Is ATG DMS true JMS implementation

问题:

It looks like ATG's implementation of JMS is achieved through scheduler whereby it polls database in specific interval through SqlJmsProvider component. I do agree that ATG's DMS does provide with all JMS feature like Queue, Topic, Durable Subscribers, Retry etc... but isin't using a scheduler to poll the DB to send ATG Order to Fulfillment an overkill ? (too many queries fired)

回答1:

From the ATG Documentation it explains that there are two JMS providers available within ATG:

• SQL JMS
• Local JMS

The difference between the two are:

Local JMS is Synchronous and extremely fast. It runs within a single transaction and is bound to a single process, thus when sending a message, it blocks while waiting for an acknowledgement. SQL JMS on the otherhand, is Asynchronous and can be used across processes (thus an order submission on Commerce can be processed on Fulfillment). SQL JMS is non-blocking so once the message is put on the queue, the requesting process can continue. This also means that Commerce can continue running, even if Fulfillment is down. The messages are also persisted in SQL JMS while they are stateless and lost during a restart for Local JMS.

Using the scheduler to poll the queue is an acceptable solution and most of the older asynchronous message queues implemented this solution. In IBM MQ Version 7 performance has been improved by reducing the amount of polling while using IBM WAS Version 6 for example the solution is also based on regular polling of the queue.

So no, polling the database on a scheduled interval is not an overkill.