Saturday, March 22, 2014

Estimation as a requirements Exercise

I explored the role of estimation in a couple of articles on Techwell recently.

In the first article I discussed how teams balance the cost of estimation (in terms of time it takes) with the value it brings to the project. Some argue that estimation isn't very useful at all, where other's say that it can be useful, but that all stakeholders may not have the same vision of the value estimation brings.

In a follow up article I explore the debate about whether to estimate in hours, which reflects effort, and time, or  points, which reflect complexity. This is a common debate, since many articles on agile advocate points, to step away from the concepts of estimate, and focus on the complexity of a feature, and also to help teams move towards the model of the estimate being valid for the team and not just a particular person. And stakeholders are often concerned about schedule and deadlines, so tend to prefer hours initially.

Different teams will come to different decisions about what works best for them. To me the most important part of the estimation discussion is the part many teams don't have, namely asking (and answering) the question of why they are estimating, and what value the estimates bring to the project given that they are now working with an agile process.

As I think more about what value estimation has brought to teams that I have worked on, I realize that the biggest value is that of having a a discussion of scope. When you have an planning meeting, a few questions come up:


  • Why people have different estimates
  • Why the estimate is larger, or smaller, than the product owner expected
  • Whether the team really understands what the story means.
Give this I'm leaning towards thinking of estimation as being more about requirements definition rather velocity, effort, or even complexity.  To that end, maybe the approach to use is one where you spend all of your planning effort defining stories in terms of small, fixed size units, and your velocity is about how many stories you finish off of a prioritized backlog. I link to a description of what this means in the points and hours article.

I'm  interested in hearing about creative approaches your teams have used for estimation. Please comment on  the Techwell articles, or here if you want to share lessons you have learned.


Monday, February 17, 2014

Pattern-Oriented Software Architecture For Dummies (Book Review)

When I received a review copy of Pattern-Oriented Software Architecture For Dummies, by Bob Hanmer, one of the leaders in the Patterns community, I was intrigued. Patterns are more complicated to understand than they appear, and I wondered how a book like this could do justice to the topic. I was not disappointed.

This book is one of the few books that is a good tour through the fullness of the patterns universe. It's an easier read than many other books on Patterns, and it covers the basic concepts of what a pattern is, and gives examples of how to use patterns correctly.
The book focuses on the Patterns from the Pattern Oriented Software Architecture series and the classic Design Patterns: Elements of Reusable Object-Oriented Software book. The book wraps up with a tour through the larger pattern world, with examples from patterns in areas such as configuration management, software process, and user interaction.

Patterns are one of the most misunderstood concepts in software. Patterns are more than just what the English language definition of the word implies, and by their nature, Patterns are not novel ideas; you’ve seen them before because they work. Because of the superficial simplicity of Patterns, using software patterns effectively can be tricky. Patterns are more than just the structure of the software. Patterns also involve the context in you apply them, and the problem that you are trying to solve. Newcomers to the concept of patterns also sometimes mistake the number of patterns in a solution with a good solution. This book does a good job of addressing these essential aspect of working with and understanding patterns.

A better title of the book might have been “Using and Understanding Patterns (for Dummies)” since I feel that most readers will walk away from the book with a better understudying of what patterns are, than about how to build architectures, but it’s a good starting point never the less. The first section of the book spends a bit more time than needed on tools and approaches for describing architecture, but the rest of the book is worth a read if you feel that you don’t understand what patterns are.

There are few books that cover that such a broad sweep of the patterns landscape so concisely. When you’re done you’ll want to read more, guided by the resource section at the end of the book. This is a good resource for a software developer who wants to learn more about patterns. Those familiar with patterns, but not patterns beyond the building block Design Patterns will find this book a good reminder that there is more to the patterns universe. This is not as thorough as a guide to architecture patterns as books like Pattern-Oriented Software Architecture Volume 1: A System of Patterns are. And it's not meant to be. But if you are looking to understand why you might care about patterns that describe working at a system level, and have not found a good resource to do this yet, this book is worth a read.