CIS 321 IS Analysis Design Chapter 2 Approaches

CIS 321—IS Analysis & Design Chapter 2: Approaches to System Development

Overview n n n Systems development can be very complex. The systems development ______ cycle (SDLC) framework can help address this complexity. Other aids in systems development are n n n methodologies models tools _____ Two major approaches to systems development: n n traditional object-oriented 2

The Basic SDLC n Project definition: n n System development project n n n A planned endeavor with a beginning and an end that produces a desired result The result is an information system A complex project requires a detailed plan Five phases of system development n n n project planning—initiate, plan, obtain approval analysis—determine requirements design—define the solution implementation—implement the solution support—maintain and enhance the system 3

Project Planning Phase n Define the problem n n n Produce the project _____ n n economic, organizational, technical, resource, schedule Staff the project n n establish milestones Confirm project _____ n n existing system proposed system select/acquire the staff and allocate time Launch the project n management approval, allocation of resources 4

Analysis Phase n Gather information n n Define system requirements n n n to discover additional requirements Prioritize requirements Generate and evaluate alternatives n n draw diagrams Build ______ of system components n n learn about the problem _____, users, stakeholders develop in-______, buy a package, contract w/ third party Review recommendations with management n choose alternative, proceed 5

Design Phase n Design and integrate the network n n Design the application architecture n n n communicating with other systems Design and integrate the database Prototype for design details n n forms, reports, screens, etc. Design the system interfaces n n addresses problem domain requirements Design the user _____ n n hardware, operating systems prototypes can be saved for the final system 6 Design and integrate the system controls (security)

Implementation Phase n Construct software components n n Verify and test n n populate the database Train users and document the system n n all possible situations Convert data n n using VB. NET, Java, etc. avoid frustrated users Install the system n prototype, parallel systems, complete changeover 7

Support Phase n Debug the system n n Upgrade the system n n _____ maintenance Enhance the system n n corrective maintenance _____ maintenance Support the users n help desk 8

SDLC & the Element of Time n Waterfall approach n n Overlapping of phases n n speed development, required by the nature of the problem _____ of phases n n each phase is completed before the next one begins perform the same phase repeatedly until it’s good enough to begin the next phase each iteration of one phase provides new information about the previous phase Divide project into miniprojects (UI, apps, DB) ______ development n deliver part of the system before the whole system 9

Aids for Completing the SDLC n Methodologies • a collection of techniques for how to use tools to create models • Models n n n Tools n n A model is an ______ of something in the real world Models can be physical, mathematical, graphical, textual Flowchart, DFD, ERD, structure chart, use case diagram, … Project planning models (PERT and Gantt charts) software support to create models or even program code Techniques n step-by-step instructions 10

Traditional Approach to System Development n Structured programming n n n Structured design n modules arranged in a structure chart modules are loosely coupled and highly _____ Structured analysis n n n Three structures: sequence, selection, _____ top-down programming (modular programming) data flow diagram (DFD) entity-relationship diagram (ERD) Information engineering (James Martin) n rigid focus on strategic planning, data, CASE 11

Object-oriented System Development (OOSD) n Object n n OO analysis n n n identifying system objects (people, devices) OO programming n n identifying problem domain objects and their relationships OO design n n A thing that encapsulates attributes and behavior C++, Java, C# A class is a specification of one type of object OOSD is more natural, leads to reuse (? ) 12

SDLC Variations n Variations of names for phases n n n Variations based on _______-computer interaction n n planning, feasibility study, investigation, strategy planning construction, transition, implementation sociotechnical systems Multiview soft systems methodology Variations based on speed of development n n _______ application development (RAD) prototyping 13

Current Trends in Development 1 n Spiral model n n highly iterative create series of prototypes begin with areas of greatest risk e. Xtreme Programming (XP) n n n developed by Kent Beck user ____ series of releases two programmers work together work only ____ hours per week 14

Current Trends in Development 2 n Unified Process (UP) n n n developed by Booch, Rumbaugh, Jacobson of _____ Software designed for OOSD uses UML (____ Modeling Language) phases: inception, elaboration, construction, transition Agile Modeling n n n developed by Scott Ambler mix between the lightweight XP and the heavy duty UP iterative and incremental teamwork simplicity 15 validation