IT1204 - Software engineering - L5
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The document outlines key concepts in software engineering, focusing on the software development life cycle (SDLC) and design processes. It highlights the importance of both conceptual and technical design phases, emphasizing criteria for evaluating design such as correctness, efficiency, and maintainability. Additionally, various software design approaches, including top-down and bottom-up design, are discussed to illustrate methodologies in organizing and implementing software modules.
IT1204 - Software engineering - L5
- 1. Software Engineering L5 Sameera Gunathilaka Lead Software Engineer ERP Technical Consultant IT1204 – Software Engineering Institute of Technology, University of Moratuwa 1
- 2. SDLC – Waterfall Model IT1204 – Software Engineering Institute of Technology, University of Moratuwa 2
- 3. IT1204 – Software Engineering Institute of Technology, University of Moratuwa 3
- 4. IT1204 – Software Engineering Institute of Technology, University of Moratuwa 4 The idea is actually transformed in to a real working system
- 5. IT1204 – Software Engineering Institute of Technology, University of Moratuwa 5 Problem Domain Solution Domain
- 6. Design phase IT1204 – Software Engineering Institute of Technology, University of Moratuwa •More creative than analysing •Problem solving activity •Bridge the requirement to code •Most critical activity 6
- 7. Two Parts design process IT1204 – Software Engineering Institute of Technology, University of Moratuwa 7
- 8. Conceptual Design IT1204 – Software Engineering Institute of Technology, University of Moratuwa 8 Where will the data come from? What will happen to data in the system? How will the system look to users? What choice would be offered to users? What is the timing of events? How will the reports and screens look like?
- 9. Technical design IT1204 – Software Engineering Institute of Technology, University of Moratuwa 9 Hardware configuration Software needs Communication interfaces I/O of the system Software Architecture Network Architecture
- 10. Design Objectives • Goal is to find the best possible design • Major criteria to evaluate a design • Correctness • Is design implement requirements? • Efficiency • Proper use of scarce resources – processor, memory, network bandwidth • Maintainability • How to fix an issue • Adding changes • Cost • Design cost is quit small but it reduce the cost in later parts.
- 11. Elements of a System Architecture - This is the conceptual model that defines the structure, behaviour and more views of a system. We can use flowcharts to represent and illustrate the architecture. Modules - This are components that handle one specific tasks in a system. A combination of the modules make up the system. they are made up of components Components - Group of re-usable code Interfaces - This is the shared boundary across which the components of a the system exchange information and relate. Data - This the management of the information and data flow.IT1204 – Software Engineering Institute of Technology, University of Moratuwa 11
- 12. Software Design Levels IT1204 – Software Engineering Institute of Technology, University of Moratuwa 12 • Understanding the proposed domain • software as a system Architectural Design • Module view of the system • What modules and how they are organized High-level Design • How to implement modules • logical structure of each module and their interfaces Detailed Design
- 13. Fundamental principles IT1204 – Software Engineering Institute of Technology, University of Moratuwa 13 • divide a software system into multiple discrete and independent modules • based on functional aspects Modularization • capability to the software to execute more than one part of code in parallel to each other • Eg: Spell checker Concurrency • How components interact – external behaviour of a component • Functional Abstraction vs Data Abstraction Abstraction
- 14. Software Design Approaches IT1204 – Software Engineering Institute of Technology, University of Moratuwa 14 Top Down Design (stepwise refinement) Bottom-up Design
- 15. Main task – Arrange a party • Subtask 1: Venue • Subtask 2: Date, Time • Subtask 3: Guest List • Subtask 4: Menu IT1204 – Software Engineering Institute of Technology, University of Moratuwa 15 When? Where? Who? Food?
- 16. Top-Down Approach IT1204 – Software Engineering Institute of Technology, University of Moratuwa 16
- 17. IT1204 – Software Engineering Institute of Technology, University of Moratuwa 17
- 18. Bottom-Up Approach IT1204 – Software Engineering Institute of Technology, University of Moratuwa 18 User predefined/ previously tested processors Save time, effort and money Don’t reinvent the wheel
- 19. IT1204 – Software Engineering Institute of Technology, University of Moratuwa 19
- 20. Design process IT1204 – Software Engineering Institute of Technology, University of Moratuwa 20
- 21. Sequential Design process IT1204 – Software Engineering Institute of Technology, University of Moratuwa 21
- 22. Thank you IT1204 – Software Engineering Institute of Technology, University of Moratuwa 22
Editor's Notes
- #4: Requirements engineering help software engineers to better understand the problem they will work to solve. It encompasses the set of tasks that lead to an understanding of what the business impact of the software will be, what the customer wants and how end-users will interact with the software.
- #5: Transformation phase The idea is actually transformed in to a real working system
- #8: Conceptual design - Satisfy the customers Technical design – Satisfy the developer
- #12: HR Sales Supply Chain Production Finance Customer Relationship
- #13: Deliver a product > pay the supplier> calculate the profit > share the profit Employee sign in > work > sing out Suppliers> Get raw materials > production > product Calculate the working hours > get the salary scale > calculate salary > calculate the company budget
- #14: Example The spell check feature in word processor is a module of software, which runs along side the word processor itself.
- #18: Objective is to arrange a party
- #20: Previous tasks have been don successful by someone previously. You can use those idea for you planning
- #22: Architectural Design > Subsystems and relation Abstract specification > What each subsystem do, Interface design> what interfaces in each subsystem Component Design> What services in each subsystem Data Structure > Database design and relationship Algorithm > How servers are implemented?