Systems Analysis Requirements Determination Requirements Structuring Alternative Generation and Selection 1. Generate a comprehensive set of alternative design strategies 2. Select the one design strategy that is most likely to result in the desired information system
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Systems Analysis Requirements Determination Requirements Structuring Alternative Generation and Selection 1.Generate a comprehensive set of alternative.
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Systems Analysis
Requirements Determination
Requirements Structuring
Alternative Generation and Selection1. Generate a comprehensive set of alternative
design strategies
2. Select the one design strategy that is most likely to result in the desired information system
Design Strategy
A particular approach to developing an Information System. It includes statements on: Functionality Hardware and software platform Method of acquisition
Build or buy?
Software Alternatives
In-house developed softwareIn-house customization of a packageIn-house software developed by contract personnelEnd-user computingOutsource a customized packageVendor customizes its packageVendor enhances its packagePackage used with no modification
Reasons to build
Satisfy unique requirements
Minimize changes in business procedures and policies
Meet constraints of existing systems and technology
Develop internal resources and capabilities
Reasons to buy
Lower costs and time
Proven reliability and performance benchmarks
Requires less technical development staff
Future upgrade provided by the vendor
Customizing software
Vendor offers individual configurations for basic packages by adding on components
Pay the vendor to make enhancements to meet your individual needs
Buy the package and make your own modifications
Outsourcing Contracts
Can provide a cost effective solution for dealing with rapid technological change Time and arrangements Fixed price Value added
?Custom build
Packaged system
Outsource
Business need
Unique Common Not core to the business
In-house expertise
Functional & technical
Functional only
Neither
Project skills
Desire to build skills
Skills are not strategic
Strategic decision
Time frame
Flexible Short Short or Flexible
Application Service Providers
Application hosting
Software as service
Internet is the delivery channel
Evaluating & Purchasing Packages
Evaluate the IS requirements
Identify potential vendors
Evaluate alternatives
Make the purchase
Install the package
Evaluate the IS requirements
Identify the key features of the system
Estimate volume and future growth
Specify any hardware constraints
Prepare a RFP or RFQ
Software
Horizontal application
Vertical application Value added reseller
Software Vendors
Hardware manufacturers
Packaged software producers
Custom software producers (consulting firms)
Enterprise solution software
In-house development
Software SourcesProducers Capabilities
Hardware manufacturers
System software and utilities
Packaged software producers
Supports generic tasks
Custom
software producers
Custom support for systems that cannot be built internally
Enterprise-wide solutions
Complete systems that cross functional boundaries
In-house developers System built from scratch
Criteria for Choosing Off-the-Shelf Software
Cost In-house versus purchased
Functionality Mandatory, essential and desired features
Vendor Support Installation Training Technical Support
Viability of Vendor
Criteria for Choosing Off-the-Shelf Software
Flexibility Ease of customization
Documentation User documentation Technical documentation
Response Time
Ease of Installation
Validating Purchased Software Information
Information from vendor
Software evaluation period
Customer references from vendor
Independent software testing service
Trade publications
Making the Purchase
Software license
Lease agreement
Maintenance agreement
Installation
Implementation Issues
Technical and social aspects of implementation need to be addressed
Training
Disruption of work
Alternative MatrixShop With Me Web Shop Shop–N-Go
Developed in C Developed in C and Java
Developed using Java
Orders sent to company using e-mail files
Can export order information to other systems
Can save orders in several file formats
Easy to customize
Easy to customize
Not easily customized
Widely used by other companies
Relatively new application
Brand new application
$150 initial fee $700 up-front $200 annually
Selecting the Best Alternative Design Strategy
Process Divide requirements into different sets of
capabilities Enumerate different potential implementation
environments that could be used to deliver the different sets of capabilities
Propose different ways to source or acquire the various sets of capabilities for the different implementation environments
Selecting the Best Alternative Design Strategy
Deliverables1. At least three substantially different system
