Introduction. CSC 440: Software Engineering Slide #1

Transcription

1 Introduction CSC 440: Software Engineering Slide #1

2 Topics 1. Course Goals 2. Programming: Small vs. Large 3. Challenges of Large Programs 4. Software Processes and Methods 5. Teams and Roles 6. Rails overview 7. Roll call and Ruby install 8. Ruby Basics 9. Assignment #1 CSC 440: Software Engineering Slide #2

3 Course Goals 1. Learn the concepts of software engineering through applying them to a semester-long team project. 2. Understand how programming in the large differs from writing small programs in previous classes. 3. Create a web application using the full stack Ruby on Rails framework as part of a small team. CSC 440: Software Engineering Slide #3

4 Programming: small vs. large CSC 440: Software Engineering Slide #4

5 Challenge of Large Programs With any nontrivial software application, the major software engineering challenge is dealing with Complexity and Change CSC 440: Software Engineering Slide #5

6 Complexity Size A large school assignment: 5-10 Java classes A compiler or interpreter: ~150 classes and interfaces A major enterprise application: hundreds of classes and interfaces. Number of Developers An individual school assignment: 1, up to 4 A medium-size project: 5-12 A major enterprise application: dozens. CSC 440: Software Engineering Slide #6

7 Complexity Technology Frameworks: Ruby on Rails, Spring, etc. Tools: Git, Heroku, Gantt charts,... Other systems: database, payment, etc. Project artifacts (written and oral) Requirements specifications, software design, design reviews, project plans, test plans, project schedules, code reviews, demos, CSC 440: Software Engineering Slide #7

8 Changes Requirements Customers don t know what they want. Customers change their minds. Marketing decides new features are necessary. Schedule We need it done sooner! Resources Technology and tools Personnel and money CSC 440: Software Engineering Slide #8

9 Participants in Software Development CUSTOMER Sponsors system development $$$, needs DEVELOPER Uses system USER Contractual obligation Needs Builds system Software system CSC 440: Software Engineering Slide #9

10 Software Process A software process is a set of activities that leads to the production of a software product. Ian Sommerville, Software Engineering, 7 th ed. A software process [is] a framework for the tasks that are required to build high-quality software. [It] defines the approach that is taken as software is engineered. Roger Pressman, Software Engineering: A Practitioner s Approach, 6 th ed. 10

11 Method A method is a reusable technique or algorithm for solving a specific problem. This is the common definition of method, not to be confused with a method (operation) of a class in the object-oriented sense. Example methods Object-oriented design techniques Source control Online bug tracking 11

12 Methodology A methodology is a collection of methods for solving a class of problems. Bernd Bruegge and Allen Dutoit, Object-Oriented Software Engineering Using UML, Patterns, and Java, 3 rd ed. [A methodology] specifies how and when each method should be used. ibid 12

13 Software Process, cont d A software process is the application of a methodology in order to develop software. Every methodology has: Beliefs and assumptions Prescribed rules of behavior Criteria to determine what s good and what s bad Sacred documents that describe the methodology and gurus who promote it Believers and nonbelievers. Methodology = religion? 13

14 Why do we need a process? People are more important than any process. Good people with a good process will outperform good people with no process every time. -- Grady Booch CSC 440: Software Engineering Slide #14

15 Software Engineering is team-based processes that manage complexity and change in order to successfully develop software products. Team-based Processes Manage complexity Manage change. } Successful software products! 15

16 Team Member Roles A role defines the set of tasks that a team member is expected to complete. A task can be technical or managerial, programming related or not. When you assign a role to a team member, you make that team member responsible for completing the role s tasks. CSC 440: Software Engineering Slide #16

17 Team Member Role Examples Project lead Software architect User interface (UI) designer HTML programmer Ruby programmer Quality assurance (tester) Database architect Database administrator Documenter etc. CSC 440: Software Engineering Slide #17

18 Team Member Roles Not all roles need to be filled in each team. Each team member must have at least one role. A team member can have more than one role simultaneously during the project. A role can be filled by more than one team member. CSC 440: Software Engineering Slide #18

