A. Bellaachia
Department of Computer Science
School of Engineering and Applied Science
The George Washington University
Washington, DC 20052

Introduction
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Software Development Process
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Language and Computer Architecture
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Language paradigms
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Language Evaluation Criteria:
 Readability

Examples: Data type, data structures, and control statements

Writability

Reliability
 Type checking

Exception handling
 Aliasing
 Maintainability

Cost
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Software Paradigms
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Five Software Paradigms

AP: Algorithmic Paradigm

AP assumes problem is well structured
 application = program to map input to output
 finite number of steps, no errors

ASE: Analysis-Synthesis-Evaluation
 like Waterfall Model
 assumes problem is well structured

It uses problem decomposition

FD: Formal Design

FD assumes problem is well structured

It is a refinement of ASE, but uses abstraction
 problem becomes a mathematical proposition
 AI: Artificial Intelligence

It is explicitly founded on the concepts of search, knowledge and heuristics

It does not assume problem is well structured

TED: Theory of Evolutionary Design

It uses the fast that software design is an evolutionary process

It does not assume problem is well structured

Nothing is fixed, everything can evolve
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Architectural Styles (major ones)

Dataflow Systems

Pipelines
– Each layer is client for layer below it
– output of one stage = input to next
– Example: Compilers

Call & Return Systems

Layered
– Each layer is client for layer below it
– advantages: incremental, extendable
– N-tier / Client-Server
– layers can be developed independently
– Examples: Operating Systems, Web-based applications

Independent-Process
 Communicating Processes:
– Using CSP to describe different process topologies

Repository
 Blackboard
– central repository for shared info
– 3 components – knowledge source, controller, repository (blackboard)
– Example: no one single answer – fingerprints
 Architecture Evaluation: Good Structure

Cohesion

Coupling
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Requirement analysis and software architecture of a domain of applications.
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Examples: Wed browsers, Web servers, Word processors, etc.
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There are three main elements of a DSSA:

Domain Model

Complete description of the domain

Achieved by experts in the domain, users, developers who have experience in the domain, etc.
 Reference Requirements
 Stable (or Fix)

Variable (or optional)

Requirements can also be broken into:
– Functional, Non-functional, Design, Implementation

List a reference of each requirement of the domain.

Reference Architecture

Make sure to state the right architecture style for the domain.

List a reference of each architectural element.
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Why use components?
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Major elements of a component:
 Specification

One or more implementations

Component Model:

Each of these component models addresses the following issues:
– How a component makes its services available to others?
– How component are named?
– How new components and their services are discovered at runtime.

A packaging approach:

Example: 2EE application is packaged as an E nterprise AR chive ( EAR ) file, a standard Java JAR file with an .ear extension.

A deployment approach:

J2EE uses deployment descriptors that are defined as in XML files named ejbjar.xml
.
•
Component Architecture
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Blackbox vs. Whitebox
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Components vs. Objects
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Components in industry verses in-house solutions
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Component disadvantages
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Definitions
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What is a Pattern?
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Categories of Patterns
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Pattern Characteristics
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Essential Elements of a Design Pattern
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Examples of design patterns:

Singleton

Adapter
 Strategy
•
Design Pattern Selection
•
How to Use a Design Pattern?
•
Idioms
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Basic of Programming Languages
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Built-in Types and Primitive Types
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Data Aggregates and Type Constructors
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Constructors
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User-defined Types and Abstract Data Types
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Strong Typing & Type Checking
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Type Compatibility
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Type Conversion
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Type and Subtypes
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Generic Types
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Monomorphic versus Polymorphic
•
The Type Structure of Representative languages
•
Implementation Models
•
Implementation of Structured Types
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Object-Oriented Programming
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Object-oriented characteristics:

Object Definition and instance creation

Encapsulation

Inheritance
 Polymorphism: “ Polymorphism (Greek for many forms) means that the same operation can be defined for many different classes, and each can be implemented in their different way.
“
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Binding in OOP:

Static vs. Dynamics
•
Implementation of OO constructs
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Functional Programming
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Functional programming characteristics
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Functions in FP: composition, Apply-to-all, etc.
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Performance
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Logic Programming
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Logic programming characteristics:
 based on relations.

