<OperationContract>
    <WebGet(UriTemplate:="/GetList?Page={Page}&Records={Records}&ID={ID}", RequestFormat:=WebMessageFormat.Json, _
        ResponseFormat:=WebMessageFormat.Json, BodyStyle:=WebMessageBodyStyle.Bare)>
    Public Function GetList(Page As Integer, Records As Integer, Optional ID As Integer = 0) _
        As Response Implements IDataManipulation.GetList

        Dim cid As Integer = _State.PropertyValue("ClassificatorID")
        Dim x As Integer = db.mtskCatalogueInClassificator.Count(Function(p) p.CatalogueID = ID And p.ClassificatorID = cid)
        Dim sFilter As String = IIf(x > 0, "Filter=ClassificatorID=" & cid, "")

        Dim oCat As tblCatalogue = (From v In db.tblCatalogue Where v.CatalogueID = ID).Single

        Dim mRes As New Response("CATALOGUE")
        If oCat.Level = 2 Then
            mRes.Rowset.rows = db.tblCatalogue.SqlQuery("mp_TreeGet 'CATALOGUE'," & oCat.CatalogueID & _
                ",2,-1,-1,3,'" & sFilter & "','LeftKey'").ToList
        Else
            mRes.Rowset.rows = db.tblCatalogue.SqlQuery("mp_TreeGet 'CATALOGUE'," & oCat.CatalogueID & _
                "," & oCat.Level & ",-1,1,3,'" & sFilter & "','LeftKey'").ToList
        End If
        Dim jss As New JavaScriptSerializer
        Debug.Print(jss.Serialize(mRes))
        Return mRes
    End Function

<DataContract>
Public Class Response
    <DataMember>
    Public SvcItem As String
    <DataMember>
    Public [Rowset] As Rowset

    Public Sub New(ByVal sObjNAme As String)
        Rowset = New Rowset
        SvcItem = sObjNAme
    End Sub
End Class

<DataContract>
Public Class Rowset
    <DataMember>
    Public localRowset As Boolean
    <DataMember>
    Public entire As Integer
    <DataMember>
    Public total As Integer
    <DataMember>
    Public rows As IEnumerable(Of Object)
End Class

$.ajax({
    type: 'GET',
    url: "http://localhost:38377/Catalogue.svc/GetList?Page=1&Records=1&ID=8",
    contentType: 'application/json; charset=utf-8',
    success: function (response, status, xhr) { alert('success: ' + xhr.responseText); },
    error: function (xhr, status, error) { 
        if(!xhr.responseText.length)alert("Error\n-----\n" + xhr.status);
        if(xhr.responseText.length)document.write(xhr.responseText); 
    }
});