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System Implementation
Gary B. Shelly, Thomas J. Cashman, and Harry J. Rosenblatt. 2007. Systems Analysis and Design. 7th Ed. Course Technology.
ดร. สลิล บุญพราหมณสํานักวิชาสารสนเทศศาสตร
MIT- 534 Systems Analysis and Design
Lecture 8
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Software Quality Assurance
• Quality assurance
• Software Engineering
Software Engineering Institute (SEI)
Capability Maturity Model (CMM)
Capability Maturity Model Integration (CMMI)
Process improvement
CMMI tracks an organization's processes, using five maturity layers
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Overview of Application Development
• to translate the logical design into program and code modules that will function properly
• Creation of the System Design
The tasks involved in system design produced an overall design and a plan for physical implementation
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Application Development Steps
Module
Start by reviewing documentation from prior SDLC phases and creating a set of program designs
After the design is created, coding can begin
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Project Management
Even a modest-sized project might have hundreds or even thousands of modules
Important to set realistic schedules, meet project deadlines, control costs, and maintain quality
Should use project management tools and techniques
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การเขียนโปรแกรม
• เปนการแปลง logic ทีอ่อกแบบโดยใช Diagram ตางๆเพื่อเขยีนโดยใชภาษาสั่งงาน (Programming language)
• โดยทั่วไปการเขียนควรใช format มาตรฐานเพื่อทําใหการดูแลโปรแกรมทําไดงาย
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Structured Application Development
• Top-down approach
• Partitioning
• Modular design
• Must proceed carefully, with constant input from programmers and IT management to achieve a sound, well-integrated structure
• Must ensure that integration capability is built into each design and thoroughly tested
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Structure Charts
Structure charts show the program modules and the relationships among them
Control module
Subordinate modules
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Module
Library module
Data Couple
Control Couple
Flag
A module uses a flag to signal a specific condition or action to another module
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Structure Charts
Condition
A condition line indicates that a control module determines which subordinate modules will be invoked, depending on a specific condition
Loop
A loop indicates that one or more modules are repeated
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Cohesion and Coupling
If you need to make a module more cohesive, you can split it into separate units, each of which performs a single function
Loosely coupled
Tightly coupled
Status flag
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Structure Chart Examples
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Drawing a Structure Chart
Step 1: Review the DFDs
Step 2: Identify Modules and Relationships
Step 3: Add Couples, Loops, and Conditions
Step 4: Analyze the Structure Chart and the Data Dictionary
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Other Structured Development Tools
Program Flowcharts
Pseudocode
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Coding
• Programming Environments
Each IT department has its own programming environment and standards
Integrated development environments (IDEs)
• Generating Code
Can generate editable program code directly from macros, keystrokes, or mouse actions
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Testing
• Syntax errors
• Desk checking
Logic errors
• Structured walkthrough, or code review
• Design walkthrough
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Unit Testing
Test data
Programmers must test programs that interact with other programs and files individually
Stub testing
Regardless of who creates the test plan, the project manager or a designated analyst also reviews the final test results
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Integration Testing
Integration testing, or link testing
Testing the programs independently does not guarantee that the data passed between them is correct
A testing sequence should not move to the integration stage unless it has performed properly in all unit tests
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Testing the System
Major objectives:
Perform a final test of all programs
Verify that the system will handle all input data properly, both valid and invalid
Ensure that the IT staff has the documentation and instructions needed to operate the system properly and that backup and restart capabilities of the system are adequate
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Demonstrate that users can interact with the system successfully
Verify that all system components are integrated properly and that actual processing situations will be handled correctly
Confirm that the information system can handle predicted volumes of data in a timely and efficient manner
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System Testing
Acceptance tests
You should regard thorough testing as a cost-effective means of providing a quality product
If conflicting views exist, management will decide whether or not to install the system after a full discussion of the options
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Documentation
• Program Documentation
• System Documentation
• Operations Documentation
• User Documentation
Online documentation
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Management Approval
• After system testing is complete, you present the results to management
• If system testing produced no technical, economical, or operational problems, management determines a schedule for system installation and evaluation
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System Installation and Evaluation
Remaining steps in systems implementation:
Prepare a separate operational and test environment
Provide training for users, managers, and IT staff
Perform data conversion and system changeover
Carry out post-implementation evaluation of the system
Present a final report to management
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Operational and Test Environments
