Lecture 5: Component-based Programming. 2 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 5-2 Objectives “Components are another term for classes,

Lecture 5:

Component-based Programming

2MicrosoftIntroducing CS using .NETJ# in Visual Studio .NET 5-2

Objectives

“Components are another term for classes, DLLs, and assemblies. Component-based programming is the logical tendency to design our programs as a set of components instead of a large monolithic app. Given the design of .NET and its Framework Class Library, J# programming is inherently component-based programming... ”

In 3 Parts:

1. Component-based programming

2. Working with .NET components

3. Creating your own .NET components


Part 1

• Component-based programming…


Component-based programming

• OO programming is component-based programming– classes are components

• .NET programming is component-based programming– DLLs are components

• Other components you'll use:

– Supplemental UI Library


.NET components

• .NET components must be installed to run a .NET program– in fact, CLR + FxCL must be installed– these are known collectively as the .NET Framework

HardwareHardware

Operating SystemOperating System

Common Language Runtime (CLR)Common Language Runtime (CLR)

.NET program.NET program.NET Framework.NET Framework

Class Library (FxCL)Class Library (FxCL).NETFramework


Installing .NET Framework

• .NET Framework is installed as part of Visual Studio .NET

• How to install on systems without VS .NET?• Pre-installed on Windows 2003 and above• Otherwise you must install 2 pieces of software, in this order:

1. .NET Framework 1.1 Redistributable: dotnetfx.exe (20MB)

2. Visual J# .NET Version 1.1 Redistributable: vjredist.exe (7MB)

• Requirements:

– Windows 98 or above


Installing .NET Framework (cont'd)

• Installing .NET Framework 1.1 Redistributable:

– http://msdn.microsoft.com/netframework/technologyinfo/howtoget/

– also available via Windows Update (IE, Tools menu, recommended)

• Installing Visual J# .NET Version 1.1 Redistributable:

– http://msdn.microsoft.com/vjsharp/downloads/howtoget/default.aspx

• Other components are installed on an "as-needed" basisSupplemental UI Library:

– see http://msdn.microsoft.com/vjsharp/supui/


Part 2

• Working with .NET components…


Programming options

• J# programming can really be done at two levels:

1. using Visual Studio .NET

2. at the command-line, much like Sun's JDK

• Let's use the command-line tools since it's easier to understand how .NET component work…


Command-line development

• Main tools:– vjc: Visual J# compiler– notepad: simple Windows text editor (any editor will

do)

• How to get started?

– open Visual Studio .NET 2003 Command Prompt

• Start menu, • All Programs, • Microsoft Visual Studio .NET 2003, • Visual Studio .NET Tools,• Visual Studio .NET 2003

Command Prompt


Example

• Let's create a simple GUI app using the Java Class Library– in particular, using the SWING classes of the JCL

• GUIApp:– outputs "ouch!" to the console each time you click the button…

C:\GUIApp> guiapp.exeouch!ouch!ouch!


GUIApp

• GUIApp is a single source code file "GUIApp.jsl":

public class GUIApp{ public static void main(String[] args) { javax.swing.JFrame frame = new javax.swing.JFrame(); java.awt.Container c = frame.getContentPane(); javax.swing.JButton button1 = new javax.swing.JButton("Click Me");

frame.setSize(100, 100); frame.setLocation(100, 100); frame.setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); c.add(button1); button1.addActionListener(new ButtonHandler());

frame.show(); }}//class

class ButtonHandler implements java.awt.event.ActionListener{ public void actionPerformed(java.awt.event.ActionEvent e) { System.out.println("ouch!"); }}//class

public class GUIApp{ public static void main(String[] args) { javax.swing.JFrame frame = new javax.swing.JFrame(); java.awt.Container c = frame.getContentPane(); javax.swing.JButton button1 = new javax.swing.JButton("Click Me");

frame.setSize(100, 100); frame.setLocation(100, 100); frame.setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); c.add(button1); button1.addActionListener(new ButtonHandler());

frame.show(); }}//class

class ButtonHandler implements java.awt.event.ActionListener{ public void actionPerformed(java.awt.event.ActionEvent e) { System.out.println("ouch!"); }}//class


Compilation

• Compile using the Visual J# compiler "vjc"– reference Supplemental UI Library to use SWING

– compiler switches: /t: build a console-based .EXE /r: reference the specified .NET component (.DLL)

C:\GUIApp> dir04/20/2004 673 GUIApp.jsl

C:\GUIApp> vjc /t:exe GUIApp.jsl /r:vjssupuilib.dllMicrosoft (R) Visual J# .NET Compiler version 7.10.3077.0For Microsoft (R) .NET Framework version 1.1.4322Copyright...

C:\GUIApp> dir04/20/2004 20,480 GUIApp.exe


Run!

• Run the .EXE from the command-line:

C:\GUIApp> guiapp.exeouch!ouch!ouch!


.NET Framework SDK

• .NET Framework SDK contains the command-line tools

– SDK = Software Development Kit

– .NET equivalent of Sun's JDK

– installed as part of Visual Studio .NET

– available separately as a free download (100MB):• http://msdn.microsoft.com/netframework/technologyinfo/howtoget/


Issues with using Swing

• Advantage of using Swing:

You can recompile without modification usings Sun’s JDK and run on any Java platform.

• Disadvantage of using Swing:

Swing programming by hand is hard and tedious and does not let you take full advantage of the Visual Studio integrated IDE.


