1. CSE 403
Software Design

2. References
Anderson, Richard. ‘Design Patterns’ Lecture
JDepend.
JavaNCSS.

3. Question to keep in mind
How is you design coupled?

4. Experts vs. Novices Experience Higher level thought Chunking Idioms
Techniques
Examples

5. Examples of expertise Chess playing Mathematics Programming
Experts view pieces in groups
Mathematics
Integration by trigonometric substitution
Programming
for (int i = 0; i < n; i++)
a[i] = b[i];

6. Design patterns in Architecture
Alexander: "Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to the problem. In such a way that you can use this solution a million times over, without ever doing it the same way twice."

7. Design Pattern Pattern name: Strip mall.
Problem: Make small commercial establishments and franchises accessible to car driving customers.
Solution: Parking area with store fronts facing parking. Uniform construction.
Consequences: Traffic flow, congestion, parking availability, building rents.

8. Gang of Four Gamma, Helm, Johnson, Vlissides
Catalog of design patterns for software

9. Classification of patterns
Creational
Abstract factory, builder, factory method, prototype, singleton
Structural
Adapter, bridge, composite, decorator, façade, flyweight, proxy
Behavioral
Chain of responsibility, command, interpreter, iterator, mediator, memento, observer, state, strategy, template method, visitor
Original GoF patterns

10. Model/View/Controller
Example of putting basic design patterns together
Model - internal representation of the data and how it changes
View - display of the model (can be more than one)
Controller - how the model is controlled by user
Goal - be able to change views and controllers without changing the model or knowing details of model

11. JDepend Example <target name="jdepend">
<jdepend format="xml" outputfile="docs/jdepend-report.xml">
<sourcespath>
<pathelement location="classes" />
</sourcespath>
<classpath location="classes" />
</jdepend>
<style basedir="docs" destdir="docs" includes="jdepend-report.xml" style="${ant.home}/etc/jdepend.xsl" />
</target>

12. JavaNCSS Example <taskdef name="javancss"
classname="javancss.JavancssAntTask"
classpath="${CLASSPATH}"/>
<target name="javancss">
<javancss srcdir="src"
includes="**/*.java"
generateReport="yes"/>
</target>

13. Setup Needed for Examples
JDepend
Make sure $JDEPEND_HOME/lib/jdepend.jar is in CLASSPATH
JavaNCSS
Make sure all Jar-files in $JAVANCSS_HOME/lib are in the CLASSPATH

14. Back to the Question How is you design coupled?
Tightly Coupled or Loosely?
MVC attempts for a Loosely Coupled System
Generally Loosely Coupled is Better