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ICellProvider Interface

NOTE: This API is now obsolete.

Enables a Web Part to communicate with a Web Part that implements the ICellConsumer interface to work with a single value item.

Namespace:  Microsoft.SharePoint.WebPartPages.Communication
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)

Syntax

<ObsoleteAttribute("Use System.Web.UI.WebControls.WebParts.IWebPartField instead")> _
Public Interface ICellProvider

Dim instance As ICellProvider
[ObsoleteAttribute("Use System.Web.UI.WebControls.WebParts.IWebPartField instead")]
public interface ICellProvider

Remarks

The ICellProvider interface should be used with Web Parts that need to pass a single value to an ICellConsumer Web Part. It can be used in scenarios where the consumer Web Part was written to handle the type of data being passed by the provider Web Part. The ICellProvider interface supports the ability to send and receive initialization arguments, which allows an ICellProvider Web Part to dynamically change its user interface to better fit the needs of the consumer part. An ICellProvider interface can be connected only to an ICellConsumer interface. When connecting an ICellProvider Web Part to an ICellConsumer Web Part, a direct connection must be used so no transformer dialog box will be displayed.

Examples

That implements the ICellProvider interface and supports running its connections code only on the server (ConnectionRunAt.Server). This Web Part can be connected to one or more Web Parts which implement the ICellConsumer interface on the server. This Web Part's user interface displays a simple text box and button. When the button is clicked, the Web Part passes the "cell" value in its text box to all other Web Parts which are connected to it.

A connectable Web Part. These steps are numbered and commented in the code example.

That implements the ICellProvider interface and supports running its connections code only on the client (ConnectionRunAt.Client). This Web Part can be connected to one or more Web Parts which implement the ICellConsumer interface on the client. This Web Part's user interface displays a simple text box and button. When the button is clicked, the Web Part passes the "cell" value in its text box to all other Web Parts which are connected to it.

A connectable Web Part. These steps are numbered and commented in the code example.

For an overview of the steps of creating a connectable Web Part, see Creating a Connectable Web Part.

' Common .NET required namespaces
Imports System
Imports System.ComponentModel
Imports System.Web.UI

' Web Part required namespaces
Imports Microsoft.SharePoint.WebPartPages
Imports System.Xml.Serialization
Imports System.Web.UI.WebControls

' Code Access Security namespaces
Imports System.Security
Imports Microsoft.SharePoint.Utilities

' Step #1: Make a reference to the Communication namespace
Imports Microsoft.SharePoint.WebPartPages.Communication

Namespace ConnectionCodeSamples
   ' Step #2: Inherit from the WebPart base class and implement 
   ' the ICellProvider interface.
   
   Public Class ServerSideCellProvider
      Inherits WebPart
      Implements ICellProvider
      
      ' Step #3: Declare the ICellProvider events.
      ' Because this class implements the ICellProvider interface, 
      ' it must 
      ' implement the interface member events CellProviderInit and 
      ' CellReady.
      Public Event CellProviderInit As CellProviderInitEventHandler 
         Implements ICellProvider.CellProviderInit
      Public Event CellReady As CellReadyEventHandler Implements 
         ICellProvider.CellReady
      
      ' Declare variables for keeping track of the connection state.
      Private _connected As Boolean = False
      Private _connectedWebPartTitle As String = String.Empty
      Private _connectedField As String = String.Empty
      Private _registrationErrorMsg As String = "An error has occurred 
         trying to register your connection interfaces."
      Private _registrationErrorOccurred As Boolean = False
      Private _notConnectedMsg As String = "NOT CONNECTED. To use this 
         Web Part, connect it to a server-side Cell Consumer Web Part."
      
      ' Declare variables for cell field names.
      Private _cellName As String = "ProvideCell"
      Private _cellDisplayName As String = "Provide Cell"
      
      ' Declare variables for the Web Part user interface.
      Private _cellButton As Button
      Private _cellInput As TextBox
      Private _connectedWebPartLabel As String = "Connected to Web 
         Part"
      Private _connectedFieldLabel As String = "Send to Field"
      Private _cellClicked As Boolean = False
       'Keep track of whether button is clicked
 
     ' Step #4: Override the EnsureInterfaces() method and call the 
     ' RegisterInterface method.
      Public Overrides Sub EnsureInterfaces()
         ' If your Web Part is installed in the bin directory and the 
         ' Code Access Security (CAS) setting doesn't 
         ' allow Web Part Connections, an exception will be thrown. To 
         ' allow your Web Part to behave 
         ' well and continue working, a try/catch block should be used 
         ' when attempting to register interfaces.
         ' Web Part Connections will only work if the level attribute 
         ' of the <trust> tag in the web.config file is set to 
         ' WSS_Minimal, WSS_Medium, or Full. By default a new 
         ' SharePoint site is installed with the trust level set to 
         ' WSS_Minimal.
         Try
            ' Register the ICellProvider Interface
            ' <param name="interfaceName">Friendly name of the 
            ' interface that is being implemented.
            ' It must be unique on the client so the _WPQ_ token is 
            ' used.</param>
            ' <param name="interfaceType">Specifies which interface is 
            ' being implemented.</param>
            ' <param name="maxConnections">Defines how many times this 
            ' interface can be connected.</param>
            ' <param name="runAtOptions">Determines where the interface 
            ' can run.</param>
            ' <param name="interfaceObject">Reference to the object 
            ' that is implementing this interface.</param>
            ' <param name="interfaceClientReference">Name used to 
            ' reference the interface on the client. 
            ' It must be unique on the client so the _WPQ_ token is 
            ' used.</param>
            ' <param name="menuLabel">Label for the interface that 
            ' appears in the UI</param>
            ' <param name="description">Description of the interface 
            ' that appears in the UI</param>
            ' <param name="allowCrossPageConnection">Specifies if the 
            ' interface can connect to a Web Part on a different page. 
            ' This is an optional parameter with a default of false. 
            ' Note that only some server side interfaces are allowed to 
            ' connect across pages by the Web Part Infrastructure. 
            ' The ICellProvider interface is not allowed to connect 
            ' across pages.</param>
            RegisterInterface("MyCellProviderInterface_WPQ_", 
               InterfaceTypes.ICellProvider, WebPart.UnlimitedConnections, 
               ConnectionRunAt.Server, Me, "CellProviderInterface_WPQ_", 
               "Provide Cell To", "Provides a single value to a cell 
               consumer Web Part.") 

