Full HTML for

Scripted foilset Overview of Basic Web and Internet Technologies

Given by Geoffrey Fox at Beijing Web Tutorial on May 27-30 1997. Foils prepared 5 July 97
Outside Index Summary of Material

We review some of the base material assumed in CPS616 using curricula material taken from CPS606
History and Structure/Size of Internet and Web
Basic Internet and Web Services
What is WebWindows and basic Web architecture
Overview of Networking for Internet
MIME HTTP
but not HTML or CGI (see separate presentations)

Table of Contents for full HTML of Overview of Basic Web and Internet Technologies

 Denote Foils where Image Critical
Denote Foils where HTML is sufficient
1 Review of Basic Web/Internet Technologies -- Networking HTTP MIME!
2 Abstract of Web Review Material
3 3 Reasons to Learn or Use Web Technologies
4 The Architecture of the World Wide Web
5 Applications based on information services typically use a Client/Server Architecture
6 Familiar Clients and Servers
7 Top-level View of the World Wide Web
8 Top-level View of the Corporate Intranet
9 Basic (CPS606) Structure of World Wide Web
10 Background on the Internet
11 History of the Internet
12 Internet Trends - Internet Hosts 1989-1997
13 Internet Trends - Internet Hosts - Overall Trend
14 Internet Trends - Internet Domains in DNS
15 Internet Trends - WWW-Prefixed Hosts
16 Internet Trends - Hosts: Three-Letter Domains
17 Internet Trends - Hosts: Two-letter Domains, >120,000 per country
18 NII Compute & Communications Capability in Year 2000 --> 2005
19 Ultimate Vision and Implementation of NII and InfoVision
20 Internet Services: Telnet
21 Internet Services: FTP
22 Internet Services: News
23 Internet Services: Mail Lists
24 Web Content is Hyperlinked Multimedia
25 Web Links can go to other Internet Services
26 Multimedia types
27 Forms and CGI Scripting
28 The CGI script returns data through the server
29 Web Search Engines
30 Web Search Indexes
31 The Current Web Client Server Model
32 Databases
33 JavaScript
34 Java
35 Future Web Technologies: VRML
36 Open Universal WebWindows --
A Revolution in the Software Industry!
37 The WebWindows Operating System
38 Examples and Why WebWindows will Dominate Software Industry?
39 Illustration of WebWindows Concept for Presentation Software
40 RCIHalloween Presentation Foil on WebFoil in WebFoil!!
41 JavaScript Based WebFoil Prototype
42 Lessons of WebFoil for WebWindows Software Development Scenario
43 The Current Web Client Server Model
44 Architecture of Web Software
45 General Web Architecture
46 Networking Basics
47 Networking Basic Definitions
48 Networking Standards: OSI Layers
49 Simplified communication protocol model
50 The TCP/IP protocol suite
51 Typical message formats
52 Networking
53 Communications Issues
54 Networking Speeds
55 Open Standards
56 Internet Documents: Drafts, Memos and Standards
57 Internet Documents - Examples
58 Message-passing Protocols
59 Internet E-Mail (RFC-822)
60 Multi-purpose Internet Mail Extension (MIME)
61 MIME - "Content-Type" Header Field
62 MIME - Base Content Types
63 MIME - Base Content Types, continued
64 Web Services - HTTP Protocol
65 Applications based on information services typically use a Client/Server Architecture
66 The World Wide Web is a collection of clients and servers called browsers and Web sites
67 HTTP - Hypertext Transport Protocol
68 HTTPD - HTTP Daemon
69 URL - Uniform Resource Locator
70 Web Links can go to other Internet Services
71 HTTP - How does it work?
72 HTTP - GET Request Example
73 HTTP - Reply Example
74 HTTP - POST Request Example

Outside Index Summary of Material

HTML version of Scripted Foils prepared 5 July 97

Foil 1 Review of Basic Web/Internet Technologies -- Networking HTTP MIME!

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
http://www.npac.syr.edu/users/gcf/cps616webreviewjune97
Material from CPS606 Assumed in CPS616
Used in Trip to China May 97
Geoffrey Fox
Syracuse University NPAC
111 College Place Syracuse NY 13244 4100
3154432163
HTML version of Scripted Foils prepared 5 July 97

Foil 2 Abstract of Web Review Material

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
We review some of the base material assumed in CPS616 using curricula material taken from CPS606
History and Structure/Size of Internet and Web
Basic Internet and Web Services
What is WebWindows and basic Web architecture
Overview of Networking for Internet
MIME HTTP
but not HTML or CGI (see separate presentations)
HTML version of Scripted Foils prepared 5 July 97

Foil 3 3 Reasons to Learn or Use Web Technologies

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
For the World Wide Web or Internet Itself
For use in Enterprise/Corporate Information Systems
  • I.e. Intranet Use
Use of Web Technology as base software Infrastructure
  • VRML for Video Games
  • JavaBeans for Component-based software
  • New (distance) Education Approaches
HTML version of Scripted Foils prepared 5 July 97

