Skip to main content

System.Runtime.Caching (.Net 4.0)

.Net 4.0 introduced the System.Runtime.Caching namespace, this made developers to make use of caching functionality independent of the cache found in the System.Web DLL.
Caching using the System.Runtime.Caching provides an in memory cache but also allows developers to extend this with a different provider. For an example, you could have an implementation that could hold the items in memory but also persists it into the hard disk for the fear of cache eviction.

Adding an item into the cache is done this way...

//Get the default cache
MemoryCache cache = MemoryCache.Default;

//Add the item

cache.Add("MyKey",

"Nairooz Nilafdeen",

DateTimeOffset.Now.AddMinutes(19));

//Get the item from the cache

if (cache.Contains("MyKey"))

{

Console.WriteLine(cache.Get("MyKey"));

}


The caching namespace also allows you to set ChangeMonitors for the cache policy, for an example, you can specify that the cache needs to expire once a file changes or the database query changes..
You can watch for a file and expire the cache after a specified time period (absolute or sliding) or when the file content changes...the code below demonstrates this.

string fileName = @"C:\ERR_LOG.log";

CacheItemPolicy policy = new CacheItemPolicy();

policy.AbsoluteExpiration = DateTimeOffset.Now.AddSeconds(40);

policy.ChangeMonitors.Add(new HostFileChangeMonitor

(new List<string> {fileName }));


cache.Add("FileKey", "Nairooz Nilafdeen", policy);


You can also attach a SqlDependency with the SqlChangeMonitor to expire the cache when a the result of a watched query changes...

SqlDependency dependency = new SqlDependency();

//initialize sql dependency heree...

policy.ChangeMonitors.Add(new SqlChangeMonitor(dependency));

Comments

Popular posts from this blog

Hosting WCF services on IIS or Windows Services?

There came one of those questions from the client whether to use II7 hosting or windows service hosting for WCF services. I tried recollecting a few points and thought of writing it down.
WCF applications can be hosted in 2 main ways- In a Windows service- On IIS 7 and aboveWhen WCF was first released, IIS 6 did not support hosting WCF applications that support Non-HTTP communication like Net.TCP or Net.MSMQ and developers had to rely on hosting these services on Windows Services.With the release of IIS 7, it was possible to deploy these Non-Http based applications also on IIS 7. Following are the benefits of using IIS 7 to host WCF applications
Less development effort
Hosting on Windows service, mandates the creating of a Windows service installer project on windows service and writing code to instantiate the service, whereas the service could just be hosted on IIS by creating an application on IIS, no further development is needed, just the service implementation is n…

Task based Asynchronous pattern, Async & Await and .NET 4.5

One of the key features in .Net 4.5 is to write asynchronous programs much easier. So if I was to write asynchronous programs in .Net 2.0/3.5, I would either follow the event based model or the callback based model. For an example, a synchronous method that does intensive work (say the DoWork()) can be made asynchronous by using the following patterns
1) Implementing the IAsyncResult pattern. in this implementation, 2 methods are exposed for the DoWork() synchronous method, the BeginDoWork() and the EndDoWork() method. The user will call the BeingDoWork() passing in the required parameters and a callback of the delegate type AsyncCallback(IAsyncResult). The BeginDoWork() will spawn a new thread a return control back to the user. Once work is completed in the spawned method, as a last step, it will call the inform the AsyncResult implementation, which in turns will call the EndDoWork() (which is the callback that was passed in to the BeginDoWork()).
2) Implementing the event pattern. Her…

MEF (Managed Extensibility Framework), .NET 4, Dependency Injection and Plug-in Development

Almost after .Net 4 was released I remember reading about MEF (Managed Extensibility Framework), this was a framework for developers to compose their application with required dependencies. At first this looks like the Unity Container used for dependency injection, but MEF is much more than a dependency container but there is nothing stopping you from using MEF as a dependency injector.I remember around 5 years back when I was in a project that created a framework that allows developers to plug-in there modules as WinForm screens. The developer would create a set of screens with the intended functionalities and the drop this component in the bin folder of the framework and then will move on to do some painful configurations for the framework to pick up the module. Dropping the component into the bin folder and doing a bit of configuration is all that s needed for the framework to pick up display the screens. Typically, the configurations would also contain metadata about the screen.Al…