The Object Constraint Language: Precise Modeling with UML (Addison-Wesley Object Technology Series) [Paperback]

Jos Warmer (Author), Anneke G. Kleppe (Author)

Book Description

ISBN-10: 0201379406 | ISBN-13: 978-0201379402 | Publication Date: October 13, 1998 | Edition: 1st

OCL complements the UML by providing a language for formally expressing the constraints of a model, a facility useful in user models as well as in the definition of the UML itself. Jos and Anneke provide a comprehensive and much-needed reference to this formalism.--Grady Booch, Ivar Jacobson, James Rumbaugh The Object Constraint Language (OCL) is a new notational language, a subset of the industry standard Unified Modeling Language, that allows software developers to write constraints over object models. These constraints are particularly useful, as they allow a developer to create a highly specific set of rules that governs the aspect of an individual object. As many software projects today require unique and complex rules that are written specifically for business models, OCL is fast becoming an integral facet of object development. This book is a practical guide to OCL for software architects, designers, and developers. Because it is designed for ease and usability, OCL is likely to gain broad acceptance. Much care has been taken during the design of OCL to ensure that the syntax is readable and writable by the average software modeler. The straightforward nature of OCL makes it a natural candidate to supersede current constraint languages. The authors' pragmatic approach and illustrative use of examples will help application developers to get up to speed quickly with this important object modeling method. Other highlights: *Detailed instruction explains how and why to use OCL, showing its relation to UML *Illuminating case study demonstrates several UML diagrams and corresponding constraints *Provides keen insight from the primary author of the OCL standard portion of the UML 1.1 standard of the OMG 0201379406B04062001

Editorial Reviews

Amazon.com Review

C/C++ programmers commonly use assert statements to ensure program values are within range. You may be surprised to learn that the ability to model such constraints is now built into the Unified Modeling Language (UML) v. 1.1 in the form of the Object Constraint Language (OCL). The Object Constraint Language shows that with simple, elegant OCL statements, a UML design can be made more logically robust and easy to understand.

The book begins with the ideas behind OCL, that it must model constraints as simply as possible. (Early formal languages such as Z and Larch often relied on mathematical symbols; not so with OCL.) The authors show that OCL can be used to model invariants (which apply conditions to classes) and in pre- and postconditions, which can be used to constrain operations of a class.

The second chapter models a simple credit card bonus program (where credit card users can earn bonus points for using their cards according to known rules). This example is good because it lets the authors show how limiting conditions can enhance a UML design. They introduce the basic data types available in OCL, as well as collections of objects such as sets, bags, and sequences.

Further sections cover advanced features, including working with collections and resolving ambiguous conditions. The authors provide hints for using OCL effectively, as well as extending OCL in new ways. (The motto here is simplicity first.) A handy appendix on OCL ensures that this very concise--yet useful--guide will bring the reader up to date on an important capability available in today's UML standard. --Richard Dragan

Review

OCL complements the UML by providing a language for formally
expressing the constraints of a model, a facility useful in user
models as well as in the definition of the UML itself. Jos and Anneke
provide a comprehensive and much-needed reference to this formalism.
-- Grady Booch, Ivar Jacobson, & James Rumbaugh

See all Editorial Reviews

Product Details

• Paperback: 144 pages
• Publisher: Addison-Wesley Professional; 1st edition (October 13, 1998)
• Language: English
• ISBN-10: 0201379406
• ISBN-13: 978-0201379402
• Product Dimensions: 9 x 7.3 x 0.4 inches
• Shipping Weight: 9.6 ounces
• Average Customer Review: 4.4 out of 5 stars  See all reviews (7 customer reviews)
• Amazon Best Sellers Rank: #961,604 in Books (See Top 100 in Books)

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8 of 8 people found the following review helpful:

4.0 out of 5 stars Solid Trustworthy Consise Desk Top Reference, September 15, 1999

By A Customer

This review is from: The Object Constraint Language: Precise Modeling with UML (Addison-Wesley Object Technology Series) (Paperback)

First, I like this book. I trust about every line of it. It is itself precise or at least as precise as possible. It summarizes things in a concise and complete way. Required prior knowledge is UML (of course). I'd recommend Fowler's beautiful UML distilled and also even more important a solid understanding of design by contract. I recommend the complete book of Bertrand Meyer "Object Oriented Software Construction". Yes I know its many month of reading.

The problem with this OCL book is the following: It is difficult to understand anything not prior understood. However once one has a grasp of understanding this book is really clarifying. So, it requires in many areas more maturity in the field than most of us including me have. So, I would wish a book, which starts of at a somewhat lower level, in a less dry diction.

6 of 6 people found the following review helpful:

5.0 out of 5 stars Excellent explanation of a language that simplifies things, March 16, 2001

By 

Charles Ashbacher (Marion, Iowa United States) - See all my reviews
(TOP 500 REVIEWER)    (VINE VOICE)    (HALL OF FAME REVIEWER)   

This review is from: The Object Constraint Language: Precise Modeling with UML (Addison-Wesley Object Technology Series) (Paperback)

To manage large computing projects, we need two things. Precise languages and the will to use them. While the Unified Modeling Language (UML) is a valuable addition to our tool set, it is limited when used to describe and restrict the behavior of our objects. The Object Constraint Language (OCL) allows for the formal description of constraints on the data to be used. Given the ability to write specific constraints on information, it is then possible to use a design by contract model in the creation of software. The advantages of such a model are obvious, in that so much of our personal and professional lives are based on contracts, albeit most are informal. Professional interactions that take place in the creation of complex software are also contracts. I have participated in many discussions of the form, "You construct this function so that it does this and I will use it to do the other thing." However, so much of this is informal, which leads to disagreements over interpretations. It is for this reason that I have long argued that the real increase in productivity from the use of formal languages will be a reduction in the amount of time needed to settle disputes over ambiguities.
While some exposure to the principles of formal logic will be helpful, it is not necessary to understand the material of the book. Knowledge of basic Boolean expressions will suffice. As the title suggests, the UML is used as the basis for the OCL. The use of the similar notation and terminology really simplifies the approach, making it very easy to pick up.
I was most impressed with the OCL as well as the explanatory style used in the book, although I must confess to having a bias towards formal languages in computing. After reading the book, I came away with an even greater appreciation for the power of formal languages, which given my nearly two decades of exposure to them, is not an easy task.
The design by contract model of computing is a very powerful mechanism whereby ambiguity can be removed from the design and implementation process. To do it properly, a formal language such as OCL is needed and this book will teach it to you in the minimal amount of time.

5 of 5 people found the following review helpful:

4.0 out of 5 stars Another good tool for your UML and RUP arsenal, August 24, 2000

By 

Linus W Freeman - See all my reviews

This review is from: The Object Constraint Language: Precise Modeling with UML (Addison-Wesley Object Technology Series) (Paperback)

The Object Constraint Language is an extension to the latest version of the Unified Modeling Language (UML). It is a formal specifications language that has an easy understandable syntax and semantics.

The sample class diagram model that is used through most of the book is semi-complex but understandable if first you have read the Unified Modeling Language Users Guide written by the three amigos: Ivar Jacobson, Brady Booch and James Rumbaugh. You may not completely grasp the sample class diagram from a conceptual or practical point of view but can understand it enough to verify how the stated constraints are valid and well formed. That is you can read the example constraints and verify their correctness by navigating the sample class diagram.

Overall I would say that the OCL removes ambiguity from UML models and better states constraints and business rules than visual notations used in UML. I recommend this book and think it can be another notch in an Object-Oriented developers arsenal to offer something more to their software projects and employers.