Question

I’m a little confused…What is the difference between a synchronous and an asynchronous connection vs. a connation formed on the basis of either connection oriented or connectionless protocols.

In other words what is the difference between (1) a synchronous and a connection oriented service and (2) what is the difference between an asynchronous and a connectionless service.

To me they seem to be one and the same at the moment…but that can’t be true…

Answer 1

A synchronous, connection oriented service has a two-way conversation. One side, usually the client, makes a request and the other side, usually a server, responds. The web is an example: a client establishes a connection, requests a file and the server serves the file or gives and error.

An asynchronous, connectionless service is a fire and forget setup. DNS (Domain Name Service) is an example: the client requests the address of suchandsuch from it's first nameserver. If a reply isn't recieved in a certain (default 120 seconds) amount of time, the client moves on to it's second nameserver and makes the request again.

Answer 2

So it is safe to assume that the words synchronous and asynchronous describe the connection type, whereas connection-oriented and connectionless are used to describe the service the connection will provide?

In which case a synchronous connection will always provide a connection oriented service
And an asynchronous connection will always provide a connectionless service?

Answer 3

Here's a link for a detailed explanation of synchronous/asynchronous at the hardware level: https://en.wikipedia.org/wiki/Comparison_of_synchronous_and_asynchronous_signalling

The notion of synchronous/asynchronous applies a bit in TCP/IP with TCP being considered a synchronous protocol and UDP (fire and forget) being asynchronous.