Systems Analysis I System Implementation

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Systems Analysis ISystem Implementation

• ISYS 200
• Glenn Booker

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System Implementation

• Now we get to actual creation of the system weve
  designed
• Notice the text covers this fairly quickly,
  since many other courses are needed to cover the
  skills and concepts needed for implementation
• Key aspects of implementation include how the
  information is distributed, providing user
  training, and choosing a good conversion strategy

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Implementing Distributed Systems

• Variations of client/server (C/S) networks have
  been widespread since the 1980s, and continue
  to evolve
• In basic form, C/S refers to some system
  processing being done by a PC-based client
  application, while other parts are done on the
  server
• Now we tend to have many types of specialized
  servers instead of just one

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Implementing Distributed Systems

• Servers can include many varieties
• File servers, to hold shared files
• Print servers, to manage print jobs
• Database servers, to run a shared database
  system
• Now we might add web servers to control access to
  our system, and various kinds of application
  servers

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Types of Networks

• The basic types of networks include
• LAN Local Area Network, a typical home or
  office-sized network
• WAN Wide Area Network, a corporate network
  which spans continents
• WLAN Wireless LAN, a LAN which uses wireless
  (Wi-Fi) connections

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Network Connections

• Common network connections include
• Ethernet cable, an 8-wire cable (RJ-45 plugs)
  similar to 4-wire phone lines (RJ-11)
• Fiber optic cable, for Gigabit and faster
  networks
• Thick and thin Ethernet cables are pretty
  obsolete

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Organizing Networks

• There are four major topologies (structures) for
  a physical computer network
• Bus
• Ring
• Star
• Hierarchical
• They may be combined in some cases, such as a
  hierarchical top level structure, and stars used
  locally

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Network Topology - Bus

• A key function to achieve connectivity among
  computers is definition of the network topology
• The bus is the simplest topology - it connects
  computers along a single line
• A peer-to-peer (server-less) network uses the bus
  topology, with AppleTalk or Ethernet

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Ring Topology

• The ring topology connects computers in a loop,
  and passes packets of data from one computer to
  the next
• IBMs Token Ring is the most famous example
• Bad if a computer falls off the network hard to
  tell who dropped the packet

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Star Network

• Many clients may be connected to each server
  across a star network
• The middle of each star is a server
• Servers are connected to each other
• Very common think of using a server for each
  department, and be able to control which
  departments can see each other

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Hierarchical Network

• This is a set of nested star networks, looks kind
  of like an organization chart
• Generally the servers get smaller the further
  down the hierarchy
• Sometimes used in very large corporations, where
  the biggest servers store company-wide or
  division-wide data

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Network Modeling

• A network for a system or an organization is
  developed to meet a need-to-know basis
• Ensure people who need to see data can get to it
• And those who dont need to, cant
• Networks are generally broken into portions or
  segments which correspond to organizational units
• One segment is the Accounting dept., another is
  the Human Resources dept., and so on

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Network Modeling

• Segments of the network are separated from each
  other by network hardware
• Routers, switches, hubs, bridges, and other toys
  are the hardware involved
• The type of hardware is chosen based on
• The protocols involved
• The distances between segments
• The amount of logic or processing needed for
  isolation

Cisco has some nice tutorials to help explain
the hardware in more detail
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Network Modeling

• Based on the type of network topology chosen, a
  network decomposition diagram (p. 628) can be
  developed to show the parts of a network, and who
  they can talk to easily
• Different symbols can be used to show hubs at the
  center of each segment, key types of users,
  groups of related workstations, and external
  networks

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Network Modeling

• In contrast, a hub connectivity diagram shows the
  hubs of your network, and how far they are from
  each other
• A more detailed version is the workstation
  connectivity diagram, which examines one segment
  (hub) and looks at the distances involved in its
  connections

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Distribution

• Since computers were invented, the amount of
  distribution of data and processing functions has
  tended to go up without end
• The ultimate incarnation is web-based computing,
  where both data storage and processing are
  distributed across possibly hundreds of computers
• While this allows more flexibility and often
  better use of resources, it adds reliability and
  security issues

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Training Users

• As a system is being implemented, several key
  aspects of training need to be managed
• While end user training is often considered,
  there may be other kinds of training needed
• Training for other user roles, including managers
• Training for support staff of the operational
  system (help desk, and system maintainers)
• Training for those who will train users
  (train-the-trainer), if there are many end users

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Training Users

• Training may also be needed on commercial
  components of the system, so vendors may need to
  provide training on how their OS or bridge works
• Training may be conducted by systems analysts,
  consultant trainers, or training staff within
  your organization

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Conducting Training

• Training needs to be planned carefully
• Need to determine its objectives and methods
• Need to determine where to conduct training
• Need to develop training materials, and keep them
  consistent with the actual system
• User training needs to be done before the system
  is implemented, but not so long that they forget
  what they learned!

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System Conversion Strategies

• To implement a new information system, you are
  presumably replacing whatever existing system (if
  any) and processes (whether manual and/or
  automated) that are currently performing the
  systems functions
• Need to choose a conversion strategy
• How to convert from doing things the old way to
  using the new system

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System Conversion Strategies

• There are about five types of conversion
  strategies to choose from (p. 636)
• Direct changeover means the old system is used
  until a stated date and time, after that, the new
  system is used
• Parallel conversion means that the old and new
  systems are used together for some period of
  time, until youre okay to shut off the old system

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System Conversion Strategies

• Gradual conversion tries to slowly phase in the
  percent of transactions handled by the new
  system, until it does everything
• Modular prototype conversion means that the new
  system is developed in chunks of functionality
  when a set of functions are ready to be released,
  it becomes operational and that part of the old
  system is shut down
• The distributed conversion strategy works
  geographically convert sites one group at a
  time until they are all done

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Security Concerns

• Both traditional and web-based systems have
  security and privacy issues
• Security concerns can be divided into physical,
  logical, and behavioral
• Physical security is making sure the computer
  facilities arent broken into, the computers
  dont get stolen, backup tapes dont grow legs,
  etc.

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Security Concerns

• Logical security is within the system software
• To ensure that users are validated,
• Passwords expire and dont get reused,
• Passwords are sufficiently complex
• User access to system functions really is
  controlled by their security profiles
• Firewalls on public Internet access points also
  fit into this category

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Security Concerns

• Behavioral security is avoiding compromise of
  your system from inside by its users
• Screening potential employees
• Making security policies clear
• Monitor behavior which may compromise the system
• Limit number of incorrect sign-on attempts
• Monitor your own software activity and look for
  suspicious activities
• Control distribution and/or encrypt system
  outputs
• Shred discarded system outputs

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Internet Security

• Basic aspects of Internet security include
• Use and maintain virus protection software
• Filter email from spam
• Restrict Internet access by employees
• Monitor network connections to the public
• Encrypt anything passing through the Internet
• The Rainbow Series of reports by the NIST is a
  widely used set of computer security standards

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Privacy Concerns

• Privacy has become a key public issue
• Establish clear privacy policies, and follow them
• Only get required information
• Make personal information optional, if you must
  ask for it
• Use anonymous sources about clients where
  possible
• Be ethical

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System Evaluation

• Once the new system is fully operational, it is
  important to evaluate its success
• Go back to the system objectives developed from
  the problems and opportunities analysis
• Measure the quantities described in the
  objectives
• Customer satisfaction, system throughput, number
  of transactions, number of bad transactions,
• Compare the measurements to the predicted values,
  and analyze differences between them