In many scenarios, there will be situations in which we are interested in receiving some kind of promotional messages/discounting messages, say for example from an e-commerce website based on a certain product that you may be interested in buying. But this may not be applicable to all messages. So in such situations, it is important to ensure that the unwanted messages get blocked or filtered. In such situations, the message filter pattern becomes very useful. The diagram depicting the message filter pattern is given as follows:
The message filter has only a single output channel. If the data present in the message matches the specific output criteria that are mentioned by the message filter, the message is routed to the output channel, else it is discarded.