1. COMP1321 Digital Infrastructure
Richard Henson
March 2018

2. Week 19 – Servers, Thin Clients, Connectivity, Mixed Networks, and Virtualisation
Objectives
Explain levels of distribution in client-server networking, and relate the use of different levels to organisational requirements
Explain the process of terminal emulation and how terminal services and other software can deliver this to the desktop
Explain virtualisation and install a virtual machine

3. A matter of Fashion or Functionality?
Very early days of networking…
no clients… (or even users!)
specialist staff only
all computer input via cards and tape
output only to printers
Original clients (e.g. “Wang VDU) early 1970s really were “dumb”!
microprocessor only just been invented!
interrupt driven processing hadn’t been implemented

4. Servers provide Services
In the early days of organisational computing, the server (host) was king
user device VDU (Visual Display Unit) or Terminal had no processing ability
everything controlled from the centre, with “dumb” terminal on employee’s desk
Central host/server
VDUs (screen
and keyboard)

5. The dawn of the “intelligent client”
First “8 bit” processor (Intel 8008) available in 1973…
two years to develop a motherboard & operating system
expected that “users” would write their own apps
1975, the first microcomputer: The Altair
scope for “intelligence on the desktop”
Many other Micros followed:
Commodore
Atari
Sinclair ZX81

6. Success of the Business Micro
By 1981, microcomputers popular in the home…
IBM PC (16 bit) was introduced to see whether business would make use of desktop computing…
Business loved the IBM micro
applications became commercially available
large organisations wanted to exchange data…
between desktops
between desktop and server

7. Desktop Machines Networked
Through OSI & IEEE802 standards, the networked PCs & LANs became possible…
Novell Netware made a PC a server
Communicated with PC clients… very popular
PCs linked to “host” computers previously using only dumb terminals…
DEC PCSA a popular step forward using TCP/IP
meant mainframes running TCP/IP could interface with microcomputers!!!

8. Ubiquitous Client platforms
Environment for running software even more miniaturised… e.g.
Intel motherboard etc./Windows 10
Diff Intel motherboard/AppleOS
Smartphone/Android
Sometimes useful to be able to run more than one platform on a single machine…

9. Clients make services accessible to users…
Servers hold secure data…
should be kept well away from users!
Users can only access data/resources on a client-server network via a request to a server
Depending on the server architecture:
make requests directly via commands inputted from a dumb terminal
make requests from an intelligent client through interprocess communication

10. Front End and Back End
As client-server computing entered most organisations…
Client desktop – previously VDU - known as “front-end” (or “front office”)
Anything to do with servers/shared applications and information stores – previously the mainframe - known as “back end” (or “back office”)

11. Clients, Platforms, and Flexibility
Demand for multiple client platforms for the user…
but multiple devices/machines expensive
virtual machine got round this

12. Virtual Machines Mounting a platform that is solely software based
running on top of an existing hardware/software platform
e.g.
Intel/Windows 7/8/10 client
Apple client

13. Virtualisation Platforms
Software environment running on top of an existing platform
allows more than one virtual machine to run on top of a traditional hardware/software platform
Client operating system installed on top of virtualisation platform

14. Examples: VMWare Virtual Box Citrix Hyper-V
Virtual machine e.g. running Windows 10
Virtual machine e.g. running Server 2016
VMWare
Virtual Box
Citrix
Hyper-V
virtualisation platform
Hardware/software platform e.g. Intel/Windows

15. Virtualisation (Windows 2016 Server, on VMware, etc.)
The use of software to allow a piece of hardware to run multiple operating system images at the same time
possible to run Windows OS under Mac OS
run multiple versions of Windows OS on the same PC
Enables the creation of a “virtual” (rather than actual) version of any software environment on the desktop, e.g. operating Systems, a server, a storage device, an application

16. “The Cloud” Outsourcing on a grand scale… “Back to the Future”
With connectivity via world wide web
“Back to the Future”
Quote from IBM in 1950s:
“I think there is a world market for about five computers.” attributed to J. Watson
“The cloud” will behave like just one massive mainframe computer providing all user services
No powerful clients needed… just enough processing at the client end to run a browser
could be a very small device (Smartphone)
could use wireless protocols to connect…

17. Web Services and The Cloud
Companies like Amazon, Google (apps), and salesforce.com have created web services (http/s) and made them available to a wider public for storing their data
this approach benefits companies most that are experience relatively quick growth
instead of getting new storage resources every year, organisations can quickly and easily purchase more "cloud space"

18. Cloud Computing Model

19. Cloud Services, the Future, and Security
Cloud computing can offer applications as-a-service as well…
a future is predicted where everything is outsourced and no kind of local CPU is even needed
employees will simply have a monitor, keyboard, and mouse that will allow them to connect to the cloud for all of their resources (!)
but will this be secure? And what comeback will organisations have if something goes wrong?

20. What (physically) is The Cloud?
Lots of servers connected together in clusters to provide different services via the www
uses essentially the same TCP/IP protocols
different ports for different applications
attractive and powerful, but…
disadvantages of outsourcing in terms of control
and with the extra challenge that the user doesn’t know where their data physically is at a particular time… SCARY?

21. Data Protection, Organisations, and the Cloud
Lot of pressure on organisations to put digital infrastructure “in the cloud”
Less hassle?
someone else managing your data
cheaper… don’t need servers or expensive staff to manage them
don’t even need “back office” premises!

22. Data Protection and the Cloud
Disadvantages…
concern about loss of control of organisational data
dependent on bandwidth of cloud provider
what if cloud provider gets hacked?
where is the data being held? “third country”?
legal concern whilst UK in the EEA…
UK soon to leave EU? And the EEA?
will then be a “third” country anyway…

23. Setting up a Virtualisation Platform
Many products available:
Citrix metaframe
VirtualBox
VMWare
Microsoft Hyper V
All available on Windows client converting it to a virtualisation platform

24. Hyper-V New for Windows 2008 Server
Subsequently available to Windows clients
PC/Laptop running Windows 10 good platform for virtualisation platforms
e.g. Hyper-V
can run several virtual machines
can even use virtual “switches” to communicate with one another…

25. Thanks for listening 