ISM 4300

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ISM 4300

• Computer Architectures
• Data Warehouses

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Mainframe Architecture

• With mainframe software architectures all
  intelligence is within the central host computer.
  
• Users interact with the host through a terminal.
• Mainframe software architectures are not tied to
  a hardware platform. User interaction can be done
  using PCs and UNIX workstations.

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Mainframe Architecture (cont)

• A limitation of mainframe software architectures
  is that they do not easily support graphical user
  interfaces or access to multiple databases from
  geographically dispersed sites.
• Can be used as a server in distributed
  client/server architectures.

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File Sharing Architecture

• Original PC networks were based on file sharing
  architectures, where the server downloads files
  from the shared location to the desktop
  environment. The requested user job is then run
  (including logic and data) in the desktop
  environment. File sharing architectures work if
  shared usage is low, update contention is low,
  and the volume of data to be transferred is low.

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File Sharing Architecture (cont)

• In the 1990s, PC LAN computing changed because
  the capacity of the file sharing was strained as
  the number of online user grew (it can only
  satisfy about 12 users simultaneously) and
  graphical user interfaces (GUIs) became popular
  (making mainframe and terminal displays appear
  out of date).

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Client/Server Architecture

• C/S introduced a database server to replace the
  file server. Using a relational database
  management system, user queries are answered
  directly.
• Reduces network traffic by providing a query
  response rather than total file transfer. It
  improves multi-user updating through a GUI front
  end to a shared database.
• Remote Procedure Calls (RPCs) or standard query
  language (SQL) statements are typically used to
  communicate between the client and server

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Two-Tier Client Server

• User system interface is usually located in the
  user's desktop environment and the database
  management services are usually in a server that
  is a more powerful machine that services many
  clients.
• Processing management is split between the user
  system interface environment and the database
  management server environment. The database
  management server provides stored procedures and
  triggers.

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Three-Tier Client Server

• There are a variety of ways of implementing this
  middle tier, such as transaction processing
  monitors, message servers, or application
  servers.
• The middle tier can perform queuing, application
  execution, and database staging.

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Three-Tier Client Server (cont)

• For example, if the middle tier provides queuing,
  the client can deliver its request to the middle
  layer and disengage because the middle tier will
  access the data and return the answer to the
  client.
• Adds scheduling and prioritization for work in
  progress.
• The three tier client/server architecture
  improves performance for large groups (in the
  thousands).

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Client/Server

• A Client Server System is more structured than
  general distributed computing. A client is
  defined as a requester of services and a server
  is defined as the provider of services. A single
  machine can be both a client and a server
  depending on the software configuration.

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Client/Server (cont)

• A client sends request to servers to execute
  tasks
• The tasks may be just to provide information, or
  to perform a complex computation (perhaps
  returning information)
• Client and servers are asymmetric
• A server may be a client of another server

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Client Network - Server
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C/S Desired Properties

• Interoperability
• Portability
• Integration
• Transparency
• Security
• Scalability
• Flexibility

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Interoperability

• The ability of two or more systems or components
  to exchange information and to use the
  information that has been exchanged
• Allows different systems to exchange meaningful
  information
• Requires standard exchange formats
• Requires standard message formats

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Portability

• A system in one environment can be installed in
  another
• Can be within the same hardware environment
• Can be within the same Operating System
  environment
• Can be within the same network environment
• Can be within the same database environment

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Transparency

• The user can read data from a site without
  knowing where it is
• The user can update data without knowing whether
  it is duplicated or not
• Tasks can be executed at various sites without
  the user knowing where they are
• Failures are dealt with

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Flexibility and Scalability

• Flexibility
• the ease with which a system or component can be
  modified for use in applications or environments
  other than those for which it was specifically
  designed
• Scalability
• the ease with which a system or component can be
  modified to fit the problem area.

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Points of Failure on C/S

• The client side of the application could crash
• The client system may have h/w problems
• The client's network card could fail
• Network contention could cause timeouts
• There may be network address conflicts
• Network elements such as routers could fail
• Transmission errors may lose messages

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Points of Failure (cont)

• The client and server versions may be
  incompatable
• The server's network card could fail
• The server system may have h/w problems
• The server s/w may crash
• The server's database may become corrupted

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Disadvantages of C/S

• Harder to build
• Less stable
• Susceptible to network load
• Lacking in specialists
• Difficult to debug
• Difficult to test
• Can be more costly than mainframe

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Distributed Computing

• A type of computing in which different components
  and objects comprising an application can be
  located on different computers connected to a
  network.
• In some distributed computing systems, each of
  the three computers could even be running a
  different operating systems.

