Service Bus Topics - Limitations

Until now we saw how we can use Service Bus Topics. Before starting to use it in a real project we need to know what are the current limitations that Service Bus Topics. In time, this limitation can change when a new version of Service Bus will be released. The following limitations are valid now, august 2012.
The size of a topic is set on creation. The maxim size accepted is 5GB. We can define a topic size from 1GB to 5GB. For Service Bus Topics we don’t need to pay the space used by the messages from the topic. Also when a message is received to a topic that exceeds the maxim size, a custom exception will be throw, which notify the client code about this problem. The good part is that we don’t have a limit of numbers that we have in a topic if we don’t exceed the maximum size of the topic.
For each topic we can have as many as 25 listeners. This is the maxim number of listeners on a relay. In the same time, the maximum numbers of relay listeners is limited to 2000. As we expect, an error is throw when this limit is reached (this behavior is for almost all limitation reached). As with the maxim number of listeners on a relay, we can have maximum 2000 subscribers per topic and a maximum 2000 SQL filter per topic. Don’t ask me from where this numbers appeared. One interesting thing here, each filter and action defined for a topic can have maximum 4KB size and each action can has as 64 expressions.
In the same order, a namespace can have as many as 10.000 topics and quest. Remarks, the maxim value is a sum between total number of Service Bus Queues and Service Bus Topics from a namespace.
The maximum size of a message is 254KB, from where the message header can have maximum 64KB. We can add as many properties we want to the header if we don’t exceed 64KB.
When we exceed one of these limitations an error is atomically throw in our code. Because of this is very easy to detect a kind or limitation reached.
In the next future I accept the limitation to disappear. Even now, I thing that for a normal application we can leave without any problem with this limitation and develop beautiful application over it.