A combination of Adapters and Filters
A Message Server is a logical component of the Plexus Message Broker that takes input from one source, possibly manipulates the message(s), and sends the output to a destination. It can take input from any of the supported communication protocols and send the message out through any of the supported protocols. In the example below, the Message Server takes a message from a Microsoft® MSMQ queue and sends the message to an IBM MQSeries® queue.
Message Servers are comprised of two Adapters and zero to two Filters. Adapters are responsible for providing messages to a network interface, such as TCP or IBM’s MQSeries®. Filters are responsible for message transformation and routing rules
Each Message Server has an A Side and a B Side as illustrated below. The A Side consists of an A-Side Adapter and an A-Side Filter. The B Side consists of a B-Side Filter and a B-Side Adapter.
There are cases where a B-Side filter is not assigned, as demonstrated by the Null Filter below.
There are also cases when the B-Side Adapter is not needed. In these cases the Loop Back Adapter is configured, as illustrated below.
Message Server functionality is defined by the combination of the Adapters, Filters and their configuration. If the A-Side and B-Side Adapters were both TCP Adapters, their behaviors could be very different based on their configuration.
A single instance of a Plexus Message Broker can support many Message Servers. The number of Message Servers supported depends on hardware configuration, message volume, message flow control issues, complexity of message transformation, and Message Server redundancy requirements.