Lecture 4 System Analysis and Design Methodologies Telematics

Lecture 4: System Analysis and Design Methodologies Telematics systems and their design Doc. Ing. Ondřej Přibyl, Ph. D. Department of applied mathematics Faculty of Transportation sciences, CTU Ondřej Přibyl L 4: SAD Methodologies page 1

Telematics systems and their design Faculty of Transportation Sciences, CTU Scope of this lecture • Part I - Overview of methodologies • Part II - Recommendation to ITS Ondřej Přibyl L 4: SAD Methodologies page 2

PART I Systems Development Methodologies Ondřej Přibyl L 4: SAD Methodologies page 3

Telematics systems and their design Faculty of Transportation Sciences, CTU Discussion • What does actually mean the term „Methodology“? Ondřej Přibyl L 4: SAD Methodologies page 4

Telematics systems and their design Faculty of Transportation Sciences, CTU • A methodology is a formalized approach to implementing the SDLC. • The methodology will vary depending on whether the emphasis is on businesses processes or on the data that supports the business. • Remember it has nothing to do with UML! Ondřej Přibyl L 4: SAD Methodologies page 5

Overview of System Development Methodologies Ondřej Přibyl L 4: SAD Methodologies page 7

Category I of the System Development Methodology: Structured Design • Adopts a formal step-by-step approach to the SDLC that moves logically from one phase to the next. • Introduces the use of formal modeling or diagramming techniques to describe a system’s basic business processes and follows a basic approach of two structured design categories. Ondřej Přibyl L 4: SAD Methodologies page 8

Waterfall Development Ondřej Přibyl L 4: SAD Methodologies page 9

Telematics systems and their design Faculty of Transportation Sciences, CTU Waterfall Development • With waterfall development- based methodologies, the analysts and users proceed sequentially from one phase to the next. Ondřej Přibyl L 4: SAD Methodologies page 10

Telematics systems and their design Faculty of Transportation Sciences, CTU Waterfall Development • Advantages: – The system requirements are identified long before programming begins. – Changes to the requirements are minimized as the project proceeds. • Disadvantages: – The design must be completely specified before programming begins. – A long time elapses between the completion of the system proposal in the analysis phase and the delivery of the system. Ondřej Přibyl L 4: SAD Methodologies page 11

Parallel Development This methodology attempts to address the long time interval between the analysis phase and the delivery of the system in case of a waterfall model. Ondřej Přibyl L 4: SAD Methodologies page 12

Telematics systems and their design Faculty of Transportation Sciences, CTU Parallel Development Ondřej Přibyl L 4: SAD Methodologies page 13

Category II of the System Development Methodology: Rapid Application Development (RAD) This methodology breaks the overall system into a series of versions that are developed sequentially. Ondřej Přibyl L 4: SAD Methodologies page 14

Telematics systems and their design Faculty of Transportation Sciences, CTU Rapid Application Development (RAD) • RAD-based methodologies adjust the SDLC phases to get some part of system developed quickly and into the hands of the users. • A system development strategy that emphasizes speed of development through extensive user involvement in the rapid, iterative, and incremental construction of series of functioning prototypes of a system that eventually evolves into the final system. • One possible subtle problem (disadvantage) with RAD-based methodologies is managing user expectations. – Prototype – a small-scale, representative, or working model of the users’ requirements or a proposed design for an information system. – Time box – the imposition of a nonextendable period of time, usually 6090 days, by which the first (or next) version of a system must be delivered into operation. Ondřej Přibyl L 4: SAD Methodologies page 15

Telematics systems and their design Faculty of Transportation Sciences, CTU Rapid Application Development • focuses on building applications in a very short amount of time; traditionally with compromises in usability, features and/or execution speed. • generically describes applications that can be designed and developed within 60 -90 days. Ondřej Přibyl L 4: SAD Methodologies page 16

Phased Development Ondřej Přibyl L 4: SAD Methodologies page 18

Telematics systems and their design Faculty of Transportation Sciences, CTU Phased development • The team categorizes the requirements into a series of versions, then the most important and fundamental requirements are bundled into the first version of the system. • The analysis phase then leads into design and implementation; however, only with the set of requirements identified for version 1. • As each version is completed, the team begins work on a new version. Ondřej Přibyl L 4: SAD Methodologies page 19

Telematics systems and their design Faculty of Transportation Sciences, CTU Phased development Ondřej Přibyl L 4: SAD Methodologies page 20

Prototyping-based Methodology A prototype is a smaller version of the system with a minimal amount of features. Prototyping-based methodologies perform the analysis, design and implementation phases concurrently. All three phases are performed repeatedly in a cycle until the system is completed. Ondřej Přibyl L 4: SAD Methodologies page 21

