JMS Messaging Models: Point-To-Point and Publish/Subscribe

Before reading this post, please go through my previous at “Introduction to JMS” to understand some JMS Basic concepts.

In this post we are going to discuss about Messaging Models supported by Java Messaging System (JMS).

Post Brief TOC:

• JMS Messaging Models
• Point-to-Point Messaging Model
• How a P2P Model works
• Possible P2P Model Messaging systems
• Publish/Subscribe Messaging Model
• How Pub/Sub Model Works
• Differences between P2P and Pub/Sub Messaging Model

JMS Messaging Models

JMS API supports two kinds of Messaging models (Programming models) to support Asynchronous Messaging between Heterogeneous Systems.

• Point-To-Point Model(P2P Model)
• Publish-Subscribe Model(Pub/Sub Model)

In next sections, we will discuss each model in details with all available scenarios.

Point-to-Point Messaging Model

Point-to-Point Messaging Model is also know as P2P Model. Below diagram shows typical Point-To-Point Messaging model in any Messaging system.

How a P2P Model works?

Point-To-Point model follows these concepts:

• P2P Model uses “Queue” as JMS Destination
• In P2P Model, a JMS Sender or JMS Producer creates and sends messages to a Queue.
• JMS Queue is an administered object, which is created in a JMS Provider by Administrator.
• In P2P Model, a JMS Receiver or JMS Consumer receives and reads messages from a Queue.
• In P2P Model, a JMS Message is delivered to one and only one JMS Consumer.
• We can configure any number of JMS Senders and JMS Receivers to a particular queue. However, any message should be delivered to one and only one Receiver.
• There is no timing dependency between JMS Sender and JMS receiver. That means the JMS Receiver can consume the messages whether it is alive or not when the JMS Sender sent that message.
• In this model, Destination stores messages till its consumed by Receiver.

Possible P2P Model Messaging systems:

In this section, we can discuss about “What are the possible ways to implement P2P Messaging Model”.
Approach-1:
In this P2P Approach, we have configured one sender and one receiver. It is very simple and straightforward approach. As there is only one-to-one connection, there is much complex in understanding this.

One sender sends messages to queue and receiver receives those messages.

Approach-2:
In this P2P Model, we have configured one sender and multiple receivers. However, communication will happen one sender to one receiver only. If Sender sends message to Receiver-1, then only that Receiver (i.e. Receiver-1) receives that message and sends ACK (Acknowledgement) back to the Sender.

Approach-3:
In this P2P Model, we have configured multiple Senders and only one Receiver. However, communication will happen one sender to one receiver only.

Approach-4:
In this P2P Model, we have configured multiple senders and multiple receivers. However, communication will happen one sender to one receiver only. If Sender-2 sends message to Receiver-2, then Only that Receiver (i.e. Receiver-2) receives that message and sends ACK (Acknowledgement) back to the Sender-2.

NOTE:-

• A P2P model may have more than one sender and more than one receiver, but each message is consumed by one and only one receiver.



Even though, this queue has more than one receiver, but each message is consumed by only one Receiver. For example, “Msg1” is only consumed by “JMS Receiver3”.

• Sometimes, same JMS client may act as a JMS Sender or a JMS Receiver.

That’s it all about P2P Messaging Model. Now we will discuss about Pub/Sub Messaging Model in coming sections.

Publish/Subscribe Messaging Model:

Pub/Sub Messaging model is again divided into two categories as shown below:

• Durable Messaging Model

Durable Model is also know as Persistent Messaging Model. In this model, Messages are stored in some kind of store in JMS Server until they deliver to destination properly.

• Non-Durable Messaging Model

Non-Durable Model is also know as Non-Persistent Messaging Model. In this model, Messages are not stored in JMS Server.

Example:-
The following diagram shows typical one Publish/Subscribe messaging system.

How Pub/Sub Model Works:

• Pub/Sub model uses Topic as JMS Destination.
• JMS Administrator uses JMS Provider Admin Console and configures all required ConnectionFactory and Topics Objects in JMS Provider.
• JMS Publisher creates and publishes messages to Topics.
• JMS Subscriber subscribes to interested Topics and consumes all messages.
• Pub/Sub Messaging model has timing dependency. That means JMS Subscriber can consume messages which are published to the Topic only after it subscribes to that Topic. Any messages posted before its subscription or any messages posted when it is inactive, cannot be delivered to that Consumer.
• Unlike P2P Model, in this model Destination does not store messages.

Just like P2P Model, Pub/Sub model also contains much possible architecture

• One Publisher and many Subscribers
• Many Publishers and one Subscriber
• Many Publishers and many Subscribers

Differences between P2P and Pub/Sub Messaging Model:

The following table explains the major differences between two JMS Messaging Models

We will discuss on “How to implement P2P Messaging Model and Pub/Sub Messaging Model Programatically” in my coming posts.

That’s it all about JMS Messaging Models. We will discuss some more JMS Concepts in my coming posts.

Please drop me a comment if you like my post or have any issues/suggestions.