Computer Networks 9

application programme

software that interacts with users and the operating system (e.g., browsers, mail clients)

application protocols

standardized set of rules that defines: message formats, message exchange patterns, semantics of message

request/reply paradigm

users send requests to servers, which then respond accordingly

Simple Mail Transfer Protocol (SMTP)

application protocol used to exchange mails

Hyper Text Transfer Protocol (HTTP)

application protocol used to communicate between web browsers and web servers

companion protocol

specifies the format of the data that can be exchanged

mail retrieval protocols

Internet Message Access Protocol (IMAP), Post Office Protocol (POP)

World Wide Web (WWW)

cooperating clients and servers communicate using HTTP

operations requested by HHTP message

GET- fetch the specified Web page, HEAD- fetch status information about the specified Web page

web caching

page that can be retrieved from a nearby cache can be displayed quicker than if it has to be fetched from across the world

web services

enable application-to-application interaction

web services architectures

SOAP- Simple Object Access Protocol, REST- Representational State Transfer

Web Services Description Language (WSDL)

specify applications details such as what operations are supported, the formats of the application data to invoke or respond to those operations and whether an operation involves a response

SOAP

procedural style

REST

data oriented/document-passing style

Domain Name System (DNS)

system used to translate host names into host addresses and to manage the network

Overlay Network

logical network implemented on the top of some underlying network

Peer-to-peer (P2P) network

allows a community of users to pool their resources providing access to a larger capabilities than any one user could afford individually