Citrix states in their article: CTX159159

CTX159159 - Troubleshooting and Explaining Session Sharing

This document was published at: http://support.citrix.com/kb/entry.jspa?externalID=CTX159159

Document ID: CTX159159, Created on: May 24, 2002, Updated: Sep 8, 2003

Products: Citrix MetaFrame XP 1.0 for Microsoft Windows 2000, Citrix MetaFrame XP 1.0 for Microsoft NT 4.0 Server Terminal Server Edition, Citrix MetaFrame 1.8 for Microsoft NT 4.0 Server Terminal Server Edition, Citrix MetaFrame 1.8 for Microsoft Windows 2000

This article explains session sharing and discusses some common scenarios.

Session sharing is the ability of a seamless published application to be executed over the same connection.

Session sharing occurs if there is an open session and another application is launched and is published to the same server as the first session. Consequently, additional published applications work in the same fashion. Session sharing for managed applications is enabled by default in MetaFrame 1.8 Service Pack 1 and MetaFrame XP for Windows Terminal Server 4.0 and MetaFrame 1.8 and MetaFrame XP for Windows 2000.

Note: The session sharing check is done prior to the connection going through load balancing.

Ensure all applications are published with the same settings. Varying results may happen when applications are set for different requirements, such as encryption.

Citrix currently does not support session sharing on the WinCE or PocketPC client with or without the PN Agent.

Example of Session Sharing

Suppose you publish, separately, each application (Word, Outlook, Access, and Excel) in the Office Suite to a load balanced server farm with five servers. Thus, you have a published application for WinWord.exe, Outlook.exe, Access.exe, and Excel.exe. You now log on to WinWord, potentially accessing any server in the farm (we will use Server 3 for our example) and now need to import an Excel spread sheet. You launch the published application for Excel. According to the rules of session sharing, if the first application is launched as a seamless application and if Excel is also published on Server 3, Excel runs as another program within the same session, as opposed to a new session being launched on this server or another server. From Citrix Server Administration, you can see that there is only one session and one license in use.

Support for this Feature

Session sharing is a feature of the Program Neighborhood Client. It occurs when you run an application as a seamless application. It will not function from a “separate window” or if launched through an ICA file with Wfica32.exe. Running Wfcrun32.exe can also be used for session sharing.

Disabling Session Sharing

In some instances, you may want to disable session sharing. One example might be for security reasons and another common one is for using Packeteer’s Packet Shaping products with ICA.

To disable session sharing, the following registry key must be present along with the following updates:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. If you are running Windows NT, be sure to update your Emergency Repair Disk (ERD).

Add the following value to disable this feature (this value does not exist by default):

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix\Wfshell\TWI\:
Type: REG_DWORD
Value: SeamlessFlags = 1

To re-enable the feature, delete this key.

You can download one of the following hotfixes or service packs to resolve this issue:

MetaFrame 1.8 Service Pack 3 for TSE - ME183T036 or later
MetaFrame 1.8 Service Pack 3 for Windows 2000 - ME183W041 or later
MetaFrame XP for TSE - MetaFrame XP Service Pack 2 for TSE or later
MetaFrame XP Feature Release 2 - XE102W029 or later

Reconnecting to a Disconnected Session with a New Application

With MetaFrame XP Feature Release 1, the same client name launches the new application in the original applications disconnected session.

The feature works as follows:

1. When a new seamless application is launched and there are disconnected sessions for this client, the browser checks whether or not any of those sessions are on a host that also publishes the new application and directs the client to that host.

2. Wsxica.dll on the host causes a reconnect to a suitable session.

3. The seamless module, Seamls20.dll, launches the application in the reconnected session.

4. The feature, by default, is ON and can be disabled, on each server, by adding a value to the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix

Type:REG_DWORD
Type: ReconnectWithNewApplication = 0

This value is ON by default in MetaFrame XP with Feature Release 3.

Session Sharing and Novell NDS

The following is an excerpt from the Advanced Concepts Guide for MetaFrame XP Feature Release 2:

Session sharing works correctly with NDS users only if the application permissions are assigned at a user or container level. Session sharing does not work if assigned at the group level.

The session sharing feature is not currently supported for custom ICA connections that are configured with NDS user credentials (under Properties > Login Information). To use the session sharing feature for custom ICA connections, do not specify user credentials for a connection on the connections Login Information tab.

Custom ICA Connections

When users run the Add New ICA Connection wizard, they must enter a distinguished name in the User Name field and a password in the Password field, and place the NDS tree name in the Domain field. Users running earlier versions of ICA Win32 Clients can also enter credentials in this manner.

Attempts to Share Sessions may Consume
more than one Connection

1. Multiple sessions can be opened if multiple configured seamless Window applications are started in rapid succession and the MetaFrame server has custom logon scripts that take longer than 20 seconds to complete. To extend this time-out value, enter the following information in the Appsrv.ini file under the [WFClient] section:

SucConnTimeout = xx

where xx is the time in seconds. Alternatively, you can apply Service Pack 3 for MetaFrame 1.8.

2. When using the pass-through client Version 985 from a MetaFrame server in a workgroup, to connect to one or more seamlessly published applications and connect to the first published application, two connections are registered on the server. Use the server’s Computer Name instead of the workgroup name in the Domain field of the Program Neighborhood Application Set Logon box. />

3. The Prompt for Password check box or default Windows NT authentication is configured on the ICA listener.

4. Applications are published with different settings; custom ICA connections have different settings.

Example: Two seamless defined custom ICA connections from the PN client with the identical settings share a session share. After changing the property of one of them to a different color depth, one connection 16 and the other connection 256, they no longer share a session.

Session Sharing in MetaFrame XP Feature Release 2

There are some misconceptions that have to do with the way the Citrix Management Console displays shared sessions. For example, a user running two session-shared applications shows two entries in the console but the sessions have the same number; that is, ica-tcp#1.

Using the Win32 Client 986 or later, connecting from a workstation to two or more seamlessly published applications on the same server show as being session-shared. This happens for either custom connections or an application set. However, if the applications are accessed non-seamlessly, two separate connections are used and shown.

If you connect to the pass-through 986 or later client that is either published or run from inside a desktop session, and then connect to two or more published applications on the same server from which you launched the pass-through client through an application set, the sessions are shown as shared.

If the connections to the two published applications are made by custom connections with the pass-through client, they show as two separate connections and each subsequent connection to a published application on the same server will be shared.

Another point to note is that when using the pass-through client and connecting to a published application that is on the same server from which the pass-through client was launched, the applications are actually launched within the Windows NT session in which the pass-through client is running. The applications do not go through ICA.

The 6.30.1050 and 6.30.1051 clients may not behave correctly, with respect to session-sharing, in a pass-through mode. Either downgrade or await the next public release of the Citrix ICA Win32 Client.