HTTP, TCP/IP and …

HTTP

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.

HTTP is an application layer protocol designed within the framework of the Internet protocol suite. Its definition presumes an underlying and reliable transport layerprotocoland Transmission Control Protocol (TCP) is commonly used. However HTTP can be adapted to use unreliable protocols such as the User Datagram Protocol(UDP), for example in HTTPU and Simple Service Discovery Protocol (SSDP).

HTTP resources are identified and located on the network by Uniform Resource Locators (URLs), using the Uniform Resource Identifiers (URI’s) schemes http and https. URIs and hyperlinks in HTML documents form inter-linked hypertext documents.

HTTP functions as a request–response protocol in the client–server computing model.web browser, for example, may be the client and an application running on a computer hosting a website may be the server. The client submits an HTTP requestmessage to the server. The server, which provides resources such as HTML files and other content, or performs other functions on behalf of the client, returns a response message to the client.

HTTP is connectionless – We know HTTP is used by client to request the server for some information over the Web. The client establishes a connection with the server before sending a request. Over this connection only, the server returns the response to client. When the response is delivered, the connection between client and server is destroyed. By chance, if the same client would like to contact the same server again, the client should establish altogether a new connection.

HTTP is stateless: As mentioned above, HTTP is connectionless and it is a direct result of HTTP being a stateless protocol. The server and client are aware of each other only during a current request. Afterwards, both of them forget about each other. Due to this nature of the protocol, neither the client nor the browser can retain information between different requests across the web pages.

HTTP is media independent: It means, any type of data can be sent by HTTP as long as both the client and the server know how to handle the data content. It is required for the client as well as the server to specify the content type using appropriate MIME-type.

TCP

In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet Protocol Suite and the Open Systems Interconnection (OSI). The protocols of the layer provide host-to-host communication services for applications.

The best-known transport protocol of TCP/IP is the Transmission Control Protocol (TCP).
. It is used for connection-oriented transmissions, whereas the connectionless User Datagram Protocol(UDP) is used for simpler messaging transmissions. TCP is the more complex protocol, due to its stateful design incorporating reliable transmission and data stream services. Other prominent protocols in this group are the Datagram Congestion Control Protocol (DCCP) and the Stream Control Transmission Protocol (SCTP).

TCP provides reliable, ordered, and error-checked delivery of a stream of octets between applications running on hosts communicating by an IP network. Major Internet applications such as the World Wide Webemailremote administration, and file transfer rely on TCP. Applications that do not require reliable data stream service may use the User Datagram Protocol (UDP), which provides a connectionless datagram service that emphasizes reduced latency over reliability.

The Transmission Control Protocol provides a communication service at an intermediate level between an application program and the Internet Protocol. It provides host-to-host connectivity at the Transport Layer of the Internet model. An application does not need to know the particular mechanisms for sending data via a link to another host, such as the required packet fragmentation on the transmission medium. At the transport layer, the protocol handles all handshaking and transmission details and presents an abstraction of the network connection to the application.

At the lower levels of the protocol stack, due to network congestion, traffic load balancing, or other unpredictable network behaviour, IP packets may be lost, duplicated, or delivered out of order. TCP detects these problems, requests re-transmission of lost data, rearranges out-of-order data and even helps minimize network congestion to reduce the occurrence of the other problems. If the data still remains undelivered, the source is notified of this failure. Once the TCP receiver has reassembled the sequence of octets originally transmitted, it passes them to the receiving application. Thus, TCP abstracts the application’s communication from the underlying networking details.

TCP is used extensively by many applications available by internet, including the World Wide Web (WWW), E-mailFile Transfer ProtocolSecure Shellpeer-to-peer file sharing, and streaming media applications.

IP by itself can be compared to something like the postal system. It allows you to address a package and drop it in the system, but there’s no direct link between you and the recipient. TCP/IP, on the other hand, establishes a connection between two hosts so that they can send messages back and forth for a period of time.

The Difference Between IPv4 and IPv6 Addresses

An IP address is binary numbers but can be stored as text for human readers. For example, a 32-bit numeric address (IPv4) is written in decimal as four numbers separated by periods. Each number can be zero to 255. For example, 1.160.10.240 could be an IP address.

IPv6 addresses are 128-bit IP address written in hexadecimal and separated by colons. An example IPv6 address could be written like this: 3ffe:1900:4545:3:200:f8ff:fe21:67cf

Flow Control: Flow control is controlled by the receiving side. It ensures that the sender only sends what the receiver can handle.

  • It makes sure that the sender does not overload the receiver.
  • It’s a local phenomenon, unlike congestion control.
  • It’s generally initiated by the sender.

Congestion control:

  • It makes sure that the network is able to handle the load of packets.
  • It’s a global phenomenon and affects every host connected with that network.
  • It’s initiated by the router.

    Flow control
     is mainly done on the receiver side, to adjust how much data the sender is injecting into the network; congestion control is mainly done on the sender side, trying to sense congestion on the network by the timing of ACK-packets, to adjust the volume of data sent to the corresponding situation.

TCP vs UDP 

TCP is a connection-oriented protocol. TCP rearranges data packets in the order specified. The speed for TCP is slower than UDP. There is absolute guarantee that the data transferred remains intact and arrives in the same order in which it was sent. TCP header size is 20 bytes. TCP is heavy-weight. TCP requires three packets to set up a socket connection, before any user data can be sent. TCP handles reliability and congestion control.

User Datagram Protocol or Universal Datagram Protocol. UDP is a connectionless protocol. UDP is also a protocol used in message transport or transfer. This is not connection based which means that one program can send a load of packets to another and that would be the end of the relationship. UDP is suitable for applications that need fast, efficient transmission, such as games. UDP’s stateless nature is also useful for servers that answer small queries from huge numbers of clients. UDP is faster because error recovery is not attempted. It is a “best effort” protocol. UDP Header size is 8 bytes.

 

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