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The standard recommended approach to customizing PersonDirectory is to modify the PersonDirectory Spring context. It is also still possible to replace the name of the class in PersonDirectorypersonDirectoryContext.xml and supply an entirely custom implementation. If you have a legacy implementation from a previous version of uPortal, this may be an attractive option.
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PersonDirectory is implemented using Spring. Currently a Spring beans.dtd-compliant XML file named personDirectorypersonDirectoryContext.xml declares the configuration of an instance of IPersonAttributeDao. The class PersonDirectory delegates to this Spring-configured IPersonAttributeDao instance to actually implement the PersonDirectory behavior. PersonDirectory uses PortalApplicationContextFacade to access the the uPortal Spring application context.
The default personDirectorypersonDirectoryContext.xml that ships with uPortal declares that the IPersonAttributeDao we want to use is the LegacyPersonAttributeDao, which parses and instantiates the "recipe" given in PersonDirs.xml.
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