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SurrogateSelector Class

Assists formatters in selection of the serialization surrogate to delegate the serialization or deserialization process to.

Namespace:  System.Runtime.Serialization
Assembly:  mscorlib (in mscorlib.dll)

public class SurrogateSelector : ISurrogateSelector

A serialization surrogate gives the users an object that can handle the serialization requirements of a different object and can transform the serialized data if necessary.

The following code example shows how to make a serialization surrogate class that knows how to properly serialize or deserialize a class that is not itself serializable. In addition, this example also shows how to recover from a SerializationException.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters;
using System.Runtime.Serialization.Formatters.Binary;

// This class is not serializable. 
class Employee 
    public String name, address;

    public Employee(String name, String address) 
    { = name;
        this.address = address;

// This class can manually serialize an Employee object. 
sealed class EmployeeSerializationSurrogate : ISerializationSurrogate 

    // Serialize the Employee object to save the object�s name and address fields. 
    public void GetObjectData(Object obj, 
        SerializationInfo info, StreamingContext context) 

        Employee emp = (Employee) obj;
        info.AddValue("address", emp.address);

    // Deserialize the Employee object to set the object�s name and address fields. 
    public Object SetObjectData(Object obj,
        SerializationInfo info, StreamingContext context,
        ISurrogateSelector selector) 

        Employee emp = (Employee) obj; = info.GetString("name");
        emp.address = info.GetString("address");
        return null;

public sealed class App 
    static void Main() 
        // This sample uses the BinaryFormatter.
        IFormatter formatter = new BinaryFormatter();

        // Create a MemoryStream that the object will be serialized into and deserialized from. 
        using (Stream stream = new MemoryStream()) 
            // Create a SurrogateSelector.
            SurrogateSelector ss = new SurrogateSelector();

            // Tell the SurrogateSelector that Employee objects are serialized and deserialized  
            // using the EmployeeSerializationSurrogate object.
            new StreamingContext(StreamingContextStates.All),
            new EmployeeSerializationSurrogate());

            // Associate the SurrogateSelector with the BinaryFormatter.
            formatter.SurrogateSelector = ss;

                // Serialize an Employee object into the memory stream.
                formatter.Serialize(stream, new Employee("Jeff", "1 Microsoft Way"));
            catch (SerializationException e) 
                Console.WriteLine("Serialization failed: {0}", e.Message);

            // Rewind the MemoryStream.
            stream.Position = 0;

                // Deserialize the Employee object from the memory stream.
                Employee emp = (Employee) formatter.Deserialize(stream);

                // Verify that it all worked.
                Console.WriteLine("Name = {0}, Address = {1}",, emp.address);
            catch (SerializationException e) 
                Console.WriteLine("Deserialization failed: {0}", e.Message);

// This code produces the following output. 
// Name = Jeff, Address = 1 Microsoft Way

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0