Course Programme

Why HotDraw?

HotDraw is two-dimensional graphics framework for structured drawing editors.

The HotDraw framework was developed in the late 1980s by Kent Beck and Ward Cunningham in Smalltalk.

HotDraw has several incarnations. Most of these implementations were proprietary.

• A VisualWorks (Cincom Smalltalk) version was developed by John Brant (the author of the first Refactory Browser).
• JHotDraw is a Java version of the original Smalltalk HotDraw framework. The rewrite in Java was done as an exercise in applying design patterns by Thomas Eggenschwiler and Erich Gamma (the latter co-author of the influential book "Design Patterns: Elements of Reusable Object-Oriented Software").

HotDraw is the first application of CRC cards, a well-known technique invented by Ward Cunningham and developed with Kent Beck in the late 1980s as a way of exploring and designing object-oriented software.

HotDraw has also inspired the work of Ralph Johnson (another member of the Gang of Four) on documenting frameworks using patterns and along with Kent Beck on how patterns generate architectures.

Check out the Annotated References section below for a rich annotated presentation of articles and other resources.

Your learning goals

Studying HotDraw can offer a number of benefits for individuals interested in software design, including:

• Developing design skills: Studying HotDraw can help software designer develop their design skills by providing a concrete example of how to apply design principles and patterns in practice. This can help designers learn to think more critically about their designs and make more informed design decisions.
• Understanding user interface design: HotDraw is primarily used in user interface design, so studying it can provide valuable insights into the design of user interfaces. It can help designers understand the fundamental concepts of user interface design, such as interaction design, visual design, and usability.
• Familiarizing with the Model-View-Controller (MVC) pattern: HotDraw is implemented using the Model-View-Controller (MVC) pattern, which is a widely used architectural pattern in software design. Studying HotDraw can help software designers understand the principles behind the MVC pattern and how to apply it in their own designs.
• Gaining exposure to Object-Oriented Programming: HotDraw is implemented using object-oriented programming and design. Studying HotDraw can help individuals gain exposure to object-oriented programming concepts, such as inheritance, polymorphism, and encapsulation.
• Better understanding of Design Patterns: HotDraw makes extensive use of design patterns: more than 20 patterns were applied in JHotDraw. HotDraw's use of design patterns can deepen one's understanding of how patterns can be applied in other software design projects, helping to create more flexible and robust systems, and can also demonstrate how design patterns can be combined for complex software development.

Overall, studying HotDraw can help software designers develop their skills and make more informed design decisions.

Programme

HotDraw design review is structured in a series of sessions.

HotDraw: CRC card review

JHotDraw: Code and Design Review

The Story Behind this Course

Francesco Cirillo tells the story behind the HotDraw Review

Annotated References

Here you can find the references used in the session commented by Francesco Cirillo:

CRC Cards

• A Laboratory for Teaching Object-Oriented Thinking - The paper in which Ward and Kent present CRC Cards.

HotDraw

• A CRC Description of HotDraw - The original set of cards written at 4am by Ward Cunningham!
• Documenting Frameworks using Patterns, Ralph Johnson, 1992 - I realise today that when I first read this article, I had absorbed 20 per cent of its informative content. Rereading it today, I have great use for those criteria it presents on how to present various patterns. (Thirty years ago - sigh! - I was more interested in the appendix describing the framework).
• Creating Tools in HotDraw by Composition, John Brant and Ralph Johnson - The part I am very interested in is what we call evolutionary refactoring today. Do you want more Vlissides solutions? See below.

JHotDraw

• JHotDraw - Patterns Applied, Kent Beck and Erich Gamma, OOPSLA, 1997 - Description of the various design challenges and how they overcame them. It is a must-read, not only for what it explains but for the simplicity with which the authors explain their solutions.
• Advanced Design with Patterns and Java, Erich Gamma, JAOO, 1998 - A more concise tutorial than the previous one on JHotDraw
• Review of the JHotDraw framework, Jolita Savolskyte - Jolita has succeeded effectively in explaining the use of different design patterns in JHotDraw.
• JHotDraw Pattern Language - Introduction to JHotDraw as a pattern language with hypercards.
• Chapter 8: Case Study: The JHotDraw Framework, Dirk Riehle - An interesting role modelling interpretation of JHotDraw design.
• Did JHotDraw Respect the Law of Good Style? Daniel Speicher, 2020 - "This study set out to explore the nature of bad smell false positives. We reviewed 1215 potential violations of the “Law of Demeter” in JHotDraw 5.1." Nice work on the nature of bad smells and programmer decisions. I like the idea that there can be "false positives."

UNIDRAW

Unidraw is a software framework for developing interactive graphical editors, designed before JHotDraw by John Vlissides (another member of the Gang of Four).

• Generalized Graphical Object Editing, John Vlissides, 1990 - "Unidraw is first and foremost an architecture for graphical object editing. We designed the architecture to fulfill the needs—unforeseen and anticipated—of graphical object editors. Our design distills the common aspects of these applications into a set of abstractions that give us leverage on the problem." Must-read. Many beautiful solutions.
• Unidraw: A Framework for Building Domain-Specific Graphical Editors, John Vlissides and Mark Linton - If you do not have time to read John Vlissides' thesis, read this paper.
• A Unidraw-Based User Interface Builder, John Vlissides and Steven Tang, 1991 - The article tells about IBuild, a user interface builder built with Unidraw.

Documenting Frameworks Using Pattern Languages

• Using Pattern Languages for Object-Oriented Programs - The first time I read about Christopher Alexander. A must-read!
• Patterns Generate Architectures, Kent Beck and Ralph Johnson 1994 - Absolutely a must-read. I like the concept of "Deriving Hot Draw". When I read these articles, I think about how teams develop software today, and I get sad.
• Documenting Frameworks Using Pattern Languages, Diana Tanase, 2003 - Useful for reviewing concepts expressed in previous papers.

Don't miss these gems!

• A Diagram for Object-Oriented Programs, Ward Cunningham and Kent Beck, 1986 - I don't have any proof. But I always thought that HotDraw's work was born with this purpose :)
• A Refactoring Tool for Smalltalk, Don Roberts, John Brant, and Ralph Johnson - Before this paper, there was no Rename Variable and Extract Method :)

About the Course

About the Trainer

Francesco Cirillo

Francesco Cirillo has worked at the forefront of the software industry for more than 30 years. In a career spanning startups, corporations and freelance consulting, he has mentored thousands of professionals, developers, managers and software teams.

In the 1990s he worked as a Senior Consultant and Mentor for Sun Microsystem, expert in Software Architectures and Software Development Processes and Java and Object-Oriented Evangelist.

Francesco is one of the pioneers of Agile Methods. He started working on XP and TDD in 1999. He was chosen by Kent Beck to develop the XP community in Europe and as reviewer of the second edition of the book Extreme Programming Explained. In 2000 he created XPLabs, the first company in Europe to offer comprehensive services on XP: software development, training and consulting.

In 2007 he created the Anti-IF Campaign to raise awareness in the international community of software developers to apply good design principles to grow software in a sustainable way.

Since 2008 Francesco stopped actively working on Agile Methods and started to develop RRP, a new method of software development. In 2013 he created Cirillo Consulting based in Berlin to offer professional training and consulting on productivity and software development.

Francesco invented the Pomodoro® Technique, a renowned time-management method used by millions of people all over the world, while being a university student looking for a way to get more done in less time.

Read the Francesco Cirillo's complete profile.

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