Since we have a good idea of what the application is, the next step is to develop the business objects or model layer of this application. Let's start out by defining a few classes that would contain the data to be used throughout the app. It is recommended, for the sake of organization, to add these to a Models folder in your project.

Let's begin with a class representing a user. The class can be created as follows:

public class User
{
  public int Id { get; set; }

  public string Username { get; set; }

  public string Password { get; set; }
}

Pretty straightforward so far; let's move on to create classes representing a conversation and a message as follows:

public class Conversation
{
  public int Id { get; set; }

  public int UserId { get; set; } 

  public string Username { get; set; }
}

public class Message
{
  public int Id { get; set; }

  public int ConversationId { get; set; }

  public int UserId { get; set; } 

  public string Username { get; set; }

  public string Text { get; set; }
}

Notice that we are using integers as identifiers for the various objects. UserId is the value that would be set by the application to change the user that the object is associated with.

Now let's go ahead and set up our solution by performing the following steps: