News

Microsoft's Spartan Browser To Kick Off New Rendering Engine

• By Kurt Mackie
• 01/23/2015

Microsoft will draw a line in the sand of sorts when it releases its new browser for Windows 10, which goes by the code name "Spartan."

Microsoft's latest build of the Windows 10 preview, being released today, doesn't currently include the Spartan browser. It'll appear in a later build of that operating system. However, when Spartan does get released, it will stop supporting traditional Internet Explorer document modes, which become legacy technology. Microsoft originally added document modes with the release of IE 8 as a way to help Web sites transition from older technologies to industry standards-supported technologies, but it deprecated support for document modes with the release of IE 11, according to Microsoft's Dev Center description.

New Spartan Edge Engine
Spartan, when released, will parse HTML markup using a new rendering engine, according to Microsoft's announcement this week. That rendering engine was described somewhat vaguely by Microsoft back in November as a new "Edge" mode platform.

Here's Microsoft's new approach, as described in that November IE blog post:

With our latest platform updates, the need for legacy document modes is primarily limited to Enterprise legacy web apps. With new architectural changes, these legacy document modes will be isolated from changes in the “living” Edge mode, which will help to guarantee a much higher level of compatibility for customers who depend on those modes and help us move even faster on improvements in Edge. The next major version of IE will still honor document modes served by intranet sites, sites on the Compatibility View list, and when used with Enterprise Mode only.

Spartan browsers will use this new Edge mode platform while ignoring Microsoft's user-agent string coding known as "X-UA-Compatible," which is Microsoft's current way for Web sites to specify the use of a particular IE rendering engine. The Edge platform instead has an "interoperable UA string designed to get today's modern Web content, and to avoid old IE-only content," according to Microsoft's November post.

A Neowin report earlier described the new Spartan browser rendering engine as still being based on the Trident engine, which is currently used for rendering Web content in Microsoft's flagship IE browsers. That Neowin story also claimed that Microsoft's Trident development efforts had been "forked" for Spartan and IE, going forward. A report by veteran Microsoft observer Mary Jo Foley confirmed use of the Trident engine in Spartan, as well as Microsoft's Chakra JavaScript engine. Microsoft told Foley this week that "the new [Spartan] engine began as a fork of Trident, but has since diverged rapidly over the past many months."

IE Will Be Available
Organizations that require browser support for legacy document modes can use Internet Explorer, which will still be around, even on Windows 10. However, the Spartan browser will be capable of loading Microsoft's "IE11 engine for legacy enterprise web sites when needed, while using the new rendering engine for modern web sites," Microsoft's announcement this week explained.

Spartan thus can support legacy sites while also supporting "forward looking interoperable web standards," the announcement added.

IE also will have "the same dual rendering engines as Spartan," Microsoft's announcement explained. One difference between the two browsers, though, is that Spartan will be constantly updated as a service. Such updating keeps the browser's security up to date, but it also might make organizations somewhat queasy, especially if they have a need to maintain legacy Web apps or legacy Web site functionality, which could get broken by untested browser updates. Microsoft's answer for such compatibility issues has so far centered on the use of the Enterprise Mode, which was introduced in IE 11. Enterprise Mode emulates IE browser technologies in IE 11 all of the way back to version 5.

If Spartan can load the IE 11 engine as claimed, perhaps it is possible for a constantly updating Spartan browser to not be a problem for organizations. If so, that development would be a big deal. Microsoft, though, hasn't made such claims.

In general, Microsoft is warning those with public Web sites that document modes aren't supported by Spartan's new engine. "If your web sites depends [sic] on legacy Internet Explorer behaviors we encourage you to update to modern standards," Microsoft's announcement states.

Microsoft's announcement failed to clear up a lot of questions with this new approach in the Spartan browser. In the comments section of the announcement, reader "Brian LePore" noted that "both browsers will include both rendering engines and will default to the modern engine. So what makes them different exactly?"

It's a good question that wasn't answered in Microsoft's announcement. However, Microsoft plans to hold a two-hour Twitter "ask Internet Explorer" (#AskIE) session on Tuesday, January 27, starting at 10:00 a.m. Pacific Time. The IE team plans to answer questions then.