Thin-Client Computing

1. Thin-Client Computing Peter Higginbotham OUCS June 2000

2. Thin Client Overiew • Applications executed entirely on server • Only user-interface events (keyboard, mouse, display, audio) processed by client • Users get complete NT/2000 desktop or just individual applications • Can access resources such as printers via server or back through client • Can integrate with Novell Netware resources and management tools

3. Thin Client Advantages • Centralised application administration • Win32 apps available to many platforms • May allow sharing of poorly networked apps • Old, low-power hardware can be used • Slow/dial-up lines can be used • Low intrusion on personal machines • Improved virus control

4. Thin Client Disadvantages • Needs high-performance central server • Most software needs tweaking to run in TS environment • Some software runs very poorly in TS environment • Some software may not run at all e.g. if has inbuilt licence monitoring • Some functionality may require Citrix Metaframe add-on - expensive

5. Thin Client Clients • Microsoft-provided: • Win32 • With Citrix Metaframe: • DOS (386 PC/2Mb RAM / DOS 4.0) • Windows 3.x • Mac • Motif

6. Thin Client Server • 12-24 Mbytes RAM per concurrent user (each user runs their own copy of any application) • 15-20 users per PIII processor • 2-6 kbps network bandwidth per user • Web

7. Server Setup • NT 4 - special TS edition • W2K - Terminal Services runs as a service in one of two modes: • Remote administration • Application Server • Switch mode via Add/Remove Programs • TS server has everything needed for basic service to Win32 clients

8. Server Setup • MS recommend that TS is not domain controller - can install as stand-alone • W2K – Active Directory not obligatory but useful • When installing, partition server disk: • System • Apps • User filestore • Profiles (desktop, prefs, start menu etc.)

9. Application Install • Generally install as on a stand-alone PC • Preferred method is via Add/Remove Programs • Command-line switch to/from install mode: • CHANGE /USER INSTALL • CHANGE /USER EXECUTE

10. Model TS Applications • Separate application files and user data • No hard-coded path names in registry • Use environment variables wherever possible e.g. %USERNAME%

11. Application Install • During installation, user registry changes shadowed to special area:HKEY Local Machine\Software\Microsoft\Windows NT\CurrentVersion\Terminal Server\Install\Software • Each user inherits a copy of this data - may need editing to ensure that file paths for INI files etc. are in a writeable place and are unique for each user, e.g. user’s home directory

12. Application Install – Office 2000 • Install using TermSrvr.mst transform • all options set as either “Run from my computer” or “unavailable” • Sets NOUSERNAME property • Increases O2K registry space on server • Use Profile Wizard to customize user default settings • http://www.microsoft.com/office/deployment/termserv.htm

13. Application Install - Office 97 • Switch to install mode • Perform standard local install • Run Application Compatibility Script • Changes file permissions • Moves files • Removes Findfast

14. Application Compatibility Scripts • CMD (batch) files • A few supplied for mainstream apps – office, IE, Netscape etc. • Use MS utilities to manipulate registry and environment variables, e.g. • ACREGL • ACSR • FINDSTR

15. Logon Scripts • May be needed to do one-off operations (file-copying etc.) e.g. first time a new user logs in • Can be in: • User’s startup folder • All Users startup folder • Could also start-up individual applications via a script file

16. Application Installation - SPSS9 • SPSS 9 - by default tries to create SPSS.JNL file in Windows temporary directory • Edit key to change path in HKLM key e.g. to h:\spss.jnl (where h: is mapping set up for home drive) or %homedrive%\%homepath%\spss.jnl

17. Application Install - Vista Exceed • Communications applications on TS all use same IP address • Unless each TS session uses a different display number, all Exceed sessions will try to output to same display. • Environment variable can be used to distinguish sessions, e.g.SESSIONNAME=RDP-TCP#4 • Can grab end of SESSIONNAME string using ACSR utility

18. Vista Exceed contd. • Extract tail of SESSIONNAME into new variable e.g. SESSION • Pass SESSION as a display-number parameter to Exceed start-up:exceed.exe -d %SESSION% • Can be useful to start up applications via a batch file rather than running executable directly.

