????? 3: ????????????????????????????????????????? IT ???????????????? (Networks)

1

• ????? 3 ?????????????????????????????????????????
  IT ???????????????? (Networks)

2
???????????? IT ??????????????????????????????????
??????

• ????????????????????? ????????????
  ??????????????????????????????????????????????????
  ??????????????????? (Information Technology)
• ??????????????????????????????????????????????????
  ???????? ??????? ????????????????????????
• ????????? ???? electronic spreadsheets (Excel)
  ??????????????????????????????? ????????????????

3
????????????? IT ??????????????????

• ?????????????????????? (Devices for data entry)
• ????????????????? (Data Processing)
• ???????????????? (Data Communication)
• ????????????????? (Information Generation)
• ????????? (Data Bases)
• ????????????????????????????????????(Data
  Modeling concepts)
• ?????????????????????????? ?????? AIS
• ???????????????????? ?
• ???????????????????? (Computer Networks)

4
????????????? ??????????? (Networks Accountants)

• ??????????????????????????????????????????????????
  ?? ?????????? AIS ???
• ??????????????????????????????????????????????????
  ?????????? ????????????????????????
  ??????????????????????????
• ??????????????????????
• ???????????????????????????
• ??????????????????????????????????

5
?????????????? IT?????????????? (Accountants)

• ?????????????????????????????????????????
  ??(Faster processing)
• ??????????????????????????????????????
  ????????????? (Greater accuracy)
• ?????????????????????????????? (Lower cost)
• ?????????????????????? ?????????????? (More
  timely)
• ???????????????? ?????????????????????????????????
  ??????
• ??????????????????????????????????????????????????
  ???????????????
• ??????????????????????????????????????????????????
  ????????????????????????? (Higher productivity)

6
???????????????????????????? Task Matching to
Computers

• ???????Computerized
• ????????????? ????????????????????????????????????
  ?? ? ???
• ???????????????????????????
• ????????? (Monitoring) and ????????????
  (controlling continuous processes)
• ????????????????? ????????????????????????????????
  ???
• ??????????????????????????????????????????????????
  ??????
• ????????????????????????????????????????

• ??
• ???????????????????????????????
• ?????????????????????????????????
• ??????????? ? ????????
• ??????????????????
• ????????????????????
• ??????????????????????????????

Figure 3-1
7
Limitations of Infoages Legacy AIS

• Large portion of personnel time and effort spent
  on systems maintenance
• Little time effort for value-added services
• Little flexibility to changing business
  conditions
• Financial and Operational data not integrated
• Difficult to generate data with both financial
  and non-financial components
• The transaction processing systems focus on chart
  of accounts classification
• Ignore the multidimensional aspects of
  transactions
• Files related to applications are not integrated
• Inefficiencies of the manual system remodeled in
  automated form
• Business processes and accounting procedures not
  analyzed and improved upon prior to conversion to
  automated form
• System not geared to generate timely
  decision-support information
• Computer programmers required to write new
  programs for ad hoc queries

8
??????????????????????????? (Types of Network
Architectures)

• Wide-Area Networks
• ???????????????????????????? (graphically
  distant)
• Local-Area Networks
• ????????????????????????????????????? (limited
  geographical area)

9
Centralized WANs - I

• Concentrates all application processing at one
  geographical location
• Consists essentially of one (or a cluster of)
  central mainframe computer(s) and one or more
  physically remote terminals
• Typically all hardware, software, and data
  processing personnel are located at corporate
  headquarters
• Advantages include
• the concentrated computing power of a large
  processor
• low operating costs per transaction leading to
  economies of scale
• can facilitate the use of a database approach
• facilitate better security provisions
• allow for greater standardization and
  professional planning and control of
  information-related activities

10
Centralized WANs - II

• Best suited for
• Firms with centralized organizational structures
• Firms with homogeneous operations
• Firms with low processing activity at remote
  sites
• Examples include
• Savings and loan institutions
• Banks with many ATMs and branches
• Merchandizing chains
• Motels
• Airlines
• Drawbacks include
• Inflexibility
• Expensive and complicated software needed
• Vulnerable to disasters as a result of complete
  dependence on central computer
• Not user-friendly

11
Distributed WANs - I

• This links fully functional computers in
  different geographical locations.
• Each remote site processes its own applications.
  However, users may not have easy access to
  centralized data or be able to transmit data and
  information rapidly.
• Computers may be interconnected by data
  communications hardware and software to other
  remote sites and to a central computer facility
  to form an enterprise-wide network.