Telematics systems and their design Faculty of Transportation Sciences, CTU Prototyping-based Methodology Ondřej Přibyl L 4: SAD Methodologies page 22

Telematics systems and their design Faculty of Transportation Sciences, CTU Prototyping-based Methodology • Advantage: – Provides a system for the users to interact with, even if it is not initially ready for use. – Helps to capture real user requirements • Disadvantage: – Often the prototype undergoes such significant changes that many initial design decisions prove to be poor ones. Ondřej Přibyl L 4: SAD Methodologies page 23

Throwaway Prototyping-based Methodology Ondřej Přibyl L 4: SAD Methodologies page 24

Telematics systems and their design Faculty of Transportation Sciences, CTU Throwaway Prototyping-based Methodology • Throwaway prototyping methodologies are similar to prototyping based methodologies. • The main difference is that throwaway prototyping IS completed during a different point in the SDLC. • Has relatively thorough analysis phase. Ondřej Přibyl L 4: SAD Methodologies page 25

Telematics systems and their design Faculty of Transportation Sciences, CTU Throwaway Prototyping-based Methodology • Throwaway or Rapid Prototyping refers to the creation of a model that will eventually be discarded rather than becoming part of the final software. • After preliminary requirements gathering, a simple working model of the system is constructed to visually show the users what their requirements may look like when they are implemented into a finished system. • Advatages – it can be done quickly. If the users can get quick feedback on their requirements, they may be able to refine them early in the development of the software. – ability to construct interfaces that the users can test. Ondřej Přibyl L 4: SAD Methodologies page 26

Category III of the System Development Methodology: Agile Development • Focuses on streamlining the SDLC by eliminating much of the modeling and documentation overhead and the time spent on those tasks. • Projects emphasize simple, iterative application development. Ondřej Přibyl L 4: SAD Methodologies page 27

Telematics systems and their design Faculty of Transportation Sciences, CTU Agile Methods • Agile methods have much in common with the Rapid Application Development • Agile methods break tasks into small increments with minimal planning and do not directly involve long-term planning. • Iterations are short time frames that typically last from one to four weeks. • Each iteration involves a cross functional team working in all functions: – planning, requirements analysis, design, coding, unit testing, and acceptance testing. • At the end of the iteration a working product is demonstrated to stakeholders. • This minimizes overall risk and allows the project to adapt to changes quickly. Ondřej Přibyl L 4: SAD Methodologies page 28

An Extreme Programming-based Methodology Ondřej Přibyl L 4: SAD Methodologies page 30

Telematics systems and their design Faculty of Transportation Sciences, CTU An Extreme Programming-based Methodology • e. Xtreme Programming (XP) was founded on four core values: – – Communication Simplicity Feedback Courage • Key principles of XP include: – Continuous testing – Simple coding – Close interaction with the end users to build systems very quickly – Smaller development teams Ondřej Přibyl L 4: SAD Methodologies page 31

Telematics systems and their design Faculty of Transportation Sciences, CTU An Extreme Programming-based Methodology Ondřej Přibyl L 4: SAD Methodologies page 32

Telematics systems and their design Faculty of Transportation Sciences, CTU SCRUM (Agile development) Source: www. redletterday. ch Ondřej Přibyl 33 L 4: SAD Methodologies page 33

Telematics systems and their design Faculty of Transportation Sciences, CTU Challenges of Agile methods • can be inefficient in large organizations and certain types of projects • Agile methods seem best for developmental and non-sequential projects • Many organizations believe that agile methodologies are too extreme and adopt a hybrid approach that mixes elements of agile and plan-driven approaches • It is all about communication! Ondřej Přibyl L 4: SAD Methodologies page 34

Selecting the Appropriate Development Methodology Ondřej Přibyl L 4: SAD Methodologies page 35

Telematics systems and their design Faculty of Transportation Sciences, CTU Selecting of methodology • Selecting a methodology is not simple, as no one methodology is always best. • Many organizations have their own standards. • The next figure summarizes some important methodology selection criteria. Ondřej Přibyl L 4: SAD Methodologies page 36

Telematics systems and their design Faculty of Transportation Sciences, CTU Criteria for Selecting a Methodology Ondřej Přibyl L 4: SAD Methodologies page 37

Telematics systems and their design Faculty of Transportation Sciences, CTU IT Project success Rate (Chaos report) • As the methodology and project management in IT projects improves, the success rate grows • How is it affected by selected methodology? Ondřej Přibyl L 4: SAD Methodologies page 44

