如何获得WCF Ajax服务的智能感知?

/// <reference path="JQuery\jquery-1.3.2.js"/>

    <asp:ScriptManager ID="ScriptManager1" runat="Server" EnablePartialRendering="false" AsyncPostBackTimeout="999999">
        <Services>
            <asp:ServiceReference path="../Services/DocLookups.svc" />
        </Services>
    </asp:ScriptManager>

<%@ ServiceHost Language="C#" Debug="true" Service="Documents.Services.DocLookups" CodeBehind="~/App_Code/DocLookups.cs" %>

[ServiceContract(Namespace = "Documents.Services", Name = "DocLookups")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class DocLookups {
...

    //Called at the begining of the page to fill in the category list
    [OperationContract]
    public SelectOption[] GetCategoriesForSelectList()
    {
        SelectOption[] Result;
        IDocumentRepository repository = new DocumentEntityRepository(ConnectionString);
        Result = (from cat in repository.GetDocCategories()
                  select new SelectOption(cat.Category_ID.ToString(), cat.CategoryName)).ToArray();
        if (Result.Length > 0)
            Result[0].Selected = true;  //Select first item 
        return Result;
    }

namespace Documents.Services {

[DataContract]
public class SelectOption
{
    //A useful DTO to use when filling a <select> element with options
    public SelectOption(string optionValue, string optionText) {
        OptionValue = optionValue;
        OptionText = optionText;
        Selected = false;
    }
    public SelectOption(string optionValue, string optionText, bool selected) {
        OptionValue = optionValue;
        OptionText = optionText;
        Selected = selected;
    }

    [DataMember]
    public string OptionValue { get; set; }
    [DataMember]
    public string OptionText { get; set; }
    [DataMember]
    public bool Selected { get; set; }
}

}

Documents.Services.DocLookups.GetCategoriesForSelectList(...

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