Hi,

I am new to Hibernate. Can any one explain whats the difference between uni directional and bi-directional mappings in hibernate??

there is no difference in uni /bi directional relations for hibernate compared to RDMS . uni directional mean you can navigate to only one side of relationship
where as for bidirectional , it is possible both ways

eg :
cat --> kittens (uni)
cat <--> kittens (bi)

you may refer to chapter 7 of reference doc