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Date: Tue, 14 Jan 1997 20:09:02 GMTServer: NCSA/1.5Content-type: text/htmlLast-modified: Wed, 05 Jun 1996 21:29:31 GMTContent-length: 14548<!-- $Date: 94/11/23 18:25:03 $ --><!-- $Revision: 1.15 $ --><!-- $Log: tutorial.html,v $Revision 1.15 94/11/23 18:25:03 18:25:03 barry (Barry Lee Roberts)Took out reference to bulletin board communication.Revision 1.14 94/11/23 16:00:13 16:00:13 goodman (Maland Brent Goodman)Put "Add or Create" back in the OIM outline.Revision 1.13 94/11/23 15:53:36 15:53:36 goodman (Maland Brent Goodman)Removed reference to Add and Create in the OIMoutline since a file add.html does not exist.I assumed it wasn't needed.Revision 1.12 94/11/23 15:29:37 15:29:37 goodman (Maland Brent Goodman)Deleted "Object Interactions" from the outline forOIM.Revision 1.11 94/11/04 17:04:29 17:04:29 goodman (Maland Brent Goodman)Hid comments from the Revision section.Revision 1.10 94/11/04 10:48:13 10:48:13 black (Paul E. Black)Add General Constraints for Behavior to OBM outline (it points tothe appropriate place in General Constraints). Change GeneralConstraints in Interactions in OIM to point to the appropriateplace in General Constraints, too. Fix comments to HTML 2.0standard, that is they end in --, optional spaces, and ><!-- Revision 1.9 94/11/04 09:49:34 09:49:34 black (Paul E. Black)Change Prior and Subsequent State Conjunctions to just Prior and SubsequentStates - conjunctions are just one type. Switch their order.Revision 1.8 94/11/02 13:36:41 13:36:41 nielson (Ben Nielson)Changed High Level Transactions to High Level TransitionsRevision 1.7 94/11/01 20:27:33 20:27:33 rohead (Sean R. Rohead)added 'interacting with multiple objects'.Revision 1.6 94/10/26 16:28:37 16:28:37 goodman (Maland Brent Goodman)A few minor changes to punctuation, etc.Revision 1.5 94/10/25 15:34:47 15:34:47 black (Paul E. Black)Add a line about getting more information by clicking on highlightedwords.Revision 1.4 94/10/24 17:57:50 17:57:50 goodman (Maland Brent Goodman)Made some spelling and grammar changes down to, but not including "Reality Representation."Revision 1.3 94/10/21 14:00:25 14:00:25 black (Paul E. Black)Finialize outline of OBM.Revision 1.2 94/10/18 14:41:04 14:41:04 goodman (Maland Brent Goodman)Added OBM outline needs file references added, also needs tweeking. --><HTML><HEAD><TITLE>OSA Tutorial</TITLE><!-- describe the document, avoid context sensative descriptions --><meta name="description" value="Tutorial for OSA (Object-oriented System Analysis)"><!-- keywords for the document --><meta name="keywords" value="tutorial, OSA, Object-Oriented, System Analysis"><!-- should be "document" unless providing a search, then "service" --><meta name="resource-type" value="document"><!-- use global for documents to be indexed outside BYU --><meta name="distribution" value="local"></HEAD><BODY><h1>An OSA Tutorial</h1>by <P><MENU><LI> <!WA0><A HREF="http://lal.cs.byu.edu/people/black.html">Paul Black</A> (p.black@ieee.org) <LI> Lei Cao (caol@bert.cs.byu.edu)<LI> <!WA1><A HREF="http://bert.cs.byu.edu/~goodman/goodman.html">Brent Goodman</A> (mbg@byu.edu)<LI> <!WA2><A HREF="http://genie.cs.byu.edu/~nielson/Ben.html">Ben Nielson</A> (nielson@cs.byu.edu)<LI> Lu Pan (pan@math.byu.edu)<LI> <!WA3><A HREF="http://bert.cs.byu.edu/~parra/amalia.html">Amalia Parra</A> (parra@bert.cs.byu.edu)<LI> Barry Roberts (barry@bert.cs.byu.edu)<LI> Sean Rohead (rohead@bert.cs.byu.edu)<LI> Roger Smith (rsmith@bert.cs.byu.edu)<LI> Mike Steed (mrs@bert.cs.byu.edu)<LI> Wei Wei (weiwei@bert.cs.byu.edu)<LI> <!WA4><A HREF="http://osm7.cs.byu.edu/people/xmk/xmk.html">Mingkang Xu</A> (xmk@osm7.cs.byu.edu)</MENU><HR><H1>How to use this hyper-document</H1>This is a hyper-text tutorial and reference manual for<strong>OSA</strong>, an Object-oriented Systems Analysis technique.<P>You can get details, further explanations, or related subjects by clickingon highlighted words.<P>The objective of this tutorial is for you to learn<OL><LI> what <strong>OSA</strong> is,<LI> how to use <strong>OSA</strong> to model the real world, and<LI> why using <strong>OSA</strong> can lead to better systems.