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Binding to Web Service or Wcf Service

Overview

You can load child items in a tag cloud dynamically through a Web service. The following steps describe how to configure RadTagCloud so that it can use a Web service to supply child items. Since Q2 2012 a WCF Web Service can be used as well.

note

Both types of Web Services must return an array of type TagCloudDataItem which has the following signature:

/// <summary>
/// This class is only for demonstration purposes.
/// The class used in this example resides in the App_Code/TagCloud folder
/// </summary>
public class TagCloudDataItem
{
    private string _text;
    private double _weight;
    private string _navigateUrl;
    private string _accessKey;
    private short _tabIndex;
    private string _toolTip;
    private string _value;

    public string Text
    {
        get { return _text; }
        set { _text = value; }
    }
    public double Weight
    {
        get { return _weight; }
        set { _weight = value; }
    }
    public string NavigateUrl
    {
        get { return _navigateUrl; }
        set { _navigateUrl = value; }
    }
    public string AccessKey
    {
        get { return _accessKey; }
        set { _accessKey = value; }
    }
    public short TabIndex
    {
        get { return _tabIndex; }
        set { _tabIndex = value; }
    }
    public string ToolTip
    {
        get { return _toolTip; }
        set { _toolTip = value; }
    }
    public string Value
    {
        get { return _value;}
        set { _value = value; }
    }
    public TagCloudDataItem()
    {
    }
    public TagCloudDataItem(string text, double weight)
    {
        _text = text;
        _weight = weight;
    }
    public TagCloudDataItem(string text, string navigateUrl, double weight)
    {
        _text = text;
        _navigateUrl = navigateUrl;
        _weight = weight;
    }
}
''' <summary>
''' This class is only for demonstration purposes.
''' The class used in this example resides in the App_Code/TagCloud folder
''' </summary>
Public Class TagCloudDataItem
    Private _text As String
    Private _weight As Double
    Private _navigateUrl As String
    Private _accessKey As String
    Private _tabIndex As Short
    Private _toolTip As String
    Private _value As String

    Public Property Text() As String
        Get
            Return _text
        End Get
        Set(ByVal value As String)
            _text = value
        End Set
    End Property
    Public Property Weight() As Double
        Get
            Return _weight
        End Get
        Set(ByVal value As Double)
            _weight = value
        End Set
    End Property
    Public Property NavigateUrl() As String
        Get
            Return _navigateUrl
        End Get
        Set(ByVal value As String)
            _navigateUrl = value
        End Set
    End Property
    Public Property AccessKey() As String
        Get
            Return _accessKey
        End Get
        Set(ByVal value As String)
            _accessKey = value
        End Set
    End Property
    Public Property TabIndex() As Short
        Get
            Return _tabIndex
        End Get
        Set(ByVal value As Short)
            _tabIndex = value
        End Set
    End Property
    Public Property ToolTip() As String
        Get
            Return _toolTip
        End Get
        Set(ByVal value As String)
            _toolTip = value
        End Set
    End Property
    Public Property Value() As String
        Get
            Return _value
        End Get
        Set(ByVal value As String)
            _value = value
        End Set
    End Property
    Public Sub New()
    End Sub
    Public Sub New(ByVal text As String, ByVal weight As Double)
        _text = text
        _weight = weight
    End Sub
    Public Sub New(ByVal text As String, ByVal navigateUrl As String, ByVal weight As Double)
        _text = text
        _navigateUrl = navigateUrl
        _weight = weight
    End Sub
End Class

Using a WebService

  1. In the properties pane for the RadTagCloud component, set the WebServiceSettings property to identify the Web service and service method:

    • Set the Path sub-property to the URL for the Web service.
    • Set the Method sub-property to the name of the method of the Web service that supplies child items.
    • Set the UseHttpGet sub-property to True to change the default HTTP method (POST).