Foil 4 The Architecture of the World Wide Web

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The World Wide Web (WWW) (the Web) is a hyperlinked collection of documents and programs that reside on computers all over the world, linked by the Internet.
This talk will show the underlying components and mechanisms that make the Web work.
  • Network protocols based on TCP/IP and a common Domain Name Service
  • Message-passing protocols based on MIME
  • Web Server architecture based on the HTTP protocol
This works on a world-wide basis is because these protocols are based on Open Standards which have been implemented by many vendors on a variety of machines. The Web software structure is strictly non- proprietary, while allowing proprietary pieces to fit in where needed.
The same architecture and software that makes the Web work is also suitable for implementing distributed applications between hetereogeneous machines and networks. This makes the architecture attractive for the corporate Intranet as well.
HTML version of Scripted Foils prepared 5 July 97

Foil 5 Applications based on information services typically use a Client/Server Architecture

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Server: A program in charge of a resource or information.
  • Operation is defined by list of services.
  • Normal mode is to listen for requests, stopping to fulfill a request when it arrives.
Client: Any program that makes a request for service from the server.
HTML version of Scripted Foils prepared 5 July 97

Foil 6 Familiar Clients and Servers

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Clients and servers send their messages over a network connection.
HTML version of Scripted Foils prepared 5 July 97

Foil 7 Top-level View of the World Wide Web

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
All over the world, users can use browsers to access information stored in multimedia document collections of web server machines. Programs are also accessible through the Common Gateway Interface (CGI).
HTML version of Scripted Foils prepared 5 July 97

Foil 8 Top-level View of the Corporate Intranet

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
All over the company, employees (and possibly affiliates and the public) can use browsers to access databases and use distributed applications stored on server machines, using web technology to interface to existing databases and applications.
HTML version of Scripted Foils prepared 5 July 97

Foil 9 Basic (CPS606) Structure of World Wide Web

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Browsers have SAME interface on ALL Computers
CGI Programs are typically written in PERL but can be essentially ANY UNIX Process and so do simulation, database access (this is Oracle WoW), advanced document processing etc.
HTML version of Scripted Foils prepared 5 July 97

Foil 10 Background on the Internet

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The Internet is a loose federation of networks.
Cooperative organization - no administration, no fees. Protocols and standards are evolved through the IETF, Internet Engineering Task Force.
Most national and international networks are members: NSFNET, ESNET, ARPANET, BITNET
All these networks are packet switched systems based on TCP/IP. Together these protocols allow for communication over a wide variety of technologies. Machines called gateways connect the networks.
Standard domain name system - names are looked up by name server to obtain routing information.
  • symbolic names: npac.syr.edu
  • internet addresses: 128.230.7.2
HTML version of Scripted Foils prepared 5 July 97

Foil 11 History of the Internet

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
1969 The first locations commissioned by DOD (ARPA)
1971 # host computers = 23
1982 Standards for TCP and IP established.
1983-4 Name server and domain name server developed.
1984 #host computers > 1,000
1986 NSFNET backbone established, 56Kbps
1987 #host computers > 10,000
1989 NSFNET backbone upgraded to T1 (1.544Mbps)
  • #host computers > 100,000
1992 Internet Society is chartered, World Wide Web released by CERN
  • NSFNET backbone upgraded to T3 (44.736Mbps)
    • #host computers > 1,000,000
1993 NSF experiments with 600 Megabit backbone
  • #host computers > 2,000,000
HTML version of Scripted Foils prepared 5 July 97

Foil 12 Internet Trends - Internet Hosts 1989-1997

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 13 Internet Trends - Internet Hosts - Overall Trend

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 14 Internet Trends - Internet Domains in DNS

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 15 Internet Trends - WWW-Prefixed Hosts

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 16 Internet Trends - Hosts: Three-Letter Domains

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 17 Internet Trends - Hosts: Two-letter Domains, >120,000 per country

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
From General Magic http://www.genmagic.com/Internet/Trends/
HTML version of Scripted Foils prepared 5 July 97

Foil 18 NII Compute & Communications Capability in Year 2000 --> 2005

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Each of three components (network connections, clients, servers) has capital value of order $10 to $100 Billion
HTML version of Scripted Foils prepared 5 July 97

Foil 19 Ultimate Vision and Implementation of NII and InfoVision

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
InfoVision is ultimate "client-server" application
  • 108 clients -- each of which could be (small) servers -- in fact Web Technology will migrate to democratic "server-server" architecture
  • 104 large (~$10M) parallel servers -- each of which could have 1000 to 10000 nodes
Democracy on the NII (Gore)
  • Everybody can access information on the NII
  • Everybody has equal opportunity to put information on the NII
HTML version of Scripted Foils prepared 5 July 97

