WWW and Complete Internet
Connectivity

LESSON 2

• Permanent Direct Connections:
  • Require dedicated high-speed lines (T1/E1, expensive).
• On-Demand Direct Connections:
  • Use a modem and a variant of TCP/IP designed for analog phone lines.
  • Commonly SLIP(Serial Line Internet Protocol) or PPP (Point to Point Protocol) lines are used with a local TCP/IP stack (Trumpet Winsock).
• Dial-Up Terminal Connections:
  • Link up to an Internet Service Provider (ISP) as if you were a terminal on the service provider's computer.
  • The most popular are:
    America On-line, Prodigy, and CompuServe.
• Mail-Only Connections:
  • Enable you only to send and receive e-mail. Most major on-line services (CompuServe, etc.) formerly only supplied e-mail. Few exist since they cannot compete with new ISPs.

Connection Components needed for PC environments:
TCP/IP Stack

• Winsock.dll
  • A library of MS-Windows routines that implement many protocols of the TCP/IP protocol stack for use on a personal computer.
• The WinSock specification, now in version 2.0 can support TCP/IP service over many types of hardware.

Packages which implement WinSock support

• Trumpet WinSock -

  Peter Tattam's shareware product from Australia.

• Chameleon -

  NetManage's TCP/IP stack which also comes with many WinSock applications.

• Win32 Libraries -

  built directly into the MS-Windows 95 and Windows NT operating systems.

• OS/2 WARP -

  IBM's windowed operating system supports the same WinSock standard and includes WinSock applications as well.

Connection Components needed for PC environments:
Network Lines

• LAN connection:
  • Via an Ethernet or Token-Ring card.
• Modem or ISDN line:
  • Hardware supported SLIP/PPP connection
  • Software-emulated SLIP/PPP connection.

Direct SLIP/PPP lines:
Connectivity Software

• Connectivity Software -

  many of the WinSock compliant connectivity applications support:

  • SLIP - Serial Line Internet Protocol
  • PPP - Point-to-Point Protocol
  • CSLIP - Compressed SLIP
• SLIP/PPP connectivity is usually provided by Internet Service Providers as a dial-in line.
• SLIP/PPP connectivity can also be emulated by software, but with a reduction in performance.

Direct SLIP/PPP lines:
Internet Service Providers

Internet Service Providers -

companies or universities which provide direct access to the Internet and it's services.

• Rutgers University currently provides hardware support for SLIP/PPP.
• Currently SLIP/PPP support at NJIT can only be achieved through emulation software.

Requirements for Emulated SLIP/PPP

The Internet Adapter (TIA)

• Provides SLIP emulation in the user account.
• Port Redirection and PPP are available newer versions.
• Widely used by Internet Service Providers.
• Very stable commercial product with support.

Slirp

• SLIP/CSLIP/PPP emulation with port redirection.
• Freeware with source code.
• Load balancing when using multiple SLIP connections
• Currently in beta version
• You need to retrieve source code for remote shell account and compile it.

TwinSock

• Freeware with source code.
• Does not require a clean 8-bit line
• Includes WinSock and dial-up application (tshost) in one package.
• Does not function with every WinSock application.
• Slow in 6-bit mode

TERM

• UNIX to UNIX connectivity
• Remote end runs in user account
• Applications should be term-aware or they should be termified
• TERM can be used on your PC via the Linux operating system.

Requirements for Emulated SLIP/PPP:
Performance and Features

• Functionality -

  the emulation program must be started prior to Internet connectivity.

• Throughput -

  less than hardware supported SLIP/PPP, but still good.

• Reliability -

  TIA seems to be most reliable, however they all crash from time to time.

• Port Redirection -

  the ability to redirect protocol messages. This allows the user to run their own servers and clients from the same PC.

Connection Components needed for PC environments:
Connection Hardware

• Modems:
  • Use analog phone lines and convert digital signals from computers to analog signals (and vice-versa).
  • 14,400 bps
  • 28,800 bps
• Most modems use compression techniques to increase throughput (V.34, V.34bis).

• ISDN -

  Integrated Services Digital Network (Narrowband) provides an alternative to modems by using a digital line.

• Basic Rate Interconnection

  Service (BRI) provides two 64kbps data channels (B) and a single signaling channel (D)

• Currently compression techniques are not used over ISDN data channels and those channels can be utilized in 1B or 2B combinations.

Connection Hardware
Cost and Availability

• Modems are inexpensive and are widely available.
• ISDN services cost more and are rapidly becoming available throughout the U.S.
• ISDN services or other future connections technologies will soon replace modems.

Review of Main Connection Components needed.

