Proxy Design Pattern C#

This short article shows you how to build Proxy Design Pattern using C#.

The design pattern define as an object representing another object by


The logical model for Proxy Design Pattern as following.


The key class in this pattern is the Proxy class.

The first class to create is the Subject Interface class. This class defines the common interface for RealSubject and Proxy so that a Proxy can be used anywhere a RealSubject is expected.

interface Subject


    void Request();



Inherit the Subject class to create Proxy class. This class maintains a reference that lets the proxy access the real subject. Proxy may refer to a Subject if the RealSubject and Subject interfaces are the same.

The Proxy class provides an interface identical to Subject’s so that a proxy can be substituted for the real subject and controls access to the real subject and may be responsible for creating and deleting it.

The other responsibilites depend on the kind of proxy:

·         remote proxies are responsible for encoding a request and its arguments and for sending the encoded request to the real subject in a different address space.

·         virtual proxies may cache additional information about the real subject so that they can postpone accessing it. For example, the ImageProxy from the Motivation caches the real images’s extent.

·         protection proxies check that the caller has the access permissions required to perform a request.


class Proxy : Subject


    private RealSubject _realSubject;


    public void Request()


        // Use ‘lazy initialization’

        if (_realSubject == null)


            _realSubject = new RealSubject();






Lastly create the RealSubject class to define the real object that the proxy represents.

class RealSubject : Subject


    //public override void Request()

    public void Request()


        Console.WriteLine(“Called RealSubject.Request()”);




The main method as below:

static void Main()


    // Create proxy and request a service

    Proxy proxy = new Proxy();



    // Wait for user




You can also download a single solution from The sample file name is My MSN ID is

About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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