Foil 20 Internet Services: Telnet

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Telnet basically allows you to log in to a system over a network just as though you were logging in from a terminal attached to the system or from a dial-up modem.
You may use telnet from a command line such as:
    • > telnet nova.npac.syr.edu
where you give the internet name of the machine that you wish to connect to. The telnet service will proceed to ask you for a name and password just as if you were logging in.
Or you may have a telnet program which prompts you for the same information.
Between two unix systems, you can use the rlogin command instead.
Mostly, you must already have an account on the machine to log in. There are a few publicly available telnet machines, such as the FAA Flight Service at duats.gtefsd.com, where student pilots can log in to get the latest weather data.
HTML version of Scripted Foils prepared 5 July 97

Foil 21 Internet Services: FTP

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
FTP (File Transfer Protocol) is the way that people transfer files from one internet machine to another.
You can use the ftp protocol directly from Unix machines using a command line:
    • > ftp internethostmachinename
where it will prompt you for an account login name and password. You will then be connected to the home directory of that account and can use commands to move around the directory structure (cd and ls) and commands get and put to copy a file to or from your original location.
Other ftp interfaces may be provided by your telnet program, or by other software programs such as fetch.
FTP will transfer files of all types and formats. If the files are large, such as images, you may want to transfer in binary mode (the default is ascii).
Some machines may provide a special ftp account called "anonymous". You use your ftp program as usual, except that the login name is "anonymous". The password can be anything, but netiquette obliges you to give your email address. The directory that you are connected to is a public directory provided by the host machine.
HTML version of Scripted Foils prepared 5 July 97

Foil 22 Internet Services: News

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Usenet newsgroups provide discussion forums on a wide range of topics. You can read the forums from a news server installed at your site.
The topics are organized into hierarchies. Some of the main categories are
  • alt - alternative topics
  • comp - computers and computing
  • misc - miscelleneous newsgroups
  • rec - recreational topics
  • sci - science-related topics
  • soc - social and cultural topics
Subtopic names are always shown as part of the hierarchy
  • sci.chem.electrochem and comp.parallel
People participate in newsgroups by contributing messages, called "posting", which everyone else on the list can read.
Some newsgroups are moderated, which means that posted messages are scanned by a human for appropriate content and style before being made public.
Many software packages are news readers, including Netscape web browsers - just ask your systems administrator what news server to use.
HTML version of Scripted Foils prepared 5 July 97

Foil 23 Internet Services: Mail Lists

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Other discussion forums on interesting topics are provided through mail lists. The discussion is delivered through your regular email.
In this case, the discussion is again provided through messages. But instead of posting the message through special software (as is the case with news readers), the message is sent to an email address, and then forwarded to everyone in the group.
Mail list addresses
  • Posting address listname@host
    • post messages by sending them to this email address
  • Adminstrative address listname-request@host
    • use this email address to subscribe and unsubscribe to a list.
  • List owner listname-owner@host
Mail lists may also be moderated.
HTML version of Scripted Foils prepared 5 July 97

Foil 24 Web Content is Hyperlinked Multimedia

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The World Wide Web is a collection of documents located all over the world, and which can have links to images, motion videos and audio files.
Links use Web addresses called URL's (Uniform Resource Locators) which have the form
  • http://www.place.org:8888/mydirectory/mydoc.html
where
  • http is the hyperlink web service
  • www.place.org is the internet name of the web server
  • 8888 is the optional port number
  • /mydirectory/ is the directory or folder path to the document within the web server document space
  • mydoc.html is the document to be retrieved (with an html file extension)
Types of files follow the standard MIME (Multipurpose Internet Mail Extensions) originally developed to include multimedia and multi-part content with electronic mail messages.
File extensions on the server tell which MIME format the file is in.
The browser is configured to have a set of helper applications or "plug-ins" to appropriately display or play files in various MIME formats.
HTML version of Scripted Foils prepared 5 July 97

Foil 25 Web Links can go to other Internet Services

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Web servers provide what is called HTTP service (for HyperText Transfer Protocol), but links can also direct connections to other Internet services.
For other services, the Web server transfers the connection to the appropriate server.
HTML version of Scripted Foils prepared 5 July 97

Foil 26 Multimedia types

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Image types:
  • GIF - Color image format where each pixel is represented from 1-8 bits. Compressed to a very compact size for images with not many colors.
  • JPEG - Color image format where each pixel represented by 24 bits, giving so-called "true color". Also compressed for reasonable sizes of images with high-resolution, photographic quality.
  • PNG - new portable networks graphics format designed for web
Audio types:
  • Basic audio types are au and snd, supported by most audio players. The entire audio file is downloaded before it is played.
  • RealAudio - ram - a format which allows the plug-in to play the audio file as it is downloaded.
Video types:
  • Quicktime - Apple video format supports synchronized audio and video and has compression schemes.
  • MPEG - is most videly used but is not synchronized. Compression scheme records differences between frames.
  • Motion JPEG
HTML version of Scripted Foils prepared 5 July 97