19 Project Teams Choose your team members wisely! Be sure you ll be able to meet and communicate with each other and work together well. No moving from team to team. Each team me by Monday, August 29 with: Subject: CSC 440 team Team Name Message body must include: Team name. A list of team members with addresses. CSC 440: Software Engineering Slide #19

20 Team Activities Generate written artifacts. Requirements specification Design document Project plan and schedule Test plan Make oral presentations Inception (requirement focus) Iteration 1 (design focus + demo) Iteration 2 (implementation focus + demo) Iteration 3 (quality focus + demo) Class attendance and participation are especially important during oral presentations! CSC 440: Software Engineering Slide #20

21 Individual Responsibilities You are personally responsible for participating and contributing to your team s work, and for understanding each part of the work for every assignment whether or not you worked on that part. CSC 440: Software Engineering Slide #21

22 Postmortem Assessment Report At the end of the semester, each student will individually turn in a short (one page) report: A brief description of what you learned in the course. An assessment of your personal accomplishments for your project team. An assessment of each of your project team members. CSC 440: Software Engineering Slide #22

23 Ruby and Rails Ruby A dynamic, object-oriented programming language Invented in 1993 by Yukihiro Matz Matsumoto Combines Perl, Smalltalk, Eiffel, Ada, and Lisp A programmer s best friend Rails Open source, full stack web framework Runs on Ruby Programmer happiness and productivity Convention over configuration CSC 440: Software Engineering Slide #23

24 Ruby on Rails Design, build, and deploy a complete web application with Ruby on Rails framework. Front end: Dynamically generated web pages Middleware: Server-side business logic Back end: Relational database repository CSC 440: Software Engineering Slide #24

25 Ruby on Rails Features Model-view-controller (MVC) architecture Representational State Transfer (REST) Object-relational mapping (ORM) Active record design pattern CSC 440: Software Engineering Slide #25

26 High-Level Architecture of a Web Application Client computer Server computer Internet connection Web browser Web server Database server CSC 440: Software Engineering Slide #26

27 Static Web Pages Client Server HTTP request Browser Web server HTML file HTTP response CSC 440: Software Engineering Slide #27

28 Dynamic Web Pages Client Server HTTP request Browser Web server Web application HTTP response Web application dynamically generates HTML for web page based on browser request. Browser cannot distinguish static and dynamic pages. CSC 440: Software Engineering Slide #28

29 Architecture of a Rails App CSC 440: Software Engineering Slide #29

30 Architecture of a Rails App Slide #30

31 Roll Call and Ruby Install Roll call If you haven t installed ruby yet, see for how to do so on your operating system. CSC 440: Software Engineering Slide #31

32 Interactive Ruby Interpreter (IRB) Uses a Read-Eval-Print-Loop (REPL) Reads what you type in Evaluates it Prints the result Loops back to read again Every Ruby method returns something. Even if it s just nil. CSC 440: Software Engineering Slide #32

33 Ruby Variables Don t need to be declared or typed in advance. Dynamic typing Types associated with values, not variables. Example: irb(main):045:0> my_var = 14 => 14 irb(main):046:0> my_var = "Buddy" => "Buddy" Naming convention: snake case All lowercase with underscores between words. CSC 440: Software Engineering Slide #33

34 Ruby Data Types: Numbers Standard arithmetic operators: + - * / % Integer division by default, unless one of the operands is made floating-point with a decimal point. % is the modulus (remainder) operator You can apply methods to numbers. Example: irb(main):015:0> 1.odd? => true Ruby naming conventions for methods: Boolean methods end with a question mark. Methods that modify their operands or anything else dangerous end with an exclamation point. CSC 440: Software Engineering Slide #34

35 Ruby Data Types: Strings Single- or double-quoted. Double-quoted strings enable string interpolation. \n for new line and \t for tab Enclose an expression with #{ and } irb(main):047:0> x = 12 => 12 irb(main):048:0> "It's exactly #{x} for\ntoday." => "It's exactly 12 for\ntoday." irb(main):049:0> puts "It's exactly #{x} for\ntoday." It's exactly 12 for today. => nil CSC 440: Software Engineering Slide #35