    ASP.NET

    <telerik:RadTagCloud RenderMode="Lightweight" ID="RadTagCloud1" runat="server" OnClientItemsRequesting="itemsRequesting" 
        OnClientItemsRequested="itemsRequested" OnClientItemsRequestFailed="itemsRequestFailed">
        <WebServiceSettings Path="VehiclesWeightByRating.asmx" Method="GetRadTagCloudItems" />
    </telerik:RadTagCloud>
    
  2. When the WebServiceSettings property is set, an empty context request will be initiated automatically. You can trigger request to the service by calling the requestItems() client-side method. This method has a single parameter, which is sent as an argument to the Web service method.

    important

    It is important to know that all current items will be removed, before the new ones are populated.

    JavaScript

    function clientFunction()
    {
        //...
        var context = "some value";
        tagCloud.requestItems(context);
        //...
    }   
    
  3. Optionally, set the OnClientItemsRequesting property to a client-side event handler that passes context information to the Web service. The Web service can use this context information to determine what child items to return or what properties to set on those child items.

    JavaScript

    //Fired before the request is sent to the Web Service
    function itemsRequesting(sender, args)
    {
        //If you want to cancel the request use
        //args.set_cancel(true);
    
        //The args.get_context()/args.set_context(value) methods get/set the parameter which will be sent to the Web Service.
        var context = args.get_context();
    }
    
  4. Optionally, set the OnClientItemsRequested and OnClientItemsRequestFailed properties to client-side event handlers that respond when the Web service has successfully loaded child items or when the Web service has generated an error while trying to service the item request, respectively.

    JavaScript

    //Fired when the items are successfully loaded.
    function itemsRequested(sender, args)
    {
        //...
    }
    
    //Fired when the request for the items fails.
    function itemsRequestFailed(sender, args)
    {
        // Disable the notifying error alert.
        args.set_cancelErrorAlert(true);
        //...
    }
    
  5. To use the integrated WebService support of RadTagCloud, the WebService should have the following signature:

[ScriptService]
public class WebServiceName : WebService
{
    [WebMethod]
    public TagCloudDataItem[] GetRadTagCloudItems(Object context)
    {
        List<TagCloudDataItem> result = new List<TagCloudDataItem>();
        //.......
        TagCloudDataItem item = new TagCloudDataItem();
        item.Text = "Item";
        item.Weight = 6.6;
        item.NavigateUrl = "NavigateUrl";
        item.AccessKey = "AccessKey";
        item.TabIndex = 5;
        item.ToolTip = "ToolTip";
        item.Value = "ToolTip";

        result.Add(item);
        //.......
        return result.ToArray();
    }
}
<ScriptService()> _
Public Class WebServiceName
    Inherits WebService
    <WebMethod()> _
    Public Function GetRadTagCloudItems(ByVal context As [Object]) As TagCloudDataItem()
        Dim result As New List(Of TagCloudDataItem)()
        '.......
        Dim item As New TagCloudDataItem()
        item.Text = "Item"
        item.Weight = 6.6
        item.NavigateUrl = "NavigateUrl"
        item.AccessKey = "AccessKey"
        item.TabIndex = 5
        item.ToolTip = "ToolTip"
        item.Value = "ToolTip"

        result.Add(item)
        '.......
        Return result.ToArray()
    End Function
End Class
note

The class that identifies an item is the same for both types of web services and is shown in the beginning of the article.

For a live example of using a Web service to populate items, see the Web Service demo.

Using a WCF Web Service

  1. In the properties pane for the RadTagCloud component, set the WebServiceSettings property to identify the WCF Web service and service method:

    • Set the Path sub-property to the URL for the Web service.
    • Set the Method sub-property to the name of the method of the WCF Web service that supplies child items.

