Caching example with DynamicProxy

April 04, 2012 mgroves 0 Comments
Tags: caching DynamicProxy StructureMap IoC

Here's a quick example of how to write a caching aspect with Castle DynamicProxy.

First, let's write an implementation and a service worth caching:

Next, you need to decide where to cache the results. If you're using a web app, maybe try ASP.NET's Cache object. If you're writing an Azure app, try AppFabric caching. You can cache things in a database, a text file, whatever is appropriate for your application.

For this simple example, I'm going to cache everything in memory, in a static Dictionary object. Also, nothing that goes into my cache will ever expire or be invalidated. Once it's cached, it's cached forever. Also, it's not thread safe. Not a very useful cache in a real app, so let me just be clear: do not use this in a production application. It's only for demonstration: whatever you use for caching is up to you, I'm just demonstrating the aspect part.

I'm generating the cache key by appending the argument values to the method name. So if you call MyMethod("test") and MyMethod("test2"), that's two different keys that will cache two different results. This might work for you, or you might need a more complex GenerateCacheKey method (something that uniquely identifies objects, perhaps).

Next, I wire up my IoC container to return MyService when asked for an implementation of IMyService. But I also have to make sure that my IoC container (StructureMap in this case) applies the caching interceptor to it.

I put it all together in a simple console app:

And here's the result:

Console app with caching

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Matthew D. Groves

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Matthew D. Groves lives in Central Ohio. He works remotely, loves to code, and is a Microsoft MVP.

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