Selecting the Best Alternative Design Strategy

Two basic steps 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 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 Deliverables 1. 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. A 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 –Midrange Compromise of features of high-end alternative with frugality of low-end alternative –High-end Solves problem in question and provides many extra features users desire

Drawing Bounds on Alternative Designs Minimum Requirements –Mandatory features versus desired features –Forms of features Data Outputs Analyses User expectations on accessibility,response time and turnaround time

Drawing Bounds on Alternative Designs Constraints on System Development –Date when system is needed –Financial and human resources –Elements of the system that cannot change –Legal and contractual considerations –Dynamics of the problem

Issues to Consider in Generating Alternatives Outsourcing –The practice of turning over responsibility of some to all of an organization’s information systems applications and operations to an outside firm –Can provide a cost effective solution

Issues to Consider in Generating Alternatives Sources of Software –Hardware manufacturers –Packaged software producers –Custom software producers –Enterprise solution software –Application Service Providers –In-house development

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 Flexibility –Ease of customization Documentation –User documentation –Technical documentation Response Time Ease of Installation

Hardware and Software Issues Existing Platform 1.Lower costs 2.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 or transferring data New Hardware and System Software 1.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

Implementation and Organizational Issues Implementation Issues –Technical and social aspects of implementation need to be addressed –Training –Disruption of work Organizational Issues –Overall cost and availability of funding –Management support –User acceptance

Internet Development: Selecting the 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 Web server and corporate network –Corporate network »Existing organizational computing infrastructure