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Systems Analysis

Systems Analysis. Requirements Determination Requirements Structuring Alternative Generation and Selection Generate a comprehensive set of alternative design strategies Select the one design strategy that is most likely to result in the desired information system. Design Strategy.

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Systems Analysis

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  1. Systems Analysis • Requirements Determination • Requirements Structuring • Alternative Generation and Selection • Generate a comprehensive set of alternative design strategies • Select the one design strategy that is most likely to result in the desired information system

  2. 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?

  3. 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

  4. 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

  5. Reasons to buy • Lower costs and time • Proven reliability and performance benchmarks • Requires less technical development staff • Future upgrade provided by the vendor

  6. 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

  7. Outsourcing Contracts • Can provide a cost effective solution for dealing with rapid technological change • Time and arrangements • Fixed price • Value added

  8. ?

  9. Application Service Providers • Application hosting • Software as service • Internet is the delivery channel

  10. Evaluating & Purchasing Packages • Evaluate the IS requirements • Identify potential vendors • Evaluate alternatives • Make the purchase • Install the package

  11. 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

  12. Software • Horizontal application • Vertical application • Value added reseller

  13. Software Vendors • Hardware manufacturers • Packaged software producers • Custom software producers (consulting firms) • Enterprise solution software • In-house development

  14. Software Sources

  15. 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

  16. Criteria for Choosing Off-the-Shelf Software • Flexibility • Ease of customization • Documentation • User documentation • Technical documentation • Response Time • Ease of Installation

  17. Validating Purchased Software Information • Information from vendor • Software evaluation period • Customer references from vendor • Independent software testing service • Trade publications

  18. Making the Purchase • Software license • Lease agreement • Maintenance agreement • Installation

  19. Implementation Issues • Technical and social aspects of implementation need to be addressed • Training • Disruption of work

  20. Alternative Matrix

  21. 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

  22. Selecting the Best Alternative Design Strategy • Deliverables • At least three substantially different system design strategies for building the replacement information system • A design strategy judged most likely to lead to the most desirable information system • An updated Baseline Project Plan (BPP) for turning the most likely design strategy into a working information system

  23. 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

  24. 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

  25. Drawing Bounds on Alternative Designs • Constraints on System Development • Time • Financial and human • Legal and contractual • Dynamics of the problem

  26. Existing Platform Lower costs Information system staff is familiar with operation and maintenance Increased odds of successfully integrating system with existing applications No added costs of converting old systems to new platform and limited data conversion costs New Hardware and System Software Some software components will only run on new platform Developing system for new platform gives organization opportunity to upgrade technology holdings New requirements may allow organization to radically change its computing operations Hardware and Software Issues

  27. Alternative Systems

  28. Alternative Systems

  29. 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

  30. 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

  31. Transition to System Design • Logical Design • input • output • processes • Physical Design • system flow charts • DFDs & ERDs • CASE Tools

  32. 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

  33. Physical ERD • Change entities to tables or files • Change attributes to fields • Add primary keys • Add foreign keys • Add system related components

  34. 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

  35. Webstore System Constraints • Christmas season rollout • Small development/support staff • Transaction-style interaction with current systems • Limited budget for consultants

  36. 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

  37. Alternative Systems • ERP system (High-end) • Stability and documentation • Required skilled internal staff • Expensive hardware and software • Big learning curve

  38. Alternative Systems • Application server/object framework (Moderate) • Excellent integration with current system • Scalability and flexibility • Requires internal development and/or consultant • Proprietary

  39. 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

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