         Catch se As SecurityException
            _registrationErrorOccurred = True
         End Try
      End Sub
      
      ' Step #6: Override the CanRunAt() method.
      ' The CanRunAt method is called by the Web Part infrastructure 
      ' during the ASP.NET PreRender event to determine where the Web 
      ' Part can run based on its current configuration.
      Public Overrides Function CanRunAt() As ConnectionRunAt
         'This Web Part can run on the server.
         Return ConnectionRunAt.Server
      End Function
      
      ' Step #7: Override the PartCommunicationConnect() method.
      ' The PartCommunicationConnect method is called by the Web Part 
      ' infrastructure to notify the Web Part that it
      ' is connected during the ASP.NET PreRender event. Relevant 
      ' information is passed to the part such as 
      ' the interface it is connected over, the Web Part it is being 
      ' connected to, and where the part will be running, 
      ' either client or server side. 
      ' <param name="interfaceName">Friendly name of the interface that 
      ' is being connected</param>
      ' <param name="connectedPart">Reference to the other Web Part 
      ' that is being connected to</param>
      ' <param name="connectedInterfaceName">Friendly name of the 
      ' interface on the other Web Part</param>
      ' <param name="runAt">Where the interface should execute</param>
      Public Overrides Sub PartCommunicationConnect(interfaceName As 
         String, connectedPart As WebPart, connectedInterfaceName As 
         String, runAt As ConnectionRunAt)
         ' Keep track of whether the Web Part is connected or not.
         If interfaceName = "MyCellProviderInterface_WPQ_" Then
            _connected = True
            _connectedWebPartTitle = SPEncode.HtmlEncode(connectedPart.Title)
         End If
      End Sub
      
      ' Step #8: Implement the CellConsumerInit event handler.
      ' The connected consumer part(s) will call this method during its 
      ' PartCommunicationInit phase
      ' to pass initialization information to this provider Web Part.
      ' <param name="sender">Reference to the Consumer Web Part</param>
      ' <param name="cellConsumerInitEventArgs">The argument data 
      ' structure passed by the Consumer Web Part</param>
      Public Sub CellConsumerInit(sender As Object, 
         cellConsumerInitEventArgs As CellConsumerInitEventArgs) 
         Implements ICellProvider.CellConsumerInit
         'Encode and store the field display name.
         _connectedField = SPEncode.HtmlEncode(cellConsumerInitEventArgs.FieldDisplayName)
      End Sub
      
      ' Step #9: Override the PartCommunicationInit() method
      ' PartCommunicationInit() is called by the Web Part 
      ' infrastructure during the ASP.NET PreRender 
      ' event to allow the part to pass initialization information to 
      ' the other connected parts.
      ' It is important to always pass initialization information as 
      ' some parts may not behave properly if this initialization 
      ' information is not received.
      Public Overrides Sub PartCommunicationInit()
        ' Check if connected
         If _connected Then 
           ' Create the InitEventArgs structure for the 
           ' CellProviderInit event.
            Dim cellProviderInitArgs As New CellProviderInitEventArgs()

            ' Set the FieldName and FieldDisplay values.
             cellProviderInitArgs.FieldName = _cellName
             cellProviderInitArgs.FieldDisplayName = _cellDisplayName

            ' Fire the CellProviderInit event. 
            RaiseEvent CellProviderInit(Me, cellProviderInitArgs)

          End If
      End Sub
      
      ' Step #10: Override the PartCommunicationMain() method.
      ' The PartCommunicationMain method is called by the Web Part 
      ' infrastructure on the client during 
      ' the ASP.NET PreRender event to allow the part to pass its 
      ' primary data to the other connected parts.
      ' It is important to always fire the CellReady event. Some parts
      ' may not behave properly if they are left waiting for this 
      ' information.
      Public Overrides Sub PartCommunicationMain()
            ' Check if connected.
            If _connected Then
                ' Create the CellReadyEventArgs data structure for the 
                ' CellProviderInit event.
                Dim cellReadyArgs As New CellReadyEventArgs()

                ' If the user clicked the button, then send the value.
                If _cellClicked Then
                    ' Set the cell to the value of the TextBox text
                    ' This is the value that will be sent to the 
                    ' Consumer
                    cellReadyArgs.Cell = _cellInput.Text
                Else
                    ' The user didn't actually click the button
                    ' so just send an empty string to the consumer.
                    cellReadyArgs.Cell = ""
                End If

                ' Fire the CellReady event.
                ' The Consumer will receive the cell value in its 
                ' CellReady event handler
                RaiseEvent CellReady(Me, cellReadyArgs)
            End If
        End Sub
      
      Protected Overrides Sub RenderWebPart(output As HtmlTextWriter)
         
         ' Check for connection interface registration error.
         If _registrationErrorOccurred Then
            output.Write(_registrationErrorMsg)
            Return
         End If
         
         ' Ensure that all of the Web Part's controls are created
         EnsureChildControls()
         
         ' Render HTML and controls if connected
         If _connected Then
            ' Render the cell label.
            output.RenderBeginTag(HtmlTextWriterTag.B)
            output.Write((_cellDisplayName + ": "))
            output.RenderEndTag()
            
            ' Render the TextBox control.
            _cellInput.RenderControl(output)
            
            ' Render the Button control.
            _cellButton.RenderControl(output)
            
            ' Line Break
            output.RenderBeginTag(HtmlTextWriterTag.Br)
            output.RenderEndTag()
            
