Open the SPFINVWP project in Visual Studio, if it is not already open.

Right-click the SPFINVWP project name, click Add, and then click New Item.

Under Installed Templates, select Visual C#, and then click Interface.

In the Name text box, type TaskInterface.cs, and then click Add.

Replace the code in TaskInterface.cs with the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace SPFINVWP
{
  public interface TaskInterface
  {
    int Id { get; }
    string Name { get; }
  }
}

Right-click the SPFINVWP project name, click Add, and then click New Item.

Under SharePoint 2010, click Web Part. In the Name text box, type ProviderWebPart1, and then click Add.

Replace the code in ProviderWebPart1.cs with the following code:

using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;
namespace SPFINVWP.ProviderWebPart1
{
  [ToolboxItemAttribute(false)]
  public class ProviderWebPart1 : Microsoft.SharePoint.WebPartPages.WebPart,
    TaskInterface
  {
    DropDownList _TaskPicker = null;
    int TaskInterface.Id
    {
      get { return int.Parse(_TaskPicker.SelectedValue); }
    }

    string TaskInterface.Name
    {
      get { return _TaskPicker.SelectedItem.ToString(); }
    }

    protected override void CreateChildControls()
    {
      try
      {
        _TaskPicker = new DropDownList();
        using (SPSite spSite = new SPSite(SPContext.Current.Web.Url))
        using (SPWeb spWeb = spSite.OpenWeb())
        {

          SPList TaskList = spWeb.Lists["Tasks"];

          foreach (SPListItem Task in TaskList.Items)
          {
            _TaskPicker.Items.Add(new ListItem(Task.Name, Task.ID.ToString()));
          }
        }
        _TaskPicker.AutoPostBack = true;

        this.Controls.Add(_TaskPicker);
      }
      catch (Exception ex)
      {
        this.Controls.Clear();
        this.Controls.Add(new LiteralControl(ex.Message));
      }

    }

    [ConnectionProvider("Task Name and ID")]
    public TaskInterface ReturnThis()
    {
      return this;
    }
  }
}

Right-click the SPFINVWP project name, click Add, and then click New Item.

Under SharePoint 2010, click Web Part. In the Name text box, type ConsumerWebPart1, and then click Add.

Replace the code in ConsumerWebPart1.cs with the following:

using System;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using Microsoft.SharePoint;
using Microsoft.SharePoint.WebControls;

namespace SPFINVWP.ConsumerWebPart1
{
    [ToolboxItemAttribute(false)]
    public class ConsumerWebPart1 : WebPart
    {
        TaskInterface _provider = null;
        Label _lbl = null;

        protected override void CreateChildControls()
        {
            try
            {
                _lbl = new Label();

                if (_provider != null)
                {
                    if (_provider.Id > 0)
                    {
                        _lbl.Text = _provider.Name + " was selected.";
                    }
                    else
                    {
                        _lbl.Text = "Nothing was selected.";
                    }
                }
                else
                {
                    _lbl.Text = "No Provider Web Part Connected.";
                }
                this.Controls.Add(_lbl);
           }
          catch (Exception ex)
          {
              this.Controls.Clear();
              this.Controls.Add(new LiteralControl(ex.Message));
          }
      }

      [ConnectionConsumer("Task Name and ID")]
      public void ReturnProvider(TaskInterface providerInterface)
      {
          _provider = providerInterface;
      }

   }
}

From the Build menu, click Deploy Solution. Correct any errors you might have.

When the deployment has succeeded with no errors, browse to the site you selected for debugging.

Click Site Actions, and then select More Options.

Under Filter By, click Page. Select Web Part Page, and then click Create.

On the New Web Part Page, in the Name text box, type ConnectionWebPartPage, and then click Create.

Add the ConsumerWebPart1 to one of the zones, and then add the ProviderWebPart1 to a different zone.

Click the down-arrow on the ConsumerWebPart1 Web Part title. Click Connections, click Get Task Name And ID From, and then Click ProviderWebPart1.