Mohammed Jeelani's Blog : SharePoint

Top 3 Reasons for the "The server instance specified was not found. Please specify the server's address and port." Error

mjeelani — Sun, 06 Mar 2005 02:03:00 GMT

The easiest way to install web parts is probably to use this utility from Microsoft called Install Assemblies - very simple and intuitive interface, takes care of creating the Safe Control entries and even creating DWPs for your web part assemblies.

Install Assemblies internally uses STSADM.EXE - more than often you will face the infamous "The server instance specified was not found. Please specify the server's address and port." error. There can be many reasons why you will face this problem, here are top three reasons I've seen in the field either while installing web parts or while using Object Model code -

1) WSS SP1 not installed on all components

Diagnosis: Go to SharePoint Central Administration -> Click Windows SharePoint Services -> Click Extend or Upgrade a Virtual Server (Second Link) -> In the virtual servers listed, do you see "Upgrade" next to your SharePoint virtual server.

Resolution: Upgrade all your components to SP1 using the STSADM.EXE util -> follow steps listed in this KB article

http://support.microsoft.com/?kbid=871149

2) You receive the above error when using SharePoint Object Model code and using the Hostname/Fully Qualified Domain Name (FQDN).

Resolution: Follow this support article http://support.microsoft.com/?kbid=832816

3) You are using SSL, your code works fine while using http://sitename but not https://sitename

Resolution: Use the IP address with https:// instead of the sitename (eg SPSite testSite = new SPSite("https://65.12.12.12");

- Mohammed Jeelani

Using XPath with XML returned by SharePoint Web services

mjeelani — Sun, 27 Feb 2005 06:23:00 GMT

I've seen quite often people writing code that parses thru XML returned by SPS Web services as strings instead of using XPath - cause the XmlDocument throws this error all the time if you dont use an XmlNameSpaceManager

"Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function."

Heres a snippet that tells you how to use the XmlNameSpaceManager to use XPath with the XmlDocument.

Dim Document As New XmlDocument
Dim xml As String

xml = "<listitems xmlns:s=""uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882"" xmlns:dt=""uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"" xmlns:rs=""urn:schemas-microsoft-com:rowset"" xmlns:z=""#RowsetSchema"" TimeStamp=""2004-12-20T20:57:26Z"" xmlns=""http://schemas.microsoft.com/sharepoint/soap/""><rs:data ItemCount=""0""></rs:data><rs:data ItemCount=""0""></rs:data></listitems>"
Document.LoadXml(xml)

'Since the XML returned by SPS contains namespace prefixes - we need to create a XmlNamespaceManager
Dim SharePointNamespacePrefix As String = "sp"
Dim SharePointNamespaceURI As String = "http://schemas.microsoft.com/sharepoint/soap/"

Dim ListItemsNamespacePrefix As String = "z"
Dim ListItemsNamespaceURI As String = "#RowsetSchema"

Dim PictureLibrariesNamespacePrefix As String = "s"
Dim PictureLibrariesNamespaceURI As String = "uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882"

Dim WebPartsNamespacePrefix As String = "dt"
Dim WebPartsNamespaceURI As String = "uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"

Dim DirectoryNamespacePrefix As String = "rs"
Dim DirectoryNamespaceURI As String = "urn:schemas-microsoft-com:rowset"

'now associate with the xmlns namespaces (part of all XML nodes returned
'from SharePoint) a namespace prefix which we can then use in the queries
Dim NamespaceMngr As XmlNamespaceManager
NamespaceMngr = New XmlNamespaceManager(Document.NameTable)

NamespaceMngr.AddNamespace(SharePointNamespacePrefix, SharePointNamespaceURI)
NamespaceMngr.AddNamespace(ListItemsNamespacePrefix, ListItemsNamespaceURI)
NamespaceMngr.AddNamespace(PictureLibrariesNamespacePrefix, PictureLibrariesNamespaceURI)
NamespaceMngr.AddNamespace(WebPartsNamespacePrefix, WebPartsNamespaceURI)
NamespaceMngr.AddNamespace(DirectoryNamespacePrefix, DirectoryNamespaceURI)

'run the XPath query and return the result nodes
Dim xNodeList As XmlNodeList
xNodeList = Document.SelectNodes("//z:row[@ows_Title]", NamespaceMngr)

Mohammed Jeelani

Impersonation / Authentication issues when using Integrated Windows Authentication and SharePoint

mjeelani — Tue, 07 Dec 2004 10:30:00 GMT

With Integrated Authentication its fairly often that people find themselves in a situation where the currently logged in users credentials are not passed from the client to a SQL server / File share / some other server that they are trying to access from SPS. I bumped into it myself and was tearing my hair apart till my colleague Walter Warren told me what the "Double-Hop Issue" was.

