Transcript Thin-Client Computing - University of Oxford

Thin-Client
Computing
Peter Higginbotham
OUCS
June 2000
Thin Client Overiew
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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
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
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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
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Thin Client Clients
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Microsoft-provided:
– Win32
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With Citrix Metaframe:
– DOS (386 PC/2Mb RAM / DOS 4.0)
– Windows 3.x
– Mac
– Motif
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
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– Web
Server Setup
NT 4 - special TS edition
 W2K - Terminal Services runs as a
service in one of two modes:
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– Remote administration
– Application Server
– Switch mode via Add/Remove Programs
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TS server has everything needed for
basic service to Win32 clients
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:
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– System
– Apps
– User filestore
– Profiles (desktop, prefs, start menu etc.)
Application Install
Generally install as on a stand-alone PC
 Preferred method is via Add/Remove
Programs
 Command-line switch to/from install
mode:
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• CHANGE /USER INSTALL
• CHANGE /USER EXECUTE
Model TS Applications
Separate application files and user data
 No hard-coded path names in registry
 Use environment variables wherever
possible e.g. %USERNAME%
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Application Install
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During installation, user registry
changes shadowed to special area:
HKEY Local Machine\Software\Microsoft\Windows
NT\CurrentVersion\Terminal Server\Install\Software
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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
Application Install – Office 2000
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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/deploym
ent/termserv.htm
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Application Install - Office 97
Switch to install mode
 Perform standard local install
 Run Application Compatibility Script
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– Changes file permissions
– Moves files
– Removes Findfast
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.
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– ACREGL
– ACSR
– FINDSTR
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:
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– User’s startup folder
– All Users startup folder
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Could also start-up individual
applications via a script file
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
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Application Install - Vista Exceed
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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
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Can grab end of SESSIONNAME string using
ACSR utility
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.
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Exceed Launch Script
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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%
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
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Server Management (W2K)
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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
Server Management (W2K)
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Terminal Services Manager tool
– Show current connections
– Show processes running
– Shadow a sessions etc.
– Kill processes/sessions
– Send messages
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)
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Client Access – Microsoft
Connections use RDP protocol - over
IP only
 Win32 Terminal Server Client
 Client Connection Manager – can preconfigure access to specific applications
 W2K - access to applications from TS
session desktop can be controlled by
Active Directory group policy
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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
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– 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
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Access to Local PC - Microsoft
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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
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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)
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Citrix Metaframe
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Offers:
–
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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
Citrix MSDOS Client
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Very low requirements:
– 80386 processor or better
– DOS 4.or or later
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Requires a TCPIP stack
– Microsoft one gives very sluggish
performance
– Novell LAN Workplace one much better
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
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Software Licensing
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Per server
– NT4 TS Edition or W2K in TS mode
– Citrix Metaframe 1.8 option (£2400)
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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
Citrix Metaframe Web Interface
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MS Terminal Services Internet
Connector license (£3,400 per server)
allows up to 200 anonymous nonemployee connections from the internet.
Other types of user need TSCALs.
More Information
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http://www.eu.microsoft.com/windows2000/gu
ide/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)