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Distributed Computing (cont)

• A set of computers connected in some way (serial
  lines, ethernet, ATM, etc)
• Each computer is able to communicate with some of
  the others
• Programs running on each computer are able to
  share information and request tasks to be
  executed

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Questions

• Is distributed computing preferred over the
  mainframe architecture?
• What are the business reasons that support (a)
  mainframe computing? (b) distributed computing?

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Distributed Computing (cont)

• One of the requirements of distributed computing
  is a set of standards that specify how objects
  communicate with one another.
• Two chief distributed computing standards CORBA
  and DCOM.

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Data Warehouse

• DATA WAREHOUSE Organizations electronic library
  stores consolidated current historic data for
  management reporting analysis
• DATA MART Small data warehouse for special
  function, e.G., Focused marketing based on
  customer info

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What is a Data Warehouse?

• "A warehouse is a subject-oriented, integrated,
  time-variant and non-volatile collection of data
  in support of management's decision making
  process".
• Bill Inmon (1990)
• "A Data Warehouse is a repository of integrated
  information, available for queries and analysis.
  Data and information are extracted from
  heterogeneous sources as they are generated.
• Anonymous

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COMPONENTS OF DATA WAREHOUSE
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Data Mining

• ON-LINE ANALYTICAL PROCESSING (OLAP) ability to
  manipulate, analyze large volumes of data from
  multiple perspectives
• MINING Seeking relationships that are not known
  in advance. A function of the software and data
  organization.

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DW Characteristics

• Subject OrientedData that gives information
  about a particular subject instead of about a
  company's ongoing operations.
• Integrated Data that is gathered into the data
  warehouse from a variety of sources and merged
  into a coherent whole.
• Time Variant All data in the data warehouse is
  identified with a particular time period.

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Data Acquisition

• The process of moving company data from the
  source systems into the warehouse.
• Often the most time-consuming and costly effort.
• Performed with software products known as ETL
  (Extract/Transform/Load) tools.
• Over 50 ETL tools on market.

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Data Cleansing

• Typically performed in conjunction with data
  acquisition.
• A complicated process that validates and, if
  necessary, corrects the data before it is
  inserted.
• AKA "data scrubbing" or "data quality assurance".

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Business Intelligences Four Areas

• Multi-dimensional Analysis Tools
• look at data from different angles
• Query Tools
• SQL and other may be 4GL
• Mining Tools
• OLAP and statistical tools
• Data Visualization Tools
• show graphical representation of data

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DW Problems

• Extracting, cleaning, loading are time-consuming
  and costly
• Difficult to contain scope users want more
• Mistakes will be found in feeder systems
• DW need data not available in any other corporate
  systems
• Training may not be applied
• Maintenance will be high
• Security of DW is greater than for TPS

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Application Service Providers

• ASP - a service provider whose specialization is
  the implementation and ongoing operations
  management of one or more networked applications
  on behalf of its customer. One key attribute
  beginning to rapidly evolve is the emphasis on
  Web-based e-business application management as an
  important differentiator from the more
  traditional outsourced client-server application
  management services.

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Why ASPs?

• ASPs own the application and operate the server
• Customers rent the application on a per use or
  monthly basis
• An advantage is low cost of entry and short setup
  time
• May be less expensive except for highly used
  applications
• Eliminates need for specialized IT infrastructure
• Can shift Internet bandwidth to the ASP who can
  leverage cost over many customers

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Mid-Tier Heavy Users of ASP

• The main beneficiary of ASPs is the mid-tier
  market. For small businesses, outsourcing
  business application software and computing
  services to an ASP is cost-prohibitive. The
  business applications in this tier of the market
  are few and simple. The small business can make
  do with a small LAN and a PC-based desktop and
  server environment, using the Web for WAN
  communication and perhaps outsourcing home page
  and e-mail operations to an ISP.

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Large Enterprises Outsource

• The majority of large enterprises already have
  outsourced or are contemplating outsourcing
  internal IT operations to a third party and their
  Web applications to a content-host-based ISP.
  Economics drives this market, but application
  control, security and legacy data force the
  high-end tier to adopt a dedicated operations
  environment rather than a shared multicompany
  environment.

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ASP Infrastructure

• The midtier market is the home territory of the
  IBM AS/400 and S/390, as well as Sun,
  Hewlett-Packard and Compaq/ DEC machines. These
  will be the computing platforms of the ASP and
  the LAN-based servers will be downgraded to
  office application devices. Access to the ASP
  will be via the Web for extranet applications and
  a virtual private network (VPN) for Intranet
  applications.

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Managing ASPs

• Managing and monitoring the ASP's performance
  will replace operations and applications
  development. The large enterprise will flourish,
  with demands for increased bandwidth, reduced
  response time and new Web-based
  transaction/database applications driving the
  upgrade of the desktop, LAN/WAN and servers.

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Infrastructure Is tres Important
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End of Data Warehouse