any java appln. that needs to access information abt 
users,machines,networks and services.
   User infn. includes security credentials ,phone 
no's ,electronic and postal mail addresses and appln 
preferences,machine infn. include network addresses,machine 
configurations etc. in addition any java appln. that needs 
to either export objects or access objects exported by 
other applications and services. Examples include 
printers,calenders and networked file systems