has also been involved in the condensation of the material of this book. Agneta Jacobson, Bud Lawson amd Lars Wiktorin have prepared material for some of the chapters.
Marten Gustafsson has substantially contributed to the analysis part of Objectory. Valuable contributions to Objectory have also been made by the following people: Sten-Erik Bergner, Per Bjork, Ann Carlbrand, Hakan Dyrhage, Christian Ehrenborg, Agneta Jacobson, Sten Jacobson, Mikael Larsson, Fredrik Lindstrom, Lars Lindroos, Benny Odenteg, Karin Palmkvist, Janne Pettersson, Birgitta Spiridon, Per Sundquist, Lars Wetterborg and Lars Wiktorin. The following users of Objectory have also contributed by feeding back experiences and ideas to enable improvements: Staffan Ehnebom, Per Hedfors, Jorgen Hellberg, Per Kilgren, Haken Lidstrom, Christian Meck, Christer Nilsson, Rune Nilsson, Goran Schefte, Fredrik Stromberg, Karin Villers, Stefan Wallin and Charoltte Wranne. The following persons have done a lot to support the tehnology described in this book: Kjell S. Andersson, Hans Brandtberg, Ingemar Carlsson, Hakan Dahl, Gunnar M. Eriksson, Bjorn Gullbrand, Lars Hallmarken, Bo Hedfors, Barbara Hedlund, Hakan Jansson, Christer Johansson, Ingemar Johnsson, Kurt Katzeff, Rolf Leidhammar, Jorma Mobrin, Jan-Erik Nordin, Anders Rockstrom, Kjell Sorme, Goran Sundelof, Per-Olof Thysselius, Ctirad Vrana and Erik Ornulf. The following people have given me strong personal inspiration and support: Dines Bjorner, Tore Bingefors, Dave Bulman, Larry Constantine, Goran Hemdal, Tom Love, Nils Lennmarker, Lars-Olof Noren, Dave Thomas and Lars-Erik Thorelli. In Sweden we do not normally thank family and friends in these circumstances, but no one beleives that results like these can be achieved without exceptional support from them. We are also grateful to the support we have been given from STU (Swedish National Board iof Industrial Development, now recognized to NUTEK) through the IT-4 program which has been part of the financial support and sponsorship for the writing of this book.
Changes to this revised printing, apart from minor general corrections and improvements, are:
- The testing chapter has been restructured and in parts rewritten, also an emphasis on early testing has been added.
- The discussion of robust object structures have been increased and also an example has been added. We hope this will better clarify why such an object structure gives more robust systems.
- The notion of a development case have been introduced as a way to adapt a general process to the specific needs of an organization or a project.
- Some people we would like to thank were unfortunately left out in the first printing and have now been added to the acknowledgment section, particularly Dave Bulman and Nils Lennmarker who have inspired the technology presented in this book.
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