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10.11. Using Multiple Cooperating Listeners

Now, the listeners discussed in this chapter are all well and good. There are plenty of applications where one of them is useful. However, there are also plenty of applications where no single listener can, in isolation, accomplish the necessary tasks. Multiple listeners need to work together.

For example, suppose that your yacht-watching listener was so successful that you are asked to expand it. Rather than tracking buying patterns of a fixed item such as a yacht, you should track orders for the current daily special to let management discover if their specials are effective. Accomplishing this task requires three listeners to cooperate: a ServletContextListener to set up application-wide information ...