Synchronous messaging –
Synchronous dictionary meaning say, occurring at the same time.
Synchronous messaging is same as the dictionary meaning. Synchronous messaging occurs when two systems or application transmits data to and fro. The data or message first enters queue then delivered to the recipient.
The further communication cannot take place until response data or message is received back to the sender. Hence sender will wait till a response from other recipient is received. Synchronous messaging is also called as Synchronous Communication.
The information is transferred in synchronous communication after every certain time interval, provided response is received from recipient end.
Example of synchronous communication can be conversation over mobile phone. Unless you receive response from other end speaker you don’t seem to take the conversation ahead.
Asynchronous messaging –
Asynchronous dictionary meaning say, not occurring at the same time.
In Asynchronous messaging information transfer takes place between the two applications or system; however the sender system will not wait for response from recipient system. The message first enters in the queue and remains there till it is not received by recipient end.
The sender can continue the message sending even if no response has been received from recipient. The response data is required but it is not required on immediate basis.
Asynchronous messaging is also called as “Fire and Forget Information Exchange” or “Message Oriented Middleware (MOM)”.
The best example of asynchronous messaging is Email service. The sender can send more mails even if the response from recipient is not received.
The additional component is required in asynchronous messaging to ensure that message present in queue is received by intended recipient. This affects performance and reliability of the system.
Hope above example and explanation clears the difference between synchronous and asynchronous.