Application Layer Chapter 2: Protocols and Socket Programming

An application-layer protocol defines types of messages exchanged, message syntax, message semantics, and rules for sending and responding to messages.

Port numbers are used to identify different processes running on the same host.

HTTP server

<p>An IP address identifies the host, while a port number identifies a specific process running on that host.</p> Signup and view all the answers

<p>Open protocols are defined in RFCs and allow for interoperability, while proprietary protocols are specific to certain applications like Skype.</p> Signup and view all the answers

<p>HTTP, FTP, SMTP, POP, IMAP, DNS, BitTorrent, DHT</p> Signup and view all the answers

<p>Client requests info or service; server responds with data and status code.</p> Signup and view all the answers

<p>Control vs. data messages, centralized vs. decentralized, stateless vs. stateful, reliable vs. unreliable message transfer.</p> Signup and view all the answers

<p>To enable communication between applications over TCP or UDP networks using sockets.</p> Signup and view all the answers

<p>It refers to the diversity and intricacy of functionalities and protocols implemented in end-user devices.</p> Signup and view all the answers

<p>Examples include email, web, text messaging, remote login, P2P file sharing, multi-user network games, streaming stored video, voice over IP, real-time video conferencing, social networking, and search.</p> Signup and view all the answers

<p>The main goal is to understand the conceptual and implementation aspects of network application protocols.</p> Signup and view all the answers

<p>In client-server architecture, there is always a server with permanent IP address, while in peer-to-peer architecture, arbitrary end systems directly communicate with each other.</p> Signup and view all the answers

<p>Processes within the same host communicate using inter-process communication, while processes in different hosts communicate by exchanging messages.</p> Signup and view all the answers

<p>Sockets allow processes to send and receive messages to/from their socket, acting as a door for communication.</p> Signup and view all the answers

<p>To provide a connectionless transport service for applications that do not require the reliability of TCP.</p> Signup and view all the answers

<p>SSL provides encryption, data integrity, and end-point authentication for TCP connections.</p> Signup and view all the answers

<p>In HTTP, the client is the browser that requests and receives Web objects, while the server is responsible for sending objects in response to requests.</p> Signup and view all the answers

<p>HTTP is stateless because the server does not maintain information about past client requests.</p> Signup and view all the answers

<p>Objects in a web page can include HTML files, JPEG images, Java applets, and audio files.</p> Signup and view all the answers

<p>No loss, loss-tolerant, minimum throughput</p> Signup and view all the answers

<p>Reliable transport, flow control, congestion control</p> Signup and view all the answers

<p>Applications that make use of whatever throughput they get</p> Signup and view all the answers

<p>Unreliable data transfer</p> Signup and view all the answers

<p>Connection-oriented, reliable: TCP and unreliable, datagrams: UDP</p> Signup and view all the answers

<p>TCP is connection-oriented, requiring setup between client and server processes, while UDP is connectionless</p> Signup and view all the answers

<p>HTTP, FTP, SMTP, POP, IMAP, DNS, BitTorrent, DHT</p> Signup and view all the answers

<p>Client requests information or service, server responds with data and status code.</p> Signup and view all the answers

<p>Control vs. data messages, centralized vs. decentralized, stateless vs. stateful, reliable vs. unreliable message transfer.</p> Signup and view all the answers

<p>To enable communication using TCP and UDP sockets.</p> Signup and view all the answers

<p>An application-layer protocol defines the types of messages exchanged, message syntax, message semantics, and rules for when and how processes send and respond to messages.</p> Signup and view all the answers

<p>Port numbers are used in conjunction with IP addresses to uniquely identify processes running on a host.</p> Signup and view all the answers

<p>Open protocols, defined in RFCs, allow for interoperability between different systems and applications.</p> Signup and view all the answers

<p>The transport service provides reliable data delivery, error detection, and flow control for applications.</p> Signup and view all the answers

<p>To send a message to a web server, one needs the server's IP address (e.g., 128.119.245.12) and the server's port number (e.g., 80).</p> Signup and view all the answers

<p>Client-server and peer-to-peer (P2P) architectures</p> Signup and view all the answers

<p>By exchanging messages</p> Signup and view all the answers

<p>To send/receive messages between processes</p> Signup and view all the answers

<p>In client-server architecture, there is always an 'always-on' server, while in P2P architecture, there is no always-on server.</p> Signup and view all the answers

<p>By exchanging messages</p> Signup and view all the answers

<p>UDP provides connectionless, unreliable transport service for applications that do not require the reliability of TCP.</p> Signup and view all the answers

<p>HTTP is stateless because the server maintains no information about past client requests. Each request is processed independently without any knowledge of previous interactions.</p> Signup and view all the answers

<p>SSL provides encrypted TCP connections, ensuring data integrity and end-point authentication.</p> Signup and view all the answers

<p>In the client/server model of HTTP, the client (such as a web browser) requests web objects, and the server (web server) responds by sending those objects.</p> Signup and view all the answers

<p>A web page consists of objects like HTML files, JPEG images, Java applets, and audio files.</p> Signup and view all the answers

<p>No loss, loss-tolerant, minimum throughput for effectiveness</p> Signup and view all the answers

<p>Applications that make use of whatever throughput they get</p> Signup and view all the answers

<p>To establish communication endpoints for data transfer</p> Signup and view all the answers

<p>Reliable transport, flow control, congestion control</p> Signup and view all the answers

<p>TCP service and UDP service</p> Signup and view all the answers

<ol> <li>Cookie header line of HTTP response message, 2) Cookie header line in next HTTP request message, 3) Cookie file kept on user’s host, managed by user’s browser, 4) Backend database at Web site</li> </ol> Signup and view all the answers

<p>Cookies can be used for authorization, shopping carts, recommendations, and user session state (e.g., Web email).</p> Signup and view all the answers

<p>The goal of web caching is to satisfy client requests without involving the origin server by storing and serving cached content.</p> Signup and view all the answers

<p>The web cache acts as both a server for the original requesting client and a client to the origin server.</p> Signup and view all the answers

<p>Web caching is implemented to reduce latency, network traffic, and server load by serving cached content to users.</p> Signup and view all the answers

<p>To build client/server applications that communicate using sockets.</p> Signup and view all the answers

<p>UDP (unreliable datagram) and TCP (reliable, byte stream-oriented).</p> Signup and view all the answers

<p>A client sends data to a server, the server processes the data, and sends back a response to the client.</p> Signup and view all the answers

<p>IP addresses identify the server's location, and port numbers specify the application or service on the server.</p> Signup and view all the answers

<p>The application layer provides the interface for end-user applications to access network services.</p> Signup and view all the answers

<p>Sockets act as the door between the application process and the end-to-end transport protocol.</p> Signup and view all the answers

<p>To enable client/server applications to communicate effectively using sockets.</p> Signup and view all the answers

<p>UDP provides unreliable datagram service, while TCP offers reliable, byte stream-oriented service.</p> Signup and view all the answers

<p>Port numbers help identify different applications or services running on a single device.</p> Signup and view all the answers

<p>Socket programming allows P2P applications to establish communication channels for direct data exchange.</p> Signup and view all the answers