design strategies for building the replacement information system
2. A design strategy judged most likely to lead to the most desirable information system
3. An updated Baseline Project Plan (BPP) for turning the most likely design strategy into a working information system
Generating Alternative Design Strategies
Best to generate three alternatives Low-end
Provides all required functionality users demand with a system that is minimally different from the current system
High-end Solves problem in question and provides many
extra features users desire Midrange
Compromise of features of high-end alternative with frugality of low-end alternative
Drawing Bounds on Alternative Designs
Minimum Requirements Mandatory features versus desired
features Forms of features
Data kept in system files System outputs Analyses to generate outputs User expectations on accessibility,response
time and turnaround time
Drawing Bounds on Alternative Designs
Constraints on System Development Time Financial and human Legal and contractual Dynamics of the problem
Hardware and Software Issues
Existing Platform1. Lower costs2. Information system staff
is familiar with operation and maintenance
3. Increased odds of successfully integrating system with existing applications
4. No added costs of converting old systems to new platform and limited data conversion costs
New Hardware and System Software1. Some software
components will only run on new platform
2. Developing system for new platform gives organization opportunity to upgrade technology holdings
3. New requirements may allow organization to radically change its computing operations
Alternative Systems
Requirements A B C
Real-time data entry
Yes Yes Yes
Automatic re-order decisions
For some items
For all items For all items
Real-time data on inventory levels
Not available
Available for some items
Fully available
Alternative Systems
Constraints A B C
Development cost $25,000 $50,000 $65,000
Hardware cost $25,000 $50,000 $50,000
Time to operation 3 months 6 months 9 months
Ease of training 1 week 2 weeks 1 week
Multi-criteria decision makingWeighted approach can be used to compare the three alternativesDecision criteria are the Constraints and RequirementsWeights are arrived at by discussion with analysis team, users and managersEach requirement and constraint is rated for each alternative 1 indicates that the alternative does not match the
request well or that it violates the constraint 5 indicates that the alternative meets or exceeds
requirements or clearly abides by the constraint
Updating the Baseline Project Plan (BPP)
The Baseline Project Plan (BPP) was developed during systems planning and selection phase
Baseline Project Plan (BPP) can be used as an outline of a status report at analysis phase
Schedule will be updated to reflect actual activities and durations
An oral presentation of project status is typically made at this phase
Transition to System Design
Logical Design input output processes
Physical Design system flow charts DFDs & ERDs CASE Tools
Physical DFDAdd implementation references in parentheses below each component
Draw a human machine boundary a line that separates the automated from the manual parts of
the system
Add system related process and data flows and stores Technical limitations Audits, controls or exception handling
Update the data elements in the data flows Add system related data elements
Update the metadata in the CASE repository
Physical ERD
Change entities to tables or files
Change attributes to fields
Add primary keys
Add foreign keys
Add system related components
Webstore System Requirements
Minimum Full integration with current systems 99.9% uptime and availability
Essential Flexibility and scalability
Desired Technical support and/or emergency response Documentation
Webstore System Constraints
Christmas season rollout
Small development/support staff
Transaction-style interaction with current systems
Limited budget for consultants
Alternative Systems
Outsource ASP (Low-end) All hardware located offsite Application developed and managed offsite Excellent emergency response Inflexible Difficult to integrate with current systems
Alternative Systems
ERP system (High-end) Stability and documentation Required skilled internal staff Expensive hardware and software Big learning curve
Alternative Systems
Application server/object framework (Moderate) Excellent integration with current system Scalability and flexibility Requires internal development and/or
consultant Proprietary
Best Alternative Design Strategy
Proposed system is a scalable, three-tier approach Scalable
The ability to seamlessly upgrade the system through either hardware upgrades, software upgrades or both
Three-tier Web Server
Provides connection to the Internet and presentation of HTML page
Applications Server Middle layer of software and hardware that lies between