1. CS251 – Software Engineering Lecture 3: Process and Life Cycle www.acadox.com/join/563R9V

2. حكمة اليوم 1. أفلم يسيروا في الأرض فتكون لهم قلوب يعقلون بها أو آذان يسمعون بها 2. فإنها لا تعمى الأبصار ولكن تعمى القلوب التي في الصدور

3. 9/21/20153 Assessment Midterm exam (10%) Final exam (60%) Project: 18~20% + 4% Assignments: 10~12%

4. 9/21/20154 Course TAs and Page http://www.acadox.com/class/2604 TAs دسوقى عبد القوى d.abdelqawy@fci-cu.edu.eg مصطفى سعد m.saad@fci-cu.edu.eg عمرو سمير a.samir@fci-cu.edu.eg دينا محمود dina.mahmoud@fci-cu.edu.eg خالد على o.khaled@fci-cu.edu.eg محمود خضير m.khodier@fci-cu.edu.eg أمنية سامى omnia.samy@fci-cu.edu.eg يمنى مجدىyomna@fci-cu.edu.eg

5. 9/21/20155 Lab Objectives Help you get deeper understanding Train you on the concepts explained in the lectures. Prepare and follow up project work Answer questions Save your time!

6. 9/21/20156 Students are given a problem description It has three Phases  Requirements and Plan  Iteration 1  Iteration 2 Group size is 3 or 4. Topics will posted ASAP Strict deadlines The Project

7. 9/21/20157 What is ‘Software Engineering’?... A term used occasionally in 1950s, 1960s Popularized in 1968 at NATO Software Engineering Conference (http://homepages.cs.ncl.ac.uk/brian.randell/NATO/)http://homepages.cs.ncl.ac.uk/brian.randell/NATO/

8. 9/21/20158 What is Software? More than computer programs. The collection of programs, documentation and configuration data that ensures correct execution. Three major types:  Generic Product: Stand alone, Sold on open market.  Customized Product: For specific customer.  Embedded Product: Built into hardware.

9. 9/21/20159 The Nature of Software Intangible:  Opposite of physical artifacts, e.g., Computer vs Windows XP  Hard to understand the development process. Easy to Reproduce:  Costly design and construction, cheap manufacturing. Malleable:  Easy to change, even without full understanding.  Untrained people can “hack” something together.

10. 9/21/201510 Software Development Problems “Software is not constrained by materials, or governed by physical laws, or by manufacturing process” ---- (Sommerville) Allows almost unbounded complexity:  Exponential growth of complexity w.r.t. to the size of a program: twice the size, four times the complexity;  Example: Windows XP has 40millions lines of source code (estimation).

11. 9/21/201511 Software Development Problems Difficulty in understanding and managing the complexity causes:  Late completion: “vaporware” that are announced but never produced  Overrunning Cost: Denver Airport Automated Baggage System, 2 billions US dollar over budget  Unreliable  Difficult to maintain  Etc…

12. 9/21/201512 What is Engineering? Systematically identify, understand, and integrate the constraints on a design to produce a successful result. Constraints may include:  available resources,  physical or technical limitations,  flexibility for future modifications and additions,  cost, manufacturability, and serviceability. Deduce specifications from the limits. Ethical Practices.

13. 9/21/201513 Quality of Good Software Usability  Easy to learn and use. Efficiency  Does not waste resources such as CPU time and memory. Dependability  Reliable, secure and safe. Maintainability  Easily evolved (modified) to meet changing requirement. Reusability  Parts can be reused, with minor or no modification.

14. 9/21/201514 Quality of Good Software Can be quite different based on your viewpoint: Customer: - Solves problems at acceptable cost (time and resource). Developer: - Easy to design and maintain User: - Easy to learn - Efficient to use - Get work done Developer Manager: - Sells more and pleases customers - Costing less to develop and maintain

15. 9/21/201515 So, ‘Software Engineering’ is IEEE Standard 610.12: The application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software, that is, the application of engineering to software. “Designing, building and maintaining large software systems”. - I. Sommerville “Multi-person construction of multi-version software”. - D. L. Parnas

16. 9/21/201516 What is Software Engineering?... “Technological and managerial discipline of software products that are developed and modified on time and within cost estimates”. – R. Fairley “Software development is not simply a case of sitting down at a terminal and typing in the program code”. – M. Priestley A discipline that guides the process of solving customers’ problems by the systematic development and evolution of large, high-quality software systems within cost, time and other constraints. – our definition

17. 9/21/2015 CPSC-4360-01, CPSC- 5360-01, Lecture 1 17

18. Course Contents Overview of Software Engineering ½ Week Software Disasters ½ Week Review of OOP1 Week Software Lifecycle and SW Engineering Processes1 Week Requirements Eng. (SRS, use cases, storyboards)1 Week Software Modeling and Analysis and UML3 Weeks Software Patterns1 Week Software Architecture 1 Week Software Construction1 Week Software Quality and Testing 1 Week Software Configuration and Project Management1 Week

19. 2. Software Life Cycle Conception Feasibility Study Requirements’ Gathering Overall Design Detailed Design Development (Coding, Programming) Testing (Unit, Integration, Acceptance) Deployment / Training Maintenance and Evolution

