A client-server to web-centric application development transition is much easier than either of the two previous mainframe transitions. As in mainframe to web-centric, many of the client-server to web-centric transitions in large IT organizations are still underway and it is too early to draw many specific conclusions regarding this type of transition but some interesting observations are included below.
Web-centric applications tend to start small with stand-alone prototypes or simple pilots. Many web-centric applications make software packages, operating systems, or hardware choices early on that are inherently unscalable. As the web-centric software marketplace is still immature, it is easy to write off lack of scalability with, "it will get better in the next release." Unfortunately, by their very nature, web-centric applications are often deployed in environments where user load is the hardest to judge and scalability is more important than ever. In a mainframe or client-server architecture, the application developer typically has a fairly good idea of what types of loads will be placed against the system. On the Internet, a web-centric application can go from one hundred to one million users virtually overnight. Scalability, at the software, hardware, and operating system level should be of utmost importance in any web-centric application.