• The environment for the actual system operation is called the operational environment or production environment
• The environment that analysts and programmers use to develop and maintain programs is called the test environment
• A separate test environment is necessary to maintain system security and integrity and protect the operational environment
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Training
Training Plan
The first step is to identify who should receive training and what training is needed
The three main groups for training are users, managers, and IT staff
You must determine how the company will provide training
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Train people in groups, with separate training programs for distinct groups
Select the most effective place to conduct the training
Provide for learning by hearing, seeing, and doing
Prepare effective training materials, including interactive tutorials
Tutorial
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Vendor Training
If the system includes the purchase of software or hardware, then vendor-supplied training is one of the features you should include in the RFPs (requests for proposal) and RFQs (requests for quotation) that you send to potential vendors
Often gives the best return on your training dollars
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Outside Training Resources
Many training consultants, institutes, and firms are available that provide either standardized or customized training packages
You can contact a training provider and obtain references from clients
Center for the Application of Information Technologies (CAIT)
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In-House Training
The IT staff and user departments often share responsibility
When developing a training program, you should keep the following guidelines in mind:
Rely on previous trainees
Train-the-trainer strategy
When Training is complete, many organizations conduct a full-scale test, or simulation
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Data Conversion
Data Conversion Strategies
The old system might be capable of exportingdata in an acceptable format for the new system or in a standard format such as ASCII or ODBC
If a standard format is not available, you must develop a program to extract the data and convert it
Often requires additional data items, which might require manual entry
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Data Conversion Security and Controls
You must ensure that all system control measures are in place and operational to protect data from unauthorized access and to help prevent erroneous input
Some errors will occur
It is essential that the new system be loaded with accurate, error-free data
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System Changeover
Direct Cutover
Involves more risk than other changeover methods
Companies often choose the direct cutover method for implementing commercial software packages
Cyclical information systems usually are converted using the direct cutover method at the beginning of a quarter, calendar year, or fiscal year
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Parallel Operation
Easier to verify that the new system is working properly under parallel operation than under direct cutover
Running both systems might place a burden on the operating environment and cause processing delay
Is not practical if the old and new systems are incompatible technically
Also is inappropriate when the two systems perform different functions
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Direct and Parallel installation
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Pilot Operation
The group that uses the new system first is called the pilot site
The old system continues to operate for the entire organization
After the system proves successful at the pilot site, it is implemented in the rest of the organization, usually using the direct cutover method
Is a combination of parallel operation and direct cutover methods
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Phased Operation
You give a part of the system to all users
The risk of errors or failures is limited to the implemented module only
Is less expensive than full parallel operation
Is not possible, however, if the system cannot be separated easily into logical modules or segments
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Post-Implementation Tasks
Post-Implementation Evaluation
Includes feedback for the following areas:
Accuracy, completeness, and timeliness of information system output
User satisfaction
System reliability and maintainability
Adequacy of system controls and security measures
Hardware efficiency and platform performance
Effectiveness of database implementation
Performance of the IT team
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Completeness and quality of documentation
Quality and effectiveness of training
Accuracy of cost-benefit estimates and development schedules
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Post-Implementation Tasks
Post-Implementation Evaluation
When evaluating a system, you should:
Interview members of management and key users
Observe users and computer operations personnel actually working with the new information system
Read all documentation and training materials
Examine all source documents, output reports, and screen displays
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Use questionnaires to gather information and opinions form a large number of users
Analyze maintenance and help desk logs
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Post-Implementation Evaluation
Users can forget details of the developmental effort if too much time elapses
Pressure to finish the project sooner usually results in an earlier evaluation in order to allow the IT department to move on to other tasks
Ideally, conducting a post-implementation evaluation should be standard practice for all information systems projects
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Your report should include the following:
Final versions of all system documentation
Planned modifications and enhancements to the system that have been identified
Recap of all systems development costs and schedules
A comparison of actual costs and schedules to the original estimates
Post-implementation evaluation, if it has been performed
Marks the end of systems development work
Final Report to Management
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