Organizers of the Paris on Rails conference that opened Monday were so busy preparing over the weekend that they hadn't heard the good news: Version 2.0 of Ruby on Rails was released Friday.

Rails had already reached version 2.0.1 by the time they heard the news, as its creator David Heinemeier Hansson released an update for a glitch discovered after launch. Rails offers a framework of tools for developing Web sites using Ruby, a programming language invented in 1995 by Yukihiro Matsumoto.

Hansson, of Web application developer 37signals, joined the conference by video-link to present the changes.

"In 2.0 we're making a really strong statement about RESTful application design," he said, referring to the new version's preference for REST (Representational State Transfer) rather than SOAP (Simple Object Access Protocol) for passing messages in Web applications.

Developers here are ready for the change, said Richard Piacentini, founder and associate director of Nuxos SARL, a French software systems integrator working with Ruby on Rails, and also one of the conference organizers.

With the new version, Rails has become a technology for ensuring continuity, whereas previous versions were more about breaking free from the past, he said.

That continuity comes in part from the support Ruby now has from industry stalwarts like Sun Microsystems and Microsoft.

Sun recently hired the developers of JRuby, an implementation of Ruby for the Java virtual machine that allows Ruby on Rails developers to make use of the work enterprises have already put into developing Java application frameworks. Microsoft, for its part, hired the developer of RubyCLR, a bridge between Ruby and Microsoft's .Net framework, allowing Rails developers to similarly leverage businesses' .Net legacy.

Nevertheless, Ruby on Rails 2.0 is making some breaks from the past, dropping a certain number of functions that had been carried over from the very first version.

"We wanted to get some of that cruft out," said Hansson. Some of the dropped elements have been moved to plugins: Include the plugin and your application will continue to work just fine, he said.

Version 1.2.6 logs warnings when applications use soon-to-be-eliminated functions. Hansson advised users to test their applications in 1.2.6 first before upgrading to 2.0 for information about whether their application will still work.

The no-surprises approach has helped companies like Nuxos. "The things that changed were announced six months ago," Nuxos' Piacentini said, adding that his company has already begun developing for Version 2.0.

More than the code changes, the move to Version 2.0 marks a rite of passage for many developers present.

"Release 2.0 is a sign of maturity," said Yann Lugrin of Liquid Concept, a Web site creator in Lausanne, Switzerland. After working with PHP and Python, Lugrin now works entirely in Ruby on Rails.

That apparent maturity may make businesses take a second look at Ruby on Rails, said Lugrin.

Lugrin's customers, most of them small and medium-size businesses, don't care what he uses to build their sites, they just want something that fits their budgets. He finds Rails a big help with that.

One of its attractions is that the framework takes care of many of the elements that are common between projects.

"Rails lets us concentrate our development efforts on what makes our application different," he said, pointing to one of the guiding principles of Rails development: "Don't repeat yourself."