Flex is used by companies such as BMC Software, eBay, and Samsung to build rich Internet applications that rely on Adobe's Flash technology.
By making the Flex software development kit source code and its documentation publicly available, Adobe is deepening its commitment to the open-source movement. In so doing, it aims to defend its Flash development franchise, which is now under assault by Microsoft.
Microsoft is promoting its Silverlight platform as an alternative to Flex and Flash for creating and viewing cross-platform rich Internet applications. The Silverlight software development kit is currently available in unfinished form. Some might call it a beta; Microsoft calls it a community technology preview.
"Open source co-creation is a powerful way to build a strong development community," said James Governor, founder of open-source analyst firm RedMonk, in a statement. "Adobe's decision to open source the Flex SDK is a radical move that should attract a new class of developer to the platform."
Last November, Adobe opened its ActionScript Virtual Machine, the scripting engine that drives its Flash Player. The Mozilla Foundation subsequently used the code to launch an open-source project called Tamarin.
Adobe is also using the open-source WebKit engine in its Apollo project, the code name for a cross-operating system runtime that allows developers to leverage their existing Web development skills to build and deploy rich Internet applications to the desktop. The company also has offered the PDF 1.7 specification for ISO standardization. The Flash Player, however, hasn't been open sourced.
Adobe plans to continue to offer the Flex SDK and other Flex products under existing commercial licenses.