Example 3: Hello World with Callback Object

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Client programs often react to changes or updates that occur in a server. For example, a client graph or spreadsheet program might need to be updated with each stock price update on a stock market server. The client has two options in this scenario: (1) periodically ask for the stock price via a method request on the stock server or (2) ask to be notified by the server whenever a price change occurs. The second option is referred to as a "callback".

Example 3 illustrates how a client program can pass a callback object to a server. The server then issues a method request on the callback object and thereby notifies the client.

Example 3 is identical to Example 1 except for the callback enhancements. This page only discusses the code necessary to these enhancements.

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