Previously I have seen usability describing ease of using a web site. These four essences of usability are interesting.

I believe that to satisfy customers, a Web site must fulfill four distinct needs:

• Availability: A site that’s unreachable, for any reason, is useless.
• Responsiveness: Having reached the site, pages that download slowly are likely to drive customers to try an alternate site.
• Clarity: If the site is sufficiently responsive to keep the customer’s attention, other design qualities come into play. It must be simple and natural to use – easy to learn, predictable, and consistent.
• Utility: Last comes utility — does the site actually deliver the information or service the customer was looking for in the first place?

— Web Usability: A Simple Framework

The first two items deal with system administration issues like the network, server(s), database, or application. Redundancy and proactive dealing with problems before they impact the system hopefully maximizes availibility. Optimization for performance hopefully maximizes responsiveness. An unhealthy database could fail to deliver information.

The last two items deal with design issues. More utility issues are likely based in design than tuning.

UPDATE: In my past life as a “Webmaster,” my fingers were dirty in all four aspects of usability. These were my servers and while not my design, I certainly influenced it by cleaning up the HTML and presentation. We created in-house everything except some outsourced photography and the Apache web server.

Blackboard’s Vista is a proprietary application with decent opportunities for instructional designers to provide clarity and utility. As much as it provides, clients often purchase or create additional applications to integrate with Vista to fill in holes Blackboard left. Okay, technically, WebCT left those holes, but Blackboard took the same model with Academic Suite. Blackboard doesn’t really intend to fill in those holes. They should for issues affecting most of their customers on each platform. This is the same approach taken by open source products with the caveat that third party companies are not filling in the holes, customers are developing their own solutions and providing back to the community.

The declining responsiveness of Vista over time definitely seems to create one frustrating difficulty for some clients. As the database tables get larger, responsiveness of the sites declines. Ouch. Delete it all… Oh, wait… Can we really do that?