"Systems Analysis Requirements Determination Requirements Structuring Alternative Generation and Selection 1 Generate a comprehensive set of alternative design strategies 2 Select t"
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 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 software In-house customization of a package In-house software developed by contract personnel End-user computing Outsource a customized package Vendor customizes its package Vendor enhances its package Package 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 Packaged Outsource build system Business Unique Common Not core to need the business In-house Functional Functional Neither expertise & technical only Project Desire to Skills are Strategic skills build skills not strategic decision Time Flexible Short Short or frame 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 Sources Producers Capabilities Hardware System software and utilities manufacturers Packaged software Supports generic tasks producers Custom Custom support for systems that software producers cannot be built internally Enterprise-wide Complete systems that cross solutions 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 Matrix Shop With Me Web Shop Shop–N-Go Developed in C Developed in C Developed using and Java Java Orders sent to Can export order Can save orders company using information to in several file e-mail files other systems formats Easy to Easy to Not easily customize customize customized Widely used by Relatively new Brand new other companies application 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 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. 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 Platform New Hardware and 1. Lower costs System Software 2. Information system staff 1. Some software is familiar with operation components will only run and maintenance on new platform 3. Increased odds of 2. Developing system for successfully integrating new platform gives system with existing organization opportunity applications to upgrade technology 4. No added costs of holdings converting old systems 3. New requirements may to new platform and allow organization to limited data conversion radically change its costs computing operations Alternative Systems Requirements A B C Real-time data Yes Yes Yes entry Automatic re- For some For all items For all order decisions items items Real-time data on Not Available for Fully inventory levels available some items 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 making Weighted approach can be used to compare the three alternatives Decision criteria are the Constraints and Requirements Weights are arrived at by discussion with analysis team, users and managers Each 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 DFD Add 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