How to Persist the dependencies across postbacks in a Web application using Unity ?

Question

This link for unity framework on msdn states "You want to be able to cache or persist the dependencies across postbacks in a Web application"

http://msdn.microsoft.com/en-us/library/dd203319.aspx#

I am not sure what all the above statement means. I am looking for an example how we can do this using Unity - not sure how Unity will resolve postbacks. Will it just persist dependency in session and retrieve it back ?

Answer 1

I have written a short example of using Session and also using Cache. I have created a test class called incrementer which is very similar to if I made the class static or at least the variable. RegisterInstance is for a Singleton Resolve

    public class Incrementer
{
    private int count;

    private object synclock = new object();

    public int GetCount()
    {
        return count;
    }

    public void Increment()
    {
        System.Threading.Monitor.Enter(synclock);
        count++;
        System.Threading.Monitor.Exit(synclock);
    }
}

public IUnityContainer SessionUnityContainer
{
    get
    {
        if (Session["SharedIncrementer"] == null)
        {
            IUnityContainer container = new UnityContainer();
            container.RegisterInstance<Incrementer>(new Incrementer());
            Session["SharedIncrementer"] = container;
        }
        return Session["SharedIncrementer"] as IUnityContainer;
    }
}

public IUnityContainer CacheUnityContainer
{
    get
    {
        if (Cache["SharedIncrementer"] == null)
        {
            IUnityContainer container = new UnityContainer();
            container.RegisterInstance<Incrementer>(new Incrementer());
            Cache["SharedIncrementer"] = container;
        }
        return Cache["SharedIncrementer"] as IUnityContainer;
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    Incrementer i1 = SessionUnityContainer.Resolve<Incrementer>();
    Incrementer i2 = CacheUnityContainer.Resolve<Incrementer>();

    for (int i = 0; i < 10; i++)
        i1.Increment();

    for (int i = 0; i < 5; i++)
        i2.Increment();

    Response.Write(i1.GetCount().ToString());
    Response.Write(i2.GetCount().ToString());
}

Hope tihs helps:

Andrew

EDIT: The following example cimply uses a singleton instance of the UnityContainer and if you keep refreshing the page will see it persisting the values previous.

public class Incrementer
{
    private int count;

    private object synclock = new object();

    public int GetCount()
    {
        return count;
    }

    public void Increment()
    {
        System.Threading.Monitor.Enter(synclock);
        count++;
        System.Threading.Monitor.Exit(synclock);
    }
}

public static class ExampleSettings
{
    private static IUnityContainer container = null;

    public static IUnityContainer Container
    {
        get
        {
            if (container == null)
            {
                container = new UnityContainer();
                container.RegisterInstance<Incrementer>(new Incrementer());
            }
            return container;
        }
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    Incrementer i1 = ExampleSettings.Container.Resolve<Incrementer>();

    for (int i = 0; i < 10; i++)
        i1.Increment();

    Response.Write(i1.GetCount().ToString());
}