            ' Render the connected Web Part's title.
            output.Write((_connectedWebPartLabel + ": "))
            output.RenderBeginTag(HtmlTextWriterTag.I)
            output.Write(_connectedWebPartTitle)
            output.RenderEndTag()
            output.Write("<br>")
            
            ' Render the connected Web Part's field name.
            output.Write((_connectedFieldLabel + ": "))
            output.RenderBeginTag(HtmlTextWriterTag.I)
            output.Write(_connectedField)
            output.RenderEndTag()
         
         Else
            ' The Web Part isn't connected
            output.Write(_notConnectedMsg)
         End If
      End Sub
      
      ' Override the CreateChildControls method to create the
      ' Web Part's user interface controls.
      Protected Overrides Sub CreateChildControls()
         ' Create the Button.
         _cellButton = New Button()
         _cellButton.ID = "CellButton"
         _cellButton.Text = "Fire CellReady"
         Controls.Add(_cellButton)
         
         ' Create the TextBox.
         _cellInput = New TextBox()
         _cellInput.ID = "CellInput"
         Controls.Add(_cellInput)
         
         ' Initialize to false -- user hasn't clicked the button yet
         _cellClicked = False
         
         ' Listen for the cell button's Click event.
         AddHandler _cellButton.Click, AddressOf CellButtonClicked
      End Sub
      
      
      ' Handle the cell button's Click event.
      Private Sub CellButtonClicked(sender As Object, e As EventArgs)
         ' User clicked button, set to true
         _cellClicked = True
      End Sub
   End Class
End Namespace
// Common .NET required namespaces
using System;
using System.ComponentModel;
using System.Web.UI;

// Web Part required namespaces
using Microsoft.SharePoint.WebPartPages;
using System.Xml.Serialization;
using System.Web.UI.WebControls;

// Code Access Security namespaces
using System.Security;
using Microsoft.SharePoint.Utilities;

// Step #1: Make a reference to the Communication namespace
using Microsoft.SharePoint.WebPartPages.Communication;

namespace ConnectionCodeSamples
{
    // Step #2: Inherit from the WebPart base class and implement 
    // the ICellProvider interface.
    public class ServerSideCellProvider : WebPart, ICellProvider
    {    
        
        // Step #3: Declare the ICellProvider events.
        // Because this class implements the ICellProvider interface, 
        // it must 
        // implement the interface member events CellProviderInit and 
        // CellReady.
        public event CellProviderInitEventHandler CellProviderInit;    
        public event CellReadyEventHandler CellReady;                

        // Declare variables for keeping track of the connection state.
        private bool _connected = false;
        private string _connectedWebPartTitle = string.Empty;
        private string _connectedField = string.Empty;
        private string _registrationErrorMsg = "An error has occurred 
           trying to register your connection interfaces.";
        private bool _registrationErrorOccurred = false;
        private string _notConnectedMsg = "NOT CONNECTED. To use this 
           Web Part, connect it to a server-side Cell Consumer Web 
           Part.";

        // Declare variables for cell field names.
        private string _cellName = "ProvideCell";
        private string _cellDisplayName = "Provide Cell";

        // Declare variables for the Web Part user interface.
        private Button _cellButton;    
        private TextBox _cellInput;
        private string _connectedWebPartLabel = "Connected to Web 
           Part";
        private string _connectedFieldLabel = "Send to Field";
        private bool _cellClicked = false;  //keep track of whether button is clicked
        
        // Step #4: Override the EnsureInterfaces() method and call the 
        // RegisterInterface method.
        public override void EnsureInterfaces()
        {
            // If your Web Part is installed in the bin directory and 
            // the Code Access Security (CAS) setting doesn't 
            // allow Web Part Connections, an exception will be thrown. 
            // To allow your Web Part to behave 
            // well and continue working, a try/catch block should be 
            // used when attempting to register interfaces.
            // Web Part Connections will only work if the level 
            // attribute of the <trust> tag in the 
            // web.config file is set to WSS_Minimal, WSS_Medium, or 
            // Full. By default a new SharePoint site
            // is installed with the trust level set to WSS_Minimal.
            try
            {
                // Register the ICellProvider Interface
                // <param name="interfaceName">Friendly name of the 
                // interface that is being implemented.
                // It must be unique on the client so the _WPQ_ token 
                // is used.</param>
                // <param name="interfaceType">Specifies which 
                // interface is being implemented.</param>
                // <param name="maxConnections">Defines how many times 
                // this interface can be connected.</param>
                // <param name="runAtOptions">Determines where the 
                // interface can run.</param>
                // <param name="interfaceObject">Reference to the 
                // object that is implementing this interface.</param>
                // <param name="interfaceClientReference">Name used to 
                // reference the interface on the client. 
                // It must be unique on the client so the _WPQ_ token 
                // is used.</param>
                // <param name="menuLabel">Label for the interface 
                // that appears in the UI</param>
                // <param name="description">Description of the 
                // interface that appears in the UI</param>
                // <param name="allowCrossPageConnection">Specifies if 
                // the interface can connect to a Web Part
                // on a different page. This is an optional parameter 
                // with a default of false. Note that only some 
                // server side interfaces are allowed to connect across 
                // pages by the Web Part Infrastructure. 
                // The ICellProvider interface is not allowed to 
                // connect across pages.</param>
                RegisterInterface("MyCellProviderInterface_WPQ_",            //InterfaceName    
                    InterfaceTypes.ICellProvider,                            //InterfaceType
                    WebPart.UnlimitedConnections,                            //MaxConnections
                    ConnectionRunAt.Server,                                  //RunAtOptions
                    this,                                                    //InterfaceObject
                    "CellProviderInterface_WPQ_",                            //InterfaceClientReference
                    "Provide Cell To",                                       //MenuLabel
                    "Provides a single value to a cell consumer Web Part."); //Description
            }
            catch(SecurityException se)
            {
                _registrationErrorOccurred = true;
            }
        }

