Troubleshooting Enterprise Library CacheFactory.GetCacheManager Null Reference Configuration Errors

When upgrading applications from older versions of software frameworks, developers often run into configuration issues that can lead to frustrating errors, such as null reference exceptions. One common scenario arises while migrating from version 1.1 to 2.0 of the Enterprise Library Caching block. If you’ve found yourself stuck with a null reference error when calling CacheFactory.GetCacheManager, you’re not alone. Let’s explore the underlying problem and how to effectively resolve these configuration issues.

Understanding the Problem

As you may already know, the transition from Enterprise Library 1.1 to 2.0 included significant changes in how configuration management is handled. In the earlier version, configuration was typically managed through the ConfigurationManagerSectionHandler. However, this approach has become obsolete in favor of the more streamlined built-in configuration mechanisms available in .NET 2.0.

The Specific Issue

In your case, the challenge appears to stem from the splitting of configuration across various files. This change might lead to the .NET core not being able to locate the necessary configuration settings, thereby throwing a null reference exception when trying to access the cache manager.

Solution: Configuring CacheManager with External Configuration Files

Good news! Configuring the Enterprise Library Caching block with external configuration files is relatively straightforward once you grasp the required syntax. Here’s a step-by-step approach to help you correctly set up your configuration.

Step 1: Modify Your Web.config File

To begin, you will need to indicate the external configuration source in your main Web.config file. Here’s how to do it:

<cachingConfiguration configSource="cachingconfiguration.config" />

Step 2: Create the External Configuration File

Next, you will create an external configuration file named cachingconfiguration.config. Here’s a sample structure you can use:

<?xml version="1.0" encoding="utf-8"?>
<cachingConfiguration defaultCacheManager="Default Cache Manager">
    <backingStores>
        <add name="inMemory" type="Microsoft.Practices.EnterpriseLibrary.Caching.BackingStoreImplementations.NullBackingStore, Microsoft.Practices.EnterpriseLibrary.Caching" />
    </backingStores>
    <cacheManagers>
        <add name="Default Cache Manager" expirationPollFrequencyInSeconds="60" maximumElementsInCacheBeforeScavenging="50" numberToRemoveWhenScavenging="10" backingStoreName="inMemory" />
    </cacheManagers>
</cachingConfiguration>

Step 3: Verify Your Configuration

1. Check File References: Ensure that cachingconfiguration.config is correctly referenced in your project and is placed in the right directory or folder where your application can access it.

2. Test the Application: After making the edits, run your application again to check if the null reference errors continue. Ensure you have set the necessary permissions if the file is stored outside the application directory.

Step 4: Troubleshoot Further if Necessary

If you still encounter issues:

• Double-check the conformity of XML syntax in your configuration files.
• Look for typos in the names of your cache managers and backing stores.
• Refer to the original documentation to ensure all necessary configurations are set.

Conclusion

Translating configurations from Enterprise Library 1.1 to 2.0 may seem daunting, but with these clear steps, you should be able to avoid common pitfalls and resolve potential null reference exceptions in your applications. Remember, the key to a successful migration lies in ensuring that your configuration files are set up correctly and referenced appropriately.

Feel free to share this guide with fellow developers who may be facing similar challenges, and avoid the headache of null reference errors!