Synchronous message passing in Client-Server architecture

We often come across a client-server architecture, it consists of a service requester machine called client and service provider machine called server. The services are exchanged between these machines using simple message passing. The message passing is of two kinds, synchronous and asynchronous. In asynchronous message passing, the machines exchange messages without any predefined order. In synchronous message passing, the machines exchange messages with a predefined order and time sequences.

Java SE provides us with all things required to communicate messages between machines. Below is the program which performs synchronous message passing between machines.