20. Process of Building a House Different Process Same life cycle

21. 2. Software Life Cycle Conception Feasibility Study Requirements’ Gathering Overall Design Detailed Design Development (Coding, Programming) Testing (Unit, Integration, Acceptance) Deployment / Training Maintenance and Evolution Specification Development Validation Evolution

22. Important Terms Software life-cycle  Phases  Development cycle and evolution cycle Software process  Discipline, activities, roles, and artifacts Iterations  Milestones

23. 2. Software Life Cycle (As in RUP) Conception Feasibility Study Requirements’ Gathering Overall Design Detailed Design Development (Coding, Programming) Testing (Unit, Integration, Acceptance) Deployment / Training Maintenance and Evolution Inception Elaboration Construction Transition

24. CS251 – Software Engineering Lecture 3: Process and Life Cycle www.acadox.com/join/563R9V

25. Phases of the Development Cycle T I M E Transition Construction Elaboration Inception Inception - Define the scope of project Elaboration - Plan project, specify features, baseline system Construction - Build the product Transition - Transition the product into end user community

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27. 9/21/201527 Software Process The set of activities and associated results that produce a software product. Four fundamental process activities:  Software Specification  Software Development  Software Validation  Software Evolution Can be organized in different ways, described at varying level of details → different software development process models

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29. 6.3. What is a Lifecycle Model? Definition. A (software/system) lifecycle model is a description of the sequence of activities carried out in an SE project, and the relative order of these activities.

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31. 9/21/201531 Activity 1: Software Specification Customers and Software Engineers  Define the software to be produced  Define the constraints on its operations Typical Stages:  Feasibility Study: Is it possible with the current technologies + within budget?  Domain Analysis: What is the background for the software?  Requirements Gathering and Analysis: What is it that the user wants?  Requirements Specification: Formal documentation on User and System requirements.  Requirements Validation: Check for realism, consistency, and completeness.

32. 9/21/201532 Activity 2: Software Development Consists of Design and Programming System Analysts  Design: decide how the requirement can be implemented. Programmers  Coding: translate high level design into real code in a chosen programming language.

33. 9/21/201533 Activity 2: Software Development Typical Stages (Design):  Architectural Design: Split into subsystems  Abstract Specification: High level specification on the services and constraints for each subsystem  Interface Design: Interface with other subsystems are defined  Component Design: Split the services and allocate to components within a subsystem  Data Structure Design: Choose appropriate data structure  Algorithm Design: Design and specify algorithm used to provide services High Level Low Level

34. 9/21/201534 Activity 2: Software Development Typical Stages (Programming):  Data structure and algorithm design (from the design stage) may be delegated to the programmer.  Personal activity. Usually without a predefined process.  Debugging: Low level testing of code. Reveals program defects (bugs).

35. 9/21/201535 Activity 3: Software Validation Software Engineer (or dedicated tester) and Customer:  Check the software to ensure it meets the customers’ requirements. Typical Stages:  Component Testing: Independent testing of individual components in subsystem.  System Testing: Testing of integrated components. Can be multi-levels, e.g., subsystem → system.  Acceptance Testing: Tested with customer supplied data. Final test before operation. Interactive activity that feedback to previous stages:  E.g., an error in component testing triggers re-coding.

36. 9/21/201536 Activity 4: Software Evolution Customers and Software Engineers:  Define changing requirements.  Modify the software system to adapt. Typical Work:  Update the system for minor new requirements, e.g., changing the telephone number from 7 digits to 8 digits, changing the date representation (the Millennium Bug).  Could be drastic, more like redevelopment, e.g., windows95 →windows98 → windowsXP.

37. 9/21/201537 Simple Software Process Example In the simplest cases, code is written directly from some statements of requirements. Process Artifact

38. 9/21/201538 Simple Software Process Example  Two processes:  ‘Analyze requirements’  ‘Write code’  Two artifacts:  ‘Requirements specification’  ‘Source code’  ‘Requirements specification’ can be written as:  an informal outline or  a highly detailed description.

39. 9/21/201539 Simple Software Process Example Software Specification:  Analyze Requirement → Requirement Documentation Software Development:  Design: Data structure and algorithm  Programming: Write Code → Source Code Debugging Software Validation:  Compare against sample outputs Software Evolution:  Not applicable.

40. 9/21/201540 A More Complex Software Process It is better to design before you code.  On larger projects, intermediate pieces of documentation are produced.

41. 9/21/201541 A More Complex Software Process  One new process:  ‘Design module structure’ - splitting the program into modules and subroutines  One new artifact:  ‘Structure chart’ – is based on the information contained in the ‘requirements specification’  Both the ‘requirements specification’ and the ‘structure chart’ are used when writing the final code.

42. 9/21/201542 A More Complex Software Process Software Specification:  Analyze Requirement → Requirement Documentation Software Development:  Design: Design of the functions/modules/classes  Programming: Write Code → Source Code Debugging Software Validation:  Compare against sample outputs Software Evolution:  Not applicable.