Foil 27 Forms and CGI Scripting

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Forms are used to allow the user to send information from the browser back to the server.
The server must provide a program, called a CGI script, that will process the user information and provide an appropriate response.
  • The information from the form is encoded in a message according to the Common Gateway Protocol and sent to the web server, along with the URL of the CGI script.
  • The server executes the CGI script, passing the encoded information.
HTML version of Scripted Foils prepared 5 July 97

Foil 28 The CGI script returns data through the server

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The CGI program parses the input from the server and performs any number of computing and data access functions:
  • looking up information in files on the server or in server databases.
  • performing computions or communicating with other machines.
  • returning already prepared documents or other multimedia files.
  • returning a document prepared "on-the-fly"
When the CGI program terminates, the server closes the connection.
HTML version of Scripted Foils prepared 5 July 97

Foil 29 Web Search Engines

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Search Engines enable users to look up text documents stored on the Web, usually by one or more keywords appearing in the document.
Information gathering and filtering
  • This is done by web "robots" - programs which automatically connect to all servers and search some number of documents - usually up to a certain "depth" of links, such as 4.
  • For each document, the robot returns keywords and other information to the search index. For example, Lycos returns: the title, any headings and subheadings, the 100 most"weighty" words, the first 20 lines, the size in bytes, and the number of words.
  • Problems with information gathering:
    • Information update
    • Information resulting from CGI scripts is not available.
    • Resource intensive: robots repeatedly connect to a site, informal protocols try to prevent "rapid fire" or "robot attack"
    • Preventing robot loops when links are circular.
HTML version of Scripted Foils prepared 5 July 97

Foil 30 Web Search Indexes

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Indexing: the information gathered by the robots is organized into an indexing database at the search server.
  • Primarily keyword indexing is currently used - some full text searching is just on single site search engines.
  • Key issue is size of resulting database.
Searching: the indexing database allows (keyword) searches by the user.
  • Queries are formed, some number of most highly ranked results are returned.
User Interface
  • uniform interface for HTTP, FTP, GOPHER, WAIS, Harvest, Lycos
Challenge of WWW search:
  • estimated total size is 30 Gigabytes, 5 million documents (many search engines now take months to crawl the web to update index files.)
  • diversity - huge distributed database, unstructured, non-relational, hierarchical information with many formats.
HTML version of Scripted Foils prepared 5 July 97

Foil 31 The Current Web Client Server Model

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
There are evolving/confusing/overlapping capabilities ...
HTML version of Scripted Foils prepared 5 July 97

Foil 32 Databases

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Many useful Web applications provide a web page interface to a commercial product database of information.
This is currently done through CGI scripting.
The database must have a programmable interface (in addition to an interactive interface). For relational databases, this has been standardized in the query language SQL.
Web queries to the database are taken from an HTML form, the information is passed to the CGI script, which makes appropriate SQL queries to the database. The results of the database query can be formatted and returned to the web page.
HTML version of Scripted Foils prepared 5 July 97

Foil 33 JavaScript

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Developed by Netscape from HTML scripting language LiveScript, and including some features of Java, that allows HTML authors to have more control over the behavior of the browser.
JavaScript is text embedded in an HTML document using the <SCRIPT> tags, which a JavaScript browser will interpret (and other browsers ignore).
JavaScript can perform animations, respond to buttons and other forms of user input, and allow the author more control over the appearance of the Web Page.
JavaScript can also provide an object-oriented view of other browser plug-in programs.
Reference: JavaScript Authoring Guide at http://home.netscape.com/eng/mozilla/Gold/handbook/javascript/
HTML version of Scripted Foils prepared 5 July 97

Foil 34 Java

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Java is a general-purpose object-oriented language developed by Sun with the capability of providing distributed computing through the Web (http://www.javasoft.com).
Browsers (HotJava, Netscape 2.0/3.0 ..) supporting Java allow arbitrarily sophisticated dynamic multimedia applications inserts called Applets, written in Java, to be embedded in the regular HTML pages and activated on each exposure of a given page.
HTML version of Scripted Foils prepared 5 July 97

Foil 35 Future Web Technologies: VRML

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
VRML is a computer graphics language for describing 3-Dimensional scenes. It was developed as a standard for the WWW from OpenInventor of SGI.
VRML includes language elements for creating simple shapes, various lighting effects, applying textures to shapes, and various points of view (referred to as cameras).
A VRML enabled browser will recogize VRML files of the form file.wrl, and create an interface where the user has controls to fly through space and examine objects.
Objects within a VRML scene may be configured as URL links to other Web pages of any document type.
VRML documents are huge - most serious current drawback to using VRML more widely on the Web is the slow download time.
New versions of VRML include motion in the scenes.
HTML version of Scripted Foils prepared 5 July 97

Foil 36 Open Universal WebWindows --
A Revolution in the Software Industry!

