Definition of a service decorator, which (by default) is derived from a service decorator method.
A note on decorator scheduling. The scheduling is based on the desired order of
behavior. Thus, if logging should occur before security checks, and security checks should occur before transaction management, then the desired decorator order is Logging, Security, Transactions. This might be specified as having Security occur after Logging, and Transactions occur after Security. It might also be specified by having Logging ordered "before:*", and Transactions ordered "after:*" with no specified scheduling for Security.
Once this order is established, decorators are
applied in reverse order. Each decorator's job is to create an
interceptor for the service, that delegates to the next implementation. This implies that the decorators are executed last to first. In the above example, the core service implementation would be passed to the Transaction decorator, resulting in the Transaction interceptor. The Transaction interceptor would be passed to the Security decorator, resulting in the Security interceptor. The Security interceptor would be passed to the Logging decorator, resulting in the Logging interceptor. Thus at runtime, the Logging interceptor will execute first, then delegate to the Security interceptor, which would delegate to the Transaction interceptor, which would finally delegate to the core service implementation.
Service decorators are part of the initial version of Tapestry IoC. Starting in release 5.1, their use has been deprecated, in favor of {@link org.apache.tapestry5.ioc.AdvisorDef}, which is based on {@link org.apache.tapestry5.ioc.services.AspectInterceptorBuilder}.
Note: service decorators are applied
around the interceptor generated via any {@link org.apache.tapestry5.ioc.AdvisorDef}s (for compatibility with Tapestry 5.0). In general, you should use service decoration or service advice, not both.