U3's Couch

Always design a thing by considering it in its next larger context — a chair in a room, a room in a house, a house in an environment, an environment in a city plan.

Introduction:

In the last post http://mohammad-yousri.blogspot.com/2009/06/happy-biztalk-to-you-part-2.html

I asked a very innocent question: Which integration approaches best address which of these criteria?

And I talked about the different approaches; do you remember the last approach? It was the Messaging, thus, we need to explain the different types of message channels. Are you ready? Go.

Let's check the following conversation between three messages; they met each other in the channel.

Message #1: Hello

Message #2: Hey, where are you going?

Message #1: I am going to System A, you?

Message #2: Don't know, I am waiting the admin to decide.

Message #3 3 3 3 3 3 3 3 3 3 3 3's…. :

Here We Go Again, Here We Go Again. the original is still there. the original is still there

Message #2: Wow, where are these 3's going?

Message #1: They are copy of 3's, and they are going to the subscribers.

• Point-to-Point Connection
  

  A point-to-point connection ensures that only one receiver receives a particular message. For this to work, the sending system must know the location of the receiving node. The sending system often must translate the message into a format that the receiving system understands.
  

  When you use point-to-point connections, each system determines the address of all the other nodes that it needs to communicate with. When target addresses or protocol details change, all the systems that communicate with the target server must be updated. As the size of your integration network grows and as the frequency of change increases, the operational cost associated with this approach becomes significant.
  

  The strength of the Point-to-Point Connection pattern is how simple it is to implement. The weakness of the Point-to-Point Connection pattern is the duplication of transformation and routing code between systems, and the high configuration cost of endpoint address changes. To minimize these weaknesses, you can add another layer of indirection between endpoints that contains a broker. (Message #1)
  

• Message Broker
  

  A message broker is a physical component that handles the communication between applications. Instead of communicating with each other, applications communicate only with the message broker. An application sends a message to the message broker, providing the logical name of the receivers. The message broker looks up applications registered under the logical name and then passes the message to them. Communication between applications involves only the sender, the message broker, and the designated receivers. The message broker does not send the message to any other applications. Use a central Message Broker that can receive messages from multiple destinations, determine the correct destination and route the message to the correct channel. (Message #2)
  

• Publish/Subscribe
  

  At a high level, the Publish/Subscribe [Buschmann96] pattern helps keep cooperating systems synchronized by one-way propagation of messages because one publisher sends a message to any number of intended subscribers.
  

  A Publish-Subscribe Channel works like this: It has one input channel that splits into multiple output channels, one for each subscriber. When an event is published into the channel, the Publish-Subscribe Channel delivers a copy of the message to each of the output channels. (Message #3)