This document discusses software architecture and provides examples of architectural styles and frameworks. It begins with an overview of software architecture and then discusses the Abstract Window Toolkit (AWT) architecture used in Java. It describes how AWT uses a two-level toolkit with native code to provide platform-independent windowing, graphics, and user interfaces. It then covers the Model-View-Controller (MVC) architecture and how it was applied in the Swing framework to improve decoupling. It concludes with a summary of the key aspects of software architecture.

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Ragini Jain
MSc CA 1st
Year (2015 - 2017)
Software Architecture

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Overview
● Software architecture
● Architectural analysis
● Architectural style
● Software Architecture and Software engineering
● Software architecture (AWT → Swing → Swing 2.x)
● Summary
● References

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Software Architecture
● A set of principal design decisions about the system.
● A blueprint for a system's construction and evolution
● Software architecture = Elements , Form, Rationale
● Software architecture deals with
– Abstraction
– Decomposition
– Composition
– Style
– Aesthetics
What How Why

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Layered Architecture Style
Java OpenJDK
Java libraries

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Case study – AWT – Problem statement
● Conceptualize and Architect a platform-independent
– Windowing
– Graphics
– User-interface widget
toolkit

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AWT architecture challenge
Java Native Code
AWT: Window , Graphics , User interface Widget
Microsoft Windows
UNIX /Solaris X11 environment

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AWT architecture is a 2-level toolkit with API
AWT Object-Oriented Abstraction
Windowing, Events and Layout managers
GUI widgets – buttons, text boxes and menus
Canvas
Drawing
surface

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Abstract Window Toolkit architecture

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Illustrative code
import java.awt.*;
import java.awt.event.*;
public class RJCanvas extends Canvas {
static {
System.loadLibrary("rjrender");
}
public native void paint(Graphics g);
public static void main(String[] args) {
Frame f = new Frame();
f.setBounds( 0, 0, 500, 110 );
f.add( new RJCanvas() );
f.addWindowListener( new WindowAdapter() {
public void windowClosing( WindowEvent ev ) {
System.exit(0);
}
} );
f.show();
}
}
librjrender.so
Canvas
Frame
Graphics Context
/usr/lib64/jvm/jre/lib/amd64/libjawt.so

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Software Architecture and Engineering
● An architecture is a composition and interplay of different elements
● Engineering delivers by using two artifacts
– Components
● Encapsulate processing and data
– eg. AWT classes, Interfaces and native library modules
– Connectors
● Application independent interaction facility
– eg. shared memory connector (Graphics context)
● Working code is the proof of the architecture and trade-offs
– Refactoring the toolkit library
● Move from heavy AWT to light-weight swing component

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Decoupled architecture
● Event handling in User Interface (UI) can be quite challenging
given a large number of components and events.
● To address this complexity, we need to incorporate Architectural
style.
– A named collection of architectural design decisions
● Event handling
– Data is the Model
– Visual representation is the View
– Code that responds to events and updates is the Controller

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Model-View Controller (MVC) architecture

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Engineering the MVC architecture
Swing MVC
public void installUI(JComponent c);
public void uninstallUI(JComponent c);

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Impact of modified MVC Swing architecture
● Separable Model architecture
– A separate model interface for each component that has a
logical data or value abstraction.
● Swing models
– GUI state model
– Application state model

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Summary
● Software Architecture is a blueprint and incorporates every facet of
the system
– Structure
– Behaviour
– Interaction
– Non-functional properties
● Not all design decisions are architectural
● Architecture evolves with experience gained from previous
versions of the software or similar designs.
● Frameworks (servlet) , Toolkits (Git), libraries (openGL) are
manifestation of software architecture.

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References
Community of thought leaders of
software architecture and patterns
Amy Fowler, Swing Architecture,
www.oracle.com/technetwork/java/architecture­142923.html

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References

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References

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Thank you.
● Questions
● Clarifications
● Suggestions
● Feedback
Ragini Jain
15030142023@sicsr.ac.in