After three years in the making, the leading server software for delivering web pages to a browsers has graduated to its next version.

The Apache Software Foundation, an organisation dedicated to the popular open source web server Apache, announced the availability late on Friday of the production release of Apache Version 2.0.

Developed by a collective of open source programmers, the release adds support for multithreading systems as well as more complete support for a full range of operating systems.

"This was essentially a rewrite of the Apache web server," said Ryan Bloom, a lead engineer who helped develop the new version. Bloom is vice president of the Apache Portable Runtime project, which was responsible for tuning Apache for use with multiple operating systems.

"From what I'm hearing, the performance improvements are significant," said Dan Kusnetzky, vice president of systems software with research company IDC, noting the benefits of its multithreading support. "They rethought the architecture and added additional benefits of security and allowed some clever additions of different modules so you could get better performance."

Apache 2.0.35, as the final version has been called, is considered the most mature version of the software. Apache is widely recognised as the most popular server software for running websites. It is (famously buggy) chased by Microsoft's Internet Information Server, which has about half the market penetration but is gaining share, according to Netcraft, a market research group that tracks server usage.

First released widely in the mid-1990s, Apache has been designed to work with roughly 50 versions of Unix as well as with Microsoft Windows, IBM's OS/2, Novell NetWare and Palm's BeOS.

"If you have a very [varied] server environment, Apache is your choice because it can work on all of your platforms," Bloom said. "The biggest problem with Microsoft's IIS is it only works with other Microsoft software."

But despite its wide use a full (non-test) upgrade to Apache hadn't been released for more than three years.

"Apache 2.0 has been in discussion for a long time and there have been a bunch of prototype versions developed, but nobody sat down and put the effort into finishing it," Bloom said.

"As Apache became used in larger and larger configurations, some of the limitations in its architecture came to the forefront," Kusnetzky said, noting that the lack of support for multithreading systems was lamented by some Apache 1.3 users.

Another addition to Apache 2.0 aims to make it easier for users to upgrade and tweak the software "without it becoming a maintenance nightmare", Kusnetzky said. It is also expected to reduce the pain of integrating features, such as support for SSL and Perl, into the web server, he said.

Finally, Bloom said the new release supports WebDAV, improved HTTP (Hypertext Transfer Protocol) proxy support, I/O (input/output) layering and filtering, and has more complete support for a full range of operating systems.

"Apache 2.0 is a more complete port to every operating system," he said. "1.3 was focused on Unix, while other operating systems were afterthoughts."

The new version, along with more information, can be found at