System Development 1 u Systems development life cycle (SDLC) l Provides overall framework for managing system development process u Two main approaches to SDLC l Traditional approach: structured systems development and information engineering l Object-oriented approach: object technologies requires different approach to analysis, design, and programming u All projects use some variation of SDLC Overview

System Development 2 u Systems development project l Planned undertaking with fixed beginning and end l Produces desired result or product l Can be a large job of thousands of hours of effort or a small one month project u Successful development project: l Provides a detailed plan to follow l Organized, methodical sequence of tasks and activities l Produces reliable, robust, and efficient system SDLC

System Development 3 Phases of the Systems Development Lifecycle (SDLC) u Project planning : initiate, ensure feasibility, plan schedule, obtain approval for project u Analysis : understand business needs and processing requirements u Design : define solution system based on requirements and analysis decisions u Implementation : construction, testing, user training, and installation of new system u Support : keep system running and improve SDLC

System Development 4 Information System Development Phases SDLC

System Development 5 SDLC and problem-solving u Similar to problem-solving approach l Organization recognizes problem (Project Planning) l Project team investigates, understands problem and solution requirements (Analysis) l Solution is specified in detail (Design) l System that solves problem built and installed (Implementation) l System used, maintained, and enhanced to continue to provide intended benefits (Support) SDLC

System Development 6 Planning Phase of SDLC u Define business problem and scope u Produce detailed project schedule u Confirm project feasibility l Economic, organizational, technical, resource, and schedule u Staff the project (resource management) u Launch project  official announcement SDLC

System Development 7 Analysis Phase of SDLC u Gather information to learn problem domain u Define system requirements u Build prototypes for discovery of requirements u Prioritize requirements u Generate and evaluate alternatives u Review recommendations with management SDLC

System Development 8 Design Phase of SDLC u Design and integrate the network u Design the application architecture u Design the user interfaces u Design the system interfaces u Design and integrate the database u Prototype for design details u Design and integrate system controls SDLC

System Development 9 Implementation Phase of SDLC u Construct software components u Verify and test u Convert data u Train users and document the system u Install the system SDLC

System Development 10 Support Phase of SDLC u Maintain system l Small patches, repairs, and updates u Enhance system l Small upgrades or enhancements to expand system capabilities l Larger enhancements may require separate development project u Support users l Help desk and/or support team SDLC

System Development 11 u Waterfall approach – each phase falls into next phase l Freeze planning specifications before analysis l Freeze analysis specifications before design l Once go over the waterfall for each phase, do not go back u Overlapping (or concurrent) phases l Waterfall is not realistic, we are not perfect l Overlaps can be more efficient than waterfall Scheduling Project u Iteration - Work activities are repeated l Each iteration refines previous result l Approach assumes no one gets it right the first time l There are a series of mini projects for each iteration u Example: Outline, rough draft, edited result u Example: Blueprint, frame, completed house

System Development 12 The waterfall approach to the SDLC SDLC

System Development 13 Overlap of Systems Development Activities

System Development 14 Iterations across life cycle phases

System Development 15 u Methodologies l Comprehensive guidelines to follow for completing every SDLC activity l Collection of models, tools, and techniques u Models l Representation of an important aspect of real world, but not same as real thing l Abstraction used to separate out aspect l Diagrams and charts l Project planning and budgeting aids Methodologies and Models

System Development 16 Some Models Used in System Development

System Development 17 u Tools l Software support that helps create models or other required project components l Range from simple drawing programs to complex CASE tools u Techniques l Collection of guidelines that help analyst complete system development activity or task l Can be step-by-step instructions or just general advice Tools and Techniques Some Tools Used in System Development

System Development 18 Some Techniques Used in System Development

System Development 19 Relationships Among Components of a Methodology

System Development 20 Two Approaches to System Development u Traditional Approach l Also called structured system development l Structured analysis and design technique (SADT) u Structured programming l Improves computer program quality l Allows other programmers to easily read and modify code l Each program module has one beginning and one ending l Three programming constructs (sequence, decision, repetition) System Development

21 Three Structured Programming Constructs

System Development 22 Top-Down Programming u Divides complex programs into hierarchy of modules u The module at top controls execution by “calling” lower level modules u Modular programming l Similar to top-down programming u One program calls other programs to work together as single system

System Development 23 Top-Down or Modular Programming

System Development 24 u Technique developed to provide design guidelines l What set of programs should be l What program should accomplish l How programs should be organized into a hierarchy u Modules are shown with structure chart u Main principle of program modules l Loosely coupled – module is independent of other modules l Highly cohesive – module has one clear task Structured Design