    ASP.NET

    <telerik:RadTagCloud RenderMode="Lightweight" ID="RadTagCloud1" runat="server"
        OnClientItemsRequesting="itemsRequesting"
        OnClientItemsRequested="itemsRequested"
        OnClientItemsRequestFailed="itemsRequestFailed">
        <WebServiceSettings Path="TagCloudWcfService.svc" Method="GetRadTagCloudItems" />
    </telerik:RadTagCloud>
    

    where the WCF WebService must be in the website, e.g.:

    ASP.NET

    <%@ ServiceHost Language="C#" Debug="true" Service="TagCloudWcfService" CodeBehind="~/App_Code/TagCloudWcfService.cs" %>
    
  2. When the WebServiceSettings property is set, an empty context request will be initiated automatically. You can trigger request to the service by calling the requestItems() client-side method. This method has a single parameter, which is sent as an argument to the Web service method.

    important

    It is important to know that all current items will be removed, before the new ones are populated.

    note

    Passing a value to a WCF service requires creating an object that will hold the data. This object will be serialized automatically. This object is received by the WCF WebService as a parameter of type IDictionary and you can access the value of the object you provided according to its name.

    JavaScript

    function clientFunction()
    {
        //...
        var context = { minUnitPrice: "500" };
        tagCloud.requestItems(context);
        //...
    }
    
  3. Optionally, set the OnClientItemsRequesting property to a client-side event handler that passes context information to the Web service. The Web service can use this context information to determine what child items to return or what properties to set on those child items. Note that setting the context requires an object as shown above.

    JavaScript

    //Fired before the request is sent to the Web Service
    function itemsRequesting(sender, args)
    {
        //If you want to cancel the request use
        //args.set_cancel(true);
    
        //The args.get_context()/args.set_context(value) methods get/set the parameter which will be sent to the Web Service.
        var context = args.get_context();
    }
    
  4. Optionally, set the OnClientItemsRequested and OnClientItemsRequestFailed properties to client-side event handlers that respond when the Web service has successfully loaded child items or when the Web service has generated an error while trying to service the item request, respectively.

    JavaScript

    //Fired when the items are successfully loaded.
    function itemsRequested(sender, args)
    {
        //...
    }
    
    //Fired when the request for the items fails.
    function itemsRequestFailed(sender, args)
    {
        // Disable the notifing error alert.
        args.set_cancelErrorAlert(true);
        //...
    }
    
  5. To use the integrated WCF WebService support of RadTagCloud, the WCF WebService should have the following signature:

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class TagCloudWcfService
{
    [OperationContract]
    public TagDataItem[] GetRadTagCloudItems(IDictionary context)
    {
        string argument = (string)context["minUnitPrice"];
        List<TagCloudDataItem> result = new List<TagCloudDataItem>();
        //.......
        TagCloudDataItem item = new TagCloudDataItem();
        item.Text = "Item";
        item.Weight = 6.6;
        item.NavigateUrl = "NavigateUrl";
        item.AccessKey = "AccessKey";
        item.TabIndex = 5;
        item.ToolTip = "ToolTip";
        item.Value = "ToolTip";

        result.Add(item);
        //.......
        return result.ToArray();
    }
}
<ServiceContract([Namespace] := "")> _
<AspNetCompatibilityRequirements(RequirementsMode:=AspNetCompatibilityRequirementsMode.Allowed)> _
Public Class TagCloudWcfService
    <OperationContract()> _
    Public Function GetRadTagCloudItems(context As IDictionary) As TagDataItem()
        Dim argument As String = DirectCast(context("minUnitPrice"), String)
        Dim result As New List(Of TagCloudDataItem)()
        '.......
        Dim item As New TagCloudDataItem()
        item.Text = "Item"
        item.Weight = 6.6
        item.NavigateUrl = "NavigateUrl"
        item.AccessKey = "AccessKey"
        item.TabIndex = 5
        item.ToolTip = "ToolTip"
        item.Value = "ToolTip"

        result.Add(item)
        '.......
        Return result.ToArray()
    End Function
End Class
note

The class that identifies an item is the same for both types of web services and is shown in the beginning of the article.

For a live example of using a WCF Web service to populate items, see the WCF Web Service demo.