Web Service doesn't return values remotely

[caeanis]

I was tasked to find a way to allow our team to dynamically pull down a set of lists within a Time Correction program we wrote. I figured that putting an xml file on a web server and use a webservice to not only call the specific lists but also allow us to update it as well. The web service does what it is supposed to do, we can retrieve a list of users, update the list with new members or delete them as we see fit. The problem is, it only appears to return data when I browse to it in the browser. When I try to do the same via the vb.net form, it doesn't error, it just doesn't return the expected string. I found that it does if I deploy the web service locally on my own box in IIS, but that of course defeats the purpose of accessing it anywhere. I noticed that when I test it using the test page that the returned string actually comes back in a separate window; I wonder if this is why our form doesn't get the data because it's not being directed back to where the request originated. Any ideas about this?

 

Thank you!

 

Caeanis

[PlausiblyDamp]

The results being displayed in a new window is just how the test page does things - it isn't affecting how the results are returned when the web service is running normally.

 

Where is the xml file the web service is handling hosted (same server? what folder? what permissions on folder?). What information are you passing to the service that could be used to identify the file in question?

 

Without seeing any code or without further information though everything is just speculation...

[caeanis]

The xml file is on the same server, same web folder as the asmx file. Here is my web service code:

Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Xml
Imports Microsoft.VisualBasic

<WebService(Namespace:="ws")> _
<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Public Class ListManager
   Inherits System.Web.Services.WebService
   Dim XmlPath As String = "list.xml"
   Dim listDoc As New XmlDocument
   Dim node As XmlNode
   Dim strList As String = ""
   Dim nms As XmlNodeList

   <WebMethod()> Public Sub SetList(ByVal cbo As String, ByVal NameList As String)
       Dim NameNode = Nothing
       Dim node As XmlNode
       Dim nms As XmlNodeList = Nothing
       Dim listDoc As XmlDocument = New XmlDocument()
       Dim ws As XmlWhitespace = listDoc.CreateWhitespace(ControlChars.CrLf)
       Dim tb As XmlWhitespace = listDoc.CreateWhitespace(ControlChars.Tab)
       On Error GoTo ErrResponse
       listDoc.Load(Server.MapPath(XmlPath))
       Select Case cbo
           Case "Name"
               nms = listDoc.SelectNodes("/List/Team/Name")
               NameNode = listDoc.SelectSingleNode("/List/Team")
           Case "Reason"
               nms = listDoc.SelectNodes("/List/Reasons/Reason")
               NameNode = listDoc.SelectSingleNode("/List/Reasons")
           Case "Type"
               nms = listDoc.SelectNodes("/List/Types/Type")
               NameNode = listDoc.SelectSingleNode("/List/Types")
       End Select
       Dim i As Integer
       'Assign the string of comma delimited values to an array
       Dim listToTxt() As String = Split(NameList, ",")
       For i = 0 To UBound(listToTxt)
           'If Item is NOT found in the collection of nodes then add it
           If IsDupe(nms, listToTxt(i)) = False Then
               node = listDoc.CreateNode(XmlNodeType.Element, "", cbo, "")
               node.InnerText = listToTxt(i)
               NameNode.AppendChild(node)
               'Indent the new node
               NameNode.InsertBefore(tb, node)
               'Insert a carriage return after the new node
               NameNode.InsertAfter(ws, node)
           End If
       Next
       listDoc.Save(Server.MapPath(XmlPath))
ErrResponse:
       If Err.Number > 0 Then
           Resume Next
       End If
   End Sub


<WebMethod()> Public Function GetList(ByVal cbo As String) As String
       On Error GoTo ErrResponse
       listDoc.Load(Server.MapPath(XmlPath))
       Select Case cbo
           Case "Name"
               nms = listDoc.SelectNodes("/List/Team/Name")
           Case "Reason"
               nms = listDoc.SelectNodes("/List/Reasons/Reason")
           Case "Type"
               nms = listDoc.SelectNodes("/List/Types/Type")
       End Select
       ' Loop through the nodes and add the names to the list
       For Each node In nms
           If Len(strList) = 0 Then
               strList += node.InnerText
           Else
               strList += "," & node.InnerText
           End If
       Next
       Return strList
ErrResponse:
       If Err.Number > 0 Then
           Resume Next
       End If
   End Function


<WebMethod()> Public Sub RemoveEntry(ByVal cbo As String, ByVal nme As String)
       On Error GoTo ErrResponse
       Dim rmNode, srchNode As System.Xml.XmlNode
       listDoc.Load(Server.MapPath(XmlPath))
       'Select the node to search
       srchNode = listDoc.SelectSingleNode("/List/" & cbo)
       ' Loop through the children nodes and find the one to remove
       For Each rmNode In srchNode.ChildNodes
           If rmNode.InnerText = nme Then
               'Remove the specified node
               srchNode.RemoveChild(rmNode)
               'Save the file
               listDoc.Save(Server.MapPath(XmlPath))
               Exit For
           End If
       Next
ErrResponse:
       If Err.Number > 0 Then
           Resume Next
       End If
   End Sub
   
Private Function IsDupe(ByVal ns As XmlNodeList, ByVal strEntry As String) As Boolean
       Dim node As XmlNode
       For Each node In ns
           If node.InnerText = strEntry Then
               Return True
               Exit Function
           End If
       Next
       Return False
   End Function
End Class

Edited May 20, 2008 by PlausiblyDamp

[PlausiblyDamp]

Is there any chance you could attach a sample of the xml file? Just to give me something to look at in a debugger...

 

At first glance however I would be cautious about using class level variables and redefining them at the method level - this can introduce all sorts of odd errors.

 

Equally you need to be careful if you are storing any state between method calls as under IIS web services are going to be be stateless unless you deliberately choose to use session variables or similar.

Edited May 20, 2008 by PlausiblyDamp

[Nate Bross]

FYI - By default session variables are stored in the IIS worker process which resets itself in order to avoid memory leaks. You can use the ASP.NET State Service to maintain session variables between IIS worker process resets.

 

To Setup the ASP.NET State Service, Go to Start >> Run >> Services.msc find the “ASP.NET State Service” go to Properties and start. (for servers, change startup type to "automatic") Also drop this in your Web.config:

 

<sessionState
     mode="StateServer"
     stateConnectionString="tcpip=127.0.0.1:42424"
     cookieless="false"
     timeout="20" />