Organizational Communications and Distributed Object Technologies

1. Organizational Communications and Distributed Object Technologies Lecture 12: .NET Master of Information System Management

2. Overview Basics Master of Information System Management

3. .NET • Runtime environment called the Common Language Runtime (CLR) • Class library called the Framework Class Library (FCL) Master of Information System Management

4. Common Language Runtime • Modern runtime environment • .NET compilers do not target a specific processor • The CLR must be present on the target machine • Safely manages code execution • JIT compilation from MSIL to machine executable • Security and Permission management Master of Information System Management

5. Framework Class Library • Object oriented • Collections, console, network and file I/O • Database and XML support • Rich server side event model • Rich client side support for GUI construction • Support for building SOAP based web services • More than 3,500 classes Master of Information System Management

6. C# Overview • C# is type safe (hard to access objects in inappropriate ways) • Automatic memory management • Exception handling • Array bounds checking • Support for checked arithmetic Master of Information System Management

7. Hello World 1 Full Namespaces // Hello World 1 in C# class MyApp { public static void Main() { System.String x = "World"; System.Console.WriteLine("Hello " + x); } } MSCorLib.dll is one among many assemblies we can include. The Basic Class Library is spread over a couple of assemblies. The .exe file has bootstrap code to run the .NET run time. MyApp is in the global namespace Compile with csc -t:exe -out:HelloUser.exe -r:MSCorLib.dll HelloUser.cs Execute MSIL Managed Code with HelloUser The code runs within the Common Language Runtime (CLR) Master of Information System Management

8. Hello World 2 Using System // Hello World 2 in C# using System; class MyApp { public static void Main() { String x = "World 2"; Console.WriteLine("Hello " + x); } } Compile With csc HelloUser.cs Execute The MS Intermediate Language .exe file with HelloUser Master of Information System Management

9. Hello World 3 Without System // Hello World 3 in C# class MyApp { public static void Main() { String x = "World 3"; Console.WriteLine("Hello " + x); } } HelloUser.cs(9,7): error CS0246: The type or namespace name 'String' could not be found (are you missing a using directive or an assembly reference?) And more errors… Master of Information System Management

10. Type System Unification 0 • The object class is the ultimate base class for both reference types and value types • Simple types in C# alias structs found in System • So, Simple types have methods int i = 3; string s = i.ToString(); • But follow the same semantics as simple types of old, e.g., i = 3; j = i; j = 2; // i still 3 Master of Information System Management

11. Type System Unification 1 class MyMathApp { public static void Main() { float x = 2.3F; // Semantics are the same System.Single y = 1.0F; // Only the syntax differs float z = x + y; System.Console.WriteLine("Result = " + z); } } Master of Information System Management

12. Type System Unification 2 // All types derive from System.Object (which corresponds to the primitive object // type.) class MyMathApp { public static void Main() { float x = 2.3F; // 2.3 is a double so use 'F' for float System.Single y = 1.0F; float z = x + y; object o = z; // object is part of C#, Object is in System System.Console.WriteLine("Object Result = " + o); } } Object Result = 3.3 Master of Information System Management

13. Parameters1 Pass By Value // C# Parameters using System; public class Parameter1 { static void inc(int x) { ++x; } public static void Main() { int a = 30; inc(a); Console.WriteLine(a); // 30 is displayed } } Master of Information System Management

14. Parameters 2 Pass by Reference // C# Parameters 2 using System; public class Parameter2 { static void inc(ref int x) { ++x; } public static void Main() { int a = 30; inc(ref a); Console.WriteLine(a); // 31 is displayed } } Master of Information System Management

15. Parameters 3 Passing Objects // C# Parameters using System; public class Student { public int age; } public class Parameter3 { static void swap(Student x, Student y) { Student t = x; x = y; y = t; } Master of Information System Management

16. public static void Main() { Student a = new Student(); a.age = 34; Student b = new Student(); b.age = 65; swap(a,b); Console.WriteLine(a.age +" " +b.age); // 34 65 } } Master of Information System Management

17. Parameter 4 Passing Objects // C# Parameters using System; public class Student { public int age; } public class Parameter4 { static void swap(ref Student x, ref Student y) { Student t = x; x = y; y = t; } Master of Information System Management

