Service Bus Topics - When we can use it (scenarios)

In the last period of time I wrote a lot about Service Bus Topics from Windows Azure. For this series of post about this subject, these will the last one (or I hope so). In this post I will try to find some scenarios when Service Bus Topics can help us to write better applications.

We can imagine that we are writing an application for a bank that processes all the transactions that are made through the internet. Each transaction can have a series of states. For each state we need to execute some actions that can change in time. All the time we have a predefined flow, that will not change in time, but beside this we will need to make some audit, maybe some tracing when we suspect that something is not okay. In the same time, depending on the country we will need also to communicate some information to government or to other 3th parts that are involved in the transactions.
To be able to do something like this we will need a system where we can process messages and add in any time new subscribers. Also it is very important to not lose any transaction. We could create a system for this, but we don’t need to create again a solution that already exists. Another solution could be BizTalk, but if the flow is not very complicated Service Bus Topics can be the best solution for our problem.
We could add any listener to a transaction in a given state very easily. We could connect 3 or for topics to create a flow where subscribers could process the requests without any kind of problem.

What do you think about an online shop? When a product from catalog is purchased by a client we need to make a lot of action that can go in parallel. We need to: notify the buyer, notify the storehouse, send a request to the courier and so on. All this actions can go in parallel. Because of this Service Bus Topics could be used without any problem. The cost of implementation a solution that is Service Bus Topics would be low.

Not only complicate scenario are suitable for Service Bus Topics. If we need to broadcast messages in a system in a way that can be filtered based on some criteria are suitable for Service Bus Topics. Let’s imagine that we are developing a system that connects hundreds of small devices of our home. From the TV to our lights or the doors. Over Service Bus Topics we can create a system that send messages to these devices and is able to broadcast and route all the messages. In the next post I will try to describe a solution for this.

Service Bus Topics can be used when we have a message that need to be processed by more than one listener. In these cases it can be one of the best solutions on the market. When we have a message that needs to be processed by only one listener we can use Service Bus Queues. We can write the code to use Service Bus Queue in a way that will permit us to migrate to Service Bus Topics without changing a line of code (only the configuration file).