36 Ruby Data Types: Strings, cont d String concatenation with the + operator. Example: String multiplication with the * operator. Example: Methods length and empty? Examples: irb(main):050:0> "Hello" + ", " + "world" => "Hello, world" irb(main):051:0> "good-bye "*3 => "good-bye good-bye good-bye " irb(main):052:0> "hello".length => 5 irb(main):053:0> "hello".empty? => false CSC 440: Software Engineering Slide #36

37 Ruby Data Types: Arrays Create by listing objects in square brackets. Example: Array elements can be any type, including array. Index elements using the [] method. Index starting at zero. Examples: list[0] list[i] Get nil if you access an element not in the array. The [] method can specify a range. Example: irb(main):011:0> list=[1, 2, 3, 4, 5, 6] => [1, 2, 3, 4, 5, 6] irb(main):012:0> list[2, 4] => [3, 4, 5, 6] CSC 440: Software Engineering Slide #37

38 Ruby Data Types: Arrays, cont d Concatenate arrays with the + operator. Returns a new array without modifying the operands. Example: Append to an array with the << operator. Modifies the array. Example: irb(main):013:0> list + ["foo", "bar"] => [1, 2, 3, 4, 5, 6, "foo", "bar"] irb(main):014:0> list << 'x' => [1, 2, 3, 4, 5, 6, "x"] irb(main):016:0> list[7] => nil irb(main):018:0> list[10]='z' => "z" irb(main):019:0> list => [1, 2, 3, 4, 5, 6, "x", nil, nil, nil, "z"]

39 Ruby Data Types: Hashes A built-in hash table type. Enclose hash values with { and }. Key-value pairs. A key can be any type, but typically a symbol. Use the [] method with a key value to access the corresponding value. Example: => is a hash rocket irb(main):025:0> dude = {:name => "Matz",:age => 50} => {:name=>"matz", :age=>50} irb(main):026:0> dude[:name] => "Matz" irb(main):027:0> dude[:age] => 50 CSC 440: Software Engineering

40 Ruby Data Types: Hashes, cont d Shortcut syntax for symbol keys. Example: irb(main):030:0> dude = { :name => "Matz", :age => 50 } => {:name=>"matz", :age=>50} irb(main):031:0> dudette = {name: "Mary",age: "won't tell"} => {:name=>"mary", :age=>"won't tell"} Methods keys and values. Examples: irb(main):034:0> dudette.keys => [:name, :age] irb(main):035:0> dude.values => ["Matz", 50] CSC 440: Software Engineering Slide #40

41 Ruby Data Types: Booleans Values true or false. Operators equal to == and not equal to!= Operators and && and or Short circuit operators && doesn t evaluate the second operand if the first operand is false. doesn t evaluate the second operand if the first operand is true. Only nil and false are considered false. Every other value is considered true, even empty strings. CSC 440: Software Engineering Slide #41

42 Ruby Data Types: Booleans, cont d Conditional assignment operator = Initialize a variable s value only if it is currently nil. Examples irb(main):038:0> x = nil => nil irb(main):039:0> y = 12 => 12 irb(main):040:0> x = 7 => 7 irb(main):041:0> y = 0 => 12 CSC 440: Software Engineering Slide #42

43 Ruby Constants The name of a constant must begin with a capital letter. By convention, the entire name is in caps. You shouldn t change the value of a constant. But Ruby will allow it after issuing a warning. Example: irb(main):054:0> PI = => irb(main):055:0> PI = 3 (irb):55: warning: already initialized constant PI (irb):54: warning: previous definition of PI was here => 3 irb(main):056:0> PI => 3 CSC 440: Software Engineering Slide #43

