Episode 240

Jimmy Bogard on Composite UIs

Episode 215

Craig Berntson on Software Gardening

Here is Steve Smith’s presentation on Common Design Patterns at the May 2012 Great Lakes Area .NET User Group (GANG).

It’s no secret that software developers, managers and analysts do a poor job estimating projects. Few IT projects complete within the time they are estimated and far more go over the original estimate than under it.

Steve McConnell knows how difficult estimation can be His 2006 book Software Estimation is subtitled Demystifying the Black Art.

Developing reasonable estimates of software projects may not be a black art, but it does cause problems and most people fail at it for a variety of reasons.

McConnell refers to estimation as an art, not because it has no basis in science, but because formulas don't tell the whole story. Experience and difficult-to-measure inputs are required to generate a complete estimate. And even then, you may still get it wrong.

When McConell lists sources of estimation error (subjectivity, missing tasks, unwarranted optimism, excess precision), it's startling how many of those factors I have experienced or contributed in my own career.

The author provides various methods for creating an estimate and guidance on improving the accuracy of your estimates. Among his advice is:

• Base your estimates on something you can measure - preferably historical data on similar projects in your own organization. Estimates based on measurable data are far superior to those based on subjective criteria.
• Estimates are never precise (they're not called "exactimates"). Present estimates as ranges and don't include more significant digits than your inputs can justify.
• If possible, get effort estimates from those who will actually perform the work. Developers vary in how quickly they can accomplish a given task - sometimes that variance is in orders of magnitude.

If part of your job includes estimating software projects, this is an essential book to guide you. Like most of McConnell’s books, I recommend it.

Episode 88

In this interview, Microsoft Product Unit Manager Cameron Skinner describes the architecture tools that his team built into Visual Studio 2010

Microsoft Product Unit Manager Cameron Skinner came to the midwest to show off the Architecture features of Visual Studio 2010. He began his tour in the Detroit area, speaking at local companies in the afternoon and at the Great Lakes Area .Net User Group (GANG) in the evening. I recorded two of his presentations, which are available here.

Here is the presentation at GANG

Part 1:

Part 2:

Part 3:

Part 4:

Part 5:

Here is the presentation at a Detroit-area company.

Part 1:

Part 2:

Part 3:

Part 4:

I began reading Agile Principles, Patterns and Practices in C# by Robert C Martin and Micah Martin after a friend recommended the chapters on pair programming.  My friend was right, of course. The Martins not only decribed pair programming but included an entertaining script of two developers pairing on a programming problem.

But, as I dove deeper into this book, I found a wealth of other information.

The book begins with a section on agile development, defining some basic terms and concepts recommended practices. It follows with a detailed section on good design practice. This second section is the most interesting, as it describes the famous SOLID principles. SOLID is an acronym for a set of good design practices:

S=Single Responsibility Principle: Each class should serve only one purpose and have only one reason to change.
O=Open-Close Principle: Classes should be open for extension but closed for modification
L=Liskov Substitution Principle: It should always be possible to substitute a derived class with its base class
I=Interface Segregation Principle: Interfaces implemented by a class are defined by the client objects that use that class; a class should implement a separate interface for each client that calls it.
D=Dependency Inversion Principle: To maintain flexibility, you should write code that depends on abstractions, such as interfaces.

Next, the authors present an overview of Unified Markup Language (UML), a graphical language used to describe software designs and requirements. Common UML diagrams and shapes are described and the author offers opinions of which ones are most useful and when to best use them.

The last half of the book is a case study of a Payroll System in which the authors use examples to illustrate the concepts introduced in the first half of the book.

Although C# is included in the title, the book does not focus on C# and almost none of the concepts are specific to any particular language. All the code examples are in C#, which makes it a bit more accessible if that is your strongest language.

The book is filled with lots of information and good advice. For example, the authors recommend an iterative approach to writing software, a test-first approach to development and encourage developers to refactoring their code frequently.

Whether you read all of Agile Principles, Patterns and Practices in C# or pick through the sections of interest, you will benefit from this book.

Episode 68

James Bender, Mike Wood and Chris Woodruff created NPlus1.org to assist software architects, lead developers and those aspiring to these roles. In this interview, James and Mike discuss the goals and accomplishments of NPlus1.

Complexity is the Enemy! 

This is the message driven home repeatedly by Roger Sessions in his book Simple Architectures for Complex Enterprises. 

Sessions recommends tackling a complex enterprise architecture by identifying the subcomponents of a complex system and dividing that system into autonomous subsystems. He refers to these subsystems as Autonomous Business Capabilities (ABCs) and the process of dividing them as a Simple Iterative Process (SIP).  

Before describing how to approach this process, Sessions presents a mathematical proof that subdividing a complex system into a set of subsystems reduces the complexity of the system as a whole. This seems intuitive to many of us, but the mathematics allow us to be more forceful in our commitment to this process. The mathematics is relatively simple (nothing beyond high school math) and he even recommends training team members in this mathematics before beginning any SIP.

A large part of an Enterprise Architect's job is to define the optimal way to partition the complex system. By applying mathematics to his model, he removes the emotions that so often dictate how a project is broken up.

The process of splitting a complex system into appropriate subsystem isn't overwhelming, but it is critical to managing complexity. According to Sessions, Each ABC should contain only elements that relate to one another; and the elements of one ABC should not relate directly to or communicate directly with any element in another ABC. Once partitioned, each ABC should be roughly the same size, although it is possible to split a subsystem further into sub-subsystems. It is also critical that communication between each subsystem take place only at a few clearly-defined points.

If this sounds like a recipe for Service Oriented Architecture, this is no coincidence. Sessions concludes his book with recommendations on moving from business partitions (ABCs) to software partitions, which he describes as "fortresses". These software partitions follow many of the same rules as ABCs created with the SIP, so making this transition is straightforward.

This is a good book for anyone who aspires to be an Architect (Enterprise or otherwise) and wants to apply a systematic approach to managing complexity.

NPlus1 is an organization designed to assist architects and lead developers and those aspiring to these roles.

The organization began last year with the launch of the NPlus1.org web site. This site features articles written by and for architects; links to screencasts and other resources; and announcements of upcoming events.

Recently, NPlus1 decided to expand its reach by organizing events of its own.  One of these events - the Architecture Summit - takes place Friday July 31 at the Microsoft office in Southfield, MI.  This event will feature three topics: "Introduction to Object Oriented Programming"; "Software Patterns"; and "How I Learned to Love Dependency Injection". The first topic is optional, as it is aimed at those who are new to Object Oriented Programming and, therefore might struggle with the concepts presented in the other two presentations.

I will be delivering the first two presentations (Intro to OOP and Software Patterns) while James Bender will deliver the Dependency Injection presentation.

It is not too late to register for this event and you can do so at https://www.clicktoattend.com/invitation.aspx?code=139245