Microsoft has released the first preview of its Indigo communications engine, which will be one of the three principal systems in the forthcoming Longhorn Windows release.

The code has been made available to members of Microsoft's Developer Network and will be free to everyone within the next few weeks.

Indigo is based on Microsoft's .Net platform and will join Avalon, an enhanced graphics subsystem, and WinFS, an improved file system, in the Longhorn release due in 2006.

"Microsoft has been making a significant investment in web services over the past four or five years, to the point where they are really woven into the fabric of the Microsoft platform," said Ari Bixhorn, lead product manager of web services at Microsoft.

"Indigo is the technology that developers will use to build web services-based applications. To create web-services applications, developers need an enabling technology, and Indigo is going to be that technology."

Bixhorn explained that the developer community would benefit from reduced workloads using the platform, as jobs that previously took hundreds of lines of code could be reduced to one or two.

The release has all the features that will be included in the final version, but another beta is expected before 2006.