Default java / jsp file which gets executed before DAM asset rendering

Hi,

I have a requirement to implement access control on DAM assets on the basis of a metadata property (tags).

Is there a default JAVA / JSP file which gets executed before rendering a DAM asset?

If yes, how can I override it?

If no, how can I add a new JSP / JAVA file to be executed before rendering of each DAM asset?

Thanks in advance,

Anurag