7' INFORMATION SYSTEMS SOFTWARE

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Managing Software Assets
February 25, 2003 Oliver Yao
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LEARNING OBJECTIVES

• DESCRIBE MAJOR TYPES OF SOFTWARE
• EXAMINE SYSTEM SOFTWARE OPERATING SYSTEMS
• EXAMINE APPLICATION LANGUAGES SOFTWARE TOOLS
• DESCRIBE APPROACHES TO SOFTWARE DEVELOPMENT
• IDENTIFY SOFTWARE ISSUES

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MANAGEMENT CHALLENGES

• 1. INCREASING COMPLEXITY SOFTWARE ERRORS
• 2. THE APPLICATION BACKLOG

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SOFTWARE

• DETAILED INSTRUCTIONS TO CONTROL COMPUTER
  OPERATIONS
• PROGRAM SET OF INSTRUCTIONS TO THE COMPUTER
• STORED PROGRAM MUST BE IN PRIMARY STORAGE
• SYSTEM SOFTWARE MANAGES COMPUTER RESOURCES
• APPLICATION SOFTWARE SPECIFIC BUSINESS
  APPLICATION

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SOFTWARE
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MULTIPROGRAMMING
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MULTITASKING

• MULTIPROGRAMMING ON A SINGLE-USER SYSTEM SUCH AS
  A MICROCOMPUTER

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MULTITHREADING

• ABILITY TO EXECUTE DIFFERENT PARTS (THREADS) OF A
  PROGRAM SIMULTANEOUSLY

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VIRTUAL STORAGE

• METHOD OF HANDLING SEVERAL PROGRAMS IN PRIMARY
  STORAGE
• PROGRAM DIVIDED INTO
• FIXED LENGTH PORTIONS (PAGES) OR
• VARIABLE LENGTH (SEGMENTS)
• CURRENT PORTIONS RESIDE IN PRIMARY STORAGE
• PORTIONS SWAPPED OUT WHEN DONE

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TIME SHARING

• MANY USERS SHARE LARGE CPU
• TIME IN CPU DIVIDED INTO SLICES (e.g. 2
  MICROSECONDS)
• EACH USER HAS ACCESS TO CPU DURING SLICE
• SINCE CPU IS FAST, CAN DO MUCH DURING TIME SLICE
• USERS JOB SWAPPED OUT AT END OF SLICE

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MULTIPROCESSING

• TWO OR MORE PARALLEL PROCESSORS IN SYSTEM
• PROGRAM CAN BE DIVIDED TO BE PROCESSED BY
  MULTIPLE CPUs
• CAN PROCESS LARGE PROGRAMS MORE RAPIDLY

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LANGUAGE TRANSLATION

• SOURCE CODE HIGH-LEVEL LANGUAGE INSTRUCTIONS
• COMPILER TRANSLATES HIGH-LEVEL CODE INTO MACHINE
  LANGUAGE
• OBJECT CODE TRANSLATED INSTRUCTIONS READY FOR
  COMPUTER

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TRANSLATION PROCESS
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GRAPHICAL USER INTERFACE (GUI)

• OPERATING SYSTEM USES
• GRAPHIC ICONS Icons, buttons, bars, boxes
• POINTER Mouse, pen, touch screen
• TO ISSUE COMMANDS
• MAKE SELECTIONS

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MICROCOMPUTER OPERATING SYSTEMS
OPERATING SYSTEM
FEATURES

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MICROCOMPUTER OPERATING SYSTEMS
OPERATING SYSTEM
FEATURES
Unix
For powerful microcomputers, workstations,
minicomputers. Multitasking, multi-user
processing, networking. Portable to various
computer platforms
Linux
Free, reliable alternative to Unix, Windows. Runs
on many Platforms. Open-source
Mac OS
For Macintosh computers. Multitasking. Powerful
graphics, multimedia
DOS
For IBM (PC-DOS) and PC (MS-DOS). Program
memory 640K
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GENERATIONS OF PROGRAMMING LANGUAGES

• 1st. Since 1940s. MACHINE LANGUAGE binary code
• 2nd. Since early 50s. ASSEMBLY LANGUAGE
  mnemonics for numeric code
• 3rd. Since mid 50s. HIGH-LEVEL LANGUAGES
• 4th. Since late 70s. MODERN APPLICATION
  PACKAGES

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HIGH-LEVEL LANGUAGES

• FORTRAN (FORmula TRANslator) Scientific,
  Engineering applications
• COBOL (COmmon Business Oriented Language)
  Predominant for transaction processing
• BASIC (Beginners All-purpose Symbolic Instruction
  Code) General purpose PC language

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HIGH-LEVEL LANGUAGES

• PASCAL Used to teach structured programming
  practices. Weak in file handling, input / output
• C and C Powerful PC Language for developing
  applications. Efficient execution cross
  platform. C is object oriented