Horn clause
•
User query processing:

Resolution

Unification
•
Performance
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Concurrency
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Concurrency requirements
•
Problems with concurrency:
 Deadlock

Starvation

Etc.
•
Process Interactions

Syntax for parallel processes
 Independent processes

Competing processes (Critical sections)

Communicating processes (May need to communicate)
•
Low-level Concurrency Primitives

Process creation and control :
 Event: Event-wait (e) and Event-signal (e)

Messages :

Remote Procedure Calls (RPCs)
•
Synchronization

Semaphores, Monitors, etc.
•
Concurrency in Java.
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Problem :
In this problem, we would like to define a DSSA for web server applications such as Apache and Internet Information Server (IIS).
The major operations of a web server include the following:
– A resource handler to determine the type of operation requested by a browser.
– Interpretation of a request protocol such as the HTTP protocol.
– An operation, called Access Control, to enforce access rule employed by the server.
– A request analysis operation to translate the location of the resource (URL) from a network location to a local file name.
– A web server has also the ability to gather information (log) about all the requests and their results.
Provide a complete DSSA for this type of applications.
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Problem:
State the major software paradigms that can be examined during the steps of the software life cycle of an application and explain why.
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Problem:
Component-based software development greatly depends on an efficient component integration strategy. You have been hired by a company and you are asked to develop a component-based system.
(a) What are the issues that you need to address in your design?
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Problem:
Give an architectural description in CSP for the following architecture:
M
0
M
2
M
5
F1 F2 O1
M
4 M
1
F3 F4
M
3
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Problem:
We have used cohesion and coupling to compare different software architectures. In this problem, we introduce a new metric, called Component Structural Complexity
(CSC). The structural complexity of a component i is defined as follows:
CSC(i) = f2out(i),
Where fout(i) is the number of components immediately subordinate to the component i, that is, the number of components directly invoked by component i
1. Design a system structural complexity (SSC) metric for the whole system using CSC metric, assuming you have a system of n components
2. Measure SSC for pipeline and layered architectures.
3. Compare SSC metric to coupling and cohesion.
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•
Problem:
(a) Describe why you would use design patterns in your application.
(b) Give an example of a design pattern and show how you would use it for a specific application.
State clearly your application.
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Sample Questions: Different Paradigms
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What the major design decisions you need to consider for:

Object-oriented programming

Requirements of OOP
 Polymorphism

Class Instance Record (CIR)

FP

Requirements of FP

Be familiar with Scheme: be able to understand scheme code

LP:

Requirements of LP
 Resolution algorithm

Unification

Query processing
 Concurrency

Requirements of concurrency.
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Sample Question
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Problem: class A { public: int a; virtual void what(){ … } virtual void who() { … }
}; class B{ public: int b virtual void what{ … }
}; class C: public A, public B { public: int c; virtual void what(){ … } virtual void who() { … } virtual void dud() { … }
};
Draw the Class Instance Record (CIR) of each class.
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Sample Question
•
Problem:
One of the programming language paradigms we have covered is logic programming.
1. Describe this paradigm and compare it to a programming language paradigm of your choice.
2. Give detailed description of the different parts of a logic program.
3. One of the drawbacks of logic programming is low performance. How would your enhance the efficiency of a logic programming compiler?
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Sample Question
•
Problem:
You are asked to extend a procedural language to become an object-oriented (OO) language.
(1) State the OO features that you need to add to your procedural language
(2) Explain how you would implement each of the features in (1)
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Sample Question
•
Problem:
Consider the following logic program:
 mother (mary, sue).
 mother (mary, bill).
 mother (sue, nancy).
 mother (sue, jeff).
 mother (jane, ron).
 father (john, sue).
 father (john, bill).
 father (bob, nancy).
 father (bob, jeff).
 Father(bill,ron).
 Parent(A,B) :- father(A,B).

Parent (A,B) :- mother(A,B).

Grandparent(C,D) :- parent(C,E), parent(E,D).
Show the trace of the processing of the following queries:
?- grandparent(Who, ron).
Add a sibling relationship to the above program and answer the following question:
?- sibling(sue, X).
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G o o d L u c k
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