</OL>The <!WA5><A HREF="#Philosophy">first part</A> of this page explains thegeneral ideas behind andapproaches of OSA: what does it do, when and how does one use it,what to expect (and not to expect), etc. <P>The <!WA6><A HREF="#Components">second part</A> explains the individualbuilding blocks from which models are constructed. <P>The <!WA7><A HREF="#References">last part</A> is reference material for OSA:a <!WA8><A HREF="http://osm7.cs.byu.edu/OSA/glossary.html">glossary</A>,a <!WA9><A HREF="http://osm7.cs.byu.edu/OSA/symbolary.html">symbolary</A>, anda <!WA10><A HREF="http://osm7.cs.byu.edu/OSA/bibliography.html">bibliography and URL's</A>.<P>We use markers in the text to indicate special parts of this tutorial.<MENU><LI> <!WA11><img src="http://osm7.cs.byu.edu/OSA/images/mark_formal.gif"> indicates the formal basis underlying the OSA model.<LI> <!WA12><img src="http://osm7.cs.byu.edu/OSA/images/mark_change.gif"> indicates changes from the book, <!WA13><A href="http://osm7.cs.byu.edu/OSA/bibliography.html#OOSA book"> Object-Oriented Systems Analysis</A>.<LI> <!WA14><img src="http://osm7.cs.byu.edu/OSA/images/mark_tentative.gif"> indicates that the concepts are somewhat tentative, that is, that the developers are not happy with it and it is likely to change.<LI> <!WA15><img src="http://osm7.cs.byu.edu/OSA/images/mark_compare.gif"> indicates comparisons with other systems analysis techniques and object-oriented languages.</MENU><HR><A NAME="Philosophy"><H1>The Philosophy of OSA</H1></A>OSA is an objected-oriented systemsanalysis technique, which we understand as the study of a specific domain of interactingobjects for the purpose of understanding and documenting their essential characteristics.It has the expressive power to represent reality. Its underlying concepts are based on formal definitions of system data and behavior modeling.<H2>Object-oriented vs. Process-oriented analysis</H2>Process-oriented analysis describes systems as a network of interacting processes. It includesdescriptions of data used by processes, which are recorded in a data dictionary. This approachoften steers the analyst away from studying system components and their interrelationshipstowards studying how the system might be designed and implemented. It is also difficult for process-oriented analysis to map concepts between a network of processes and objects existingin a real-world system.<p>As opposed to process-oriented analysis, object-oriented analysis modularizes an analysis documentalong the same object boundaries that exist in a real-world system. In addition, this approach alsoorganizes all knowledge about each system object in a single logical location in the analysis document.Thus, information about a system object is easier to locate in object-oriented analysis than inother analysis methods. The object-oriented approach also encourages analysts to concentrate on "what" rather than "how", which reduces the temptation to skip prematurely to design. To make it easier to understand information about objects, object-oriented techniques provide forms of abstraction including aggregation, generalization and classification. <p><H2>Model-driven (vs. Method-driven) analysis</H2>A method-driven approach consists of a fixed sequence of steps tofollow. That is, a system is developed by some method, such as thewaterfall method or the spiral model. In practice, these steps cannot be followed exactly. When development problems areencountered, the analyst must adjust the order of steps, adapt theprocedures, and make exceptions to rules. The analyst is left to rely on experience and underlying principles, which may be undocumented andare poorly understood.<P>A model-driven technique, on the other hand, provides a prespecified set of fundamental concepts with which to model the system under study. This aids analysts in building models as best suits their needs.The philosophy of the model-driven technique is that the most important thing to learn is not a ⌨️ 快捷键说明
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