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
In future one will NOT write software for either
  • Windows95/NT, UNIX, Digital VMS, IBM VM etc.
Rather one will write software for WebWindows defined as the operating environment for World Wide Web
WebWindows builds on top of Web Servers and Web Client open interfaces as in
  • CGI interface for Servers
  • Java or equivalent applet technology for clients
Applications written for WebWindows will be portable to all computers running Web Servers or Clients which hide hardware and native O/S specifics
HTML version of Scripted Foils prepared 5 July 97

Foil 37 The WebWindows Operating System

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
WebWindows Interface
HTML version of Scripted Foils prepared 5 July 97

Foil 38 Examples and Why WebWindows will Dominate Software Industry?

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Further WebWindows Software will be modular and allow plug and play insertion of capabilities developed around the Web World -- not a bunch of isolated stovepipe solutions
  • WebWindows leverages not only universal hardware but also all the world's creative energy
As an example some of Current Netscape and last year(!) NPAC's WebTools implements UNIX shell/PC file manager capabilities in terms CGI scripts -- allows universal access to these capabilities including powerful Web based (mh) mail
NPAC's WebFoil is HotJava/Netscape 1,2,3 Open replacement for Powerpoint/Persuasion
Particular Application areas (Business, Healthcare, Education) will be built on top of generic NII services so that for instance
  • Healthcare video delivery builds on technology developed for CNN etc.
HTML version of Scripted Foils prepared 5 July 97

Foil 39 Illustration of WebWindows Concept for Presentation Software

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Persuasion and Powerpoint are rather similar monolithic packages which can for instance only be clumsily ported to UNIX as cannot access internal data-structures defining foils
WebFoil (NPAC prototype WebWindows presentation package) has
Extended open HTML source manipulated by powerful PERL5 scripts allowing global changes and linkages of foils from many sources
  • This plays role of outline which is a somewhat crippled open version of Persuasion/Powerpoint foils defining text alone
Backend Oracle database illustrating modular WebWindows approach
Using Appropriate templates WebFoil Uses Hotjava or Netscape 1,2 or 3 to display HTML with full Web Power including applets to enable Multimedia and dynamic presentations
HTML version of Scripted Foils prepared 5 July 97

Foil 40 RCIHalloween Presentation Foil on WebFoil in WebFoil!!

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Initial webfoil 0.1 release Halloween 1995
HTML version of Scripted Foils prepared 5 July 97

Foil 41 JavaScript Based WebFoil Prototype

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Rome Laboratory Collaborative and Interactive Visualization Jan 31,96
HTML version of Scripted Foils prepared 5 July 97

Foil 42 Lessons of WebFoil for WebWindows Software Development Scenario

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The WebTop Productivity environment will be built in a more modular fashion than current PC Windows or Macintosh arena
  • e.g. future WebWindows presentation, word processor etc. packages will be built from many different modules coming from different commercial or public domain sources
Java or equivalent future technology is key to understanding how WebWindows application/service software will look as it allows balanced client server applications to be built
Note require an open display software so can produce appropriate customized interfaces for browsing, presenting, word processing etc.
HTML version of Scripted Foils prepared 5 July 97

Foil 43 The Current Web Client Server Model

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
There are evolving/confusing/overlapping capabilities ...
HTML version of Scripted Foils prepared 5 July 97

Foil 44 Architecture of Web Software

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Application Specific NII Specific Services for
  • Education
  • HealthCare
  • Commerce
  • Manufacturing etc.
HTML version of Scripted Foils prepared 5 July 97

Foil 45 General Web Architecture

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
We have a set of Services hosted by Web Servers and accessed by clients
Groups of clients (electronic societies) are linked by collaboration systems such as TANGO
Access
Resources
Store
Multimedia Information
TANGO Server
File Systems
and/or Database
Object Broker
Database
Simulation
Computer
Person2
Shared
WhiteBoard
Shared Client Appl
Person1
General User
HTML version of Scripted Foils prepared 5 July 97

Foil 46 Networking Basics

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The first section of this talk covers basic networking terminology, the OSI networking layers, the TCP/IP protocol, and routing.
HTML version of Scripted Foils prepared 5 July 97

Foil 47 Networking Basic Definitions

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
A computer network is a communication system for connecting end-systems usually called hosts.
A local area network, LAN, connects computer systems within a few kilometers, usually within a single building. A common technology is Ethernet, which operates at 10Mbps (million bits per second). Computers or workstations connect to the LAN via an interface card.
A wide area network, WAN, connects computers in different cities or countries. A common technology is leased telephone lines operating between 9600 bps and 1.544 Mbps.
Computers in a network use a set of protocols to communicate.
HTML version of Scripted Foils prepared 5 July 97

