Is it meaningful to create a own backend in java?

in my project I have different applications that all need a database connection (all "apps" are running on the same server) now my question is, what is better:

one "backend" that get requested from the apps through netty or something and has the one and only mongodb connection and cache with redis

or

all apps have mongodb connection and global cache with redis

Thanks in advance

TG

//edit all applications are for the same project so they will need the same data