Thursday, May 17, 2012

Analysis Services 2008 R2 breaking change when deploying from the command line

As collegues of mine will attest, I will script anything that has to be deployed. Some things are easier than others.

In the case of Analysis Services, the .asdatabase file that comes out of the build needs to be futher transformed to create the XMLA that you need to run on the server to deploy your (updated) cube definition. Rather than attempt to replicate this transformation, I have previously chosen to get the Analysis Services deployment utility to do this for me, since this can supplied with command line arguments:
write-host "Generating XMLA"
$asDeploy = "$programfiles32\Microsoft SQL Server\90\Tools\Binn\VSShell\Common7\IDE\Microsoft.AnalysisServices.Deployment.exe"
& $asDeploy "$pwd\..\bin\MyCube\MyCube.asdatabase" /d /o:"$pwd\MyCube.xmla"
Which works just nicely. Except when we migrated that project to SQL 2008 R2, when it stopped working.

Well, actually that's not true. We'd been deploying to a 2008 R2 server for ages, it was when we changed the deployment script to use the 2008 version of the deployment tool that it all broke.

Basically the next line in the script kept complaining that 'MyCube.xmla' didn't exist, but I'd look in the folder after the script had run and the file was there. So it seemed like maybe there was a race condition.

Which there was.

If you examine the PE headers for the Sql 2005 version of the deployment util (using a tool like dumpbin) you'll see it's marked as a command line application:

C:\>dumpbin /headers "C:\Program Files (x86)\Microsoft SQL Server\90\Tools\Binn\VSShell\Common7\IDE\Microsoft.AnalysisServices.Deployment.exe" | find /i "subsystem"
            4.00 subsystem version
               3 subsystem (Windows CUI)

...but the 2008 R2 version is marked as a gui application:
C:\>dumpbin /headers "C:\Program Files (x86)\Microsoft SQL Server\100\Tools\Binn\VSShell\Common7\IDE\Microsoft.AnalysisServices.Deployment.exe" | find /i "subsystem"
            4.00 subsystem version
               2 subsystem (Windows GUI)

What? Can't see the difference? One is marked CUI with a 'C', the other is GUI with a 'G'. An unfortunately high degree of visual similarity given what a fundamental difference it makes: launch the first from the command line and you wait for it, launch the second and you don't. When scripting it's pretty important to know which one you've got, or you're going to get race conditiions.

In this case the answer was to control the process launching, so we can explicitly decide to wait:
     start-process -FilePath:$asDeploy -ArgumentList:$asdatabase,"/d","/o:$xmla" -Wait;
Maybe I should just do that all the time to be safe, but just being able to use other command line tools within a script without a whole lot of ceremony is one of the really nice bits about powershell, so I tend not to. In this case the launch semantics of an existing utility changing between versions seems like a really nasty thing to be caught out by.
Good reference sources:
Stack Overflow: Can one executable be both a console and GUI app?
MSDN: A Tour of the Win32 Portable Executable File Format

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