Foil 48 Networking Standards: OSI Layers

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Network communication protocols are usually described via a set of layering conventions from the International Standards Organization (ISO) known as the Open Systems Interconnection (OSI) Model.
HTML version of Scripted Foils prepared 5 July 97

Foil 49 Simplified communication protocol model

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
We simplify the model to the four lowest software layers - user applications use the process layer and the remaining three are usually included in the operating system, such as Unix, which has an OSI stack to process messages through the layers.
HTML version of Scripted Foils prepared 5 July 97

Foil 50 The TCP/IP protocol suite

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
TCP - Transmission Control Protocol. A connection-oriented protocol used by most Internet applications to provide a reliable, full-duplex, byte stream for a user process.
UDP - User Datagram Protocol. A connectionless protocol for user processes. Also not reliable.
ICMP - Internet Control Message Protocol. Handles error and control information between gateways and hosts.
IP - Internet Protocol. Provides the packet delivery service for the upper layers.
ARP - Address Resolution Protocol. Maps an Internet address into a hardware address.
RARP - Reverse Address Resolution Protocol.
HTML version of Scripted Foils prepared 5 July 97

Foil 51 Typical message formats

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Each layer adds control information to the message - this process is called encapsulation.
HTML version of Scripted Foils prepared 5 July 97

Foil 52 Networking

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The Internet is a packet-switched network. Each message (or document) is broken up into a number of packets. Each packet has an address. A computer called a router sits on the local network and decides where to send it first on its way to its final address. Each computer along the network connection examines messages that come in and either keeps it or reroutes it along its way. The message is reassembled on the other end.
HTML version of Scripted Foils prepared 5 July 97

Foil 53 Communications Issues

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Multiplexing - Different protocols can be used to send different messages through the same network.
Fragmentation and reassembly - Most networks have a maximum packet size. In the TCP/IP protocols, the IP layer breaks up two long packets into a sequence of shorter frames, which are reassembled on the other side.
Sequencing is the property that data is received by the receiver in the same order as transmitted by the sender, which is not true in a packet-switched network.
Error control guarantees that error-free data is received by the application programs. Data can either get corrupted by the transmission medium or get lost. Checksums are added to the data and received data is acknowledged. If there is any problem, retransmission occurs.
Flow control assures that the sender doesn't overwhelm the receiver by sending data at a faster rate than it can process.
Error and flow control are handled on an end-to-end basis by TCP and on a hop-by-hop basis by IP. (A hop goes to only one intermediate machine on the network route.)
HTML version of Scripted Foils prepared 5 July 97

Foil 54 Networking Speeds

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Performance of network delivery depends on the size of the message, the capacity of the various pieces of network that the message may travel along and the congestion of the network.
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Foil 55 Open Standards

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
All the network protocols just discussed are agreed on by various standards committees. The principal standards organization of the Internet is the Internet Engineering Task Force (IETF). The principal standards organization of the WWW is the World Wide Web Consortium (W3C).
HTML version of Scripted Foils prepared 5 July 97

Foil 56 Internet Documents: Drafts, Memos and Standards

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Some material presented here comes from Internet documents. Here is a summary of various document formats you may find.
Internet Drafts
  • Working documents of the (IETF), its Area and Working Groups.
  • Other groups may also distribute Internet Drafts.
  • Some of these IDs are labelled by IETF-#.
  • IDs are valid for a maximum of 6 months and may be updated, replaced or obsoleted by other documents at any time.
Internet Memos
  • Referred to as RFC-# (Request for Comments)
  • More formal and complete than Internet Drafts, usually represent standard proposals/candidates.
  • Some RFCs become obsolete by subsequent RFCs, some others make it as standards
Internet Standards
  • Labelled by STD-# and often associated with the RFC-# specs (e.g. Internet E-Mail is referred to as FRC-822 or STD-11)
HTML version of Scripted Foils prepared 5 July 97

Foil 57 Internet Documents - Examples

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Here are a few sample Internet documents relevant for Internet and WWW message-passing.
RFC-822: Crocker, D., "Standard for the Format of ARPA Internet Text Messages", SRD 11, RFC 822, UDEL, 1982.
RFC-1036: R. Horton and R. Adams, "Standard for Interchange of USENET Messages", RFC 850, AT&T, December 1987.
RFC-1521: Borenstein, N. and Freed, N., "MIME (Multipurpose Internet Mail Extension) Part One: Mechanisms for Specifying and Describing the Format of Internet Message Bodies", RFC 1521, Bellcore, September 1993.
RFC-1524: Borenstein, N. "A User Agent Configuration Mechanism for Multimedia Mail Format Information", RFC 1524, Bellcore, September 1993.
Internet Draft: Tim Berners-Lee, "Basic HTTP", CERN, 1992/3.
HTML version of Scripted Foils prepared 5 July 97

