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COMP2322 Network Management. Richard Henson Worcester Business School March 2016. Week 5 – Thin Clients, Connectivity, Mixed Networks, and Virtualisation. Objectives Explain levels of distribution in client-server networking, and relate choice to organisational requirements
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COMP2322 Network Management Richard Henson Worcester Business School March 2016
Week 5 – Thin Clients, Connectivity, Mixed Networks, and Virtualisation • Objectives • Explain levels of distribution in client-server networking, and relate choice to organisational requirements • Explain dumb terminals/terminal emulation and how terminal services and other software can deliver this ecomically to the desktop • Explain virtualisation and install a virtual machine
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 (or VDUS) early 1970s, really were “dumb”! • microprocessor only just been invented! • interrupt driven processing hadn’t been implemented
The dawn of the “intelligent client” • First “8 bit” processor (Intel 8008) available in 1973… • Two more years to develop a motherboard & operating system • 1975, the first microcomputer: The Altair • scope for “intelligence on the desktop” • expected that “users” would write their own apps • By 1981, microcomputers popular in the home… • IBM PC introduced to see whether business would make use of desktop computing…
Success of the Business Micro • Businesses used the IBM micro • applications became commercially available • large organisations wanted to exchange data… • between desktops • between desktop and server • Through OSI & IEEE802 standards, the networked PC & LANs became possible: • centralised computers could interface with microcomputers • popular early implementations: • Novell Netware • DEC PCSA
Servers provide Services • In the early days, the server (host) was king • user device VDU (Visual Display Unit) or Terminal had no processing ability • everything controlled from the centre • Once microcomputers could connect to servers • host-VDU/terminal -> server-client • clients provided richer user experience • But, servers retained control • provided client access to resources via services
Client platforms • Environment for running software… e.g. • Intel motherboard etc./Windows 7 • Intel motherboard etc./AppleOS • Smartphone/Android • Sometimes useful to be able to run more than one platform on a single machine.
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
Virtual Machines • Replacement of an existing hardware/software platform by a platform that is solely software based • Virtual Machine still has to run on an existing platform e.g. • Intel/Windows 7/8/10 client • Apple client
Virtualisation Platforms • Software environment running on top of an existing environment • 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
Examples: • VMWare • Virtual Box • Citrix • Hyper-V Virtual machine e.g. running Windows 10 Virtual machine e.g. running Server 2008 virtualisation platform Hardware/software platform e.g. Intel/Windows
Virtualisation (Windows 2008 Server, Citrix, 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 or networks, an application
“The Cloud” • Outsourcing on a grand scale… • 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 FAT clients needed… just enough processing at the client end to run a browser • could be a very small device • could use wireless protocols to connect…
Web Services and The Cloud • Companies like Amazon, Google (apps), and salesforce.com have created web services (XML/http) 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"
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?
What (physically) is The Cloud? • Lots of servers connected together in clusters to provide different services via the www • Attractive and powerful, but… • disadvantages of outsourcing in terms of control • and with the extra challenge that the user doesn’t know where there data physically is at a particular time… SCARY? • Server location also a matter of some concern for legal reasons…