Simple NHibernate Architecture

using System;
using System.Data;
using System.Collections.Generic;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using Business;

public partial class _Default : System.Web.UI.Page 
{
	private Product _product
	{
		get { return (Product) Session["Product"];}
		set { Session["Product"] = value; }
	}
    protected void Page_Load(object sender, EventArgs e)
    {
		if (!this.IsPostBack)
		{			
			Bind();
		}
    }

	protected override void OnInit(EventArgs e)
	{
		base.OnInit(e);
		this.gvProduct.RowEditing +=new GridViewEditEventHandler(gvProduct_RowEditing);
		this.gvProduct.RowDeleting += new GridViewDeleteEventHandler(gvProduct_RowDeleting);
		this.btnSave.Click += new EventHandler(btnSave_Click);
	}

	void btnSave_Click(object sender, EventArgs e)
	{
		if (_product == null)
			_product = new Product();
		_product.Name = txtName.Text;
		_product.Weight = Convert.ToDecimal(txtWeight.Text);
		_product.Save();
		ClearFields();
		Bind();
	}

	void gvProduct_RowDeleting(object sender, GridViewDeleteEventArgs e)
	{
		Product product = Product.Get(Convert.ToInt32(gvProduct.DataKeys[e.RowIndex].Value));
		product.Delete();
		Bind();
	}

	void gvProduct_RowEditing(object sender, GridViewEditEventArgs e)
	{
		_product = Product.Get(Convert.ToInt32( gvProduct.DataKeys[e.NewEditIndex].Value ));
		txtName.Text = _product.Name;
		txtWeight.Text = _product.Weight.ToString();
	}

	private void Bind()
	{
		gvProduct.DataSource = Product.Select();
		gvProduct.DataKeyNames = new string[] { "ID" };
		gvProduct.DataBind();
	}

	private void ClearFields()
	{
		txtName.Text = "";
		txtWeight.Text = "";
		_product = null;
	}
}