04-11-2016, 11:36 AM
1464427277-java.ppt (Size: 967 KB / Downloads: 9)
Agenda
Internet and its Evolution
Internet Tools
Web and its Programming
Java for Internet Programming
Java Nuts and Bolts
Java Platform
Developing Applets and Applications
Challenges and Future Directions
What is the Internet ?
Internet Technology Evolution
Internet is much bigger than what we think
More than 25 years old
More than doubling every year
Technology effect
suddenly every body sees the need for a technology
like the radio or the TV
10 terabytes flows everyday
Internet
Use of internet advertisement/elections/newspapers
information is public
Ubiquitous technology
Network is the computer
Intranets - internal TCP/IP nets
PC accounts for 55% of total IT
Applications tied to platform - API lock-in
Internet Evolution
Early Internet
Early Internet supported only email .
File Transfer Protocol development - ftp sites.
Network News was added to the Internet.
Archie - A program to canvass anonymous ftp sites and create a database of what is available
Gopher- A menu-driven interface used to search for information.
Archie and Gopher could answer questions only like ‘what FTP server contains info about “xx” ‘
World Wide Web
World Wide Web conceptualized by Tim Berners-Lee at CERN in Switzerland
Concept of Hypertext led to the development of the Hypertext Markup Language (HTML)
Tim Berners-Lee proposed the ‘Browser’ program
Scientists at CERN designed a TCP/IP based protocol to share Hypertext information called HTTP.
WWW officially is described as a” Wide-area hypermedia information retrieval initiative aiming to give universal access to a large universe of documents.
HTML
Hypertext -A little Hype and a Little Text.
Hypertext point to information which can be local or remotely located.
HTML -Derivative of the SGML( Standard Generalized Markup Language).
HTML -information , commands for the Browser for formatting documents.
HTML -The de-facto language for publishing on the Internet.
Hypermedia- Hyper-links to Multimedia.
Internet Tools
Browsers- A tool used to view documents on the WWW
Web servers - Machines which run the HTTP-server Software that respond to HTTP requests which it receives
Authoring Tools - Editors specially made for editing HTML documents
Filters -Tools to convert legacy documents to HTML format
Scripting -Languages used for scripting
WAIS- Wide Area Information Servers (WAIS) for indexing and doing full text searches
How does the Web work ?
Web -Designed around Client/Server Architecture
Web Clients ( Web Browsers ) -send requests for documents to any Web Server
Web Server -Program that responds to HTTP requests
Hyperlink
Web client connects to the specified Web Server
The server responds by sending the information asked for
The Browser formats the received HTML data and displays it
How does the Web Work
HTML document
<HTML>
<TITLE>Centre for Development of Advanced Computing
</TITLE>
<BODY BGCOLOR=“#E7CC” TEXT=“#000000” LINK=“#0000FF”>
...
...
<A HREF=“mailto:webmaster[at]cdacb.ernet.in> webmaster</A>
</BODY>
</HTML>
URLs
URLs- The Hypertext links we use today are known as Universal Resource Locator
URLs-Each name is unique across the Internet
An URL looks like this
http://system.domain.ext:999/dir1/dir2/d....html?blue#
Parts of a URL are,
Service type, System Name, Port, Directory path, Filename,Search Components or Variables
Service type, System Name, Directory path are the required parts of the URL
CGI (Common Gateway Interface)
CGI makes the Web a Two-way interface
CGI -lets the user run a script when a web page is accessed
Information from the Web Client is received through simple ‘fill-in-the-forms’ kind of interface
FORMS - Integrates data sheets, menus , check boxes
CGI makes the Web interactive
CGI -complicated to setup ,requires PERL knowledge
HTML books talk less about CGI
Authoring tools and Filters
Authoring tools- Editors for HTML documents
Editors similar to WYSIWYG word processing programs
Semi-WYSIWYG or completely WYSIWYG
Provide syntax checking and correction
Filters -Convert legacy documents to HTML format
Filters are useful when the documents already exist
Authoring tools- HoTMetaL, HTML Assistant -Shareware
Preconfigured v/s Integrated Internet Products
Integrated Internet Products- From multiple vendors
Preconfigured Systems- Web Server and a Client ready to use
Sun’s Netra Internet Server
SGI’s WebFORCE Indy and WebFORCE Challenge S
Apple’s Internet Server Solution
DEC’s Internet AlphaServer
Integraph’s Web Server 10
Future Directions
Additions to HTML (Grammar, Maths, Display control)
VRML (Virtual Reality Markup Language)
Security - Using Scrambling and Encryption
Common Client Interface (CCI)- Allows Clients to pass information back and forth between the Browser and the External Viewer
Charge Mechanisms
Performance Enhancements- Sending a page and graphics for that page in one connection