19. Exceed Launch Script • ACSR search replace infile outfile Echo %SESSIONNAME%>%TEMP%\id Acsr "#" "Set SESSION=" %TEMP%\id %TEMP%\Session.cmd Call %TEMP%\Session.cmd Cd /d N:\Program Files\Exceed.nt Start Exceed.exe -d %SESSION%

20. Problem Applications • Where paths are hard-wired outside registry • 16-bit applications, i.e. poor performance and use more memory • DOS applications – hog CPU doing keyboard polling • DOS graphics – hog bandwidth • Graphics apps – limited to 256 colours

21. Server Management (W2K) • Terminal Services Configuration tool • Server Settings • Types of access e.g. Internet • Handling of per-session temp files • Connections - per-protocol • Encryption level • Logon Settings • Remote Control settings

22. Server Management (W2K) • Terminal Services Manager tool • Show current connections • Show processes running • Shadow a sessions etc. • Kill processes/sessions • Send messages

23. Command-Line Tools (W2K) • change logon (enable/disable logons) • query [user|process|session] • reset (kill sessions) • tskill (kill process) • msg (send message to users) • shadow • cprofile (cleans up user profiles)

24. Client Access – Microsoft • Connections use RDP protocol - over IP only • Win32 Terminal Server Client • Client Connection Manager – can pre-configure access to specific applications • W2K - access to applications from TS session desktop can be controlled by Active Directory group policy

25. Client Access – Citrix • Connections use ICA protocol – over IP, IPX/SPX, NetBEUI • Multiple client platforms • Program Neighbourhood utility can replace Windows desktop with palette of applications • Can be run on client or as session application • Only works on same subnet • Anonymous Users option – automates housekeeping of accounts • Seamless windows – app runs in what looks like a local window

26. Access to Local PC - Microsoft • Enable local file/print sharing then either:- Map Network Drive from Explorer, or- run NET USE commands within TS session to connect back to own machine, e.g. NET USE Z: \\PETER\MyDocs NET USE LPT1: \\%CLIENTNAME%\BJ10 • DRVMAP in W2K Resource Kit – automates process for W2K workstations • W2K TS provides inbuilt local printer access

27. Access to Local PC – Citrix • Transparent access to local drives and printers • Server’s own local drives (A:, C: etc) can be remapped to M:, N: etc to allow usre’s local drives to use standard letter assignments • Support for local audio (also available via other add-ons e.g. NCD ThinPathPlus)

28. Citrix Metaframe • Offers: • Support for extra clients • Transparent access to local devices • Efficient ICA protocol • Session shadowing (now in W2K) + multiple shadowing • Simplified application publishing via Program Neighbourhood • Server farms (optional) – don’t need to know which server is providing apps. • Load balancing

29. Citrix MSDOS Client • Very low requirements: • 80386 processor or better • DOS 4.or or later • Requires a TCPIP stack • Microsoft one gives very sluggish performance • Novell LAN Workplace one much better

30. Integration with Netware • Can install Netware client on a TS. Clients can then authenticate to an existing NDS tree. • Client can be managed using ZenWorks e.g. to provide printers, restrict access to desktop etc. • NAL can be used to manage access to applications

31. Software Licensing • Per server • NT4 TS Edition or W2K in TS mode • Citrix Metaframe 1.8 option (£2400) • Per client • Windows client access licence (CAL) • Non-W2K clients also need TS client access licence (TSCAL) • Citrix user licence option (£160) • Actual client software is free

32. Citrix Metaframe Web Interface • MS Terminal Services Internet Connector license (£3,400 per server) allows up to 200 anonymous non-employee connections from the internet. Other types of user need TSCALs.

33. More Information • http://www.eu.microsoft.com/windows2000/guide/server/features/terminalsvcs.asp • http://www.citrix.co.uk • http://www.ncd.com • \\bodley\10\technet\setup.exe • http://www.thinnet.com • http://www.thinplanet.com • Windows 2000 Server – Mark Minasi (Ch 14)