Communication between Web Parts

Following steps describes how to create two Web Parts that can communicate with each other:
1) Create a Contract create class.
ITextContract.cs

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

namespace ConsumerProviderWebPart
{
    public interface ITextContract
    {
        string CustomerName { get;set; }
    }
}

2) Create a Provider class.

Provider.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace ConsumerProviderWebPart
{
    public class Provider : WebPart, ITextContract
    {
        TextBox tb = new TextBox();
        Button btn = new Button();

        protected override void CreateChildControls()
        {
            btn.Text = "Click Me";
            btn.Click += new EventHandler(btn_Click);

            tb.Text = "Avinash";
            CustomerName = tb.Text;

            this.Controls.Add(tb);
            this.Controls.Add(btn);
        }

        protected override void Render(HtmlTextWriter writer)
        {
            EnsureChildControls();
            RenderChildren(writer);
        }

        void btn_Click(object sender, EventArgs e)
        {
            CustomerName = tb.Text;
        }

        [ConnectionProvider("Customer Provider")]
        public ITextContract ProvideCustomerCommunicationPoint()
        {
            return this as ITextContract;
        }

        #region ITextContract Members

        private string _CustomerName = "";

        public string CustomerName
        {
            get
            {
                return _CustomerName;
            }
            set
            {
                _CustomerName = value;
            }
        }

        #endregion
    }
}

3) Create a Consumer class.

Consumer.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;

namespace ConsumerProviderWebPart
{
    public class Consumer : WebPart
    {
        private ITextContract providerWebPart;

        [ConnectionConsumer("Customer Consumer")]
        public void ReceiveCustomerName(ITextContract provider)
        {
            providerWebPart = provider;
        }

        protected override void Render(HtmlTextWriter writer)
        {
            if (providerWebPart != null)
                writer.Write("Value provided is : " + providerWebPart.CustomerName);
            base.Render(writer);
        }
    }
}

4) Strong-named the project.
5) Register the dll in GAC.
6) Make entry in your site web.config file.

web.config

<SafeControl Assembly="ConsumerProviderWebPart, Version=1.0.2713.19492, Culture=neutral, PublicKeyToken=f565ecbfa7f79652" Namespace="ConsumerProviderWebPart" TypeName="*" Safe="True" />

7) Create Provider.webpart file.

Provider.webpart

<?xml version="1.0" encoding="utf-8"?>
<webParts>
  <webPart xmlns="http://schemas.microsoft.com/WebPart/v3">
    <metaData>
      <type name="ConsumerProviderWebPart.Provider" />
      <importErrorMessage>Cannot import this Web Part.</importErrorMessage>
    </metaData>
    <data>
      <properties>
        <property name="Title" type="string">Provider</property>
        <property name="Description" type="string">Provider Web Part.</property>
      </properties>
    </data>
  </webPart>
</webParts>

8) Create Cosumer.webpart file.
Consumer.webpart

<?xml version="1.0" encoding="utf-8"?>
<webParts>
  <webPart xmlns="http://schemas.microsoft.com/WebPart/v3">
    <metaData>
      <type name="ConsumerProviderWebPart.Consumer" />
      <importErrorMessage>
        Cannot import this Web Part.
      </importErrorMessage>
    </metaData>
    <data>
      <properties>
        <property name="Title" type="string">Consumer</property>
        <property name="Description" type="string">Consumer Web Part.</property>
      </properties>
    </data>
  </webPart>
</webParts>

9) Add both Provider and Consumer web parts in your site.
10) Establish connections between Provider and Consumer web part as shown in following snapshots:

Provider connection:



Consumer connection:



11) Test communication between two web parts by writing some text in Provider’s text box. Then press Provider’s button.



12) Typed text gets displayed in Consumer web part.



Suggested Links:
1) Custom Web Part Connections in SharePoint 2007
http://ablog.apress.com/?p=1300