Advanced Programming

Giuseppe Attardi

Dipartimento di Informatica Università di Pisa

Università di Pisa

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

Instructors

Giuseppe Attardi Office: 292 Mail: [email protected]

Haoyuan Li Office: 373 Mail: [email protected]

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

Requirements



Cannot start from scratch



Reusable components are needed



OS + libraries not enough

Elements of a Solution



Software Framework



Component Model



Execution Environment

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

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”

Application Framework



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

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

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: Don’t call us, we’ll call you



Default behavior



Extensibility: usually by selective overriding



Non-modifiable framework code

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

Examples of Frameworks



GUI

– – –

MFC Gnome Qt



General

–

Spring



Web

– – –

ASP.Net

GWT Rails

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

Framework Design



Intellectual Challenging Task



Requires a deep understanding of the problem domain



Requires mastering of software patterns, OO methods and polymorphism in particular

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

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

Syllabus

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

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

Advanced Techniques



Generic Programming

– – –

C++ templates C# Generics Java Generics



Generative Programming

– – – – –

Metaprogramming Reflection Template Aspect Oriented Programming Generators

Interoperability



Process level: interprocess communication



Language level: CORBA/IDL



Object level: DCOM

Component Based Programming



COM



JavaBeans



.NET (Assembly, Reflection, Interfaces, Attributes)



OSGi

Web Programming



Web Services, SOA



Web Frameworks



Web 2.0

Web Services



XML, XML-Schema



SOAP, RPC, Rest



WSDL



UDDI

Web Frameworks and Applications



Asp.Net



ADO.Net



J2EE



Java Server Faces



AJAX: XHR, YUI, GWT



Mashup and Service Oriented Architecture

Scripting Languages



Perl



Python



JavaScript



PHP

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.

Assessment



Mid Term Paper: early November, one week homework



Term Paper: at the end of the course, one month homework

Run-time Environments

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

Controlling execution



Avoid damages



Install/uninstall is a nightmare



Component software?

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

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

Question



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

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?

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]

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

PHP Assignement

$str = ‘Ciao.’; $str2 = $str; $str{strlen($str) – 1} = ‘!’; echo $str2;



$var = $othervar

–

Performs copy of the value of $othervar



$var = &$othervar

–

Assignment by reference

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?

General Function Invoker

invoke(fun, argn, arglist) { if (n==0) return f(); else if (n==1) return f(arg[0]); else return fun(arg[0], arg[1], .. , arg[n-1]); }

Basic Data Types



Strings in C, Pascal and C++ are different



Array in row or column order?

Language Interoperability



C# and Cobol bark at each other

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#)"); } }

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.

Barfing dogs

public class Demo { public static void Main() { Dog d = new Dog(); BigDog b = new BigDog(); d.RollOver(); b.RollOver(); } }

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

Home Work



Develop a simple implementation of primitives:

–

void* malloc(size_t size)

–

void free(void*)



Discuss the limits of the solution