12
Distributed WANs - II

• Distributed databases are useful when
• Large volumes of data need to be processed at
  remote locations
• Managers and employees need very fast access to
  data on a frequent basis
• Databases may be distributed by replication or
  partition.
• Replication Copies of files from the main data
  base are stored at remote locations
• Partition Segments of files are allocated to
  various locations within the network
• This avoids data redundancy, but increases the
  complexity of transmitting data throughout the
  network
• Likely to become the dominant approach as
  technology improves
• At present most data bases are a hybrid of the
  two approaches

13
Benefits of Distributed WANs

• Can be responsive to diverse needs of users
• Enable network facilities to be used efficiently
  since processing jobs can be routed to unused
  computer systems in the network
• Are robust against individual computer failures
• Flexible and adaptable to change
• Best suited for firms with
• Decentralized organizational structures
• Diverse operations or user groups
• Clustered functions at various locations
• Multiple products
• Manufacturing operations
• A variety of services

14
Drawbacks of Distributed WANs

• Difficulty in maintaining adequate control and
  security
• Each distributed processing location needs its
  own set of controls and security measures
• Given the smallness of each location,
  organizational independence is not easily
  achieved
• Managers may sacrifice control and security for
  greater productivity
• Difficulty and cost of coordinating the
  relatively independent and sometimes incompatible
  computer systems
• Added costs for multiple computers, other system
  components, and communication services

15
????????????????? (LANs)

• A LAN may be connected to other LANs and/or WANs
  via hardware devices known as gateways or bridges
• At the heart of a LAN is the workstation
• Microcomputer-based workstation
• Traditional workstation
• Super workstation

16
Peer-to-Peer LANs

• In smaller LANs, every workstation functions as
  both a client and a server
• This allows all users to share data and files on
  all workstations
• Called peer-to-peer network since no workstations
  are dedicated to perform only server functions
• Compared to a server network, peer-to-peer
  networks are less costly, easier to install, and
  compare well against server networks of similar
  size
• Number expected to significantly increase in the
  near future

17
Server Networks

• May interconnect hundreds of workstations
• More difficult to manage and interpret than
  peer-to-peer networks
• Provide greater security than peer-to-peer
  networks
• At least one workstation is dedicated to
  performing specific server tasks
• Examples include
• Servers
• Database servers
• Print servers
• Communications servers
• Transaction processing servers
• Large server networks often contain multiple
  servers

18
The Network Operating System

• In peer-to-peer networks, the Network Operating
  Software (NOS) is installed in each user
  workstation
• In a server network, most of the NOS is installed
  in the file server and a portion also resides in
  each workstation
• To run centralized LAN applications, the NOS
  installed in the file server interacts with the
  NOS and the local operating system installed in
  the workstation. The client workstation NOS
  initiates a request to the file server NOS to
  load files and programs into the client
  workstations RAM
• In a peer-to-peer network, a client NOS initiates
  a request to another client NOS, which also
  functions as a server, to load the requested
  files and/or programs into RAM

19
More Networks

• Examples of pre-developed network configurations
  resident in Network Interface Cards include
  Ethernet, Token Ring, and ARC-net
• The International Standards Organization has
  issued the Open Systems Interconnection (OSI)
  model
• Open Systems Architecture
• Seamless exchange of data, files, and software
  between LANs and WANs built with multiple
  vendors hardware, software, and networking
  components

20
Client/Server Networks

• This model splits data processing between a user
  workstation (client) and one or more servers
• Majority of servers are dedicated database
  servers, thereby enabling client to share data
  and files, conduct database searches, and update
  the database
• One of the fastest growing segments of IT

21
Cooperative Client/Server Computing

• Most commonly implemented mode of client/server
  architecture
• Facilitates the optimal sharing of computer
  resources since the client(s) and server(s)
  jointly process the data
• Clients typically employ Graphical User
  Interfaces (GUIs)
• Data-processing locale is transparent to the user

22
Network Topologies

• The STAR and RING topologies apply to both
  distributed WANs and LANs
• The BUS topology applies only to LANs
• All three found in client/server networks
• All three may be combined to form hybrid
  configurations

23
The STAR Configuration
Figure 3-3a
24
The RING Configuration
Figure 3-3b
25
The BUS Configuration
Figure 3-3c
26
Enterprise-wide Processing and Data Systems

• Enterprise-wide on-line transaction processing
  systems collect and process mission-critical
  accounting and operational applications
• Enterprise Resource Planning Systems (ERP) such
  as SAP R/3 overcome the limitations of legacy
  applications
• Firms typically develop two types of On-line
  Analytical Processing (OLAP) systems that
  supplement ERP or legacy systems
• A firm can model the relevant aspects of business
  events contained within the business processes
  allowing for the use of relational
  database-related query language commands
• Firms can create a data mart or data warehouse to
  generate predefined reports for executives and
  other managers

27
Data Marts and Data Warehouses

• Both Data Marts and Data Warehouses organize and
  store copies of informational or decision
  support data
• A Data Mart stores copies of decision support
  data in a data base for a portion of a company
• A Data Warehouse stores copies of decision
  support data in an integrated data base for an
  entire enterprise
• As opposed to applications-oriented data in
  legacy systems, data in a data mart or warehouse
  are stored by subject areas (e.g., customers)
• Data may be stored in both summarized or raw
  form
• Both have drill down and data mining features

28
Specialized Inter-organizational Systems/Networks

• Internet Commerce and Electronic Commerce
• Point-of-Sale Systems/Networks
• Electronic Funds Transfer (EFT) Systems
• Electronic Data Interchange (EDI) Systems
• Value Added Networks (VANs)
• The Internet (TCP/IP)
• The World Wide Web (WWW)
• Hypertext information retrieval system
• Intranets
• Extranets