Example #2

• A better example of SWING– Visual Sorting demo…

public VisualSorting(){ super("VisualSorting"); URL u = VisualSorting.class.getResource("Random.jpg"); icon= new ImageIcon(u);

// create AlgorithmPanels, and the mainControlPanel populateAlgorithmsPane(); mainControlPanel = new MainControlPanel (this);

// add the algorithmPanel, and mainControlPanel to the contentPanel getContentPane().setLayout (new GridBagLayout()); GridBagConstraints gConstraints = new GridBagConstraints(); gConstraints.anchor = GridBagConstraints.CENTER; gConstraints.fill = GridBagConstraints.BOTH; gConstraints.gridx = GridBagConstraints.RELATIVE; gConstraints.gridy = GridBagConstraints.RELATIVE; gConstraints.gridwidth = GridBagConstraints.REMAINDER; gConstraints.gridheight = 650; . . .

public VisualSorting(){ super("VisualSorting"); URL u = VisualSorting.class.getResource("Random.jpg"); icon= new ImageIcon(u);

// create AlgorithmPanels, and the mainControlPanel populateAlgorithmsPane(); mainControlPanel = new MainControlPanel (this);

// add the algorithmPanel, and mainControlPanel to the contentPanel getContentPane().setLayout (new GridBagLayout()); GridBagConstraints gConstraints = new GridBagConstraints(); gConstraints.anchor = GridBagConstraints.CENTER; gConstraints.fill = GridBagConstraints.BOTH; gConstraints.gridx = GridBagConstraints.RELATIVE; gConstraints.gridy = GridBagConstraints.RELATIVE; gConstraints.gridwidth = GridBagConstraints.REMAINDER; gConstraints.gridheight = 650; . . .

public static void main(String args[]){ VisualSorting sd = new VisualSorting(); sd.setSize((int) (520 * 1.61), 520); sd.setResizable(false); sd.reset(); sd.show();}

public static void main(String args[]){ VisualSorting sd = new VisualSorting(); sd.setSize((int) (520 * 1.61), 520); sd.setResizable(false); sd.reset(); sd.show();}


Part 3

• Creating your own .NET components…


Motivation

• Professionals create their own components for many reasons:

– Team programming: each builds their own component and tests separately.

– Multi-language programming: components in different languages are built (e.g. VB, J#, C++) and then integrated.

– Component reuse– Component updating: Components can be updated

independently to fix bugs


Example: N-Tier design

• Business applications commonly follow an N-Tier design– application is logically divided by task areas– physically built as a set of components

Business.dll

Presentation

Tier

Data AccessTier

e.g. read and write from

customer files or database

DataTier

e.g. data source, like

files or database

Business LogicTier

e.g. purchase products or pay

employees

GUI.exe DataAccess.dll


Component-based BankingApp

• Let's rebuild the BankingApp as a set of components:

transactions.txt

customers.txt

App.jslApp.jslCustomer.jslCustomer.jsl

CustomersIO.jslCustomersIO.jslTransactions.jslTransactions.jsl

Transactions.dllBankingApp.exe Customers.dll


(1) Customers.dll

• First, build the lower-level data access tier, Customers.dll:– in this case we target (/t:) a library, not an exe

– Rather than /t:library we can abbreviate to /t:l

C:\BankingApp> dir *.jsl04/20/2004 1,039 App.jsl04/20/2004 743 Customer.jsl04/20/2004 1,603 CustomersIO.jsl04/20/2004 1,443 Transactions.jsl

C:\BankingApp> vjc /t:library Customer.jsl CustomersIO.jsl /out:Customers.dllMicrosoft (R) Visual J# .NET Compiler version 7.10.3077.0For Microsoft (R) .NET Framework version 1.1.4322Copyright...

C:\BankingApp> dir *.dll04/20/2004 20,480 Customers.dll


(2) Transactions.dll

• Second, build the middle-level business tier, Transactions.dll:– reference Customers.dll to gain access to definition of Customer


C:\BankingApp> vjc /t:library Transactions.jsl /r:Customers.dll /out:Trans actions.dllMicrosoft (R) Visual J# .NET Compiler version 7.10.3077.0For Microsoft (R) .NET Framework version 1.1.4322Copyright...

C:\BankingApp> dir *.dll04/20/2004 20,480 Customers.dll04/20/2004 20.480 Transactions.dll


(3) BankingApp.exe

• Third, build the presentation tier .EXE, BankingApp.exe:– references both Customers.dll and Transactions.dll


C:\BankingApp> vjc /t:exe App.jsl /r:Customers.dll /r:Transactions.dll /out:Ba nkingApp.exeMicrosoft (R) Visual J# .NET Compiler version 7.10.3077.0For Microsoft (R) .NET Framework version 1.1.4322Copyright...

C:\BankingApp> dir *.dll;*.exe04/20/2004 20,480 Customers.dll04/20/2004 20.480 Transactions.dll04/20/2004 20,480 BankingApp.exe


Run!

• BankingApp runs exactly as before…


If .NET can't find component?

• If a referenced .DLL cannot be found, program fails to run…• Example:

– move Customers.dll out of folder, and try running app…

move to desktop…


Summary

• .NET is built using component-based programming• J# programming is component-based programming• Professional programming is component-based programming

Documents

Lecture 5: Component-based Programming. 2 MicrosoftIntroducing CS using.NETJ# in Visual Studio.NET 5-2 Objectives “Components are another term for classes,