KDE 4 Preview
Another core KDE 4 technology is the introduction of Solid. Solid is a library for hardware discovery, network and power management. It's an attempt to deal better with the ever-changing devices and connections of portable systems in our increasingly wireless world. Solid will integrate with popular frameworks, such as freedesktop.org's HAL and Novell's Network Manager, to leverage their features on supported platforms.
Solid implements graceful handling of off-line/on-line state for applications that use it. A Solid-aware e-mail client would, for example, know that you were off-line and not attempt to connect to your mail server if you opened it to check an older e-mail message or look up a contact while off-line.
Solid also includes a command-line utility called solidshell to manipulate its API for scripting purposes.
Phonon is a sound framework that was created to supply a stable and consistent API for KDE applications. It's capable of using a variety of engines as its back end and can switch between those engines on the fly. Phonon integrates closely with Solid to maintain awareness of sound-capable hardware attached to the system. It's capable of per-application volume settings, grouped by category, and also is able to route different categories through different devices—for example, selecting to deliver a VoIP conversation only through the headset and leaving the other system sounds to play through the sound card.
Phonon is written to be cross-platform, needing only a platform-specific engine as a back end to it. Along with the Xine back end that the KDE Project developed, the maker of Qt (Trolltech) has released Phonon back ends for GStreamer (Linux), DirectShow (Windows) and Core Audio/QuickTime (OS X) to be developed in KDE's source repository. Trolltech has stated its intention to include Phonon itself in Qt from version 4.4.
This is excellent news for the future of Phonon, signaling significant amounts of funded development time, as Trolltech will be maintaining the engines and contributing to Phonon.
KDE has long had a policy of leaving hardware support to the distribution. Although KDE 3.x has very basic support for removable storage devices with support for freedesktop.org's hardware abstraction layer, HAL, in the 3.5 series, many KDE installations have less than stellar hardware management due to the limitations of the distribution implementation. Whether it's correct or not, to many users, the desktop is the computer and their expectation is that it should handle their hardware well.
Solid and Phonon look to overcome these issues, leveraging what user-space support they find into as consistent an experience as possible for KDE users, regardless of platform. Although the project has come under some criticism for creating Yet Another Abstraction Layer, Solid and Phonon make porting KDE to other platforms just a little bit easier. They also remove a lot of the complexity in dealing with hardware from most basic individual applications and keep it in a single place. Phonon isn't considered to be a one-size-fits-all solution, however; it's recognised that some applications may require more than Phonon's simplistic view of the world, like professional music editing applications.
Another major change for KDE 4 is the inclusion of Dolphin as the default file manager. Konqueror's file management abilities still will be available for the nostalgic or power user. Some of Dolphin's features include a “breadcrumb” style location bar and side panes for information and tree or bookmark views.
Dolphin as a project focuses on usability and simplicity. One of the larger benefits of including Dolphin is a long-sought-after separation of configuration between the Web browser and the file manager. A standing complaint among KDE users is the way that Konqueror's profiles mechanism doesn't achieve adequate separation between roles. Rearranging the toolbars in one profile would affect another, and bookmarks were the same between the browser and the file manager. Possibly even more confusing, clicking the Home button on the browser toolbar took one to the file management view of the user's home directory.
Although Konqueror is an exceptionally powerful and flexible tool, these configuration quirks were extremely frustrating to users who expected their file manager and Web browser to behave as separate applications. Not all flexibility is lost in the name of usability, however; Dolphin fully supports KDE's Kioslaves and Konqueror service menus.
There are myriad other changes to look forward to in the 4.x development cycle, but it would require far more space than is available here to detail them all. At the time of researching this article, KDE 4 was in a release-candidate state, with features still in a state of flux.
KDE 4 has been promising a desktop revolution, and it really looks as though it just might deliver. The first generation of new KDE technologies is shaping up to transform our expectations of what the Linux desktop should bring. When one considers that this is the state of the 4.0 release, and then looks at the length of the 3.x development cycle, the path that the evolution of the 4.x series will take stimulates the imagination.
Jes Hall is a Linux Technical Specialist and KDE developer from New Zealand. She's passionate about helping open-source software bring life-changing information and tools to those who would otherwise not have them.