For example, if the middle tier provides queuing, the client can deliver its request to the middle layer and disengage because the middle tier will access the data and return the answer to the client. In addition the middle layer adds scheduling and prioritization for work in progress. Three tier architecture with transaction processing monitor technology. The transaction is accepted by the monitor, which queues it and then takes responsibility for managing it to completion, thus freeing up the client. Three tier with message server.
Messaging is another way to implement three tier architectures.
Messages are prioritized and processed asynchronously. Messages consist of headers that contain priority information, and the address and identification number. The message server connects to the relational DBMS and other data sources. The difference between TP monitor technology and message server is that the message server architecture focuses on intelligent messages, whereas the TP Monitor environment has the intelligence in the monitor, and treats transactions as dumb data packets. Three tier with an application server.