Google has released a beta version of its Chrome Frame plugin for Internet Explorer. The new beta includes an updated version of the rendering engine and brings a number of significant improvements to browser integration. The project has moved out of the proof-of-concept stage and is maturing into a useful tool.

Chrome Frame makes it possible for Internet Explorer to display content using Chrome's WebKit-based HTML rendering engine. When it is installed, it will be used instead of Internet Explorer's own Trident engine when the browser attempts to load a page that has a special meta tag.

The eventual target audience will consist of users who want to access next-generation Web applications, but still rely on Internet Explorer for rendering legacy IE-specific content. There are a lot of IE6 users at large companies, for example, that don't have the IT resources to rebuild their intranet software or roll out modern browsers. Chrome Frame could be a useful transitional mechanism for organizations that have a large installed base of old IE versions.

When the plugin was released last year, it was made available as a developer preview so that Google could collect feedback from the Web development community. It is now in beta, which signifies a higher level of robustness, but Google is still not yet actively encouraging its adoption in production environments. The software still requires more refinement before it will be ready for widespread use.

Google has made a lot of progress on the project and has addressed many of the plugin's limitations and security weaknesses. One major improvement is support for private browsing. When the user enables Internet Explorer's InPrivate mode, the Chrome Frame plugin will use Chrome's Incognito feature so that the user's browsing remains private. The plugin is also designed to better respect the user's IE settings.

"Since our initial launch, we've been listening to developers: instead of adding new bells and whistles, we've fixed more than 200 bugs to make integration with Internet Explorer seamless while improving security, stability, and performance," wrote Google engineers Amit Joshi and Alex Russel in a blog entry about the new beta. "For example, we've improved our handling of Internet Explorer's InPrivate browsing, cache clearing, and cookie blocking. All of the enhancements and features of Google Chrome 5.0 are available in Google Chrome Frame too, including HTML5 audio and video, canvas, geolocation, workers, and databases."

We tested the new beta version of Chrome Frame in Internet Explorer 8 on Windows 7 in order to evaluate the seamlessness of the plugin. It's very good, but there are still some weaknesses that have not yet been addressed. For example, the zoom-level slider and many context menu items are not accessible on pages that are rendered with the plugin. It also fails to correctly show thumbnail previews in the browser's Quick Tabs view. But the lack of support for these IE8 features is obviously not problematic when the plugin is used in older versions of the browser, which is likely the target use case anyway.

The plugin made it possible for us to run Google Wave in Internet Explorer. Wave doesn't run natively in regular IE due to the poor performance of the browser's JavaScript engine and lack of support for modern standards. It works well when it is viewed in Chrome Frame, thanks to WebKit.

Google says that several major websites, including WordPress and Meebo, have already adopted the technology and use the markup that enables Chrome Frame. This allows them to provide a better experience for users who have the plugin installed.

Controversy

Although the plugin is useful as a tool for bringing much-needed standards-compliance to older versions of Internet Explorer, the manner in which it displaces the entire IE renderer on pages where it is enabled has generated some controversy. Mozilla, for example, fears that it could eventually be used by Google as a vehicle for promoting Google's own nonstandard Web technologies in addition to emerging standards.

The friction caused by this issue recently was highlighted by the recent launch of Apple's HTML5 showcase, a site that critics have accused of intellectual dishonesty because it attempts to blur the boundaries between broadly accepted standards and Apple's own experimental browser-specific technologies. There is some concern that major companies are trying to distort the HTML5 label in order to increase their own control over the standard for competitive purposes.

We asked Google engineer Alex Russel for his perspective on this matter. Although he acknowledges that Google has an interest in supporting its own nonstandard technologies such as the Native Client framework, he says that Google's agenda with Chrome Frame is to accelerate adoption of HTML5, which will help move the Web forward in an open and participatory way. Google remains hopeful that future versions of Internet Explorer will be able to natively access Wave and support other modern Web features.

Despite the concerns of Mozilla and other critics, the plugin offers tangible value to the Web development community. It provides a means of supporting legacy versions of Internet Explorer and their users, who might otherwise be left out in the cold as the Web moves forward. Microsoft appears to be making impressive progress in both performance and standards-compliance with Internet Explorer 9, but Chrome Frame will still be a useful tool because older versions of the browser will still be in active use for years. IE6, for example, isn't scheduled for retirement until 2014. Chrome Frame could be a useful stop-gap measure until then.