1. Software Design and Development
COM 1205
First lecture, first class Sep25.
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2. Introduction
Software engineering, modeling, design, software architecture
Programming languages
Hands-on, practical, useful
What the course is about
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3. Summary of Course
How to design and implement flexible object-oriented software using the principles of adaptiveness in combination with UML and Java. Learning principles behind XML.
How to design and implement flexible 100% pure Java software.
What audience will learn
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4. Who is in Attendance?
Software developers who have some experience with object-oriented programming.
Should know concepts of OOP, like classes, methods, and late binding.
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5. Aspect-Oriented Progr. Adaptive Programming DemeterJ Java and DJ
Featured in MIT Technology Magazine 2001 as a Top Ten Technology
Agenda
Aspect-Oriented Progr.
Adaptive Programming
DemeterJ
Java and DJ
Java environment
UML
XML
strategy graphs
class graphs
object graphs
state graphs
principles
heuristics
patterns
idioms
theorems
algorithms
requirements
domain analysis
design
implementation
use cases
interfaces
traversals
visitors
packages
Demeter Method
iterative development
spiral model
Extreme Programming
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6. Agenda
UML class diagrams. Perspective: analysis, design, implementation
Class graphs as special cases of UML class diagrams
Textual representation of class graphs
Default implementation of UML class diagrams as class graphs
topics covered and time allotted to each
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7. Agenda UML interaction diagrams
sequence diagrams
collaboration diagrams
improving interaction diagrams to make them specification languages
XML data type definitions and documents
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8. Agenda Class graphs in textual form (construction, alternation)
object graphs (graphical and textual form)
object graphs defined by class graphs
add repetition classes and optional parts
translating class graphs to Java
topics covered and time allotted to each
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9. Agenda annotating class graph with syntax: class dictionary
printing objects and language defined by class dictionary
grammars, parsing, ambiguous grammars, undecidable problem
LL(1) grammars, robustness of sentences
etc.
topics covered and time allotted to each
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10. Overview good separation of concerns is the goal
concerns should be cleanly localized
programs should look like designs
Big picture
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11. Adaptive Programming Programs adapt to interesting context changes
Structure-shy behavior
Succinct representation of traversals
Programming in terms of graph constraints
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12. Cross-cutting of concerns
better program
ordinary program
structure-shy
functionality
Components
structure
Aspect 1
avoid tangled programs
AOP
synchronization
Aspect 2
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13. Aspect-Oriented Programming
components and aspect descriptions
High-level view,
implementation may
be different
From Gregor:
maybe source code should say: intermediate source code
add:
picture of a preprocessor style implementation of an AOP system
not all AOP systems will be preprocessor like. It is reasonable
to expect that in the future the better ones won’t be
this is a picture of what AOP is equivalent to, not necessarily how it works.
general AOP
Source Code
(tangled code)
weaver
(compile-
time)
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14. Examples of Aspects Synchronization of methods across classes
Remote invocation (using Java RMI)
Quality of Service (QoS)
Failure handling
External use (e.g., being a Java bean)
Replication, Migration
etc.
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15. Connections explain adaptive programming in terms of patterns
Aspect-Oriented Programming (AOP) is a generalization of Adaptive Programming (AP)
correspondence:
adaptive program : object-oriented program = sentence : object graph
explain how individual topics fit together
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16. Vocabulary Graph, nodes, edges, labels
Class graph, construction, alternation
Object graph, satisfying class graph
UML class diagram
Grammar, printing, parsing
Define terms, glossary
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17. Vocabulary Traversals, visitors Strategy graphs, path set 11/16/2018
Define terms, glossary
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18. Overview this lecture Basic UML class diagrams
Traversals/Collaborating classes
Traversal strategy graphs
Adaptive programming
Tools for adaptive programming
DemeterJ and AP/Studio
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19. 1: Basic UML class diagrams
Graph with nodes and directed edges and labels for nodes and edges
Nodes: classes, edges: relationships
labels: class kind, edge kind, cardinality
explain details
give an example
exercise to re-enforce learning
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20. UML Class Diagram busStops BusRoute BusStopList buses 0..* BusStop
BusList
Example for developing strategies and writing adaptive programs
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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21. 2: Traversals / Collaborating classes
To process objects we need to traverse them
Traversal can be specified by a group of collaborating classes
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22. Collaborating Classes
use connectivity in class graph to define them succinctly
using strategy graphs
separating structure from behavior
teasing out the structure aspect
from Customer to Agent
from Company to Employee
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23. What's the problem? TANGLING
OOAD Z
customer service
center
teller service
self-service
Collab-1 C1 C4 C2 C3 C5
Collab-4
Collab-2
Collab-3
Object-oriented languages do not provide adequate constructs to capture
collaborations between several classes.
