Aliases are used in many situations for example if a component defines a resource by some name and another component want to use that resource by different name suiting to naming of that component aliasing is useful . See following piece of code to make alias of a bean. Here CAdataSource aliased to CBdataSource and then again CBdataSource aliased to AppdataSource.

<alias name="CAdataSource" alias="CBdataSource"/>
<alias name="CBdataSource" alias="AppdataSource" />