        // Step #6: Override the CanRunAt() method.
        // The CanRunAt method is called by the Web Part infrastructure 
        // during the ASP.NET PreRender event
        // to determine where the Web Part can run based on its current 
        // configuration.
        public override ConnectionRunAt CanRunAt()
        {
            //This Web Part can run on the server.
            return ConnectionRunAt.Server;
        }

        // Step #7: Override the PartCommunicationConnect() method.
        // The PartCommunicationConnect method is called by the Web 
        // Part infrastructure to notify the Web Part that it
        // is connected during the ASP.NET PreRender event. Relevant 
        // information is passed to the part such as 
        // the interface it is connected over, the Web Part it is being 
        // connected to, and where the part will be running, 
        // either client or server side. 
        // <param name="interfaceName">Friendly name of the interface 
        // that is being connected</param>
        // <param name="connectedPart">Reference to the other Web Part 
        // that is being connected to</param>
        // <param name="connectedInterfaceName">Friendly name of the 
        // interface on the other Web Part</param>
        // <param name="runAt">Where the interface should 
        // execute</param>
        public override void PartCommunicationConnect(
            string interfaceName,
            WebPart connectedPart,
            string connectedInterfaceName,
            ConnectionRunAt runAt)
        {
            // Keep track of whether the Web Part is connected or not.
            if (interfaceName == "MyCellProviderInterface_WPQ_")
            {
                _connected = true;
                _connectedWebPartTitle = 
                   SPEncode.HtmlEncode(connectedPart.Title);
            }
        }

        // Step #8: Implement the CellConsumerInit event handler.
        // The connected consumer part(s) will call this method during 
        // its PartCommunicationInit phase
        // to pass initialization information to this provider Web 
        // Part.
        // <param name="sender">Reference to the Consumer Web 
        // Part</param>
        // <param name="cellConsumerInitEventArgs">The argument data 
        // structure passed by the Consumer Web Part</param>
        public void CellConsumerInit(object sender, 
           CellConsumerInitEventArgs cellConsumerInitEventArgs)
        {
            //Encode and store the field display name.
            _connectedField = SPEncode.HtmlEncode(cellConsumerInitEventArgs.FieldDisplayName);

        }

        // Step #9: Override the PartCommunicationInit() method
        // PartCommunicationInit() is called by the Web Part 
        // infrastructure during the ASP.NET PreRender 
        // event to allow the part to pass initialization information 
        // to the other connected parts.
        // It is important to always pass initialization information as 
        // some parts
        // may not behave properly if this initialization information 
        // is not received.
        public override void PartCommunicationInit()
        {
            // Check if connected
            if(_connected)
            {
                // If there is a listener, fire the CellProviderInit 
                // event.
                if (CellProviderInit != null)
                {
                    // Create the InitEventArgs structure for the 
                    // CellProviderInit event.
                    CellProviderInitEventArgs cellProviderInitArgs = 
                       new CellProviderInitEventArgs();
                    
                    // Set the FieldName and FieldDisplay values.
                    cellProviderInitArgs.FieldName = _cellName;
                    cellProviderInitArgs.FieldDisplayName = 
                      _cellDisplayName;
                    
                    // Fire the CellProviderInit event.
                    CellProviderInit(this, cellProviderInitArgs);
                }
            }
        }

        // Step #10: Override the PartCommunicationMain() method.
        // The PartCommunicationMain method is called by the Web Part 
        // infrastructure on the client during 
        // the ASP.NET PreRender event to allow the part to pass its 
        // primary data to the other connected parts.
        // It is important to always fire the CellReady event. Some 
        // parts may not behave properly if they are left waiting for 
        // this information.
        public override void PartCommunicationMain()
        {
            // Check if connected.
            if(_connected)
            {
                // If there is a listener, fire the CellReady event.
                if (CellReady != null)
                {
                    // Create the CellReadyEventArgs data structure for 
                    // the CellProviderInit event.
                    CellReadyEventArgs cellReadyArgs = new 
                       CellReadyEventArgs();

                    // If the user clicked the button, then send the 
                    // value.
                    if (_cellClicked)
                    {
                        // Set the cell to the value of the TextBox 
                        // text.
                        // This is the value that will be sent to the 
                        // Consumer
                        cellReadyArgs.Cell = _cellInput.Text;
                    }
                    else
                    {
                        // The user didn't actually click the button
                        // so just send an empty string to the 
                        // consumer.
                        cellReadyArgs.Cell = "";
                    }

                    // Fire the CellReady event.
                    // The Consumer will receive the cell value in its 
                    // CellReady event handler
                    CellReady(this, cellReadyArgs);
                }
            }
        }

        protected override void RenderWebPart(HtmlTextWriter output)
        {
        
            // Check for connection interface registration error.
            if (_registrationErrorOccurred)
            {
                output.Write(_registrationErrorMsg);
                return;
            }

            // Ensure that all of the Web Part's controls are created
            EnsureChildControls();

            // Render HTML and controls if connected
            if(_connected)
            {
                // Render the cell label.
                output.RenderBeginTag(HtmlTextWriterTag.B);
                output.Write(_cellDisplayName + ": ");
                output.RenderEndTag();

                // Render the TextBox control.
                _cellInput.RenderControl(output);

                // Render the Button control.
                _cellButton.RenderControl(output);
                
                // Line Break
                output.RenderBeginTag(HtmlTextWriterTag.Br);
                output.RenderEndTag();

                // Render the connected Web Part's title.
                output.Write(_connectedWebPartLabel + ": ");
                output.RenderBeginTag(HtmlTextWriterTag.I);
                output.Write(_connectedWebPartTitle);
                output.RenderEndTag();
                output.Write("<br>");

                // Render the connected Web Part's field name.
                output.Write(_connectedFieldLabel + ": ");
                output.RenderBeginTag(HtmlTextWriterTag.I);
                output.Write(_connectedField);
                output.RenderEndTag();

            }
            else
            {
                // The Web Part isn't connected
                output.Write(_notConnectedMsg);
            }
        }

