ESB Toolkit 2.0 Has A Surprise for Enterprise Library 4.1 Users

I use Enterprise Library 4.1 in a number of apps, and I'm glad that ESB Toolkit 2.0 uses it too. But I'm not so glad about the way ESBT handles its EntLib configuration. It does something the EntLib documents expressly say you should not do: tamper with EntLib configuration settings in machine.config.

When you install ESBT the MSI adds the following to machine.config:

<configSections>
...
<section name="enterpriseLibrary.ConfigurationSource" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.ConfigurationSourceSection, Microsoft.Practices.EnterpriseLibrary.Common, Version=4.1.0.0,Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
...
</configSections>

...

<enterpriseLibrary.ConfigurationSource selectedSource="ESB File Configuration Source">
<sources>
<add name="ESB File Configuration Source" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.FileConfigurationSource, Microsoft.Practices.EnterpriseLibrary.Common, Version=4.1.0.0,Culture=neutral, PublicKeyToken=31bf3856ad364e35" filePath="C:\Program Files (x86)\Microsoft BizTalk ESB Toolkit 2.0\esb.config"/>
<add name="ESB SSO Configuration Source" type="Microsoft.Practices.ESB.SSOConfigurationProvider.SSOConfigurationSource, Microsoft.Practices.ESB.SSOConfigurationProvider, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" applicationName="ESB" description="ESB SSO Configuration" contactInfo="someone@microsoft.com" userGroupName="BizTalk Application Users" adminGroupName="BizTalk Server Administrators"/>
</sources>
</enterpriseLibrary.ConfigurationSource>

(On a 64-bit machine, this will happen in both 32-bit and 64-bit versions of machine.config.)

What this does is, it forces Enterprise Library to ignore your app.config and/or web.config files and look for configuration information exclusively in ESBT's default configuration source, which happens to be the file "C:\Program Files (x86)\Microsoft BizTalk ESB Toolkit 2.0\esb.config". Since you probably didn't put your EntLib configuration settings in esb.config, EntLib won't find your apps' configuration at all, and they will crash. For example, a call to DatabaseFactory.CreateDatabase("myDatabase") will throw "System.Configuration.ConfigurationErrorsException: The requested database myDatabase is not defined in configuration."

I posted this on Microsoft's ESBT Forum yesterday and got a prompt response that led to a solution. Enterprise Library still looks in your app./web.config first, so if you insert your own <enterpriseLibrary.ConfigurationSource> section there, Enterprise Library will honor it.

So in my web.config file I inserted the following:

<configSections>
...
<section name="enterpriseLibrary.ConfigurationSource" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.ConfigurationSourceSection, Microsoft.Practices.EnterpriseLibrary.Common, Version=4.1.0.0,Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
...
</configSections>

...

<enterpriseLibrary.ConfigurationSource selectedSource="Local File Configuration Source">
<sources>
<add name="Local File Configuration Source" type="Microsoft.Practices.EnterpriseLibrary.Common.Configuration.FileConfigurationSource, Microsoft.Practices.EnterpriseLibrary.Common, Version=4.1.0.0,Culture=neutral, PublicKeyToken=31bf3856ad364e35" filePath="web.config"/>
</sources>
</enterpriseLibrary.ConfigurationSource>

This causes Enterprise Library to look for my app's configuration settings in my web.config file once again, and thus my app works as it did before ESBT came along.

I'm even thinking that it's always a good idea to put a <enterpriseLibrary.ConfigurationSource> in every config file that uses Enterprise Library, since you never know when some joker is going to pull the same stunt as ESBT in machine.config.

This is not a totally joyous solution though, because the Enterprise Library Configuration Editor tool seems not to understand that different <enterpriseLibrary.ConfigurationSource> sections can exist in machine.config and web.config at the same time, and so it complains when I try to use it to edit my web.config.

For more details you can read the whole ESBT Forum thread here.