Telematics systems and their design Faculty of Transportation Sciences, CTU Project success rates Source: Dr. Dobbs IT Survey 2010 http: //www. ddj. com/security/226500046 Ondřej Přibyl L 4: SAD Methodologies page 45

Telematics systems and their design Faculty of Transportation Sciences, CTU Agile projects are 3 times more successful http: //www. controlchaos. com/storage/S 3 D%20 First%20 Chapter. pdf Ondřej Přibyl L 4: SAD Methodologies page 46

Telematics systems and their design Faculty of Transportation Sciences, CTU Effectiveness of development Paradigms Ondřej Přibyl L 4: SAD Methodologies page 47

PART II Methodology recommended for ITS 1. SEMP Framework (FHWA for ITS) 2. Methodology to design ITS (CZ) Ondřej Přibyl L 4: SAD Methodologies page 48

Telematics systems and their design Faculty of Transportation Sciences, CTU SEMP Framework (http: //www. fhwa. dot. gov/cadiv/segb/index. htm) Ondřej Přibyl L 4: SAD Methodologies page 49

Telematics systems and their design Faculty of Transportation Sciences, CTU 1. System Engineering Management Plan (SEMP) Ondřej Přibyl L 4: SAD Methodologies page 50

Faculty of Transportation Sciences, CTU Telematics systems and their design 1. System Engineering Process – Main features – Based on common Vee development model • Consists of the following major phases: » » System decomposition (Step 1 – 5) System implementation (Step 6) System composition (Step 7 – 10) System operation (Step 11) – Unified Modeling Language (UML) is used to cover the steps in the model (concept, requirements design, test cases, etc. ) – Defines – Major steps, – Deliverables, and – Responsibilities. Ondřej Přibyl L 4: SAD Methodologies page 51

Telematics systems and their design Faculty of Transportation Sciences, CTU 2. Methodology recommended for ITS Systems • Described in “Methodology to design ITS” (CTU, In Czech, 2009) • Based on SSADM (Structured System Analysis and Design Methodology) – Analysis of the current system • Feasibility stage – Outline business specification • Concept preparation – Detailed business specification • Requirements specification stage – Logical data design • In this stage, technically feasible options are described – Logical process design • logical designs and processes are updated – Physical design • to specify the physical data and process design Ondřej Přibyl L 4: SAD Methodologies page 52

Telematics systems and their design Faculty of Transportation Sciences, CTU ITS process – an overview Part 1 Part 2 Part 3 Part 4 Part 5 Ondřej Přibyl L 4: SAD Methodologies page 53

Faculty of Transportation Sciences, CTU Telematics systems and their design Analysis and Design of ITS Systems (Part 1) • System concept – Based on ITS architecture – Includes current state analysis – Includes definition of objectives • Define actors – See lecture notes Ondřej Přibyl • Define User needs – RFP and other user documents – Based on ITS architecture – Based on system concept L 4: SAD Methodologies page 54

Telematics systems and their design Faculty of Transportation Sciences, CTU Analysis and Design of ITS Systems (Part 2) • System Requirements Specification (SRS) – Based on user needs – Based on standards – Based on state of the art know-how Ondřej Přibyl L 4: SAD Methodologies page 55

Telematics systems and their design Faculty of Transportation Sciences, CTU Analysis and Design of ITS Systems (Part 3) • Use case diagram • Behavior description / processes – Textual process / Activity diagram / interaction diagram Ondřej Přibyl L 4: SAD Methodologies page 56

Telematics systems and their design Faculty of Transportation Sciences, CTU Analysis and Design of ITS Systems (Part 4) • Physical model – HW components – Interactions among components – Communication architecture – Interface specification – Assignement of functions (use cases) to HW • Data model (Structures) – ER Model Ondřej Přibyl L 4: SAD Methodologies page 57

Telematics systems and their design Faculty of Transportation Sciences, CTU Analysis and Design of ITS Systems (Part 5) Ondřej Přibyl L 4: SAD Methodologies page 58

Faculty of Transportation Sciences, CTU Telematics systems and their design Summary of major steps and deliverables System concept 1. Preparing system concept 2. Requirement analysis – Specify User needs – Define Requirements on the system Functional 3. Functionality analysis architecture – Define actors in the system – Define use cases and assign them to particular actors – Define exact functionality for each use case 4. Data model • Creating of an entity-relationship (E-R) model • Definition of all tables and their relationships 5. Component design/physical design • Major physical components • Assignment of functions (use cases) to physical components • Interface definition Ondřej Přibyl Requirements specification Database design Physical architecture L 4: SAD Methodologies page 59