CORBA supports server callback
Client programs often need to react to changes or updates that occur on the server, such as changes in stock price. The client can either
- periodically call a method that checks for updated information
- ask to be notified by the server whenever a change occurs
The second option is called a callback.
In CORBA, you can create two interfaces in one module:
- the regular services interface that specifies which methods the client can call on the server
- a callback interface that specifies a method on the client side that the server can call to report updates.
- Note that this is really using the server/server architecture of the ORBs.