Client-Server Programming Spring Semester, 2005 Introduction
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CS 580 Client-Server Programming Spring Semester, 2005 Doc 1 Introduction

Contents

Course Introduction

Introduction to Client-Server

What is Client-Server?

What Client-Server Requires of a Programmer

Programming Issues

Naming Convention for Classes, Variables & Methods

Names

Comments

Commenting Data Declarations

Copyright ©, All rights reserved. 2004 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent ( http://www.opencontent.org/opl.shtml) license defines the copyright on this document

References

Code Complete by Steve McConnell

Course Introduction

Course Outline

Introduction

Testing

Source Version Control

Network Basics

GUI

Client Development Issues

Concurrency

Server Types & Structure

Client-Server Protocols

Logging

Databases

Security

Web based Applications

• CGI, Fast-CGI, Servlets

Web Services

Advanced topics

This outline will be changed during the semester.

Main Points of Class

Common design issues & solutions for building a server

Issues in designing a client-server network protocol

Handling Concurrency

Accessing databases

Programming issues dealing with working on client-server code

Programming languages for the Course

Java

• We will be using parts of JDK 1.5

Smalltalk – VisualWorks 7.3

C#

• Not supported

What does it mean to “Know” Java, C# or Smalltalk

Basic syntax of the language

Core API

• No one knows the entire API of either language
• You should have good grasp of the common or core API
• Collections, Files, Exceptions, Streams

Language culture - Ways of doing things in each language

• Java Doc
• Searching the API
• Compiling/running code
• Using Smalltalk browsers
• Naming conventions

Object-oriented programming

Introduction to Client-Server

What is Client-Server?

Client

• Application that initiates peer-to-peer communication
• Translate user requests into requests for data from server via protocol
• GUI often used to interact with user

Server

• Any program that waits for incoming communication requests from a client
• Extracts requested information from data and return to client
• Common Issues
  • Authentication
  • Authorization
  • Data Security
  • Privacy
  • Protection
  • Concurrency

What this Course is not

An advanced (or beginning) Networking course

How to use a client builder application/system

• Powerbuilder

What this Course covers

Skills & knowledge required to build client-server applications

What Client-Server Requires of a Programmer

• Designing robust protocols

• Network programming

• Designing usable computer-human interfaces

• Good documentation skills

• Good debugging skills

• Understand the information flow of the company/customer

• Mastery of concurrency

• Multi-platform development

• Database programming

• Security

Programming Issues

Naming Convention for Classes, Variables & Methods

• Use full words – avoid abrvtns

Pascal Casing

Capitalize the first character of each word

SomeClassName

Camel Casing

Capitalize the first character of each word except the first word

someVariableName

Names

"Finding good names is the hardest part of OO Programming"

"Names should fully and accurately describe the entity the variable represents"

What role does the variable play in the program?

Some Examples of Names, Good and Bad

Names should be as short as possible and still convey meaning to the reader

Comments

"Comments are easier to write poorly than well, and comments can be more damaging than helpful"

What does this do?

for i := 1 to Num do
 MeetsCriteria[ i ] := True;
for  i := 1 to Num / 2  do begin
 j := i + i;
 while ( j <= Num ) do begin
  MeetsCriteria[ j ] := False;
  j := j + i;
 end;
for i := 1 to Mun do
 if MeetsCriteria[ i ] then
  writeln( i, ' meets criteria ' );
   

   
for PrimeCandidate:= 1 to Num do
   IsPrime[ PrimeCandidate] := True;
   
for  Factor:= 1 to Num / 2  do begin
   FactorableNumber := Factor + Factor ;
   while ( FactorableNumber <= Num ) do begin
      IsPrime[ FactorableNumber ] := False;
      FactorableNumber := FactorableNumber + Factor ;
   end;
end;
   
for PrimeCandidate:= 1 to Num do
   if IsPrime[ PrimeCandidate] then
      writeln( PrimeCandidate, ' is Prime ' );
   
   

Good Programming Style is the Foundation of Well Commented Program

Commenting Paragraphs of Code

Write comments at the level of the code's intent

Comment the why rather than the how

Make every comment count

Document surprises

Avoid abbreviations

How verses Why

How

/* if allocation flag is zero */
   
if ( AllocFlag == 0 ) ...

Why

/* if allocating a new member */
   
if ( AllocFlag == 0 ) ...

Even Better

if ( AllocFlag == NEW_MEMBER ) ...

{ check each character in "InputStr" until a 
  dollar sign is found or all characters have 
  been checked }
   
Done   := false;
MaxPos := Length( InputStr );
i      := 1;
while ( (not Done) and (i <= MaxLen) ) begin
   if ( InputStr[ i ] = '$' ) then
      Done := True
   else
      i := i + 1
end;
   

{ find the command-word terminator }
   
Done   := false;
MaxPos := Length( InputStr );
i      := 1;
   
while ( (not Done) and (i <= MaxPos ) ) begin
   if ( InputStr[ i ] = '$' ) then
      Done := True
   else
      i := i + 1
end;

{ find the command-word terminator }
   
FoundTheEnd      := false;
MaxCommandLength := Length( InputStr );
Index            := 1;
   
while ((not FoundTheEnd) and 
       (Index <= MaxCommandLength)) begin
   
   if ( InputStr[ Index ] = '$' ) then
      FoundTheEnd := True;
   else
      Index := Index + 1;
end;

Commenting Data Declarations

Comment the units of numeric data

Comment the range of allowable numeric values

Comment coded meanings

var
   CursorX:      1..MaxCols;   { horizontal screen position of cursor }
   CursorY:      1..MaxRows;   { vertical position of cursor on screen }
   
   AntennaLength:   Real;   { length of antenna in meters: >= 2 }
   SignalStrength:   Integer;   { strength of signal in kilowatts: >= 1 }
   
   CharCode:      0..255;   { ASCII character code }
   CharAttib:      Integer;   { 0=Plain; 1=Italic; 2=Bold  }
   CharSize:         4..127;   { size of character in points }
   
Comment limitations on input data
   
Document flags to the bit level

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