Advanced Programming

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Advanced Programming

• Giuseppe Attardi
• Dipartimento di Informatica
• Università di Pisa

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Language is an instrument of human reason,not
merely a medium for the expression of thought.G.
Boole, An Investigation of the Laws of Thought,
1854
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Instructors
Giuseppe Attardi Office 292 Mail
attardi_at_di.unipi.it
Haoyuan Li Office 373 Mail li_at_di.unipi.it
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Introduction

• Programming in the 21 century
• Software as complex as ever
• Command line interface not enough
• Data must be structured in a DB
• Single computer not enough
• Software development is a group activity

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Requirements

• Cannot start from scratch
• Reusable components are needed
• OS libraries not enough

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Elements of a Solution

• Software Framework
• Component Model
• Execution Environment

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More Complex Software

• Object-Oriented Programming allows ever larger
  applications to be built
• Require increased high-level application and
  system oversight
• Multi-tier applications development increases the
  choices on how to build applications
• A new Software Architect Role is needed

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Software Architect

• Creating, defining or choosing an application
  framework
• Creating the component design
• Structure a complex application into pieces
• Understand the interactions and dependencies
  among components
• Select the platform based on cost/performance
  criteria
• Organize and supervise the construction site

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Application Framework

• A software framework used to implement the
  standard structure of an application for a
  specific development environment

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Software Framework

• A collection of common code providing generic
  functionality that can be selectively overridden
  or specialized by user code providing specific
  functionality
• Frameworks, like software libraries, provide
  reusable abstractions of code wrapped in a
  well-defined API

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Framework Features

• Inversion of control
• unlike in libraries, the overall program's flow
  of control is not dictated by the caller, but by
  the framework
• Hollywood Principle Dont call us, well call
  you
• Default behavior
• Extensibility usually by selective overriding
• Non-modifiable framework code

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OO Software Framework

• Object-oriented programming frameworks consists
  in a set of abstract classes
• An application can be built simply inheriting
  from pre-existing classes in the framework
• Instantiation of a framework consists of
  composing and subclassing the existing classes

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Examples of Frameworks

• GUI
• MFC
• Gnome
• Qt
• General
• Spring
• Web
• ASP.Net
• GWT
• Rails

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Benefits of Frameworks

• Drives solution
• Dictates how to fill-in-the-blanks
• Helps solving recurring problems
• Designed for reuse
• High value, since reduces cost of development

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Framework Design

• Intellectual Challenging Task
• Requires a deep understanding of the problem
  domain
• Requires mastering of software patterns, OO
  methods and polymorphism in particular

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Course Objectives

• Understand programming language technology
• Execution Models
• Run-time
• Analyze programming metaphors
• Objects
• Components
• Pattern
• Learn advanced programming techniques
• Understand their limits ad how to overcome them

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Course Objectives

• Explain how high level programming concepts and
  metaphors map into executable systems and which
  are their costs and limitations
• Acquaint with modern principles, techniques, and
  best practices of advanced software construction
• Introduce techniques of programming at higher
  abstraction levels, in particular generative
  programming, component programming and web
  computing
• Present state-of-the-art frameworks incorporating
  these techniques

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Syllabus
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Programming Language Foundations

• Syntax, Parsing, Abstract Syntax Tree, Parser
  Generators
• Names, Scope, Binding
• Parameter Passing
• Static and Dynamic Allocaltion Stack, Heap
• Types, Inheritance, Polymorphism, Overloading
• Delegates, Closures
• Exception Handling

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Run-time Systems

• Virtual Execution Environment
• Memory Management
• Thread Management
• Exception Handling
• Security
• Debugging Support
• AOT and JIT Compilation
• Dynamic Link/Load
• Reflection
• Verification
• Language Interoperability

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Advanced Techniques

• Generic Programming
• C templates
• C Generics
• Java Generics
• Generative Programming
• Metaprogramming
• Reflection
• Template
• Aspect Oriented Programming
• Generators

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Interoperability

• Process level interprocess communication
• Language level CORBA/IDL
• Object level DCOM

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Component Based Programming

• COM
• JavaBeans
• .NET (Assembly, Reflection, Interfaces,
  Attributes)
• OSGi

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Web Programming

• Web Services, SOA
• Web Frameworks
• Web 2.0

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Web Services

• XML, XML-Schema
• SOAP, RPC, Rest
• WSDL
• UDDI

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Web Frameworks and Applications

• Asp.Net
• ADO.Net
• J2EE
• Java Server Faces
• AJAX XHR, YUI, GWT
• Mashup and Service Oriented Architecture

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Scripting Languages

• Perl
• Python
• JavaScript
• PHP

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Text Books

• Programming Language Pragmatics, third ed.,
  Michael L. Scott, Morgan-Kaufmann, 2009.
• Generative Programming Methods, Tools, and
  Applications, Krzysztof Czarnecki, Ulrich
  Eisenecker, Addison-Wesley, 2000.
• Object Thinking , David West, Microsoft Press,
  2004.

