Use of BAL in 3 tier architecture?How to call methods from DAL to BAL

I am a newbie to 3 tier architecture and below is my DAL code

public static int Insert(string firstname, string lastname, DateTime dob, string gender,string email, string password)
    {
        // bool flag = false;
        SqlParameter pid;
        SqlParameter result;

        SqlConnection con = Generic.DBConnection.OpenConnection();

        try
        {

            SqlCommand cmd1 = new SqlCommand("Insertreg", con);
            cmd1.CommandType = CommandType.StoredProcedure;
            cmd1.Parameters.AddWithValue("@FirstName", firstname);
            cmd1.Parameters.AddWithValue("@LastName", lastname);
            cmd1.Parameters.AddWithValue("@Dob", dob);
            cmd1.Parameters.AddWithValue("@Gender", gender);
           cmd1.Parameters.AddWithValue("@EmailId", email);
            cmd1.Parameters.AddWithValue("@Password", password);
            result = cmd1.Parameters.Add("@result", System.Data.SqlDbType.Int);
            result.Direction = System.Data.ParameterDirection.Output;
            pid = cmd1.Parameters.Add("@id", System.Data.SqlDbType.Int);
            pid.Direction = System.Data.ParameterDirection.Output;
            return cmd1.ExecuteNonQuery();


            con.Close();

        }
        catch (Exception ex)
        {
            throw ex;
        }
    }

this in BAL

 public int insert(string firstname,string lastname,DateTime dob,string gender,string email,string password)
    {
      ProfileMasterDAL dal=new ProfileMasterDAL();
      try
      {
          return ProfileMasterDAL.Insert(firstname, lastname, dob, gender,email, password);
      }
      catch (Exception ex)
      {

          throw ex;
      }
        finally
      {
          dal = null;
      }

    }

I my UI

  ProfileMasterBLL pmBLL = new ProfileMasterBLL();
 pmBLL.insert(firstname, lastname, dob, gender, mobile, country, state, email, password);

Is this the correct way to code in 3 tier??I mean how to call methods from DAL to BAL and into UI?If not suggest me some good way.Thanks.

---

Normally I do the following:

Define a Business Layer (BL, you call it BAL). This contains the definitions of you business entities. It also defines interfaces to retrieve/save/delete data for whatever patterns you use (repository, context, etc).

Define a Data Access Layer (DAL). This contains the actual implementation for the retrieve/save/delete interfaces.

Define a UI layer. This contains UI elements (forms, controls, models, controllers, etc), which can use the BL to load data.

The references are the following:

The BL doesn't know the DAL or the UI.

The DAL knows the BL. The DAL does not know the UI.

THe UI knows the BL. The UI does not know the DAL.

The big question for you probably is, how does the BL retrieve/save/delete data when it doesn't know the DAL, and therefore cannot create an instance of a class in the DAL. Well, this is where a little Dependency Injection comes in handy. All you have to wire up is the injection of the DAL-class to the BL-interface.

Hope this makes sense. I use it as my standard 3-tier implementation, and it works absolutely without problems. Specifically, I use Entity Framework with POCO for entities, and the DI I use is a custom one, but any of the ones out there will do.

UPDATE

The BL does not know the DAL.

The BL defines an interface (lets call it IRepository) which it can use to do what it needs to do.

The DAL defines a class (Repository) which implements the interface IRepository. So the actual implementation of the repository is in the DAL.

Obviously the BL cannot create an instance of the repository directly. This is where dependency injection comes in, this allows the developer to create an instance of a class where it normally cannot be done. A simple crude version of this, is to use reflection.

I hope this makes more sense.

---

You can you the following sample code for 3 tier architecture :-

CLASS - BAL.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections;

public class BAL
{
    DAL objDAL;
    public BAL()
    {

    }

    public string _Name;
    public string Name
    {
        get { return _Name; }
        set { _Name = value; }
    }

    public int insert()
    {
        objDAL = new DAL();
        int val = 0;
        try
        {
            Hashtable objHash = new Hashtable();
            objHash.Add("@Name", Convert.ToString(_Name));
            val = objDAL.Insert("Your SP Name", objHash);
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            objDAL = null;
        }
        return val;
    }
}

CLASS - DAL.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Collections;

public class DAL : IDisposable
{
    SqlConnection con;

    public DAL()
    {
        con = new SqlConnection("Connection String");
    }

    public int Insert(string CMD, Hashtable objHash)
    {
        int val = 0;
        try
        {
            SqlCommand cmd1 = new SqlCommand(CMD, con);
            cmd1.CommandType = CommandType.StoredProcedure;
            foreach (DictionaryEntry de in objHash)
            {
                cmd1.Parameters.AddWithValue(Convert.ToString(de.Key), Convert.ToString(de.Value));
            }
            con.Open();
            val = cmd1.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {
            con.Close();
        }
        return val;
    }

    #region IDisposable Members

    public void Dispose()
    {
        throw new NotImplementedException();
    }

    #endregion
}

UI:-

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{

    BAL objBAL;

    protected void Page_Load(object sender, EventArgs e)
    {
        Insert();
    }

    public void Insert()
    {
        int val = 0;
        objBAL = new BAL();
        objBAL.Name = "stackoverflow";
        try
        {
            val = objBAL.insert();
        }
        catch { }
        finally
        {
            objBAL = null;
        }
        if (val != 0)
        {
            //Insert sucessful
        }
        else
        {
            //Error in Insert.
        }
    }
}

Hope this will help full.

---

It might help you to see some actual code. I suggest you download NetTiers, run it against your db schema and see the outputted code for the implementation details.

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