WCF How to make DataContract for an external class
<p>I want to use an already existing class from an other solution in my wcf service. So I have to add DataContract to it. </p>

<p>What is the best way of achieving this? 
I heard DataContract Surrogate would be a way but I don't really get how I have to use it.</p>

<p><strong>existing class</strong></p>

<pre><code>public class Person
{
    public string Name{get; set;}
    public long Size{get; set;}
    public DateTime Birthdate{get; set;}

    public Person(string name, long size, DateTime birthdate)
    {
        this.Name = name;
        this.Size = size;
        this.Birthdate = birthdate;
    }
}
</code></pre>

<p>That is how the external class looks like. Could someone show me an example how I have to put it in my wcf service.</p>

<p><strong>EDIT</strong></p>

<p>I have a windows service in which I have this class Person. My method in the windows service returns a list of Persons so <code>List&lt;Person&gt;</code>. Now I am trying to pass this list to my wcf service. Therefore I need to add DataContract to that class. Do I have to write a new class in the wcf service or can I hand over my class form the windows service. </p>