Question Window form & web service

[damxuanthai]

Hi all Prof.

Today I have a problem on Web service that I can not find the way to get out.

The Problem is

I made a webservice and put it on my host
"http://damxuanthai.edu.vn/damxuanthai01.asmx"

In which, I have a webmethod to select and return a datashet from one database mdb file.

<WebMethod()> _
    Public Function SelectDataShet() As DataSet
        Dim strConnectionToDatabase As String = "Provider=Microsoft.Jet.Oledb.4.0; Data Source =" & strPublicMDBpath
        Dim cls As New clsDoDatabase(strConnectionToDatabase)
        Dim dtsOut As New DataSet
        cls.FillData_ToDataShet(dtsOut, strQuiry)
        Return dtsOut
    End Function

This web function can work online well when be called by any .aspx files in my site

Now I make make a Window form contain 1 datagridview and 1 button, I try to get my datashet:

        Dim Mb As New Online.damxuanthai01
        Dim dtbList As New DataSet        
        dtbList = Mb.SelectDataShet
        DataGridView1.DataSource = dtbList.Tables(0)

But It make an Error

System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.NullReferenceException: Object reference not set to an instance of an object. at damxuanthai01.SelectDataShet() --- End of inner exception stack trace ---

I don't know to solve this Error.

I am hopefully waitting for some solutions.

 

[damxuanthai]

Hi all,

Over 70 bros read this thread but NO any ANSWERs.

To JohnH: Please help me on this problem.

 

[rcombs4]

First off the SelectDataShet Method needs two parameters.

But check your webservice. The method clsDoDatabase is prob. killing your DS

 

[damxuanthai]

First off the SelectDataShet Method needs two parameters.

But check your webservice. The method clsDoDatabase is prob. killing your DS

Thank rcombs4

Actually, clsDodatabase is a class which use to access to database. It cause no error while running inside an ASP page application that perform in the same host (http://...) with this web service. The coding cause this Error in Window form application only.

Anyway, thank alot for reply.

I would like to see another ideas.