        // Override the CreateChildControls method to create the
        // Web Part's user interface controls.
        protected override void CreateChildControls()
        {
            // Create the Button.
            _cellButton = new Button();
            _cellButton.ID = "CellButton";
            _cellButton.Text = "Fire CellReady";
            Controls.Add(_cellButton);
        
            // Create the TextBox.
            _cellInput = new TextBox();
            _cellInput.ID = "CellInput";
            Controls.Add(_cellInput);

            // Initialize to false -- user hasn't clicked the 
            // button yet
            _cellClicked = false; 

            // Listen for the cell button's Click event.
            _cellButton.Click += new EventHandler(CellButtonClicked);
        }

        // Handle the cell button's Click event.
        private void CellButtonClicked(object sender, EventArgs e)
        {
            // User clicked button, set to true
            _cellClicked = true; 
        }
    }
}
' Common .NET required namespaces.
Imports System
Imports System.ComponentModel
Imports System.Web.UI

' WebPart Required namespaces.
Imports Microsoft.SharePoint.WebPartPages
Imports System.Xml.Serialization
Imports System.Web.UI.WebControls

' Code Access Security namespaces.
Imports System.Security
Imports Microsoft.SharePoint.Utilities

'Step #1: Make a Reference to the Communication Namespace
Imports Microsoft.SharePoint.WebPartPages.Communication

Namespace ConnectionCodeSamples
   ' Step #2: Inherit from the WebPart base class and implement the 
   ' ICellProvider interface.
   
   Public Class ClientSideCellProvider
      Inherits WebPart
      Implements ICellProvider
      ' Step #3: Declare the ICellProvider events.
      ' Because this class implements the ICellProvider interface, it 
      ' must declare the interface member events CellProviderInit and 
      ' CellReady. However, because this is a client side Web Part the 
      ' actual code for these events will be implemented 
      ' on the client. See the myInit() and myMain() functions in 
      ' the JavaScript rendered to the client
      ' in the RenderWebPart method.
      Public Event CellProviderInit As CellProviderInitEventHandler 
         Implements ICellProvider.CellProviderInit
      Public Event CellReady As CellReadyEventHandler Implements 
         ICellProvider.CellReady
      
      ' Declare variables for keeping track of the connection state.
      Private _connected As Boolean = False
      Private _connectedWebPartTitle As String = String.Empty
      Private _registrationErrorMsg As String = "An error has occurred 
         trying to register your connection interfaces."
      Private _registrationErrorOccurred As Boolean = False
      Private _notConnectedMsg As String = "NOT CONNECTED. To use this 
         Web Part, connect it to a client-side Cell Consumer Web Part."
      
      ' Step #4: Override the EnsureInterfaces() method and call the 
      ' RegisterInterface method.
      Public Overrides Sub EnsureInterfaces()
         ' If your Web Part is installed in the bin directory and the 
         ' Code Access Security (CAS) setting doesn't 
         ' allow Web Part Connections, an exception will be thrown. To 
         ' allow your Web Part to behave 
         ' well and continue working, a try/catch block should be used 
         ' when attempting to register interfaces.
         ' Web Part Connections will only work if the level attribute 
         ' of the <trust> tag in the web.config file is set to 
         ' WSS_Minimal, WSS_Medium, or Full. By default a new 
         ' SharePoint site
         ' is installed with the trust level set to WSS_Minimal.
         Try
            ' Register the ICellProvider Interface
            ' <param name="interfaceName">Friendly name of the 
            ' interface that is being implemented.
            '    It must be unique on the client so the _WPQ_ token is 
            ' used.</param>
            ' <param name="interfaceType">Specifies which interface is 
            ' being implemented.</param>
            ' <param name="maxConnections">Defines how many times this 
            ' interface can be connected.</param>
            ' <param name="runAtOptions">Determines where the interface 
            ' can run.</param>
            ' <param name="interfaceObject">Reference to the object 
            ' that is implementing this interface.</param>
            ' <param name="interfaceClientReference">Name used to 
            ' reference the interface on the client. 
            ' It must be unique on the client so the _WPQ_ token is 
            ' used.</param>
            ' <param name="menuLabel">Label for the interface that 
            ' appears in the UI</param>
            ' <param name="description">Description of the interface 
            ' that appears in the UI</param>
            ' <param name="allowCrossPageConnection">Specifies if the 
            ' interface can connect to a Web Part
            ' on a different page. This is an optional parameter with a 
            ' default of false. Note that only some 
            ' server side interfaces are allowed to go cross page by 
            ' the Web Part Infrastructure. 
            ' The ICellProvider interface is not allowed to go cross 
            ' page.</param>
            RegisterInterface("MyCellProviderInterface_WPQ_", 
               InterfaceTypes.ICellProvider, 
               WebPart.UnlimitedConnections, ConnectionRunAt.Client, 
               Me, "CellProviderInterface_WPQ_", "Provide Cell To", 
               "Provides a single value to a cell consumer Web Part.")
         Catch se As SecurityException
            _registrationErrorOccurred = True
         End Try
      End Sub
      
      ' Step #6: Override the CanRunAt() method.
      ' The CanRunAt method is called by the Web Part infrastructure 
      ' during the ASP.NET PreRender event
      ' to determine where the Web Part can run based on its current 
      ' configuration.
      Public Overrides Function CanRunAt() As ConnectionRunAt
         ' This Web Part can run on the client.
         Return ConnectionRunAt.Client
      End Function
      
