Systems Analysis Requirements Determination Requirements Structuring Alternative Generation and Selection 1.Generate a comprehensive set of alternative.

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

Webserver and corporate network Corporate network

Existing organizational computing infrastructure