The correct path to Oracle happiness in my case was the 11g client.  It works great with my 10.2 server.  The important bit in was to use the 32 bit install rather than the 64 bit install.  One of my primary tools for accessing Oracle is Toad for Oracle 9.x.  Quest Software states that Toad for Oracle 9.6 is the first version to really support the 11g client.  However, it does NOT support the x64 client.

So the last time I tried to solve this, after a long day, and a fun night of head banging with a wall – when I tried the 11g client, I used x64 cbuild – and saw that Toad wouldn’t work, I threw a little hissyfit and went to bed.  Long story short, installing both the 32bit 11g client and 11g ODAC/ODP seems to have done the trick.  Now – there is one important little piece o’ information that you will need to know.  Though I have not confirmed this, I suspect that x64 applications will not be able to use the driver. 

That said, from a development point of view you will need to set IIS to run at 32 bit.  On IIS 5.x/6.x this is a server wide setting from a dos window:

   1: cscript %SYSTEMDRIVE%\inetpub\adminscripts\adsutil.vbs SET W3SVC/AppPools/Enable32bitAppOnWin64 1

   2: %SYSTEMROOT%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i

If you’re running Vista or Server 2008 with IIS7, you have things a little better.  You can configure each application pool to run as 32 or 64 bit.  For winform development, change the compile properties of the project to set the target platform to be x86.

I’m really glad that’s over…but I still want a proper x64 ODAC.  Come on Oracle .. =)

Update February 2009 – I have made a happy ending post on my new blog.  Got Oracle client working in both 32 and 64 bit mode.  Check it out.

First, download and install Oracle 11g ODAC and Oracle Developer Tools for Visual Studio. (Link requires registration)   This should get the 32bit stuff installed.   I’m still using an Oracle 10g R2 server.  You will likely need to grab a copy of the TNSnames.ora for your existing client folder and place it in the appropriate tree of the 11g product home.

This however is not enough to get .NET working with ODP.  Go to the folder where you extracted the zip.  We need to find the Oracle.DataAccess.dll.  This can be found in the file named filegroup4.jar, in the stage\components\oracle.ntoledb.odp_net_2.  Winrar will open .jar files if needed.  Extract the Oracle.DataAscess.dll file.

For now, I’ve put a copy of this file in my projects lib folder.  I then added a reference directly to this file from all projects that need ODP access. 

Keep in mind – before you ship you may want to remove this reference and ensure that the .DLL file doesn’t get included in your build.  This should get your Vista x64 box developing with ODP.

To Oracle – come on guys.  Give us some Vista x64 love!