Usability is a quality attribute of a system, which encompasses learnability, efficiency, memorability, error recovery, and end-user satisfaction.
June 30, 2006
URL:http://www.drdobbs.com/architecture-and-design/bridging-the-gap/189401954
Scott is the practice leader of the Agile Modeling and Agile Unified Process (AUP) methods. His latest book is Refactoring Databases: Evolutionary Database Design (Addison-Wesley, 2006). He can be contacted at www.ambysoft.com/scottAmbler.html.
Usability is a quality attribute of a system, which encompasses learnability, efficiency, memorability, error recovery, and end-user satisfaction. There are several common methods for addressing usability within software development: Alan Cooper's interaction design, user-centered design that was popularized in the late 1980s, and more recently Larry Constantine's usage-centered design (UCD). Although each method has its nuances, for simplicity I use the term "user experience design" (UED) to refer to them.
I believe that UED is critical to the success of agile software development techniques. UED helps to increase your chances of building the right software by placing emphasis on the usage necessary for roles to meet their goals and thereby identifying the behavior the software should have. Because UED practices can be applied with varying degrees of formality, they are compatible with the variety of agile methodologies available to us today.
There is a growing recognition within both the agile and UED communities that they can benefit by working closely with each other. There is even an active agile usability mailing list, [email protected], where agile and UED practitioners interact regularly. Unfortunately, there are several challenges that need to be overcome if we're to work together effectively, and just the fact that we talk about two different communities indicates that we have a problem. These challenges are embodied by the different philosophies (see Table 1) within each community.
So how can we overcome the differences between the two communities? The key is to make UED practices usable to agile software developers, and to do that they must reflect the realities of the agile lifecycle.
This can be accomplished by:
For the sake of this discussion, user testing encompasses both acceptance testing and usability testing. The agile community has embraced the importance of acceptance testing, having built tools such as Fit and Fitness to help automate this effort. The automated tests will be run often, at least daily if not several times a day. Manual user testing, on the other hand, is typically done an iteration behind. At the end of an iteration, many agile teams will deploy the working system into a QA/testing environment where user and system testing is performed. The team continues on, developing version N+1 of the system while obtaining defect reports pertaining to version N. These defect reports are treated just like any other requirement: They are estimated, prioritized, and put on the requirements stack to be addressed at some point in the future.
If you want usable software, then you're going to have to test for usability. With usability testing, you observe end users in a controlled setting to see how they actually use, or misuse, your system. True usability testing requires repeated testing with numbers of users under controlled settings, and on agile projects usability testing should occur during the user testing effort following each iteration.
It is very easy to suggest that agile practitioners take the time to learn UED skills, and to adopt appropriate guidelines. However, these skills are competing for attention along with other equally important skills such as database design and modeling. Similarly, although UED practitioners need to become generalizing specialists, the industry still rewards specializationUED specialists are paid very well, and most organizations expect them to focus on doing that specific sort of work. Agile practitioners also suffer from this challenge: Why take an introductory UI design course when you can take a Java programming course, which leads to certification and greater pay?
The agile and UED communities are still miles apart, but luckily there is a movement afoot to bring them together. Hopefully, this column has helped the situation.
A Call to Action
If the agile and UED communities are going to work together effectively, they need to find a middle ground. I believe that middle ground exists, but that both communities need to adopt several changes in order to succeed. Agilists must:
• Learn UED skills.
• Accept that usability is a critical quality factor.
• Adopt UI and usage style guidelines.
Similarly, UED professionals must:
• Become generalizing specialists.
• Become embedded in agile teams.
• Give agile approaches a chance.
• Recognize that there is more to agile than XP. |
Suggested Reading
• Agile Software Development and Usability, by Scott Ambler, (www.agilemodeling.com/essays/agileUsability.htm ) covers in greater detail how to address UED issues on agile projects.
• Process Agility and Software Usability: Toward Lightweight Usage-Centered Design, by Larry Constantine (www.foruse.com/articles/agiledesign.pdf).
• Are Agile and Usability Methodologies Compatible?, by Alain Desilets (www.carleton.ca/hotlab/hottopics/Articles/June2005-AreAgileandUxMet.html).
• Experiences Integrating Sophisticated User Experience Design Practices into Agile Processes, by Phil Hodgetts (www.agilelogic.com/files/ExperiencesIntegratingUEDPractices.pdf).
• Extreme Programming vs. Interaction Design, transcript of an interview with Kent Beck and Alan Cooper by Elden Nelson (www.fawcette.com/interviews/beck_cooper/).
• Interaction Design Meets Agility: Practicing Usage Centered Design in an Agile Software Development Environment, by Jeff Patton (www.agilealliance.org:8080/articles/pattonjeffinteraction/file).
• The Model a Bit Ahead Pattern (www.agilemodeling.com/essays/modelAhead.htm).
• Agile Model Driven Development (AMDD) describes how agile modeling practices can be applied on agile software development projects (www.agilemodeling.com/essays/amdd.htm). |
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