44 Ruby Conditional Statements if elsif... else... end Example: irb(main):060:0> age = 21 => 21 irb(main):061:0> if age < 13 irb(main):062:1> puts "Child" irb(main):063:1> elsif age < 18 irb(main):064:1> puts "Teen" irb(main):065:1> else irb(main):066:1> puts "Adult" irb(main):067:1> end Adult => nil CSC 440: Software Engineering Slide #44

45 Ruby Conditional Statements, cont d unless end Example: irb(main):068:0> name = "Tony" => "Tony" irb(main):069:0> if!name.empty? irb(main):070:1> puts name irb(main):071:1> end Tony => nil irb(main):072:0> unless name.empty? irb(main):073:1> puts name irb(main):074:1> end Tony => nil CSC 440: Software Engineering Slide #45

46 Ruby Conditional Statements, cont d One-line expressions Examples: irb(main):075:0> puts name if!name.empty? Tony => nil irb(main):076:0> puts name unless name.empty? Tony => nil CSC 440: Software Engineering Slide #46

47 Ruby Iteration Use the each method on a list or hash to iterate over the elements. Example: irb(main):094:0> countdown = [3, 2, 1, "Blastoff!"] => [3, 2, 1, "Blastoff!"] irb(main):095:0> countdown.each do elmt irb(main):096:1* puts elmt irb(main):097:1> end Blastoff! => [3, 2, 1, "Blastoff!"] CSC 440: Software Engineering Slide #47

48 Ruby Iteration, cont d Use { } instead of do end for one liners. irb(main):098:0> countdown.each { elmt puts elmt } Blastoff! => [3, 2, 1, "Blastoff!"] CSC 440: Software Engineering Slide #48

49 Ruby Iteration, cont d Use each_with_index if you need array index. irb(main):098:0> c=countdown irb(main):099:0> c.each_with_index do elmt, index irb(main):100:1* puts "Item #{index} is #{elmt}" irb(main):101:1> end Item 0 is 3 Item 1 is 2 Item 2 is 1 Item 3 is Blastoff! => [3, 2, 1, "Blastoff!"] CSC 440: Software Engineering Slide #49

50 Ruby Iteration, cont d Iterate over a hash. Example: irb(main):090:0> dude.each { key, value irb(main):091:1* puts "The #{key} is #{value}." irb(main):092:1> } The name is Matz. The age is 50. => {:name=>"matz", :age=>50} CSC 440: Software Engineering Slide #50

51 Ruby Iteration, cont d Iterate over a hash in order of hash keys. Example: irb(main):039:0> dude.keys.sort.each do key irb(main):040:1* puts "Key #{key} has value #{dude[key]}" irb(main):041:1> end Key age has value 50 Key name has value Matz => [:age, :name] CSC 440: Software Engineering Slide #51

52 Ruby Methods Define your own methods with def. Example: irb(main):112:0> def say_hello(name = "world") irb(main):113:1> puts "Hello, #{name}!" irb(main):114:1> end => :say_hello Use snake case for method names. Formal parameters can have default values. A method definition returns the method name. CSC 440: Software Engineering Slide #52

53 Ruby Methods, cont d irb(main):112:0> def say_hello(name = "world") irb(main):113:1> puts "Hello, #{name}!" irb(main):114:1> end puts returns nil => :say_hello A method returns the value of the last statement that it executed. Examples: Parentheses are optional around method arguments. irb(main):119:0> say_hello Hello, world! => nil irb(main):120:0> say_hello("ron") Hello, Ron! => nil irb(main):121:0> say_hello "Mary" Hello, Mary! => nil 53

54 Ruby Methods, cont d You can raise an exception. irb(main):122:0> def factorial(n) irb(main):123:1> if n < 1 irb(main):124:2> raise "Argument #{n} must be > 0" irb(main):125:2> elsif n == 1 irb(main):126:2> 1 irb(main):127:2> else irb(main):128:2* n*factorial(n-1) irb(main):129:2> end irb(main):130:1> end => :factorial irb(main):131:0> factorial 5 => 120 irb(main):132:0> factorial 0 RuntimeError: Argument 0 must be > 0 from (irb):124:in `factorial' from (irb):132 from /usr/local/bin/irb:11:in `<main>' CSC 440: Software Engineering Slide #54

