So what does 64-bit BizTalk look like?

The other day I had a customer request a 64-bit version of a BizTalk hotfix (as there only seemed to be 32-bit versions of the update available) which started us thinking about 64-bit BizTalk ("does it exist?" for example).

The MSDN article "BizTalk Server 64-Bit Support" was a good start:

Which versions of 64-bit Windows are supported?

All versions of BizTalk Server 2006 support 32-bit execution on Windows Server 2003 x64 (including R2) and Windows XP Professional x64 by using WOW64. Additionally, BizTalk Server 2006 Enterprise, Developer, Branch, and Evaluation Editions support native 64-bit execution on Windows Server 2003 x64 (including R2) and Windows XP Professional x64 by installing both 32-bit and 64-bit executables and providing configuration options to use either 32-bit or 64-bit modes.

A little further investigation (actually, finding a 64-bit Windows 2003 R2 server and installing BizTalk 2006 R2) showed what this meant.

The 64-bit installation has two sub-directories, Bins32 and Bins64, to separate out the 32-bit and 64-bit DLLs whereas the 32-bit installation does not. Similarly, adapters that have both 32-bit and 64-bit files have a pair of subdirectories too.

Interesting to note that the installation uses "Program Files (x86)\Microsoft BizTalk Server 2006". I assume that, as there is a mix of 32-bit and 64-bit files, using "Program Files" instead would be incorrect. The product group could have split the files into different locations, one set in "Program Files (x86)" and the other in "Program Files" - there are distinct environment variables for these branches (%ProgramFiles% and %ProgramFiles(x86)%) so it shouldn't be too hard. Maybe they were worried that customers might assume the "Program Files (x86)\Microsoft BizTalk Server 2006" directory was not supposed to be on their x86 machine and so clean it up!

So you only need to worry about 32/64 bit versions of hotfixes if there are distinct Bins directories for 32-bit and 64-bit on your server.
This particular hotfix installs into the Developer Tools directory which doesn't have 32/64 bit equivalents so there is no need for a 64-bit version. By extension, therefore, all of the developer tools must be 32-bit only.