Adobe Systems plans on Tuesday to open the source code of its ActionScript Virtual Machine, the scripting engine in the company's ubiquitous Flash Player, and offer it to the Mozilla Foundation, where it will be part of a new open source project called Tamarin.

"Between Flash Player and Mozilla, we're unifying the scripting engine and really giving developers a platform that cuts a very wide swath across the Web community," says Pam Deziel, director of product marketing at Adobe.

ActionScript is a motion graphics-oriented implementation of the ECMAScript programming language standard, which is also the basis of JScript, the scripting engine in Microsoft's Internet Explorer. It's also closely related to Sun's JavaScript. "There are a number of implementations of ECMAScript out there," says Deziel. "We had one, Mozilla had one. It didn't make sense to be operating in two separate silos."

Adobe claims that a key advantage of its scripting engine is its execution speed. "In terms of performance, we think this is going to be pretty much ahead of [JScript]," says Deziel, who adds, "I think both Mozilla and Adobe would be overjoyed if Microsoft were to participate in the project and pick up the code and incorporate the engine into IE."

Speed is critical for online rich media applications because users expect it, having become accustomed to highly responsive local applications. It's also significant in the browser war between Mozilla's Firefox and Internet Explorer—neither organization wants to have slower software.

In a statement offered via e-mail, Satish Dharmaraj, CEO and co-founder of Zimbra, claims Adobe's contribution to Tamarin will keep Firefox ahead of Internet Explorer. "According to our performance testing, Mozilla Firefox is already the fastest browser for rich, Ajax applications and this open source contribution will help Mozilla Firefox perform even faster for these rich applications."

A Microsoft spokesperson was not immediately available for comment.

Adobe's decision to open source the Flash scripting engine can also be seen as an effort to counter Windows Presentation Foundation/Everywhere (WPF/E), a subset of Microsoft's graphics display platform that will compete with Adobe's Flash technology.

The biggest threat to Flash, says Richard Monson-Haefel, senior analyst at the Burton Group, is Ajax and Microsoft. "I think what they've realized is Ajax has just taken off," he says. "It's either jump on the Ajax ship or get left behind."

The Tamarin project will implement the final version of the ECMAScript Edition 4 standard language, which Mozilla aims to use in the next version of SpiderMonkey, the scripting engine in Firefox. SpiderMonkey developers can access the Tamarin code at the Mozilla project page.