      ' Step #7: Override the PartCommunicationConnect() method.
      ' The PartCommunicationConnect method is called by the Web Part 
      ' infrastructure to notify the Web Part that it
      ' is connected during the ASP.NET PreRender event. Relevant 
      ' information is passed to the part such as 
      ' the interface it is connected over, the Web Part it is being 
      ' conected to, and where the part will be running, 
      ' either client or server side. 
      ' <param name="interfaceName">Friendly name of the interface that 
      ' is being connected</param>
      ' <param name="connectedPart">Reference to the other Web Part 
      ' that is being connected to</param>
      ' <param name="connectedInterfaceName">Friendly name of the 
      ' interface on the other Web Part</param>
      ' <param name="runAt">Where the interface should execute</param>
      Public Overrides Sub PartCommunicationConnect(interfaceName As 
         String, connectedPart As WebPart, connectedInterfaceName As 
         String, runAt As ConnectionRunAt)
         ' Keep track of whether the Web Part is connected or not.
         If interfaceName = "MyCellProviderInterface_WPQ_" Then
            _connected = True
            _connectedWebPartTitle = SPEncode.HtmlEncode(connectedPart.Title)
         End If
      End Sub
      
      ' Step #8: Implement the CellConsumerInit event handler.
      ' The connected consumer part(s) will call this method during its 
      ' PartCommunicationInit phase
      ' to pass initialization information to the provider Web Part.
      ' <param name="sender">Reference to the Consumer Web Part</param>
      ' <param name="cellConsumerInitEventArgs">The args passed by the 
      ' Consumer Web Part</param>
      Public Sub CellConsumerInit(sender As Object, 
         cellConsumerInitEventArgs As CellConsumerInitEventArgs) 
         Implements ICellProvider.CellConsumerInit
      End Sub
      
      ' Because this class implements the ICellProvider interface, it 
      ' must implement the interface member CellConsumerInit. However, 
      ' because this is a client-side Web Part, the actual code for 
      ' this method will be implemented on the client. See the 
      ' myCellConsumerInit() function in the JavaScript rendered to the 
      ' client in the RenderWebPart method.
      
      Protected Overrides Sub RenderWebPart(output As HtmlTextWriter)
         ' Check for connection interface registration error
         If _registrationErrorOccurred Then
            output.Write(_registrationErrorMsg)
            Return
         End If
         
         ' ************* CLIENT-SIDE CONNECTION CODE ***************
         ' Steps 9-11 are implemented in the following client code
         ' 
         ' Step #9: Implement PartCommunicationInit Function (see 
         ' myInit JavaScript Function)
         ' PartCommunicationInit() is called by the Web Part 
         ' infrastructure on the client
         ' to allow the part to pass initialization information to the other connected parts.
         ' It is important to always pass initialization information. 
         ' Some parts
         ' may not behave properly if this initialization information 
         ' is not received.
         ' 
         ' Step #10: Implement PartCommunicationMain Function (see 
         ' myMain JavaScript Function)
         ' PartCommunicationMain() is called by the Web Part 
         ' infrastructure on the client
         ' to allow the part to pass its primary data to the other 
         ' connected parts.
         ' It is important to always fire the CellReady event. Some 
         ' parts may not behave properly if they are left waiting for 
         ' this information.
          
         ' Step #11: Implement CellConsumerInit Function (see 
         ' myCellConsumerInit JavaScript Function)
         ' This is the client-side implementation of step #8.
         ' Render script if connected
         If _connected Then
            output.Write(ReplaceTokens( _
                "<P>" + ControlChars.Lf _
                + "   <B>Provide Cell: </B>" + ControlChars.Lf _
                + "   <INPUT TYPE=""text"" ID=""CellInput_WPQ_""/>" + 
                   ControlChars.Lf _
                + "   <INPUT TYPE=""button"" ID=""CellButton_WPQ_"" 
                   onclick=""CellButtonClick_WPQ_()"" VALUE=""Fire 
                   CellReady""/><br><br>" + ControlChars.Lf _
                + "   Connected to Web Part: <I>" + 
                _connectedWebPartTitle + "</I><br>" + ControlChars.Lf _
                + "   Send to Field: <I><span 
                   ID=""ConnectedField_WPQ_""></span></I>" + 
                   ControlChars.Lf _
                + "</P>" + ControlChars.Lf _
                + "<SCRIPT LANGUAGE=""JavaScript"">" + ControlChars.Lf _
                + "<!-- " + ControlChars.Lf _
                + "   var CellProviderInterface_WPQ_ = new 
                   Provider_WPQ_();" + ControlChars.Lf _
                + "   function Provider_WPQ_()" + ControlChars.Lf _
                + "   {" + ControlChars.Lf _
                + "      this.PartCommunicationInit = myInit;" + 
                   ControlChars.Lf _
                + "      this.PartCommunicationMain = myMain;" + 
                   ControlChars.Lf _
                + "      this.CellConsumerInit = myCellConsumerInit;" + 
                   ControlChars.Lf _
                + "      function myInit()" + ControlChars.Lf _
                + "      {" + ControlChars.Lf _
                + "         var cellProviderInitEventArgs = new 
                   Object();" + ControlChars.Lf _
                + "         cellProviderInitEventArgs.FieldName = 
                   ""ProvideCell"";" + ControlChars.Lf _
                + "         cellProviderInitEventArgs.FieldDisplayName 
                   = ""Provide Cell"";" + ControlChars.Lf _
                + "         WPSC.RaiseConnectionEvent(""MyCellProviderInterface_WPQ_"", 
   ""CellProviderInit"", cellProviderInitEventArgs);" + ControlChars.Lf _
                + "      }" + ControlChars.Lf _
                + "      function myMain()" + ControlChars.Lf _
                + "      {" + ControlChars.Lf _
                + "         var cellReadyEventArgs = new Object();" + 
                   ControlChars.Lf _
                + "         cellReadyEventArgs.Cell = null;" + 
                   ControlChars.Lf _
                + "         WPSC.RaiseConnectionEvent(""MyCellProviderInterface_WPQ_"", 
   ""CellReady"", cellReadyEventArgs);" + ControlChars.Lf _
                + "      }" + ControlChars.Lf _
                + "      function myCellConsumerInit(sender, 
                   cellConsumerInitEventArgs)" + ControlChars.Lf _
                + "      {" + ControlChars.Lf _
                + "         document.all(""ConnectedField_WPQ_"").innerText = cellConsumerInitEventArgs.FieldDisplayName;" + ControlChars.Lf _
                + "      }" + ControlChars.Lf _
                + "   }" + ControlChars.Lf _
                + "   function CellButtonClick_WPQ_()" + 
                   ControlChars.Lf _
                + "   {" + ControlChars.Lf _
                + "      var cellReadyEventArgs = new Object();" + 
                   ControlChars.Lf _
                + "      cellReadyEventArgs.Cell = 
                   document.all(""CellInput_WPQ_"").value;" + 
                   ControlChars.Lf _
                + "     WPSC.RaiseConnectionEvent(""MyCellProviderInterface_WPQ_"", ""CellReady"", cellReadyEventArgs);" _
                + ControlChars.Lf + "   }" + ControlChars.Lf _
                + "//-->" + ControlChars.Lf _
                + "</SCRIPT>" + ControlChars.Lf))
        
