Institute Academy

Communication between two device called data flow. Data flow are three type. i) simplex : in simplex mode the communication is unidirectional, as on a one way sreet. Only one of the two device on a link can transmit the other can only receive. Example – radio, keyboard, monitor. ii)half duplex : in half duplex, each station can both transmit and receive  but not at the same time, when one device is sending the other can only receive and vice versa. Example – walkies-talkies. iii) full duplex : in full duplex mode , both station can transmit and revive at a same time simultaneously. Mobile phone.

Cookie:  The world wide web was originally designed as a stateless entity. A client send a request , a server responds, their relationship is over. The original design of www retrieving publicly available document, exactly fits this purpose. Today web has other function; some listed hare.    i) some websites need to allow access to registered client only. ii)some website are just advertising iii)some web sites are used as portals, the user select the web pages he wants to see. Etc iv) create and send from server site and receive and store from client web browser.

uniform resource locator:   i) url stands for uniform resource locator ii) a uniform resource locator in the address of resource on the internet iii) a url indicate the location of a resource as well the protocol used to access it. iv) a URL contain following information a) the protocol  used to a access the resources b) the location of the server c) the port number of the server etc.   URL Component   i) protocol: the protocol is the client/server program used to retrieve the document, many different protocol can retrieve the document. The most commonly use today HTTP. ii) host : the host is the computer on which the information is located . although the name of the computer can be alias. Iii) port; the url can optionally contain the port number of the server. If the port is included , it is inserted between host and path and it is separated from host by a colon iv)path : path is the path name of the file where the information is located.