Java Message Service (JMS)

JMS API uses two messaging models:

1. Point-to-point, or Queuing, Model
   JMS is loosely coupled by the virtue of an intermediary component, a queue. Thus, software components communicate indirectly. This means that message-sending software components will not require knowledge about the receiving software component. This model is characterized by:
   
   
   • Only one component is receiving the message.
   • The source component is not operating when the receiving component receives the message.
   • The receiving component is not operating when the message is sent.
   • Messages successfully processed are being acknowledged by the receiving component.

   
   

2. Publish-and-Subscribe Model
   This model works as an anonymous bulletin board. A subscribing component may register the need to receive messages on a specified topic, but neither component (publisher or subscriber) is required to know about the other. This model is characterized by multiple components receiving the message and a timing dependency between publishing components and subscribing components as follows:
   
   
   • The publisher component creates a message topic for other components to subscribe to.
   • The subscriber component remains able to receive messages, unless a durable subscription is established.
   • If a durable subscription is established, messages published while the subscriber is not able to receive messages will be redistributed whenever the receiving component reconnects.