Hi guys,

I'm building my first enterprise grade solution (at least I'm attempting to make it enterprise grade). I'm trying to follow best practice design patterns but am starting to worry that I might be going too far with abstraction.

I'm trying to build my asp.net webforms (in C#) app as an n-tier application. I've created a Data Access Layer using an XSD strongly-typed dataset that interfaces with a SQL server backend. I access the DAL through some Business Layer Objects that I've created on a 1:1 basis to the datatables in the dataset (eg, a UsersBLL class for the Users datatable in the dataset). I'm doing checks inside the BLL to make sure that data passed to DAL is following the business rules of the application. That's all well and good. Where I'm getting stuck though is the point at which I connect the BLL to the presentation layer. For example, my UsersBLL class deals mostly with whole datatables, as it's interfacing with the DAL. Should I now create a separate "User" (Singular) class that maps out the properties of a single user, rather than multiple users? This way I don't have to do any searching through datatables in the presentation layer, as I could use the properties created in the User class. Or would it be better to somehow try to handle this inside the UsersBLL?

Sorry if this sounds a little complicated... Below is the code from the UsersBLL:

using System;
using System.Data;
using PedChallenge.DAL.PedDataSetTableAdapters;

[System.ComponentModel.DataObject]
public class UsersBLL
{
    private UsersTableAdapter _UsersAdapter = null;
    protected UsersTableAdapter Adapter
    {
        get
        {
            if (_UsersAdapter == null)
                _UsersAdapter = new UsersTableAdapter();

            return _UsersAdapter;
        }
    }


    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Select, true)]
    public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsers()
    {
        return Adapter.GetUsers();
    }

    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Select, false)]
    public PedChallenge.DAL.PedDataSet.UsersDataTable GetUserByUserID(int userID)
    {
        return Adapter.GetUserByUserID(userID);
    }

    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Select, false)]
    public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsersByTeamID(int teamID)
    {
        return Adapter.GetUsersByTeamID(teamID);
    }


    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Select, false)]
    public PedChallenge.DAL.PedDataSet.UsersDataTable GetUsersByEmail(string Email)
    {
        return Adapter.GetUserByEmail(Email);
    }


    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Insert, true)]
    public bool AddUser(int? teamID, string FirstName, string LastName, 
        string Email, string Role, int LocationID)
    {
        // Create a new UsersRow instance
        PedChallenge.DAL.PedDataSet.UsersDataTable Users = new PedChallenge.DAL.PedDataSet.UsersDataTable();
        PedChallenge.DAL.PedDataSet.UsersRow user = Users.NewUsersRow();

        if (UserExists(Users, Email) == true)
            return false;


        if (teamID == null) user.SetTeamIDNull();
        else user.TeamID = teamID.Value;
        user.FirstName = FirstName;
        user.LastName = LastName;
        user.Email = Email;
        user.Role = Role;
        user.LocationID = LocationID;

        // Add the new user
        Users.AddUsersRow(user);
        int rowsAffected = Adapter.Update(Users);

        // Return true if precisely one row was inserted,
        // otherwise false
        return rowsAffected == 1;
    }

    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Update, true)]
    public bool UpdateUser(int userID, int? teamID, string FirstName, string LastName,
        string Email, string Role, int LocationID)
    {
        PedChallenge.DAL.PedDataSet.UsersDataTable Users = Adapter.GetUserByUserID(userID);
        if (Users.Count == 0)
            // no matching record found, return false
            return false;

        PedChallenge.DAL.PedDataSet.UsersRow user = Users[0];

        if (teamID == null) user.SetTeamIDNull();
        else user.TeamID = teamID.Value;
        user.FirstName = FirstName;
        user.LastName = LastName;
        user.Email = Email;
        user.Role = Role;
        user.LocationID = LocationID;

        // Update the product record
        int rowsAffected = Adapter.Update(user);

        // Return true if precisely one row was updated,
        // otherwise false
        return rowsAffected == 1;
    }

    [System.ComponentModel.DataObjectMethodAttribute
        (System.ComponentModel.DataObjectMethodType.Delete, true)]
    public bool DeleteUser(int userID)
    {
        int rowsAffected = Adapter.Delete(userID);

        // Return true if precisely one row was deleted,
        // otherwise false
        return rowsAffected == 1;
    }

    private bool UserExists(PedChallenge.DAL.PedDataSet.UsersDataTable users, string email)
    {
        // Check if user email already exists
        foreach (PedChallenge.DAL.PedDataSet.UsersRow userRow in users)
        {
            if (userRow.Email == email)
                return true;
        }
        return false;
    }
}

Some guidance in the right direction would be greatly appreciated!!

Thanks all!

Max