Interface used by the DefaultBeanDefinitionDocumentReader to handle custom, nested (directly under a <bean>) tags.

Decoration may also occur based on custom attributes applied to the <bean> tag. Implementations are free to turn the metadata in the custom tag into as many BeanDefinitions as required and to transform the org.springframework.beans.factory.config.BeanDefinition of the enclosing <bean> tag, potentially even returning a completely different org.springframework.beans.factory.config.BeanDefinition to replace the original.

BeanDefinitionDecorators should be aware that they may be part of a chain. In particular, a BeanDefinitionDecorator should be aware that a previous BeanDefinitionDecorator may have replaced the original org.springframework.beans.factory.config.BeanDefinition with a org.springframework.aop.framework.ProxyFactoryBean definition allowing for custom interceptors to be added.

BeanDefinitionDecorators that wish to add an interceptor to the enclosing bean should extend org.springframework.aop.config.AbstractInterceptorDrivenBeanDefinitionDecorator which handles the chaining ensuring that only one proxy is created and that it contains all interceptors from the chain.

The parser locates a BeanDefinitionDecorator from the NamespaceHandler for the namespace in which the custom tag resides.