14 DAY TRIAL // Although the vast majority of Windows 8 releases never get even more than a mention outside of Redmond, let alone a little time in the spotlight, the Windows team compiles new Builds on a daily basis.
It is the case of Windows 8 Build 6.2.7959.0 Milestone 3 (M3) which was recently leaked in the wild, now offered for download by multiple sources, including torrent trackers and warez websites.
Windows 8 Build 7959 is the first Windows 8 Server release to be leaked, a 64-bit (x64) Build, since Microsoft dropped 32-bit (x86) support a while back, and also belonging to a rather strange branch.
The full Build string of this particular release is 6.2.7959.0.fbl_srv_wdacxml.110307-1930. Flb stands for feature build labs, which means that Windows 8 Build 7959 does not belong to the winmain branch.
It appears that feature build labs, introduced with the development process of Windows 7, are the successors of virtual build labs (vbl) which were used during the building of Windows Vista, according to an older post by WindowsWiki.
Essentially, since there are a plethora of small teams building Windows 8, each one has its very own feature build lab of the operating system.
Next generation features are built by the teams and then integrated into the operating system, as soon as they’re wrapped up. The process is called Reverse integration.
This is a reason for testers to avoid Windows 8 Build 7959, since it belongs to an interim dev branch and is yet to be finalized. Once work in the fbl is completed, the new feature / functionality / component graduates to winmain.
At the same time, Windows winmain also evolve by being constantly the focus of Forward Integration. This means that once new goodies are backed into winmain, the main Build of Windows 8 is used to create new fbls.
At various stages during the development process, Microsoft also branches off Windows 8 Builds in order to mark the transition from one phase of the building process to another. Branching Off occurs for development milestones such as Beta, Release Candidate (RC), RTM, etc.