Has been recognized in different forms in the object-oriented community:
OO accommodates the addition of new variants of data types better than
procedural programming but, the opposite is true when new operations on existing
data types are needed
visitor pattern: the matter of concern -- definition of new operations on
an existing object structure (aggregation is involved besides inheritance)
several works complain the lack of constructs for expressing
collaboration-based designs C1 C4 C2 C3
Implementation C5
Collaboration --
a distinct (relatively independent aspect of an application that involves several
participants, or roles
roles played by application classes
each class may play different roles in different collaborations
each role embodies a separate aspect of the overall class behavior
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Collaboration-based design s Require to view oo applications in two different ways:
(a) in terms of participants or types involved
(b) in terms of the tasks or concerns of the design

24. Collaborating Classes
find all persons waiting at any bus stop on a bus route
busStops
BusRoute
BusStopList
OO solution:
one method
for each red
class
buses
0..*
BusStop
BusList
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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25. 3: Traversal Strategy Graphs
Want to define traversals succinctly
Use strategy graphs to express abstraction of class diagram
Express traversal intent: useful for documentation of object-oriented programs
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26. find all persons waiting at any bus stop on a bus route
Traversal Strategy
first try: from BusRoute to Person
busStops
BusRoute
BusStopList
buses
0..*
BusStop
BusList
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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27. find all persons waiting at any bus stop on a bus route
Traversal Strategy
from BusRoute through BusStop to Person
busStops
BusRoute
BusStopList
buses
0..*
BusStop
BusList
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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28. find all persons waiting at any bus stop on a bus route
Traversal Strategy
Altern.: from BusRoute bypassing Bus to Person
busStops
BusRoute
BusStopList
buses
0..*
BusStop
BusList
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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29. Robustness of Strategy
find all persons waiting at any bus stop on a bus route
Robustness of Strategy
from BusRoute through BusStop to Person
villages
BusRoute
BusStopList
busses
VillageList
busStops
0..*
0..*
BusStop
BusList
Village
waiting
0..*
passengers
Bus
PersonList
Person
0..*
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30. Filter out noise in class diagram
only three out of seven classes
are mentioned in traversal
strategy!
from BusRoute through BusStop to Person
explain why strategy better
replaces traversal methods for the classes
BusRoute VillageList Village BusStopList BusStop
PersonList Person
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31. Why Traversal Strategies?
Law of Demeter: a method should talk only to its
friends:
arguments and part objects (computed or stored)
and newly created objects
Dilemma:
Small method problem of OO (if followed) or
Unmaintainable code (if not followed)
Traversal strategies are the solution to this dilemma
problem solved by traversal strategies
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32. 4: Adaptive Programming
How can we use strategies to program?
Need to do useful work besides traversing: visitors
Incremental behavior composition using visitors
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33. Styles of Adaptive Programming
Traditional: parameterize by class graph; strategy is part of adaptive program
Traditional optimized: parameterize by class graph and strategy graph; reuse pair of class graph and strategy graph.
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34. Writing Adaptive Programs with Strategies (DJ=pure Java)
String WPS=“from BusRoute through BusStop to Person”
class BusRoute {
int countPersons(ClassGraph cg) {
String WPS=“from BusRoute through BusStop to Person”
Integer result = (Integer)
cg.traverse(this, WPS, new Visitor(){ int r ;
public void before(Person host){ r++; }
public void start() { r = 0;}
public Object getReturnValue()
{return new Integer ( r);}
}); return result.intValue();} }
can we really program with strategies? Here is how.
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35. Writing Adaptive Programs with Strategies (DJ=pure Java)
// Prepare the class graph
ClassGraph classGraph = new ClassGraph();
int r = aBusRoute.countPersons(classGraph);
can we really program with strategies? Here is how.
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36. Writing Adaptive Programs with Strategies (DJ=pure Java)
String WPStrategy=“from BusRoute through BusStop to Person”
class BusRoute {
int countPersons(TraversalGraph WP) {
Integer result = (Integer)
WP.traverse(this, new Visitor(){ int r ;
public void before(Person host){ r++; }
public void start() { r = 0;}
public Object getReturnValue()
{return new Integer ( r);}
}); return result.intValue();} }
can we really program with strategies? Here is how.
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37. Writing Adaptive Programs with Strategies (DJ=pure Java)
String WPStrategy=“from BusRoute through BusStop to Person”
// Prepare the traversal for the current class graph
ClassGraph classGraph = new ClassGraph();
TraversalGraph WPTraversal = new TraversalGraph
(WPStrategy, classGraph);
int r = aBusRoute.countPersons(WPTraversal);
can we really program with strategies? Here is how.
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38. Writing Adaptive Programs with Strategies (DJ=pure Java)
class Utility {
static
int countPersons(ObjectGraphSlice countSlice){
Integer result = (Integer)
countSlice.traverse(new Visitor(){ int r ;
public void before(Person host){ r++; }
public void start() { r = 0;}
public Object getReturnValue()
{return new Integer ( r);}
});
return result.intValue(); }
can we really program with strategies? Here is how.
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39. Writing Adaptive Programs with Strategies (DJ=pure Java)
String WPStrategy=“from BusRoute through BusStop to Person”
// Prepare the slice for the current class graph
ClassGraph classGraph = new ClassGraph();
ObjectGraph objectGraph = new ObjectGraph(aBusRoute);
ObjectGraphSlice whatToCount =
new ObjectGraphSlice(objectGraph, WPStrategy);
int r = Utility.countPersons(whatToCount);
can we really program with strategies? Here is how.
