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Contributing to a Service
Main Article: Tapestry IoC cookbook - Service ConfigurationsConfiguration
The Tapestry module makes a contribution into the service configuration:
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Ordered configurations are very similar to unordered configurations ... the difference is that the configuration is provided to the service as a parameter of type List. This is used when the order of operations counts. Often these configurations are related to a design pattern such as Chain of Command or Pipeline.
Here, the example is the Dispatcher interface; a Dispatcher inside Tapestry is roughly equivalent to a servlet, though a touch more active. It is passed a Request and decides if the URL for the Request is something it can handle; if so it will process the request, send a response, and return true.
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The MasterDispatcher service configuration defines a Chain of Command and we can provide the implementation using virtually no code:
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The last type of service configuration is the mapped service configuration. Here we relate a key, often a string, to some value. The contributions are ultimately combined to form a Map.
Tapestry IoC's symbol mechanism allows configuration values to be defined and perhaps overridden, then provided to services via injection, using the @Value annotation.
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