Foil 58 Message-passing Protocols

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
HTML version of Scripted Foils prepared 5 July 97

Foil 59 Internet E-Mail (RFC-822)

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
We all know and use it, but here is a formal specification.
Each message is a stream of 7-bit ASCII chars which contains a header and optional (newline separated) body.
Header consists of a set of entries with one entry per line given by a colon separated key:value pair.
Key contains no spaces or tabs and cannot exceed 63 chars.
Body is a fully unstructured sequence of ASCII chars.
There is a finite set of standard keys and an extension mechanism via the "X"-prefix. The standard set (as used by MH) is:
Date Bcc Resent-Date Resent-Fcc
From Fcc Resent-From resent-
Sender Message-ID Resent-To Message-Id
To Subject Resent-cc Forwarded
cc In-Reply-To Resent-Bcc Replied
HTML version of Scripted Foils prepared 5 July 97

Foil 60 Multi-purpose Internet Mail Extension (MIME)

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Goals
  • Multimedia, multi-language, multi-component extension of RFC-822
  • Full backward compatibility with RFC-822
  • Open design to incorporate multiple well-known formats
  • Easy extension to new types and formats
Retain RFC-822 header+body format
Add new header fields
Allow for multipart multimedia bodies
Include media type and encoding information in new header fields such as: Content-Type, Content-Description, Content-Transfer-Encoding, Content-ID
Retain 7-bit ASCII for all valid encoding schemes
Implement multi-component bodies via a special 'magic type' Content-Type: multipart
HTML version of Scripted Foils prepared 5 July 97

Foil 61 MIME - "Content-Type" Header Field

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Two level hierarchical typing scheme adopted of the form: basetype/subtype
Seven base media types are defined this minimal set is enforced, i.e. all extensions must pass the whole ID->RFC->STD process.
Allow for less restrictive subtyping the base types, for example:
  • Content-Type: text/plain
  • Content-Type: text/richtext
Some standard subtypes are specified and many more are expected. New subtypes must be registered with the IANA (Internet Assigned Numbers Authority).
Private experimental subtypes prefixed with "X-" may be used freely and without registration.
Seven base types are: text, image, audio, video, multipart, message, application.
HTML version of Scripted Foils prepared 5 July 97

Foil 62 MIME - Base Content Types

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
text
  • subtypes: plain (just ASCII) and richtext (a simple markup extension including <bold>, <italic> etc. tags)
  • character sets can be further specified in the header value field as follows:
    • Content-type: text/plain; charset=us-ascii
  • Other charsets can be used to support other languages such as iso-8859-1 (French) or iso-2022-JP (Japanese). These charsets need to be encoded in one of two encoding modes: base64 or quoted-printable. The latter retains ASCII subset and is more natural for non-ASCII extensions.
image
  • Standard subtypes: gif, jpeg. Others expected.
  • base64 is a natural encoding scheme for binary media - it packs three 8-bit chars into four 7-bit chars.
audio
  • Standard subtype: single-channel 8KHz u-law. Others expected.
video
  • Standard subtype: mpeg. Others plausible.
HTML version of Scripted Foils prepared 5 July 97

Foil 63 MIME - Base Content Types, continued

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
multipart
  • Specifies a MIME message composed of several parts with possible different Content-Type fields.
  • Parts are separated by a boundary string, specified in the multipart header entry
  • Subtypes: mixed (serial combination of media), parallel (for parallel presentation if possible), alternative (multiple representations of the same data) and digest (all parts are messages)
message
  • Subtypes: rfc822 (standard ARPA e-mail format), partial (a single chunk of a larger message, chopped into pieces for transmission and then reassembled), external-body (pointer to a remote data - similar to typerlink/URL but different representation)
application
  • Current subtypes: postscript, ODA
  • Placeholder for "anything else" - several interactive/custom/creative extensions expected here
  • Already registered: Andrew-inset,t ATOMICMAIL (Bellcore)
HTML version of Scripted Foils prepared 5 July 97

Foil 64 Web Services - HTTP Protocol

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
HTML version of Scripted Foils prepared 5 July 97

Foil 65 Applications based on information services typically use a Client/Server Architecture

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Server: A program in charge of a resource or information.
  • Operation is defined by list of services.
  • Normal mode is to listen for requests, stopping to fulfill a request when it arrives.
Client: Any program that makes a request for service from the server.
HTML version of Scripted Foils prepared 5 July 97

Foil 66 The World Wide Web is a collection of clients and servers called browsers and Web sites

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
Web servers provide access to a collection of files containing hyperlinked information
  • primary service is to send text files, images, digitized video
  • can also provide customized services through the form/CGI script interface
Browsers provide an easy graphical interface for users to request information. The client machine also provides viewers for a standard set of image and video formats.
The interface is kept very simple to run on all networks and most machines.
HTML version of Scripted Foils prepared 5 July 97

