Post on 26-Dec-2015
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Objectives
Describe the systems development life cycle, who participates in it, and why it is important
Discuss systems development tools
Understand how systems development projects are investigated
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Objectives (continued)
Describe how an existing system can be evaluated
Discuss what is involved in planning a new system
List the steps to implement a new or modified system
Describe the importance of updating and monitoring a system
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An Overview of Systems Development
Systems development process Typically called a systems development life cycle
(SDLC) Systems investigation and analysis
Looks at the existing system and determines if it can and should be improved
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An Overview of Systems Development (continued)
Systems design and implementation Modifying an existing system or developing a new
one Maintenance and review
Makes sure that the new or modified system is operating as intended
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Participants in Systems Development System stakeholders
Individuals who will benefit from systems development project
Users Individuals who will be interacting with the system
on a regular basis Managers
People most capable of initiating and maintaining change
Systems analyst Specializes in analyzing and designing systems
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Why Start a Systems Development Project? Creative analysis
Investigating new approaches to existing problems Critical analysis
Being skeptical and doubtful Questioning whether or not the current computer
system is still effective and efficient Systems development process
Begins with gathering information on users’ needs
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End-User Systems Development The development of computer systems by
Individuals outside of the formal computer systems planning and departmental structure
Systems developed by end users Range from the very small to those of significant
organizational value
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Tools and Techniques for Systems Development
Systems development tools Can greatly simplify the systems development
process Include
Computer-aided software engineering tools Flowcharts, decision tables Project management tools, prototyping, Outsourcing, and object-oriented systems
development
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Computer-Aided Software Engineering
Software engineering Employs computer-aided software engineering
(CASE) tools CASE tools
Automate many systems development tasks Allow more than one person to work on the same
system at the same time via a multiuser interface
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Flowcharts
Reveal the path from a starting point to the final destination
Can display various amounts of detail When developing a system
General flowchart describes the overall purpose and structure of the system
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Decision Tables
Can be used as an alternative to or in conjunction with flowcharts
In general, a decision table displays The various conditions that could exist The different actions that the computer should take
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Project Management Tools
Purpose is to plan, monitor, and control necessary development activities
Program Evaluation and Review Technique (PERT) Creates three time estimates for an activity
The shortest possible time The most likely time The longest possible time
Gantt charting A grid that lists activities and deadlines
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Prototyping
The creation of a preliminary model or version of a major subsystem
Iterative approach to systems development Each phase of the SDLC is repeated several times
(iterated)
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Outsourcing
Use of outside company to take over portions of its workload
Guidelines to make outsourcing a success Keep tight controls on the outsourcing project. Treat outsourcing companies as partners Start with smaller outsourcing job Create effective communications channels between
the organization and the outsourcing company
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Object-Oriented Systems Development An extension of object-oriented programming Can be used during all phases of systems
development Organizations
Have saved time and money using the object-oriented approach to systems development
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Systems Investigation
Overall purpose Determine whether objectives of existing system
satisfy the goals of the organization Attempts to answer the following questions
What primary problems might a new or enhanced system solve?
What opportunities might a new or enhanced system provide?
What are the potential costs? What are the associated risks?
