问题
I have a design problem .
My application has multiple Java EE components ,In simple terms one acts as a service provider(Non UI) and others are consumers(UI webapp) .
The consumer gets the configuration data from the service provider(this basically reads the data from DB) during the start up and stores it in the Cache.
The cache gets refreshed after periodic time to reflect any changes done at the database.
The Problem
Apart from the cache refresh, I also want to notify the consumers when someone changes the DB that configuration has been changed please reload it.
What notification mechanisms can I use to achieve this?
回答1:
I would go with JMS topics/queues. The producer sending a "REFRESH_CACHE" message on a topic and all consumers listening to this
回答2:
I would use a topic for it. When the database changes you can send a message to the topic and all clients listen to it, can show a message.
回答3:
Take a look at the Observer design pattern. You can store consumers in a list and notify them when something interesting happens.
回答4:
You may need OBSERVER pattern.
It notifies the consumers (your UI apps) using Callback. You can use JMS for notifications.
来源：https://stackoverflow.com/questions/2407159/notification-between-java-ee-components