"The network is the computer"

The network is the computer.

- Sun Microsystems

Building Dynamic Web Pages

Client-Server Architectures (Section 1.4)

Client-Side Scripting (Chapters 3 & 4)

Web Servers (Chapter 5)

Server-Side Processing (Chapters 6, 8 & 10)

Programs vs. Scripts

Computers only understand programs written in a specially designed machine language:

Machine language programs are hard to write.

They are machine-specific.

In contrast, high-level languages:

Are easier to write because they are modeled on well-understood human formalisms.

Require a program to translate them into machine language:

Compiler

Interpreter

High-Level Language Example

Compilers

Interpreters

An interpreter decodes a script written in a high-level language, executing it on-the-fly.

Interpreted scripts tend to run more slowly than compiled programs.

Client/Server Technologies

James Gosling (1956- )
Java

1995

A hybrid of compilation and interpretation

Based on a virtual machine

Designed for a heterogeneous, networked environment.

Client-Side Scripting

Example: An Acme Attack Planner

Technologies:

Forms (http://www.w3schools.com/html/html_forms.asp)

JavaScript (http://www.w3schools.com/js)

HTML Forms

Form Input Boxes

Form Selection Lists

Form Radio Buttons

Form Check Boxes

Form Command/Reset Buttons

Post vs. Get

JavaScript

JavaScript is designed to add interactivity to HTML web pages:

Developed by Netscape

has a C/C++/Java-like syntax

JavaScript ≠ Java

It is not object-oriented.

It has limited capabilities.

HTML and JavaScript

HTML and JavaScript (cont.)

Script Functions

Script Functions (cont.)

An Image Swapper

Slide 35

JavaScript Reference Material

JavaScript data types (Netscape 2.0):

Boolean true, false

Number:Integer 1, 0, 1, 2, 3

Number:Floating Point 3.141, -3.01, 36e9

Number:Octal 05, 06, 07, 010

Number:Hexadecimal 0x8, 0x9, 0xA, 0xB

String "cat", "dog", ""

Null null

A JavaScript Reference/Tutorial:

http://www.w3schools.com/js/

Client/Server Architectures

Web Servers

Computers running software that processes information requests from web clients

Web servers communicate with clients using the Hypertext Transfer Protocol (HTTP).

Web servers provide access to many information types, e.g.:

html, text, gif, postscript,…

front ends to applications

Hyper-Text Transfer Protocol

Web servers communicate with clients using HTTP:

Request Types, e.g.:

GET

POST

Response Types, e.g.:

200

404

The HTTP protocol is:

Stateless

Anonymous

HTTP – A Static Page

HTTP – Client-Side Processing

HTTP – Server-Side Processing

Tim Berners-Lee (1955- )
World Wide Web

The world's first web server (info.cern.ch) on Dec. 25, 1990.

Included the key elements of the WWW:

URL

HTTP

HTML

Virtual Document Tree

File system structure ≠ Virtual document tree

The server computer maintains a standard, hierarchical file system.

The server software provides access only to the files in its virtual document tree.

Handling Multiple Users

HTTP servers/Application processors must hand multiple client requests.

How to run application processes:

Within the server process itself

One separate server process per request

Some combination of the two (e.g., threads)

HTTPS

HTTPS is HTTP working over the secure sockets layer (SSL).

SSL provides:

Encryption

Authentication

Comparing IIS and Apache

Apache

Open Source

Most commonly used

Seen as more reliable and more secure

Internet Information Server

Microsoft

Better integration with ASP.Net

Nicer administration IDE

Client/Server Architectures

Server-Side Scripting

Examples:

Acme new user registration

Acme products table

Technologies:

.Net Framework (http://www.w3schools.com/ngws)

VB.Net (http://msdn.microsoft.com/vbasic/)

ASP.Net (http://www.w3schools.com/aspnet)

ADO.Net (http://www.w3schools.com/aspnet/aspnet_dbconnection.asp)

.Net Framework

Microsoft’s network-oriented development architecture

Components:

Common language runtime

Class library

.Net vs. Java

Similar technologies

.Net (late 1990s/early 2000s)

Cleaner/newer implementation

Tightly integrated with Windows

Nicer IDEs

Java (mid-1990s)

Multi-platform

Loosely integrated with the OS

Java community process

VB.Net

Not just for GUIs anymore:

VB.Net != VB6

VB.Net @ Java

Compiled, server or client-side

Integrated with Microsoft’s .Net framework and development tools

VB.Net: Data Types

VB.Net: Control Structures

VB.Net: Procedures

ASP.Net

Active Server Pages

Component of the .Net framework

Supports dynamic web pages:

Web Forms (.aspx)

Rich & HTML server controls

Validation server controls

Web Services (.asmx)

ASP.Net Processing

ASP.Net vs. ASP

ASP is an older technology (1996).

ASP.Net:

Supports hybrid server/client-side event handlers

Separates HTML from “backing” code

Compiles its code

ASP.Net vs. JSP

ASP.Net

Microsoft platforms only

Widely used and supported

Supports multiple .Net languages

JSP

Multi-platform support

Less widely used

Java only

A Simple Example (cont.)

ASP.Net in VS.Net

Web Forms

Server Controls

Server Controls (cont.)

Validation Controls

Validation Controls (cont.)

Custom Validators

Custom Validators (cont.)

Event Handlers

Event Handlers (cont.)

Database Programming

The world of information technology revolves around databases.

Most database work is done through database application programs.

Approaches to database programming:

Embedded SQL commands

Database API

A new database language

Impedance Mismatch

ADO.Net

ActiveX Data Objects

Microsoft’s generic database API

Comparisons:

ADO.Net vs ODBC/JDBC

ADO.Net vs ADO

ADO.Net Example

ADO.Net Classes

SqlConnections

All interactions between the VB program and the database will be done through this object.