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Feasibility Analysis Technical feasibility
Concerned with whether or not hardware/software can be acquired or developed to solve the problem
Economic feasibility Determines if the project makes financial sense
Legal feasibility Determines whether laws or regulations may
prevent or limit a systems development project
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Feasibility Analysis (continued) Operational feasibility
Measure of whether or not the project can be put into action or operation
Schedule feasibility Determines if the project can be completed in a
reasonable amount of time
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Systems Analysis
Attempts to understand how the existing system helps solve the problem identified in systems investigation
Overall emphasis To gather data on the existing system and the
requirements for the new system To consider alternative solutions to the problem and
the feasibility of the solutions
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General Analysis Considerations Formalized analysis procedure involves
Collecting appropriate data Analyzing the data Determining new system requirements and project
priorities
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Collecting Data
Purpose To seek additional information about problems
identified during systems investigation Techniques
Interviews Direct observation Outputs Questionnaires Other Data Collection Methods
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Requirements Analysis
Purpose To determine user, stakeholder, and organizational
needs Tools and techniques
Asking Directly Critical Success Factors Joint Application Development Rapid Application Development
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Systems Design
Overall purpose To select and plan a system that meets the
requirements needed to deliver the problem solution Results
A new or modified system
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Generating Systems Design Alternatives First step of design
Investigate alternatives for all components Request for information (RFI)
Asks a computer systems vendor to provide information about its products or services
Request for quotes (RFQ) Asks a computer systems company to give prices
for its products or services Request for proposal (RFP)
Generated during systems development
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Systems Implementation
Includes Hardware acquisition Software acquisition or development User preparation Hiring and training of personnel Site and data preparation Installation, testing, startup, and user acceptance
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Acquiring Hardware
Most people and organizations acquire hardware and computers by Purchasing, leasing, or renting computer resources
from a computer systems vendor “Pay as you go computing”
Organization pays only for the computer power it uses
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Selecting and Acquiring Software:Make, Buy, or Rent Program specification
Description of what the software must accomplish Algorithm
Step-by-step sequence of computer instructions Syntax errors
Errors in the use of the programming language syntax
Logic errors Errors in the programming logic
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Acquiring Database and Telecommunications Systems A database is one of the most important parts of
system development Many projects involve a database May require both hardware and software acquisition
Telecommunications is one of the fastest growing business applications May require both hardware and software acquisition
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User Preparation
Readying users and stakeholders for the new or modified system
Can include Marketing Training Documentation Support
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Site Preparation
Location of the new system needs to be prepared For a small system
May mean rearranging the furniture Larger systems
May require special wiring and air conditioning
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Data Preparation
Converting manual files into computer files Data conversion
May be required to transform the existing computerized files into the proper format
Permanent data Must be placed on a permanent storage device
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Installation
Placing computer equipment on the site and making it operational
For a small systems development project May require making room on top of a desk for a new
PC Plugging it into a wall outlet Following the manufacturer’s instructions to turn it
on
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Testing
Unit testing Developing test data that will force the computer to
execute every statement in the program System testing
Requires the testing of all programs together Volume testing
Ensures that entire system can handle a large amount of data under normal operating conditions
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Testing (continued)
Integration testing Ensures that new programs can interact with other
major applications Acceptance testing
Ensures that new or modified system is operating as intended
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Startup
Direct conversion Stopping the old system and starting the new one
on a given date Phase-in approach
New system is slowly phased in, while old one is slowly phased out
Pilot startup Running a pilot or small version of the new system
along with the old
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User Acceptance and Documentation
User acceptance document Agreement signed by user that a phase of the
complete system is approved Documentation
Includes all materials that describe the new or modified system
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User Acceptance and Documentation (continued)
Systems documentation Describes the technical aspects of the new or
modified system User documentation
Describes how the system can be used by noncomputer personnel
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Systems Maintenance and Review
Final steps of systems development Involves checking, changing, and enhancing the
system
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Reasons for Maintenance
New requests from stakeholders, users, and managers
Bugs or errors in the program Technical and hardware problems Corporate mergers and acquisitions Governmental regulations that require changes in
programs
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The Financial Implications of Maintenance
For older programs Cost of maintenance can be up to five times greater
than cost of development Average programmer
Can spend from 50% - over 75% of his/her time maintaining programs
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Systems Review
Final phase of the systems development life cycle Analyzing systems to make sure that they are
operating as intended Two types of review procedures
Event-driven review Time-driven review
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Summary
Phases of the SDLC Investigation, analysis, design
Implementation, maintenance, review Common system development tools and techniques
CASE tools Flowcharts Decision tables
Systems investigation First step in the development of a new or modified
computer system
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Summary (continued) Systems analysis
The examination of existing systems Systems design
Prepares detailed design needs for new system or modifications to the existing one
Systems implementation Includes hardware acquisition, software acquisition
or development, and user preparation Systems maintenance
Involves checking, changing, and enhancing the system