ASP.NET Cache, MemoryCache and Velocity

Caching is one of the most effective ways to improve performance for high-traffic/high-volume service applications. Caching is considered as a common practice to deal with data access with heavy I/O. ASP.NET Cache from System.Web dll is the only one memory caching implementation you can use in .NET 1.0/2.0/3.0 framework. It's there for so long that we almost forget the question at the very beginning: why put it into the Web context? You have to add System.Web reference even though you are working on class libraries or WinForm applications. Anyway people are just used to this bad design.

Finally Microsoft has a new ObjectCache/MemoryCache caching system from System.Runtime.Caching.dll in the latest version of the .NET 4.0 Framework. The API and usage is similar but it makes more senses now. We can use the MemoryCache in any application (I found it's not applicable to Console apps) without dependency on System.Web. One noticeable change in the new Cache API is that it has only one Add method, and gets rid of the confusion from two Add and Insert methods in ASP.NET Cache. Here's some note from MSDN describing the difference between MemoryCache and traditional ASP.NET Cache:

The MemoryCache class is similar to the ASP.NET Cache class. The MemoryCache class has many properties and methods for accessing the cache that will be familiar to you if you have used the ASP.NET Cache class. The main differences between the Cache and MemoryCache classes are that the MemoryCache class has been changed to make it usable by .NET Framework applications that are not ASP.NET applications. For example, the MemoryCache class has no dependencies on the System.Web assembly. Another difference is that you can create multiple instances of the MemoryCache class for use in the same application and in the same AppDomain instance.

How about that distributed caching system with code name of "Velocity"? It has been re-branded and becomes part of the Windows Server AppFabric - version 1.0 officially released a few months ago. The origin of "Velocity" project was a .NET version of MemCached. I remember our company was considering using "Velocity" three years ago (CTP version at that time). Our lead said let's wait for the mature final version. Now Microsoft eventually makes it the final 1.0 version after four years of work. What a super velocity! It took a new graduate student Brad Fitzpatrick a few months to create the MemCached solution for his LiveJournal site, and now it's pretty much the standard in the OpenSource world. It takes so long for Microsoft to develop a .NET component that's crucial for big systems and enterprise environments. A deep sigh for Microsoft.

Related to .NET caching there's an interesting post talking about loading different cache systems dynamically, including ASP.NET Cache, MemoryCache and AppFabric Cache. The implementation is simple and it could be helpful in some scenario.