55 Ruby Classes A class name must be capitalized. A class definition can include an initialize method as the constructor. Private instance variables start CSC 440: Software Engineering Slide #55

56 Ruby Classes, cont d irb(main):133:0> class Person irb(main):134:1> def initialize(name) = name irb(main):136:2> end irb(main):137:1> irb(main):138:1* def greet irb(main):139:2> puts "Hi, I'm #{@name}." irb(main):140:2> end irb(main):141:1> end => :greet irb(main):142:0> guy = Person.new("Ron") => irb(main):143:0> guy.greet Hi, I'm Ron. => nil CSC 440: Software Engineering Slide #56

57 Getter and Setter Methods Instance variables are private. irb(main):146:0> guy.name NoMethodError: undefined method `name' for from (irb):146 from /usr/local/bin/irb:11:in `<main> Use the class method attr_accessor to automatically define getters and setters for instance variables. CSC 440: Software Engineering Slide #57

58 Getter and Setter Methods, cont d irb(main):153:0> class MutablePoint irb(main):154:1> attr_accessor :x, :y irb(main):155:1> irb(main):156:1* def initialize(x, = x, y irb(main):158:2> end irb(main):159:1> end :initialize irb(main):162:0> p = MutablePoint.new(10, irb(main):164:0> p.x => 10 irb(main):165:0> p.x = 100 => 100 irb(main):166:0> p CSC 440: Software Engineering Slide #58

59 Getter and Setter Methods, cont d Use attr_reader to define only getters. You can re-open an already-defined class at run time to dynamically add methods, such as new getters and setters. irb(main):147:0> class Person irb(main):148:1> attr_accessor :name irb(main):149:1> end => nil irb(main):150:0> guy.name => "Ron" irb(main):151:0> guy.name = "Bill" => "Bill" irb(main):152:0> guy.greet Hi, I'm Bill. => nil CSC 440: Software Engineering Slide #59

60 Ruby has Single Inheritance A student is a person. irb(main):175:0> class Student < Person irb(main):176:1> def study irb(main):177:2> puts "ZzzzZzzz" irb(main):178:2> end irb(main):179:1> end => :study irb(main):180:0> stud = Student.new("Julie") => irb(main):181:0> stud.greet Hi, I'm Julie. => nil irb(main):182:0> stud.study ZzzzZzzz => nil CSC 440: Software Engineering Slide #60

61 Ruby Formatted Output Ruby has a printf function similar to C. Example: irb(main):009:0> i = 10 => 10 irb(main):010:0> str = "Foo" => "Foo" irb(main):011:0> printf("%5d %s\n", i, str) 10 Foo => nil 61

62 Ruby File I/O Use File.open to open a text file for reading. Example: irb(main):012:0> input = File.open("widgets.csv", "r") => #<File:widgets.csv> Use readline to read the next text line. Example: irb(main):013:0> input.readline => "STATE,PLANT,DEPT,EMPID,NAME,COUNT\n" CSC 440: Software Engineering Slide #62

63 Ruby File I/O Loop to read and process one text line after another. Example: irb(main):014:0> input.each do line irb(main):015:1* puts line irb(main):016:1> end 12,34,56,789,George Carter,4 12,34,56,799,Mary Clinton,6 12,34,57,639,Alfred Lincoln,8 12,40,57,710,Kim Kennedy,8 12,40,57,990,Jina Johnson,6 12,40,75,426,Ruby Roosevelt,10 12,40,75,551,John Washington,7 33,22,11,297,Hilda Hoover,10 33,22,11,428,Ted Truman,11 33,22,11,808,Nora Nixon,3 33,22,14,629,Mabel Bush,9 33,27,19,321,Chris Adams,5 => #<File:widgets.csv> CSC 440: Software Engineering Slide #63

