Computer Networks PCCST501 Semester 5 KTU CS 2024 Scheme - Dr Binu V P

  Detailed Comparison of TCP/IP and OSI Model Introduction The two most important networking models are: OSI Model TCP/IP Protocol Suite Both models use layered architecture to describe network communication, but they differ in: Design Number of layers Purpose Protocol implementation The OSI model is mainly a reference model , while TCP/IP is the practical protocol suite used in the Internet . Basic Overview Feature OSI Model TCP/IP Model Developed By         ISO           DARPA/DoD Full Form      Open Systems Interconnection           Control Protocol / Internet                                 Type      Reference model            Protocol suite Number of Layers      7         ...

  Client–Server Communication Using Socket In the client-server paradigm , communication takes place between two application programs called processes : Client Process → sends a request for a service Server Process → waits for requests, processes them, and sends responses The server runs continuously and waits for clients, while the client runs only when service is needed. Several APIs have been designed for communication. Three among them are common: socket interface, Transport Layer Interface (TLI), and STREAM.We will focus on socket only Socket Interface To enable communication between client and server processes, the operating system provides an Application Programming Interface (API) called a socket interface . A socket is an abstraction or data structure created by an application program for communication through the network. It acts like a communication endpoint between two processes. Communication Flow The client sends a request through its socket. ...

  Introduction to the Application Layer The Application Layer is the topmost layer of the TCP/IP protocol suite. It is the layer that directly provides services to users and user applications. Communication at the application layer is based on: Logical communication This means that two application programs communicate as if there were a direct connection between them, although the actual communication passes through many devices and network layers. The figure illustrates a communication scenario between two organizations: Sky Research and Scientific Books . A scientist at Sky Research wants to order a research book from the online bookseller Scientific Books. The computer at Sky Research is represented as Alice . The server at Scientific Books is represented as Bob . At the application layer , communication between Alice and Bob is considered logical communication . This means that both application layers behave as if there is a direct two-way connection between them for...

  Web Documents Introduction A web document is a file or resource stored on a web server that can be accessed using a web browser through the World Wide Web (WWW). Based on how they are created and processed, web documents are classified into three types: Static Documents Dynamic Documents Active Documents Types of Web Documents Type Created Executed Content Static Document      Before request      Server only           Fixed Dynamic Document      At request time      Server           Changes with each request Active Document      Before request      Client (Browser)           Interactive 1. Static Documents Definition A static document is a web page whose contents are created in advance and stored on the web server. Whenever a client requests the page, the server sends a copy of the ...

  Uniform Resource Locator (URL) Introduction A Uniform Resource Locator (URL) is the unique address of a web page or resource on the World Wide Web. It specifies the location of the resource and the protocol required to access it. A URL enables a web browser to locate and retrieve a web page from a web server. Definition A Uniform Resource Locator (URL) is the unique address used to identify and access a web page or other resource on the Internet. Components of a URL According to the textbook, a URL consists of four identifiers : Protocol Host Port Path 1. Protocol The protocol specifies the client-server application used to access the resource. Common protocols include: HTTP (HyperText Transfer Protocol) – Used for web pages FTP (File Transfer Protocol) – Used for file transfer Example: http:// ftp:// 2. Host The host identifies the web server where the resource is stored. The host can be: An IP address , e.g., 64.23.56.17 A domain...

Introduction The World Wide Web (WWW) is a distributed client–server application that allows users to access information stored on web servers across the Internet. The Web was first proposed by Tim Berners-Lee in 1989 at CERN to enable researchers at different locations to share research documents. Commercial use of the Web began in the early 1990s. The Web is a repository of information where documents, called web pages , are distributed across servers worldwide and connected through hyperlinks. Features of the World Wide Web The popularity of the Web is mainly due to two important features: 1. Distributed Web pages are stored on different servers around the world. Any organization can add new web pages without affecting existing servers. This allows the Web to grow continuously. 2. Linked Web pages are connected using hyperlinks . A web page can reference another page stored on the same server or a different server. Clicking a hyperlink retrieves the link...