         Else
            ' The Web Part isn't connected.
            output.Write(_notConnectedMsg)
         End If
      End Sub
   End Class
End Namespace
// Common .NET required namespaces.
using System;
using System.ComponentModel;
using System.Web.UI;

// WebPart Required namespaces.
using Microsoft.SharePoint.WebPartPages;
using System.Xml.Serialization;
using System.Web.UI.WebControls;

// Code Access Security namespaces.
using System.Security;
using Microsoft.SharePoint.Utilities;

//Step #1: Make a Reference to the Communication Namespace
using Microsoft.SharePoint.WebPartPages.Communication;

namespace ConnectionCodeSamples
{
    // Step #2: Inherit from the WebPart base class and implement the 
    // ICellProvider interface.
    public class ClientSideCellProvider : WebPart, ICellProvider
    {    
        // Step #3: Declare the ICellProvider events.
        // Because this class implements the ICellProvider interface, 
        // it must declare the interface member events CellProviderInit 
        // and CellReady. However, because this is a client side Web 
        // Part the actual code for these events will be implemented 
        // on the client. See the myInit() and myMain() functions in 
        // the JavaScript rendered to the client
        // in the RenderWebPart method.
        public event CellProviderInitEventHandler CellProviderInit;
        public event CellReadyEventHandler CellReady;                

        // Declare variables for keeping track of the connection state.
        private bool _connected = false;
        private string _connectedWebPartTitle = string.Empty;
        private string _registrationErrorMsg = "An error has occurred 
           trying to register your connection interfaces.";
        private bool _registrationErrorOccurred = false;
        private string _notConnectedMsg = "NOT CONNECTED. To use this 
           Web Part, connect it to a client-side Cell Consumer Web 
           Part.";
        
        // Step #4: Override the EnsureInterfaces() method and call the 
        // RegisterInterface method.
        public override void EnsureInterfaces()
        {
            // If your Web Part is installed in the bin directory and 
            // the Code Access Security (CAS) setting doesn't 
            // allow Web Part Connections, an exception will be thrown. 
            // To allow your Web Part to behave 
            // well and continue working, a try/catch block should be 
            // used when attempting to register interfaces.
            // Web Part Connections will only work if the level 
            // attribute of the <trust> tag in the 
            // web.config file is set to WSS_Minimal, WSS_Medium, or 
            // Full. By default a new SharePoint site
            // is installed with the trust level set to WSS_Minimal.
            try
            {
                // Register the ICellProvider Interface
                // <param name="interfaceName">Friendly name of the 
                // interface that is being implemented.
                //    It must be unique on the client so the _WPQ_ 
                // token is used.</param>
                // <param name="interfaceType">Specifies which 
                // interface is being implemented.</param>
                // <param name="maxConnections">Defines how many times 
                // this interface can be connected.</param>
                // <param name="runAtOptions">Determines where the 
                // interface can run.</param>
                // <param name="interfaceObject">Reference to the 
                // object that is implementing this interface.</param>
                // <param name="interfaceClientReference">Name used to 
                // reference the interface on the client. 
                // It must be unique on the client so the _WPQ_ token 
                // is used.</param>
                // <param name="menuLabel">Label for the interface 
                // that appears in the UI</param>
                // <param name="description">Description of the 
                // interface that appears in the UI</param>
                // <param name="allowCrossPageConnection">Specifies if 
                // the interface can connect to a Web Part
                // on a different page. This is an optional parameter 
                // with a default of false. Note that only some 
                // server side interfaces are allowed to go cross page 
                // by the Web Part Infrastructure. 
                // The ICellProvider interface is not allowed to go 
                // cross page.</param>
                RegisterInterface("MyCellProviderInterface_WPQ_",            //InterfaceName    
                    InterfaceTypes.ICellProvider,                            //InterfaceType
                    WebPart.UnlimitedConnections,                            //MaxConnections
                    ConnectionRunAt.Client,                                  //RunAtOptions
                    this,                                                    //InterfaceObject
                    "CellProviderInterface_WPQ_",                            //InterfaceClientReference
                    "Provide Cell To",                                       //MenuLabel
                    "Provides a single value to a cell consumer Web Part."); //Description
            }
            catch(SecurityException se)
            {
                _registrationErrorOccurred = true;
            }
        }

        // Step #6: Override the CanRunAt() method.
        // The CanRunAt method is called by the Web Part infrastructure 
        // during the ASP.NET PreRender event
        // to determine where the Web Part can run based on its current 
        // configuration.
        public override ConnectionRunAt CanRunAt()
        {
            // This Web Part can run on the client.
            return ConnectionRunAt.Client;
        }