64 Assignment #1: Ruby Program Print a detail report with rolled-up sums. Input will be a CSV (comma-separated values) text file generated from an Excel spreadsheet. The first line of the file contains column headers. The subsequent detail lines each contains how many widgets an employee made. STATE,PLANT,DEPT,EMPID,NAME,COUNT 12,34,56,789,George Carter,4 12,34,56,799,Mary Clinton,6 12,34,57,639,Alfred Lincoln,8 12,40,57,710,Kim Kennedy,8... CSC 440: Software Engineering Slide #64

65 Assignment #1, cont d STATE,PLANT,DEPT,EMPID,NAME,COUNT 12,34,56,789,George Carter,4 12,34,56,799,Mary Clinton,6 12,34,57,639,Alfred Lincoln,8 12,40,57,710,Kim Kennedy,8... Each detail line contains: State code Plant code Department code Employee ID Employee name Count of widgets made by the employee CSC 440: Software Engineering Slide #65

66 Assignment #1, cont d STATE,PLANT,DEPT,EMPID,NAME,COUNT 12,34,56,789,George Carter,4 12,34,56,799,Mary Clinton,6 12,34,57,639,Alfred Lincoln,8 12,40,57,710,Kim Kennedy,8... A state contains one or more plants. A plant contains one or more departments. A department has one or more employees. Each plant s department codes are separate from another plant s department codes. Detail lines are sorted first by state code, then by plant code, then by department code, then by employee ID. CSC 440: Software Engineering Slide #66

67 Assignment #1, cont d A detail report contains the information from all the input detail lines. The report totals for each department the number of widgets made by the employees of that department. It totals for each plant the number of widgets made by the departments of that plant. It totals for each state the number of widgets made by the plants of that state. It computes the grand total number of widgets. CSC 440: Software Engineering Slide #67

68 Assignment #1, cont d Input file widgets.csv: STATE,PLANT,DEPT,EMPID,NAME,COUNT 12,34,56,789,George Carter,4 12,34,56,799,Mary Clinton,6 12,34,57,639,Alfred Lincoln,8 12,40,57,710,Kim Kennedy,8 12,40,57,990,Jina Johnson,6 12,40,75,426,Ruby Roosevelt,10 12,40,75,551,John Washington,7 33,22,11,297,Hilda Hoover,10 33,22,11,428,Ted Truman,11 33,22,11,808,Nora Nixon,3 33,22,14,629,Mabel Bush,9 33,27,19,321,Chris Adams,5 CSC 440: Software Engineering Slide #68

69 STATE PLANT DEPT EMPID COUNT NAME Assignment #1 Final output: Your output should have the same field spacing and blank lines. The stars indicate the levels of total George Carter Mary Clinton 10 TOTAL FOR DEPT 56 * Alfred Lincoln 8 TOTAL FOR DEPT 57 * 18 TOTAL FOR PLANT 34 ** Kim Kennedy Jina Johnson 14 TOTAL FOR DEPT 57 * Ruby Roosevelt John Washington 17 TOTAL FOR DEPT 75 * 31 TOTAL FOR PLANT 40 ** 49 TOTAL FOR STATE 12 *** Hilda Hoover Ted Truman Nora Nixon 24 TOTAL FOR DEPT 11 * Mabel Bush 9 TOTAL FOR DEPT 14 * 33 TOTAL FOR PLANT 22 ** Chris Adams 5 TOTAL FOR DEPT 19 * 5 TOTAL FOR PLANT 27 ** 38 TOTAL FOR STATE 33 *** 87 GRAND TOTAL **** CSC 440: Software Engineering Slide #69

70 Assignment #1, cont d This is an individual assignment to be done by each student. Create a zip file containing: Your Ruby program Widgets.rb A text file containing output from running your program. Cut and paste from the standard output. Submit your program to Blackboard: Assignment #1 Due Monday, August 29 at 6:00 PM CSC 440: Software Engineering Slide #70

71 Acknowledgements Many slides in this presentation are adapted from slides created by Professor Ron Mak at SJSU. CSC 440: Software Engineering Slide #71