18. public static void Main() { Student a = new Student(); a.age = 34; Student b = new Student(); b.age = 65; swap(ref a,ref b); Console.WriteLine(a.age +" " +b.age); // 65 34 } } Master of Information System Management

19. Parameters 5 Out Parameters // C# Parameters using System; public class Student { public int age; } public class Parameter5 { static void MakeAStudent(out Student x) { x = new Student(); // assignment is required } Master of Information System Management

20. public static void Main() { Student a; MakeAStudent(out a); a.age = 34; Console.WriteLine(a.age); // 34 is displayed } } Master of Information System Management

21. Parameter 6 Passing Arrays // C# Parameters using System; public class Parameter6 { static decimal Multiply(params decimal[] a) { decimal amt = 0.0m; foreach(decimal i in a) amt += i; return amt; } Master of Information System Management

22. public static void Main() { decimal[] x = { 2.0m, 3.0m, 1.0m }; Console.WriteLine(Multiply(x)); // 6.0 is displayed } } Master of Information System Management

23. Classes 1 // Classes may have members with protection levels // The default is private. class Student { public string name; int age; public Student(string n, int a) { name = n; age = a; } } class MyClassApp { public static void Main() { Student s = new Student("Mike",23); System.Console.WriteLine("Student " + s.name); // illegal to try to display the age from here } } Master of Information System Management

24. Classes 2 internal class Student { public string name; int age; public Student(string n, int a) { // Classes default to 'internal' visibility. name = n; // MyClassApp is public and therefore age = a; // visible to external // assemblies. } } public class MyClassApp { public static void Main() { Student s = new Student("Mike",23); System.Console.WriteLine("Student " + s); } } Student Student Master of Information System Management

25. Classes 3 Properties using System; class Student { private string name; private int age; public String StudentName { set { name = value; } get { return name; } } Master of Information System Management

26. public int StudentAge { set { age = value; } get { return age; } } } public class MyClassApp { public static void Main() { Student s = new Student(); s.StudentName = "Mike"; // calls set s.StudentAge = 23; // calls set // call get Console.WriteLine(s.StudentName + ":" + s.StudentAge); } } Mike:23 Master of Information System Management

27. Classes 4 Inheritance // C# Classes and Inheritance using System; class Student { private string name; private int age; public String StudentName { set { name = value; } get { return name; } } Master of Information System Management

28. public int StudentAge { set { age = value; } get { return age; } } } Master of Information System Management

29. class GradStudent : Student { private String underGraduateDegree; public String Degree { set { underGraduateDegree = value; } get { return underGraduateDegree; } } } Master of Information System Management

30. public class DemoInheritance { public static void Main() { GradStudent s = new GradStudent(); s.StudentName = "Mike"; s.StudentAge = 23; s.Degree = "Philosophy"; Console.WriteLine(s.StudentName + ":" + s.StudentAge + ":" + s.Degree); } } Mike:23:Philosophy Master of Information System Management

31. Classes 5 Polymorphism // C# Classes and Polymorphism using System; public class Student { private string name; private int age; public String StudentName { set { name = value; } get { return name; } } Master of Information System Management

32. public int StudentAge { set { age = value; } get { return age; } } } Master of Information System Management

33. public class GradStudent : Student { private String underGraduateDegree; public String Degree { set { underGraduateDegree = value; } get { return underGraduateDegree; } } } Master of Information System Management

34. public class DoctoralStudent : GradStudent { private String thesisTitle; public String ThesisTitle { get { return thesisTitle; } } public DoctoralStudent(string thesis) { thesisTitle = thesis; } } Master of Information System Management

35. public class DemoInheritance { public static void Main() { GradStudent s = new GradStudent(); DoctoralStudent d = new DoctoralStudent("The Semantic Web"); s.StudentName = "Mike"; s.StudentAge = 23; d.StudentName = "Sue"; d.StudentAge = 25; Console.WriteLine(s.StudentName + ":" + s.StudentAge); Console.WriteLine(d.StudentName + ":" + d.StudentAge); Display(s); Display(d); } public static void Display(Student x) { // Method takes any Student Console.WriteLine(x.StudentName + ":" + x.StudentAge); } } Master of Information System Management

36. Type Constructors 1 // Classes may have "Type Constructors" internal class Student { public static int numberOfStudentsCreated; static Student() { // must take no args numberOfStudentsCreated = 0; } public string name; int age; public Student(string n, int a) { name = n; age = a; numberOfStudentsCreated++; } } Master of Information System Management