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Assessment

• Mid Term Paper early November, one week homework
  
• Term Paper at the end of the course, one month
  homework

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Run-time Environments
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Run-Time Environments

• Java Virtual Machine
• .NET Common Language Runtime
• Provide a virtual execution environment
• Exposes a structure organized into elements
• Not a simple abstraction of physical resources

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Controlling execution

• Avoid damages
• Install/uninstall is a nightmare
• Component software?

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Benefits

• Programmers
• Use of library and tools
• Shorter integration time
• Higher productivity
• Tool Developers
• Avoid the need to care about infrastructure and
  interoperability
• Administrators and Users
• Benefit from packages solutions
• Independence from processors or OS

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Common Language Infrastructure

• Exposes all items in a unified type system
• Packages elements in self-describing units
• Loads and resolves interdependencies at runtime
• Exposes information that allows verifying the
  type-safety
• Execution Engine enforces politics
• Metadata available at runtime enables dynamic and
  extensible solutions

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Question

• Is it feasible to build a runtime common to all
  programming languages?

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More in detail

• Prolog
• How to implement logic variable?
• Can one use the Warren-Abstract-Machine?
• PHP 3
• Why assignment has unusual behavior?
• LISP
• How to handle multiple-values?

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Prolog example

• append(X, Y, Z) -
• append(NIL, Y, Y) -
• append(A . X, Y, A . Z ) - append(X, Y, Z).
• - append(a . b . c, d . e, R)
• R a . b . c . d . e

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Prolog backtrack

• - append(X, Y, a . b)
• - append(X, NIL, a . b)
• X NIL
• Y a . b
• X a
• Y b
• X a . b
• Y NIL

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PHP Assignement

• str Ciao.
• str2 str
• strstrlen(str) 1 !
• echo str2
• var othervar
• Performs copy of the value of othervar
• var othervar
• Assignment by reference

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Control

• Can we implement tail-recursion in C?
• How to handle synchronization?
• Function pointers?
• How to invoke an arbitrary function given a list
  of arguments?

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General Function Invoker

• invoke(fun, argn, arglist)
• if (n0)
• return f()
• else if (n1)
• return f(arg0)
• else
• return fun(arg0, arg1, .. , argn-1)

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Basic Data Types

• Strings in C, Pascal and C are different
• Array in row or column order?

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Language Interoperability

• C and Cobol bark at each other

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C dog

• using System
• public class Dog
• public virtual void RollOver ()
  Console.WriteLine("Scratch my tummy.") Bark()
• public virtual void Bark () Console.WriteLine("
  WOOF WOOF (C)")

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Cobol BigDog

• 000010 CLASS-ID. BigDog INHERITS Dog.
• 000020 ENVIRONMENT DIVISION.
• 000040 CONFIGURATION SECTION.
• 000050 REPOSITORY.
• 000060 CLASS Dog.
• 000070 OBJECT.
• 000080 PROCEDURE DIVISION.
• 000090 METHOD-ID. Bark OVERRIDE.
• 000160 PROCEDURE DIVISION.
• DISPLAY "WOOF WOOF (COBOL)".
• 000210 END METHOD Bark.
• 000220 END OBJECT.
• 000230 END CLASS BigDog.

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Barfing dogs

• public class Demo public static void
  Main() Dog d new Dog()
  BigDog b new BigDog()
  d.RollOver() b.RollOver()
  

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Final Term Paper

• Aims at exercising ability to conceive and
  implement full solutions to a nontrivial problem
• Examples
• ASP Code generator with regular expression
  matcher
• Implement a DSL for handling persistent object
  containers
• SOAP protocol and SOAP server
• Code generator for searching an object DB
• Xpath and XSLT Intrepreter
• Language for generating network protocols
• AJAX Framework

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Home Work

• Develop a simple implementation of primitives
• void malloc(size_t size)
• void free(void)
• Discuss the limits of the solution