• TCP/IP Protocol Stack:
• WinSock
• Network Lines:
  • Connectivity Software
  • Shell account or SLIP/PPP dial-up line from a Internet Service Provider.
• Connection Hardware:
  • Analog / Digital Network Connection

Getting the software components needed for connectivity

• Connect to a popular software site on the Internet.
  • wuarchive.wustl.edu
  • ftp.cdrom.com
• Use FTP to download software.
• Uncompress the software and install.
• Register your shareware or pay software costs (if apply).

Dial-up access to NJIT

• Using your connecting software dial:
  • 201-596-3500
  • 201-596-2927
  • 201-623-5771
• Connect to the appropriate server:
  >connect hertz
  
• Login into your account:
  >login:___________
  >Password:_______
  
• Start your SLIP/PPP emulator program.

• When connecting to Rutgers:
  • Dial the appropriate numbers
  • Type: slip default
  • Set your local IP address to the one provided.

Configuring your network connection:
Trumpet connection to NJIT

Web Servers, Browsers and Other Applications:

• Many web browsers & servers exist. Most commonly know are web browsers (web clients) which interact with web servers using the Hyper Text Transport Protocol (HTTP). Servers interact using the HTTPD (daemon process).
• Web Browsers (Clients) - are used to access the WWW and can be graphical or text-based.
• Web Servers - can be run on remote or local machines that have access to the Internet.

Web Client:
Netscape Navigator

• Netscape - is the de-facto standard browser on the Internet today.
• Netscape users account for approximately 70% of all web users.
• Netscape supports the absolute latest proposed HTML specifications including:
  • Tables
  • Advanced Forms
  • Object Linking and Embedding (OLE)

Web Client:
Enhanced Mosaic

• NCSA's Mosaic browser - was the first of its type, and in combination with Netscape, accounts for 90% of the browsers used by WWW users.
• Enhanced Mosaic supports many advanced HTML features including:
  • Tables
  • Forms
  • Common Client Interface (CCI) - which allows the client to control other local applications through the browser itself.

Web Client:
Hot Java (Java Language)

• Hot Java is an advanced interactive web browser that was created by Sun Microsystems.
• The Java browser can access HTML documents as well as interactive programs called applets written in the Java language.
• Java applets are read and executed locally by the client to produce interactive media features in the browser, including:
  • Animation, In-page Video, Sounds, etc.

Web Client:
Web Space (VRML)

• Webspace is a WWW browser produced by Silicon Graphics Inc. and TGV that supports the Virtual Reality Modeling Language (VRML).
• The VRML mark-up language provides a way to represent 3-D images and environments on the WWW.
• Webspace is one of many VRML browsers that is currently available on the Internet.

Various Winsock Applications

• Many applications are available as shareware that implement popular network features and functions, including:

Hyper-Text Markup Language and Transport Protocol

• Hyper-Text -

  text documents written to allow hyper-linking (jumping) to other material. All web documents are commonly referred to as hyper-text, even if they include other data types.

• Hypermedia documents -

  are a true definition of web documents. They may contain many types of data and may be traversed in a non-linear fashion via links from one place in a document to another or between separate document files.

• HTML (Hyper-Text Markup Language) -

  Allows users to create their own hypermedia documents using standardized mark-up tags. Currently, the HTML specification is entering version 3.0

• HTTP (Hyper-Text Transport Protocol) -

  born at CERN in Geneva, HTTP is a lightweight protocol that can support simple, stateless connections between web browsers and servers through a hyper-text interface.

• URL (Universal Resource Locator) -

  is an Internet address of a specific file located on an Internet accessible computer.

Illustration of HTTP in action

• Click on a hyper-link:
  • The web client establishes a TCP/IP connection to that location (URL) and retrieves the file/document.
• Request for document:
  • GET/index.html HTTP/1.0
  • Accept: text/plain
  • Accept: text/html
• Response - Web server retrieves the document and sends it to the client along with information on the document.
  • HTTP/1.0 200 OK
  • Date: 09/08/95
  • Server: NCSA/1.4
  • Location: URL
  • Content-type: text/html

Layout of an HTML document

<HTML>
<HEAD>

. . . . . . . . <META> <TITLE>

</HEAD>
<BODY>

. . . . . . . . Body tags

</BODY>
</HTML>

HTML Body Tags:

• <H1> Large Header </H1>...<H6>
• <P>, <HR>
• <B>, <I>
• <UL>, <OL>
• <A HREF=" "> Hyper-text </A>
• <TABLE>, <FORM>
• Attributes:
  • Align, Alt, Width, Height, Input, etc.

WWW Home-Pages

• What are home-pages?
  • Personalized HTML documents which reflect a little about yourself (index.html)
• Components of a typical home-page:
  • Text and images.
  • Background patterns and colors.
  • Bulleted or numbered items.
  • Contact information and hyper-mail links.