37. public class MyClassApp { public static void Main() { Student s = new Student("Mike",23); Student t = new Student("Sue",23); System.Console.WriteLine("Student's created = " + Student.numberOfStudentsCreated); } } HelloUser Student's created = 2 Master of Information System Management

38. GUI Programming (1) using System; using System.Windows.Forms; public class WindowGreeting { private String m_userName; public String UserName { set { m_userName = value; } get { return m_userName; } } Master of Information System Management

39. public void Greet() { MessageBox.Show("Hello " + m_userName); } public static void Main(String[] a) { WindowGreeting wg = new WindowGreeting(); wg.UserName = "Mike"; wg.Greet(); } } Master of Information System Management

40. Master of Information System Management

41. GUI Programming (2) csc -r:System.Windows.Forms.dll NewOne.cs NewOne The escape key works too. Master of Information System Management

42. GUI Programming (2) using System; using System.Drawing; using System.Windows.Forms; // Inherit from Form to control window public class WindowGreeting : Form { private String m_userName; private Button m_btnClose; private Label m_label; public WindowGreeting() { Console.WriteLine("constructing"); m_label = new Label(); m_label.Location = new Point(16,16); m_label.Size = new Size(136,24); m_label.Text = ""; Master of Information System Management

43. m_btnClose = new Button(); m_btnClose.Location = new Point(48,50); m_btnClose.Size = new Size(56,24); m_btnClose.Text = "Discard"; m_btnClose.Click += new EventHandler(CloseButton_Click); this.Controls.Add(m_label); this.Controls.Add(m_btnClose); this.ClientSize = new Size(150, 90); this.CancelButton = m_btnClose; } Master of Information System Management

44. void CloseButton_Click(Object sender, EventArgs e) { this.Close(); } public String UserName { set { m_userName = value; } get { return m_userName; } } public static void Main(String[] a) { WindowGreeting wg = new WindowGreeting(); wg.ShowDialog(); } } Master of Information System Management

45. Networking 1 Visit a Web Site // Snarf.cs from C# in a Nutshell // Snarf.exe http://www.oreilly.com/catalog/csharpnut using System; using System.IO; using System.Net; using System.Text; class Snarf { static void Main(String[] args) { // args[0] holds a URL from the command line WebRequest req = WebRequest.Create(args[0]); WebResponse resp = req.GetResponse(); Master of Information System Management

46. // read the data from the URL Stream s = resp.GetResponseStream(); StreamReader sr = new StreamReader(s,Encoding.ASCII); String doc = sr.ReadToEnd(); Console.WriteLine(doc); } } Suppose IIS is running with a virtual directory called MyNewWebApps Snarf http://localhost/MyNewWebApps/Index.html Displays the HTML code on the DOS Screen Master of Information System Management

47. Distributed Objects using System.Runtime.Remoting.Channels.Tcp; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting; using System; class MyClient { public static void Main() { ChannelServices.RegisterChannel(new TcpClientChannel()); RemoteStudent r = (RemoteStudent) Activator.GetObject( typeof(RemoteStudent), "tcp://localhost:6502/somestudent"); This client assumes the server is running. Master of Information System Management

48. String name = r.getName(); int age = r.getAge(); Console.WriteLine("Student Name: " + name + " Age: " + age); } } Directory before compilation MyClient.cs Student.dll Student.cs Server.cs Compile with csc -t:exe -r:Student.dll MyClient.cs Run with MyClient Student Name: Mike Age: 23 Master of Information System Management

49. The Remote Object // A Remote Student Object saved in Student.cs using System; public class RemoteStudent : MarshalByRefObject { private int age = 23; private String name = "Mike"; public int getAge() { return age; } public String getName() { return name; } } Compile with csc -t:library Student.cs Produces a DLL file Student.dll Master of Information System Management

50. Publish the Object with Server.cs using System.Runtime.Remoting.Channels.Tcp; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting; using System; class MyApp { public static void Main() { ChannelServices.RegisterChannel( new TcpServerChannel(6502)); RemotingConfiguration.RegisterWellKnownServiceType( Type.GetType("RemoteStudent, Student"), "SomeStudent", WellKnownObjectMode.SingleCall); Master of Information System Management