        // Step #7: Override the PartCommunicationConnect() method.
        // The PartCommunicationConnect method is called by the Web 
        // Part infrastructure to notify the Web Part that it
        // is connected during the ASP.NET PreRender event. Relevant 
        // information is passed to the part such as 
        // the interface it is connected over, the Web Part it is being 
        // conected to, and where the part will be running, 
        // either client or server side. 
        // <param name="interfaceName">Friendly name of the interface 
        // that is being connected</param>
        // <param name="connectedPart">Reference to the other Web Part 
        // that is being connected to</param>
        // <param name="connectedInterfaceName">Friendly name of the 
        // interface on the other Web Part</param>
        // <param name="runAt">Where the interface should 
        // execute</param>
        public override void PartCommunicationConnect(
            string interfaceName,
            WebPart connectedPart,
            string connectedInterfaceName,
            ConnectionRunAt runAt)
        {
            // Keep track of whether the Web Part is connected or not.
            if (interfaceName == "MyCellProviderInterface_WPQ_")
            {
                _connected = true;
                _connectedWebPartTitle = SPEncode.HtmlEncode(connectedPart.Title);
            }
        }

        // Step #8: Implement the CellConsumerInit event handler.
        // The connected consumer part(s) will call this method during 
        // its PartCommunicationInit phase
        // to pass initialization information to the provider Web Part.
        // <param name="sender">Reference to the Consumer Web 
        // Part</param>
        // <param name="cellConsumerInitEventArgs">The args passed by 
        // the Consumer Web Part</param>
        public void CellConsumerInit(object sender, CellConsumerInitEventArgs cellConsumerInitEventArgs)
        {
            // Because this class implements the ICellProvider 
            // interface, it must 
            // implement the interface member CellConsumerInit. 
            // However, because this is a client-side 
            // Web Part, the actual code for this method will be 
            // implemented on the client. See the 
            // myCellConsumerInit() function in the JavaScript rendered 
            // to the client in the RenderWebPart method.
        }

        protected override void RenderWebPart(HtmlTextWriter output)
        {
            // Check for connection interface registration error
            if (_registrationErrorOccurred)
            {
                output.Write(_registrationErrorMsg);
                return;
            }

            // ************* CLIENT-SIDE CONNECTION CODE 
            // ***************
            // Steps 9-11 are implemented in the following client code
            // 
            // Step #9: Implement PartCommunicationInit Function (see 
            // myInit JavaScript Function)
            // PartCommunicationInit() is called by the Web Part 
            // infrastructure on the client
            // to allow the part to pass initialization information to 
            // the other connected parts.
            // It is important to always pass initialization 
            // information. Some parts
            // may not behave properly if this initialization 
            // information is not received.
            // 
            // Step #10: Implement PartCommunicationMain Function (see 
            // myMain JavaScript Function)
            // PartCommunicationMain() is called by the Web Part 
            // infrastructure on the client
            // to allow the part to pass its primary data to the other 
            // connected parts.
            // It is important to always fire the CellReady event. Some 
            // parts may not behave properly if they are left waiting 
            // for this information.
            // 
            // Step #11: Implement CellConsumerInit Function (see 
            // myCellConsumerInit JavaScript Function)
            // This is the client-side implementation of step #8.

            // Render script if connected
            if(_connected)
            {
                output.Write(ReplaceTokens(
                    "<P>\n"
                    + "   <B>Provide Cell: </B>\n"
                    + "   <INPUT TYPE=\"text\" ID=\"CellInput_WPQ_\"/>\n"
                    + "   <INPUT TYPE=\"button\" ID=\"CellButton_WPQ_\" 
                       onclick=\"CellButtonClick_WPQ_()\" VALUE=\"Fire 
                       CellReady\"/><br><br>\n"
                    + "   Connected to Web Part: <I>" + 
                        _connectedWebPartTitle + "</I><br>\n"
                    + "   Send to Field: <I><span 
                       ID=\"ConnectedField_WPQ_\"></span></I>\n"
                    + "</P>\n"

                    + "<SCRIPT LANGUAGE=\"JavaScript\">\n"
                    + "<!-- \n"
                    + "   var CellProviderInterface_WPQ_ = new 
                       Provider_WPQ_();\n"

                    + "   function Provider_WPQ_()\n"
                    + "   {\n"                    
                    + "      this.PartCommunicationInit = myInit;\n"
                    + "      this.PartCommunicationMain = myMain;\n"
                    + "      this.CellConsumerInit = 
                       myCellConsumerInit;\n"

                    + "      function myInit()\n"
                    + "      {\n"
                    + "         var cellProviderInitEventArgs = new 
                       Object();\n"
                    + "         cellProviderInitEventArgs.FieldName = 
                       \"ProvideCell\";\n"
                    + "         
                       cellProviderInitEventArgs.FieldDisplayName = 
                       \"Provide Cell\";\n"

                    + "         WPSC.RaiseConnectionEvent(\"MyCellProviderInterface_WPQ_\", \"CellProviderInit\", cellProviderInitEventArgs);\n"
                    + "      }\n"

                    + "      function myMain()\n"
                    + "      {\n"
                    + "         var cellReadyEventArgs = new 
                       Object();\n"
                    + "         cellReadyEventArgs.Cell = null;\n"

                    + "         WPSC.RaiseConnectionEvent(\"MyCellProviderInterface_WPQ_\", \"CellReady\", cellReadyEventArgs);\n"
                    + "      }\n"

                    + "      function myCellConsumerInit(sender, cellConsumerInitEventArgs)\n"
                    + "      {\n"
                    + "         document.all(\"ConnectedField_WPQ_\").innerText = 
   cellConsumerInitEventArgs.FieldDisplayName;\n"
                    + "      }\n"
                    + "   }\n"

                    + "   function CellButtonClick_WPQ_()\n"
                    + "   {\n"
                    + "      var cellReadyEventArgs = new Object();\n"
                    + "      cellReadyEventArgs.Cell = 
                       document.all(\"CellInput_WPQ_\").value;\n"

                    + "     WPSC.RaiseConnectionEvent(\"MyCellProviderInterface_WPQ_\", \"CellReady\", cellReadyEventArgs);\n"
                    + "   }\n"
                    + "//-->\n"
                    + "</SCRIPT>\n"));
            }
            else
            {
                // The Web Part isn't connected.
                output.Write(_notConnectedMsg);
            }

        }
    }
}

See Also

Reference

ICellProvider Members

Microsoft.SharePoint.WebPartPages.Communication Namespace