Though I’ve titled this blog under SharePoint this actually applies to ASP.NET as well. The problem I faced was that i was creating an ASP.NET web page that consumes the SharePoint Search web service. The ASP.NET app was hosted on a different IIS machine than SPS. The ASP.NET application had Integrated Windows Authentication turned on. All was fine when I was testing the ASP.NET page right from the server where IIS was running, however, when I tried running the same page from another workstation - I kept getting 401 - Unauthorized access errors.

This problem is due to Integrated Windows Authentication that’s turned on in IIS for the ASP.NET application virtual directory. The issue is known as the "Double Hop" issue - when we use Integrated Security, the user credentials are passed from the client system (in this case the different station) to the server that’s running IIS (in this case the ASP.NET application). When the IIS running the ASP.NET app makes a request to the SharePoint server (a second hop) it cannot pass the user credentials passed from the client system. This is a little known documented limitation in IIS, you can refer to a KB on http://support.microsoft.com/default.aspx?scid=kb;en-us;264921 (check the limitations section under Windows NT Challenge/Response - Integrated Windows Authentication was formerly named NTLM, or Windows NT Challenge/Response authentication).

There are 3 ways to workaround this problem

1) Turn of Windows Integrated Authentication and turn on Basic Authentication
2) Hardcode the credentials passed to SharePoint in the ASP.NET application code
3) Turn on Kerbrose Authentication

Option 1) Turn of Windows Integrated Authentication and turn on Basic Authentication

You can turn off Integrated Authentication and turn on Basic Authentication on the virtual directory running the ASP.NET application. With this you should be prompted for your user name and password every time you try to access the ASP.NET application and unlike Integrated Windows Authentication - your credentials are passed even in the second hop.

Note that the drawbacks of this option are
i) in Basic Authentication the user credentials are passed as clear text
ii) users will get a pop-up asking for user credentials every time they try to access your page.

Option 2) Pass user credentials using code

My code used the default credentials from the credential cache - however you can hardcode the credentials that are passed to SharePoint. In the SPS web service case i had to create a NetworkCredential object with the user credentials hardcoded and set the object to the Credentials property of the QueryService proxy object.

Changed the line from

qs.Credentials = System.Net.CredentialCache.DefaultCredentials;

To
qs.Credentials = new System.Net.NetworkCredential("<User Name", "<Password>", "<Domain Name>");

In the case of a Fileshare, etc - you will need to use an unmanaged API to impersonate the user on the SPS machine, here is an MSDN article to do that http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemSecurityPrincipalWindowsIdentityClassImpersonateTopic.asp

You can alternatively instead of hardcoding the credentials in code - you can put them in the Web.Config file and retrieve at run time. If you do this - you should also encrypt the password.

Option 3) Turn on Kerberos Authentication

You need to turn on Kerberos on IIS and configure SharePoint for this - you can refer to this KB article for the exact steps http://support.microsoft.com/?id=832769

Any of these three options should resolve the problem.

Mohammed Jeelani

Creating a WebPart that works both as a consumer and a provider

mjeelani — Sat, 06 Nov 2004 02:48:00 GMT

If you ever have to create a web part that needs to act both like a provider and a consumer in which case you'll need to implement more than one Interface, you'll need to create separate classes that implement the separate interfaces...

To make a web part work both as a provider and a consumer you'll need to create three classes...

1) public class CellProviderInterface : ICellProvider
2) public class CellConsumerInterface : ICellConsumer
3) public class WebPart1 : Microsoft.SharePoint.WebPartPages.WebPart

In classes CellProviderInterface and CellConsumerInterface you'll have to implement the ICellProvider and ICellConsumer interfaces.

In your WebPart class you need to instantiate the two classes that implement the ICellProvider and ICellConsumer (viz. CellProviderInterface and CellConsumerInterface)

//instantiate your classes
CellConsumerInterface oCellConsumerInterface = new CellConsumerInterface();
CellProviderInterface oCellProviderInterface = new CellProviderInterface();

And When you register your interface's in the overridden EnsureInterfaces() you need use the instances of these two classes.

public override void EnsureInterfaces()
{
// Register the ICellProvider interface
RegisterInterface("CellProvider_WPQ_",
  "ICellProvider",
  WebPart.UnlimitedConnections,
  ConnectionRunAt.Server,
  oCellProviderInterface,
  "CellProvider_WPQ_",
  "Provides a cell to",
  "Provides a cell of data");

// Register the ICellConsumer interface.
RegisterInterface("CellConsumer_WPQ_",
  "ICellConsumer",
  WebPart.UnlimitedConnections,
  ConnectionRunAt.Server,
  oCellConsumerInterface,
  "CellConsumer_WPQ_",
  "Consumes a cell from",
  "Consumes a cell of data");
}

Here’s some sample code that does something very similar….

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/spptsdk/html/smpxCreateConnectableWPMultipleInterface_SV01080585.asp?frame=true

Jeelani