This document discusses resource sharing and the World Wide Web. It defines resource sharing as accessing resources like hardware, data, and services across multiple administrative domains. It describes the client-server model and how clients make remote requests of servers. The document then discusses the key components that enable the World Wide Web - HTML for content and layout, URLs for identifying resources, and HTTP for client-server interactions. It explains how browsers retrieve and interpret HTML files from web servers using URLs and HTTP. The document concludes by noting some challenges of the distributed nature of the web, like heterogeneity, transparency, and security.

1. Lecture No.2
Resource sharing and Web
Dr.M.Gokuldhev
AP/CSE

2.  Resource sharing means the existing resources in a computing system can
be accessed or remotely accessed across multiple administrative domains.
RESOURCE SHARING is the primary motivation of distributed computing.
Resources types
 Hardware, e.g. printer, scanner, camera
 Data, e.g. file, database, web page
 More specific functionality, e.g. search engine, file
Service
manage a collection of related resources and present their
functionalities to users and applications
Resource sharing

3.  Server
A Component on networked computer that accepts requests from
processes on other computers to perform a service and responds
appropriately.
 Client
the requesting process
 Remote invocation
A complete interaction between client and server, from the point
when the client sends its request to when it receives the server’s response
Resource sharing (cont.)

4. Typical OSI Layer

5.  Shared file and printer access require an operating system on the client.
 The OS supports access to resources on a server using Application layer
protocol and Transport Layer Protocol.
 Modern operating systems for personal computers include distributed file
systems that support file sharing,
Common file systems and protocols
Primary operating system Application protocol Transport protocol
Mac OS SMB, Apple Filing Protocol
•TCP,
•UDP
Unix-like systems
Network File
System (NFS), SMB
•TCP or
•UDP
MS-DOS, Windows
SMB (Server Message
block)
•TCP,
•NBT (includes UDP),
•NBF, or
•other NetBIOS transports
Novell NetWare (server)
MS-DOS, Windows (client)
•NCP (Network Control
Protocol)
•SAP (Service Access
Point)
•Sequenced Packet
Exchange SPX (over IPX),
or
•TCP

6.  The World Wide Web (WWW), commonly known as the Web, is
an information system where documents and other web resources are
identified by Uniform Resource Locators (URLs, such
as https://example.com/), which may be interlinked by hyperlinks, and are
accessible over the Internet.
Motivation of WWW:
 Documents sharing
 Web is an open system: it can be extended and implemented in new ways
without disturbing its existing functionality.
 Its operation is based on communication standards and document standards
 Respect to the types of ‘resource’ that can be published and shared on it.
World wide Web (WWW)

7. * HyperText Markup Language
- A language for specifying the content and layout of pages
* Uniform Resource Locators
- Identify documents and other resources
* A client-server architecture with HTTP
- By with browsers and other clients fetch documents and other resources
from web servers
Components of WWW

8. HTML
- HTML text is stored in a file of a web server.
- A browser retrieves the contents of this file
from a web server.
-The browser interprets the HTML text
-The server can infer the content type from
the filename extension.
URL
 HTTP URLs are the most widely used
 An HTTP URL has two main jobs to do:
- To identify which web server maintains the
resource
- To identify which of the resources at that server
Components of WWW(Cont.)

10. HTTP
Defines the ways in which browsers and any other types of
client interact with web servers
Main features:
Request-replay interaction
Simple access control
Dynamic content

11.  Heterogeneity: It enables users to approach and run the
application over a heterogeneous collection of computers and networks.
 Transparency: It is understood as the protection from the user as well
as the 'application programmer' of separation of the component in the
distributed system. Location, Migration, Access, relocation, concurrency,
Failure, Replication, persistence are some terms of transparency in the
distributed system.
 Security: Integrity, Confidentiality, and availability are three
components of security.
web challenge in the distributed
system

12. Queries??