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40. Writing Adaptive Programs with Strategies (DemeterJ)
strategy: from BusRoute through BusStop to Person
BusRoute {
int printCountWaitingPersons() // traversal/visitor weaving
through BusStop to Person (PrintPersonVisitor); }
PrintPersonVisitor {
before Person {{ … }} … }
PersonVisitor {init {{ r = 0; }} … }
can we really program with strategies? Here is how.
THIS IS NOT JAVA
Extension of Java: keywords: init
through bypassing to before after etc.
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41. Writing Adaptive Programs with Strategies (DemeterJ)
strategy: from BusRoute through BusStop to Person
BusRoute {
traversal waitingPersons(PersonVisitor) {
through BusStop to Person; } // from is implicit
int printCountWaitingPersons() // traversal/visitor weaving
= waitingPersons(PrintPersonVisitor);}
PrintPersonVisitor {
before Person {{ … }} … }
PersonVisitor {init {{ r = 0; }} … }
THIS IS NOT JAVA
can we really program with strategies? Here is how.
Extension of Java: keywords: traversal init
through bypassing to before after etc.
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42. Taxi driver analogy
Streets and intersections correspond to class graph
Traversal strategy determines how the taxi will navigate through the streets
You can take pictures before and after intersections
You can veto sub traversals
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43. Programming in Large Families
Two adaptive programs A1
Class Graphs A2
adaptive programming is programming in LARGE families
A1 family
Object-Oriented Programs
A2 family
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44. Strategy ClassGraph ObjectGraph Adaptive Programming is use-case based
Bold names
refer to DJ
classes.
is use-case based
abstraction of
ClassGraph
New: abstractions of class diagrams
notice affinity to design patterns: some of them also talk about families
of class structures
explain strategies
defines family of
ObjectGraph
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45. Strategy ObjectGraph Adaptive Programming defines traversals of
explain strategies
ObjectGraph
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46. Strategy Visitor Adaptive Programming guides and informs 11/16/2018
explain strategies
Visitor
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47. Strategies
BusRoute BusStop Person
Nodes: positive information: Mark corner stones in class graph: Overall topology
of collaborating classes. 3 nodes:
from BusRoute
through BusStop
to Person
explain strategies
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48. Strategies Edges: negative information: Delete edges from class graph.
bypassing edges incident with Bus
BusRoute Person
Edges: negative information:
Delete edges from class graph.
explain strategies
from BusRoute bypassing Bus to Person
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49. 5: Tools for Adaptive Programming
free and commercial tools available
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50. Free Tools on WWW DJ and AP Library Demeter/C++ DemeterJ
Demeter/StKlos
Dem/Perl5
Dem/C++
Dem/CLOS
Demeter/Object Pascal
this technology is catching on
last four developed outside our group
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51. Commercial Tools available on WWW
StructureBuilder from Tendril Software Inc.
(bought by WebGain)
has support for DJ style actions
Neeraj Sangal, CEO
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52. Benefits of Adaptive Programming
robustness to changes
shorter programs
design matches program
more understandable code
partially automated evolution
keep all benefits of OO technology
improved productivity
ideas can be used without tools
Applicable to design and documentation
of your current systems.
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53. DemeterJ www.ccs.neu.edu/research/demeter class diagrams functionality
strategies
visitors
etc.
Executable
Java code for your favorite
commercial Java Software Development Environment
more details on Demeter/Java
weaver
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54. DemeterJ in DemeterJ structure (*.cd) class diagrams
focus of this lecture
compiler/
weaver
structure-shy
behavior
(*.beh)
strategies and
visitors
structure-shy
communication
(*.ridl)
distribution
more details on Demeter components and aspects
structure-shy
object description
(*.input, at runtime)
synchronization (*.cool)
multi threading
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55. Cross-cutting in DemeterJ
generated
Java program
DemeterJ program
structure-shy
functionality
structure
replicated!
aspect descriptions are not just copied into programs, they may be replicated several times.
synchronization
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56. AP Studio visual development of traversal strategies relative
to class diagram
visual feedback about collaborating classes
visual development of annotated UML class diagrams
drawing class diagrams and visualizing strategies
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57. Strengths of DemeterJ Theory Novel algorithms for strategies
Formal semantics
correctness theorems
Practice
Extensive feedback (8 years)
Reflective implementation
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58. Meeting the Needs DemeterJ
Easier evolution of class diagrams (with strategy diagrams)
Easier evolution of behavior (with visitors)
Easier evolution of objects (with sentences)
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59. Real Life Used in several commercial projects
Implemented by several independent developers
Used in several courses, both academic and commercial
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60. Summary
What has been learned: Simple UML class diagrams, strategies and adaptive programs
How can you apply:
DemeterJ takes adaptive programs as input
Document object-oriented programs with strategies
Design in terms of traversals and visitors
state what has been learned
define ways to apply training
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61. Where to get more information
Adaptive Programming book
DJ home page
UML Distilled
DemeterJ home page
Course home page:
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62. Feedback
Request feedback of training session
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