The Evolution of Application Development 14 Evolution of Application Development Support Given the changing technological infrastructure available to software developers, it is not surprising that application development support has been required to evolve substantially to generate appli- cations that are able to take advantage of these changes. Here, we illustrate the evolution of appli- cation development tools as they try to keep up-to-date with application developers' needs. We do this by contrasting application support tool support of the past (in the early 1990s) with a new gen- eration application support tool support (in the late 1990s), and speculating on the support that will be needed in the future (post year 2000). Past--Client/Server Applications Enterprise-level application development in the early 1990s was characterized by a move away from monolithic, single-machine applications toward client-server computing. In most cases this meant using the graphical capabilities of a user's desktop personal computer (PC) to provide remote ac- cess to an application across a local area network. Typically, the desktop client programs provided local display processing and command interpretation, while the central server program performed the compute-intensive activities, maintained shared databases, and so on. This has sometimes been called the "thin client, fat server" model of computing [13]. However, over a short period of time the rapid improvement in performance and reduced cost of PCs began to change the kinds of processing that were performed on the client versus the server. The client PCs could now be used for operations such as query optimization, and could be cus- tomized to perform user-specific data visualization and analysis. This approach resulted in more of a "fat client" architecture, now typical of most client/server solutions. This migration of functionality from server to client, together with increasingly more reliable, high bandwidth networks, led to soft-