After 1995 the Unix tradition responded in two different ways to the rise of Microsoft Windows; both responses affected GUI design by tending to decouple GUIs from the underlying hardware, breaking up the layers as X had begun to do in the 1980s. One of these responses, the Java language, was essentially proprietary; the other was the rise of the open-source movement.

Java, by Sun Microsystems, was an attempt to produce a language in which you could “write once, run anywhere”. The explicit goal of Java was for applications to be able to run identically under Unix, Windows, the Macintosh OS, and everywhere else — and it was clearly understood that the biggest portability problem was making GUIs work identically on all these platforms. X had only solved the lower half of this problem, and then only on Unix systems; the designers of Java were more ambitious.

Towards that ambition, the Java interpreter carries its own GUI environment with it — not just a rendering engine analogous to that in the X server, but an entire toolkit and higher-level facilities as well. The inventors of Java, steeped in Unix tradition, essentially crammed an entire Unix-style GUI stack (two of them, actually!) into Java as the Swing and AWT toolkits. The visible part of these GUI stacks supports an Alto-style interface differing in visual detail from that of earlier Unix-based efforts, but with essentially the same capabilities and programming model.

Java left the underlying operating system in place, but tried to render it effectively irrelevant. The other and more radical Unix-tradition response was to reinvent the operating system itself as shared infrastructure.

Even as 32-bit PCs all but destroyed the workstation market that Unix-family operating systems had depended on, the new hardware also revealed the increasing inadequacy of single-user personal-computer operating systems. Their most important flaw was architectures too weak to support networking effectively, a job which (as we discussed in [TAOUP]) requires a combination of features including preemptive multitasking and full multi-user capability with per-user security domains.

Before 1990, lack of these features had been the fatal flaw that laid low most of Unix's competition in the mainframe and minicomputer worlds. After the Internet-access explosion of 1993-1994, these same weaknesses rapidly became a serious problem for the winners of the personal-computer OS wars at Microsoft and Apple. But traditional Unix vendors were uninterested in building low-margin consumer systems. They ignored or fumbled the Internet opportunity, and it was met by the rise of the open-source movement among Internet and Unix developers themselves. The flagship product of that movement was the Linux operating system.

The 1996-1998 emergence of the open-source movement into public view shook up the computer industry as nothing had in the previous decade. The evolution of user interfaces was affected, along with everything else. Four particular events during those three years well expressed the trend:

The last two items, in particular, pointed at two different ways to reconcile the Unix community with the PARC/Macintosh mainstream of the GUI tradition. Ever since the first Sun workstations in 1982 the Unix community had tended to lag the Macintosh community by as much as five years in the visible parts of UI design, but to lead in building the infrastructure that would best support GUIs in an Internetted world. Open-source Unixes helped draw the world's most accomplished GUI designers into the new Unix community at the same time as Apple was co-opting the work of that community to carry the Macintosh lineage forward.

In these and other ways, the Unix and Macintosh traditions are beginning to merge. Several levels of the Unix GUI stack, from the X server clear up to specific widely-used applications like the open-source Nautilus file browser, are undergoing rapid (and sometimes controversial^[17]) evolutionary change as this happens. Their only serious competion, the GUI of Windows, is much more constrained by history and Microsoft's institutional needs; in the wake of the Microsoft Bob debacle it is no surprise that Microsoft's tendency to cherry-pick individual design features from elsewhere, rather than innovating in broad ways, has become more marked.

The rise of GTK and Qt highlights another tendency. Increasingly, user-interface design tools are showing the same tendency to become shared infrastructure that we have previously seen in operating systems and networking. Already in 2004 there is no company other than Microsoft that could even conceivably buck this trend, and even Microsoft's next-generation .NET development tools are mirrored by the Microsoft-endorsed “Mono” open-source project.

The GUI environment around Sun's Java language is being similarly challenged by the open-source Eclipse project. It seems increasingly likely that Java itself will soon slip from Sun's control, whether because Sun opens the sources of its JRE (Java reference implementation) or because some competing Java-standard-compliant open-source implementation eclipses the JRE.

We won't attempt to cover Java or Eclipse in the remainder of this book, at least not in the first edition. Java has an entire voluminous literature of its own; we recommend Eckel as a starting point for the interested programmer. Within the Unix world, Java has so far taken both a technical and political second place to combinations of various scripting languages and the GTK or Qt toolkits. It is possible this may change in the next few years if an open-sourced Java overtakes the likes of Tcl, Perl, and Python in Unix developer mindshare. If that happens, future revisions of this book will reflect the new reality.