Connects should be closed when no longer needed.

SqlCommands

Commands are VB objects that represent standard SQL command as strings.

These strings are passed to the database to be executed.

DataSets/DataReaders

DataSets are a cache of the real database on the local machine.

They can contain tables resulting from many queries.

A DataReader is a forward-read-only version of DataSet.

SqlDataAdaptors

DataAdaptors mediate the communication between the DBMS tables and the VB program DataSet/DataReader(s)

ADO.Net Code

ADO.Net Code (2)

ADO.Net Code (3)

Database Updates

Database Updates (2)

Database Updates (3)


	Client-Server Architectures (Section 1.4)
	Client-Side Scripting (Chapters 3 & 4)
	Web Servers (Chapter 5)
	Server-Side Processing (Chapters 6, 8 & 10)


Computers only understand programs written in a specially designed machine language:
	Machine language programs are hard to write.
	They are machine-specific.
In contrast, high-level languages:
	Are easier to write because they are modeled on well-understood human formalisms.
	Require a program to translate them into machine language:
		Compiler
		Interpreter


	An interpreter decodes a script written in a high-level language, executing it on-the-fly.




	Interpreted scripts tend to run more slowly than compiled programs.



	1995
	A hybrid of compilation and interpretation
	Based on a virtual machine
	Designed for a heterogeneous, networked environment.


	Example: An Acme Attack Planner
	Technologies:
		Forms (http://www.w3schools.com/html/html_forms.asp)
		JavaScript (http://www.w3schools.com/js)


	JavaScript is designed to add interactivity to HTML web pages:
		Developed by Netscape
		has a C/C++/Java-like syntax
	JavaScript ≠ Java
		It is not object-oriented.
		It has limited capabilities.


	JavaScript data types (Netscape 2.0):
		Boolean true, false
		Number:Integer 1, 0, 1, 2, 3
		Number:Floating Point 3.141, -3.01, 36e9
		Number:Octal 05, 06, 07, 010
		Number:Hexadecimal 0x8, 0x9, 0xA, 0xB
		String "cat", "dog", ""
		Null null
	A JavaScript Reference/Tutorial:
		http://www.w3schools.com/js/


	Computers running software that processes information requests from web clients
	Web servers communicate with clients using the Hypertext Transfer Protocol (HTTP).
	Web servers provide access to many information types, e.g.:
		html, text, gif, postscript,…
		front ends to applications


Web servers communicate with clients using HTTP:
	Request Types, e.g.:
		GET
		POST
	Response Types, e.g.:
		200
		404
The HTTP protocol is:
	Stateless
	Anonymous


	The world's first web server (info.cern.ch) on Dec. 25, 1990.
	Included the key elements of the WWW:
		URL
		HTTP
		HTML


	File system structure ≠ Virtual document tree
		The server computer maintains a standard, hierarchical file system.
		The server software provides access only to the files in its virtual document tree.


	HTTP servers/Application processors must hand multiple client requests.
	How to run application processes:
		Within the server process itself

		One separate server process per request

		Some combination of the two (e.g., threads)


	HTTPS is HTTP working over the secure sockets layer (SSL).
	SSL provides:
		Encryption

		Authentication


	Apache
		Open Source
		Most commonly used
		Seen as more reliable and more secure
	Internet Information Server
		Microsoft
		Better integration with ASP.Net
		Nicer administration IDE


	Examples:
		Acme new user registration
		Acme products table
	Technologies:
		.Net Framework (http://www.w3schools.com/ngws)
		VB.Net (http://msdn.microsoft.com/vbasic/)
		ASP.Net (http://www.w3schools.com/aspnet)
		ADO.Net (http://www.w3schools.com/aspnet/aspnet_dbconnection.asp)


	Microsoft’s network-oriented development architecture
	Components:
		Common language runtime

		Class library


	Similar technologies
	.Net (late 1990s/early 2000s)
		Cleaner/newer implementation
		Tightly integrated with Windows
		Nicer IDEs
	Java (mid-1990s)
		Multi-platform
		Loosely integrated with the OS
		Java community process


	Not just for GUIs anymore:
		VB.Net != VB6
		VB.Net @ Java
	Compiled, server or client-side
	Integrated with Microsoft’s .Net framework and development tools


Active Server Pages
Component of the .Net framework
Supports dynamic web pages:
	Web Forms (.aspx)
		Rich & HTML server controls
		Validation server controls
	Web Services (.asmx)


	ASP is an older technology (1996).
	ASP.Net:
		Supports hybrid server/client-side event handlers
		Separates HTML from “backing” code
		Compiles its code


	ASP.Net
		Microsoft platforms only
		Widely used and supported
		Supports multiple .Net languages
	JSP
		Multi-platform support
		Less widely used
		Java only


	The world of information technology revolves around databases.
	Most database work is done through database application programs.
	Approaches to database programming:
		Embedded SQL commands
		Database API
		A new database language


	ActiveX Data Objects
	Microsoft’s generic database API
	Comparisons:
		ADO.Net vs ODBC/JDBC

		ADO.Net vs ADO


	All interactions between the VB program and the database will be done through this object.
	Connects should be closed when no longer needed.


	Commands are VB objects that represent standard SQL command as strings.
	These strings are passed to the database to be executed.


	DataSets are a cache of the real database on the local machine.
	They can contain tables resulting from many queries.
	A DataReader is a forward-read-only version of DataSet.


	DataAdaptors mediate the communication between the DBMS tables and the VB program DataSet/DataReader(s)