Foil 67 HTTP - Hypertext Transport Protocol

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
HTTP provides an upper level to the Internet, that is, it is built on top of a back-bone network with all the packets flowing from client to server and vice versa using the standard TCP/IP protocol.
It uses MIME formats and concepts, but does not fully conform to MIME as the WWW is not a mail system.
HTTP protocol is compatible with other network services such as FTP (File Transfer Protocol), NNTP (Network News Transport Protocol).
  • On a UNIX-based machine, the basic services are enumerated in the file /etc/services. Each service cooresponds to a standard port. For example, telnet is mapped to port 43, and FTP is mapped to port 21. All ports below 1024 are privileged - only the system administrator can determine port use.
The HTTP service is standardly assigned to port 80 - it provides a much shorter service connection than the other services.
HTML version of Scripted Foils prepared 5 July 97

Foil 68 HTTPD - HTTP Daemon

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
The HTTP daemon is the server which responds to the Internet service requests on standard port 80 (or on another custom port). The server program is available from NCSA and is easily installed by editing a set of configuration files which give directory locations for documents, cgi scripts, error messages and icons, and which allows for options regarding path names, domain access, and so on.
HTML version of Scripted Foils prepared 5 July 97

Foil 69 URL - Uniform Resource Locator

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
A URL has the standard form
  • service://machine:port/file.file-extension
HTML hyperlinks typically use the service http for linking to other documents and media files. Some other internet services can also be used such as
  • ftp://machine/file.file-extension.
In this way, a Web server can provide other Internet services through the browser interface.
The machine is an Internet address and can either be a symbolic name provided by the Domain Name Service (DNS) or the IP numbers.
If the port is not specified, it defaults to 80.
The file.file-extension is given by any Unix path name starting from the directory known to the server as "document root". Which path names are valid is one of the options of the server - whether "public_html" is automatically put into the path name and whether paths starting with "~username" are allowed.
In the http service, the file-extension is used to tell the browser what helper application to use to view the file. Typical file extensions are html, gif, jpeg, mpeg, au, ram, etc.
HTML version of Scripted Foils prepared 5 July 97

Foil 70 Web Links can go to other Internet Services

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
For other services, the Web server transfers the connection to the appropriate server.
HTML version of Scripted Foils prepared 5 July 97

Foil 71 HTTP - How does it work?

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
On each hyperlink click, the browser (client) initiates a connection with the server at the "machine" (e.g. using UNIX BSD connect call on the default port 80, or a custom user-defined port)
A request is sent to the server, formatted as a MIME-like message.
The server replies with another MIME-like message which is received by the browser and either formatted in the browser window or viewed with a helper application.
The connection is closed on both sides. (The exception to this is the "server push" connection.)
HTML version of Scripted Foils prepared 5 July 97

Foil 72 HTTP - GET Request Example

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
GET /document.html HTTP/1.0
Accept: www/source
Accept: text/html
Accept: image/gif
User-Agent: Lynx/2.2 libww/2.14
From: mnotulli@ukonaix.cc.ukans.edu
  • -- blank-line-terminating-the-request --
First line syntax is always: METHOD URL ProtocolVersion
The following lines form a header of an (extended) MIME message
"User-Agent" specifies the browser type
"Accept" specifies MIME types recognized by the browser
The server is expected to provide the requested data in one of these acceptable formats.
HTML version of Scripted Foils prepared 5 July 97

Foil 73 HTTP - Reply Example

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
HTTP/1.0 200 OK
Date: Wednesday, 02-Feb-95 23:04:12 GMT
Server: NCSA/1.1
MIME-version: 1.0
Last-modified: Monday, 15-Nov-94 23:33:16 GMT
Content-type: text/html
Content-length: 2345 --
  • -- blank-line-separating-header-and-body--
<HTML><HEAD>
<TITLE> Document Title </TITLE>
. . .
This message contains both header and body
Some replies contain only header (e.g. error reports, such as HTTP/1.0 404 Not Found)
GET request also contained header only, whereas POST request (see next example) contains both header and body
HTML version of Scripted Foils prepared 5 July 97

Foil 74 HTTP - POST Request Example

From Overview of Basic Web and Internet Technologies Beijing Web Tutorial -- May 27-30 1997. *
Full HTML Index
POST /cgi-bin/post-query HTTP/1.0
Accept: www/source
Accept: text/html
Accept: video/mpeg
Accept: image/x-rgb
Accept: application/postscript
User-Agent: Lynx/2.2 libwww/2.14
From: grobe@unanaix.cc.ukans.edu
Content-type: application/x-www-form-urlencoded
Content-length: 150
  • --blank-line-separating-header-and-body---
org=Academic%20Computing%20Services
&users=10000
&browser=lynx
&contact=Michael%20Grobe%20grobe@kuhbuh.cc.ukans.edu
Both header and body present in POST requests - the body is typically used to pass a form contents to the server.
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