System Development 25 Structure Chart Created Using Structured Design Technique

System Development 26 u Define what system needs to do (processing requirements) u Define data system needs to store and use (data requirements) u Define inputs and outputs u Define how functions work together to accomplish tasks u Data flow diagrams and entity relationship diagrams show results of structured analysis Structured Analysis

System Development 27 Data Flow Diagram (DFD) created using Structured Analysis Technique

System Development 28 Entity-Relationship Diagram (ERD) created using the Structured Analysis technique

System Development 29 Structured Analysis Leads to Structured Design and Structured Programming

System Development 30 u Refinement to structured development u Methodology with strategic planning, data modeling, automated tools focus u More rigorous and complete than SADT u Uses process dependency diagram u Industry merged key concepts from structured development and information engineering approaches into traditional approach Information Engineering

System Development 31 u Views information system as collection of interacting objects that work together to accomplish tasks l Objects - things in computer system that can respond to messages l No processes, programs, data entities, or files are defined – just objects u Object-oriented analysis (OOA) l Defines types of objects that do work of system l Shows how objects interact with users to complete tasks Object-Oriented Approach

System Development 32 Object-Oriented Approach Object-Oriented Approach to Systems

System Development 33 u Object-oriented design (OOD) l Defines object types needed to communicate with people and devices in system l Shows how objects interact to complete tasks l Refines each type of object for implementation with specific language of environment u Object-oriented programming (OOP) l Writing statements in programming language to define what each type of object does u Benefits of OOA include naturalness and reuse Object-Oriented Approach

System Development 34 Class Diagram Created During OO Analysis

System Development 35 u Many variations of SDLC in practice l No matter which one, tasks are similar u Based on variation of names for phases l SDLC compared to IE compared to UP u Based on emphasis on people l User-centered design, participatory design u Based on speed of development l Rapid application development (RAD) l Prototyping SDLC Variations

System Development 36 Life Cycles with Different Names for Phases

System Development 37 Current Trends in Development u Spiral Model l Highly iterative approach l Works around the phases (analysis, design, construction, testing, integration with previous prototype component) in a spiral until project is complete l Initial planning is to do just enough analysis to build initial prototype l Each iteration in the spiral addresses greatest risk

System Development 38 The Spiral Life Cycle Model

System Development 39 u Recent, lightweight, development approach to keep process simple and efficient u Describes system support needed and required system functionality through informal user stories u Has users describe acceptance tests to demonstrate defined outcomes u Relies on continuous testing and integration, heavy user involvement, programming done by small teams Extreme Programming

System Development 40 u Object-oriented development approach u Offered by IBM / Rational l Booch, Rumbaugh, Jacobson u Unified Modeling Language (UML) used primarily for modeling u UML can be used with any OO methodology u UP defines 4 life cycle phases l Inception, elaboration, construction, transition u Reinforces six best practices l Develop iteratively l Define and manage system requirements l Use component architectures l Create visual models l Verify quality l Control changes Unified Process

System Development 41 u Hybrid of XP and UP (Scott Ambler) has more models than XP, less documents than UP u Interactive and Incremental Modeling: l Apply right models l Create several models in parallel l Model in small increments u Teamwork: l Get active stakeholder participation l Encourage collective ownership l Model with others and display models publicly Agile Modeling u Simplicity: l Use simple content l Depict models simply l Use simplest modeling tools u Validation l Consider testability l Prove model is right with code

System Development 42 Tools to Support System Development u Computer-Aided System Engineering (CASE) l Automated tools to improve the speed and quality of system development work l Contains database of information about system called repository u Upper CASE - support for analysis and design u Lower CASE - support for implementation u ICASE - integrated CASE tools

System Development 43 CASE Tool Repository Contains all System Information

System Development 44 u Systems development projects are organized around the SDLC u SDLC Phases include project planning, analysis, design, implementation, and support to be completed for each project u Systems developers learn SDLC based on the sequential waterfall approach u In practice, phases overlap and projects contain many iterations of analysis, design, and implementation activities Summary u All development approaches use a SDLC to manage the project. u Models, techniques, and tools make up a systems development methodology u System development methodologies are based on traditional approach or object-oriented approach u System development methodology provides guidelines to complete every activity in the SDLC u Original SDLC was waterfall approach u Most SDLC use iteration across phases u Rapid application development (RAD) goal is to speed up development u Current trends include: spiral model, eXtreme Programming (XP), Unified Process (UP) and Agile Modeling u CASE tools are designed to help analysts complete tasks