Public Class Sample

    Public Sub CodeSample_getusers()
        Dim strXML As String = String.Empty

        Dim dsOutput As DataSet = Nothing
        Dim guid As String = String.Empty
        Dim sb As New System.Text.StringBuilder
        Try
            sb = New System.Text.StringBuilder
            'Building API QueryString
            sb.Append("fct=getusers")
            sb.Append(String.Format("&guid={0}", "144e59f8-6cfc-4f56-9926-6780bc8b076f"))
            sb.Append(String.Format("&filteruserid={0}", "NULL"))
            sb.Append(String.Format("&filteraccesslevel={0}", "NULL"))
            sb.Append(String.Format("&filterusergroupid={0}", "NULL"))
            sb.Append(String.Format("&filteraccessstatus={0}", "NULL"))
            sb.Append(String.Format("&filterassignedprojectid={0}", "NULL"))
            sb.Append(String.Format("&filteractive={0}", "NULL"))
            sb.Append(String.Format("&filterusername={0}", "NULL"))
            sb.Append(String.Format("&ispmview={0}", False))
            sb.Append(String.Format("&texttosearch={0}", "NULL"))
            sb.Append(String.Format("&sortorder={0}", "NULL"))
            sb.Append(String.Format("&forcombo={0}", "NULL"))
            sb.Append(String.Format("&pagenumber={0}", "NULL"))
            sb.Append(String.Format("&rowsperpage={0}", 50))
            sb.Append(String.Format("&asynccall={0}", False))
            sb.Append(String.Format("&asynccallid={0}", "NULL"))
            sb.Append(String.Format("&exportdomainevaleur={0}", "NULL"))
            sb.Append(String.Format("&exporttype={0}", "NULL"))
            sb.Append(String.Format("&exportdelimiter={0}", "NULL"))
            sb.Append(String.Format("&exportdecimalsymbol={0}", "NULL"))
            sb.Append(String.Format("&exportlcid={0}", 0))
            sb.Append(String.Format("&exportonscreencolumnsonly={0}", True))
            sb.Append(String.Format("&exportview={0}", 0))
            sb.Append(String.Format("&exportviewother={0}", "NULL"))
            sb.Append(String.Format("&exportfieldstodisplay={0}", "NULL"))
            sb.Append(String.Format("&exportremovehtmlonly={0}", True))
            sb.Append(String.Format("&exportenablefilterxls={0}", False))
            sb.Append(String.Format("&format={0}", "DS"))

            'Calling API
            strXML = CallHttp("https://api.aceproject.com/", sb.ToString)
            'Retreive Output structure generate by API
            dsOutput = Deserialize(Of DataSet)(strXML)
            If dsOutput IsNot Nothing AndAlso dsOutput.Tables.Count > 0 Then
                If dsOutput.Tables.Contains("dtAPIErrors") Then
                    Throw New Exception(String.Format("{0}: {1}", _
                                                      dsOutput.Tables(0).Rows(0).Item("ErrorNumber").ToString, _
                                                      dsOutput.Tables(0).Rows(0).Item("ErrorDescription").ToString))
                End If
            End If
        Catch ex As Exception
            Throw
        Finally
            If sb IsNot Nothing Then sb = Nothing
            If dsOutput IsNot Nothing Then
                dsOutput.Dispose()
                dsOutput = Nothing
            End If
        End Try
    End Sub

    Private Shared Function CallHttp( ByVal url As String, _ 
                                      ByVal params As String) As String
        Dim loHttp As System.Net.HttpWebRequest
        loHttp = CType(System.Net.WebRequest.Create(url), System.Net.HttpWebRequest)
        loHttp.Method = "POST"
        Dim requestWriter As System.IO.StreamWriter = New System.IO.StreamWriter(loHttp.GetRequestStream())

        If Not String.IsNullOrEmpty(params) Then
            requestWriter.Write(params)
        End If
        requestWriter.Close()
        loHttp.ContentType = "application/x-www-form-urlencoded"
        loHttp.Headers.Set("Pragma", "no-cache")
        loHttp.AllowAutoRedirect = True
        loHttp.KeepAlive = True
        loHttp.Timeout = 30 * 1000

        Dim loWebResponse As System.Net.HttpWebResponse = CType(loHttp.GetResponse(), System.Net.HttpWebResponse)
        Dim enc As Encoding = System.Text.Encoding.UTF8
        Dim loResponseStream As System.IO.StreamReader = New System.IO.StreamReader(loWebResponse.GetResponseStream(), enc)
        Dim lcHtml As String = loResponseStream.ReadToEnd()

        loWebResponse.Close()
        loResponseStream.Close()

        Return lcHtml
    End Function


    Private Shared Function Deserialize(Of T)( ByVal strXML As String) As T
        Dim objet As T = Nothing
        Dim objType As Type = GetType(T)
        Try
            If Not String.IsNullOrEmpty(strXML) Then
                Dim objSerializer As New System.Xml.Serialization.XmlSerializer(objType)
                Dim objText As New System.Text.StringBuilder()
                Dim objXmlReader As New System.IO.StringReader(strXML)
                objet = DirectCast(objSerializer.Deserialize(objXmlReader), T)
                objXmlReader.Close()
            End If
            Return objet
        Catch ex As Exception
            Throw
        Finally
            If objet IsNot Nothing Then objet = Nothing
        End Try
    End Function

End Class