Instant messaging vs Messaging service?

Question

I am reading a bit about the message oriented middleware for SOA. The question which is not clear to me is difference between Instant messaging and Messaging service. Could someone help me to understand this ?

Answer 1

Instant messaging is communication between humans using text messages.

Messaging service is event communication between machines using messages. Those messages are typically packed with information about an event that needs to be processed somehow. There are some pattern commonly implemented by messaging services.

• Publish/Subscribe - A publisher sends events to multiple subscribers that can decide what events they want to subscribe to.
• Message queue - Messages are sent to a queue used to hold events in a buffer. The messages awaits a consumer to consume messages and process the events. This implements a decoupling in time between systems as well as workload balancing.

Message events typically hold data in some machine readable format, such as XML, JSON, EDIFACT etc.

Another way to look at it: Messaging services can be used to build instant messaging software. The XMPP protocol is an example of that.