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FOURTH GENERATION LANGUAGES (4GL)

• CAN BE EMPLOYED BY END USERS
• NONPROCEDURAL
• CAN DEVELOP APPLICATIONS QUICKLY
• NATURAL LANGUAGES
• SIX CATEGORIES

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FOURTH GENERATION LANGUAGES (4GL)

• 1. QUERY LANGUAGES
• Rapidly retrieve data
• Interactive/ on-line
• May use NATURAL LANGUAGE
• Support special requests for data from
  relational databases

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FOURTH GENERATION LANGUAGES (4GL)

• 2. REPORT GENERATORS
• Create customized reports
• Wide range of formats
• 3. GRAPHICS LANGUAGES
• Can manipulate drawings, graphs, photos, videos
• Presentation managers

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FOURTH GENERATION LANGUAGES (4GL)

• 4. APPLICATION GENERATORS
• User specifies computer needs
• Generator creates logic and code for application
• Greatly reduces development time

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FOURTH GENERATION LANGUAGES (4GL)

• 5. VERY HIGH-LEVEL PROGRAMMING LANGUAGES
• Professional programmer productivity tool
• Uses fewer instructions
• Reduces development time

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FOURTH GENERATION LANGUAGES (4GL)

• 7. SOFTWARE PACKAGE Commercially available set
  of programs...
• WORD PROCESSING
• SPREADSHEETS
• DATA MANAGEMENT
• PRESENTATION MANAGEMENT
• INTEGRATED SOFTWARE PACKAGES NOW COMBINE THESE
  TO SIMPLIFY LEARNING AND USE

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SOFTWARE TOOLS

• WORD PROCESSING
• SPREADSHEETS
• DATA MANAGEMENT
• PRESENTATION GRAPHICS
• INTEGRATED SOFTWARE SUITES
• E-MAIL
• WEB BROWSERS
• GROUPWARE

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GROUPWARE CAPABILITIES

• GROUP WRITING COMMENTING
• ELECTRONIC MAIL DISTRIBUTION
• SCHEDULING MEETINGS APPOINTMENTS
• SHARED FILES DATABASES
• SHARED TIME LINES PLANS
• ELECTRONIC MEETINGS CONFERENCES

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MIDDLEWARE

• SOFTWARE ALLOWS DIFFERENT APPLICATIONS TO
  EXCHANGE DATA

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OBJECT-ORIENTED PROGRAMMING

• COMBINES DATA PROCEDURES INTO A SINGLE OBJECT
• PROGRAM SENDS MESSAGE TO OBJECT TO PERFORM
  EMBEDDED PROCEDURE
• OBJECTS DATA ENCAPSULATED FROM REST OF SYSTEM
• CREATES REUSABLE CODE
• REDUCES TIME AND COST OF WRITING SOFTWARE

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OBJECT-ORIENTED PROGRAMMING

• VISUAL PROGRAMMING SELECT AND ARRANGE OBJECTS
  RATHER THAN WRITE CODE
• CLASS ALL OBJECTS OF A CLASS HAVE ALL FEATURES
  OF THAT CLASS
• INHERITANCE SPECIFIC CLASS RECEIVES FEATURES OF
  A MORE GENERAL CLASS
• OVERRIDE SUBCLASS MAY OVERRIDE INHERITED METHOD
  (e.g. Printout of an HOURLY worker pay check may
  differ from that of a WEEKLY worker

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OBJECT-ORIENTED PROGRAMMING

• JAVA Sun Microsystems OBJECT-ORIENTED
  PROGRAMMING LANGUAGE
• APPLET TINY PROGRAM TO EXECUTE SMALL FUNCTION
• APPLETS DOWNLOADED FROM NETWORK
• RUN ON ANY COMPUTER OPERATING SYSTEM
• RESULT SAVED ON NETWORK, NOT ON PC
• ONLY NETWORK VERSION OF SOFTWARE NEEDS UPGRADE

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OBJECT-ORIENTED PROGRAMMING

• ActiveX Controls for Windows software
  environment to enable OBJECTS e.g.,
• CHARTS
• TABLES
• ANIMATIONS
• to be EMBEDDED IN A WEB PAGE

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WEB PAGE DEVELOPMENT LANGUAGES

• HTML Hypertext markup language, current favorite
  for Web pages
• XML eXtensible Markup Language, further
  development of HTML describes data more fully
• XHTML Hybrid may replace HTML as standard for
  Web

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MANAGING SOFTWARE ASSETS

• RENT OR BUILD DECISIONS
• APPLICATION SERVICE
• PROVIDERS
• SOFTWARE MAINTENANCE

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SELECTING ORGANIZATIONAL SOFTWARE

• APPROPRIATENESS
• EFFICIENCY
• COMPATIBILITY
• SUPPORT