of their choosing (OSI or IP) without rewriting SVR4-compliant Transport-Independent RPC (TI-RPC) applications or rebuilding the operating system. Sun introduced the NIS+ directory service in Solaris to supersede NIS, which required co-existence of the two directory services within an enterprise to ease migration. Sun engineers Thomas Maslen and Sanjay Dani were the first to design and implement the Name Service Switch. They fulfilled Solaris requirements with the nsswitch.conf file specification and the implementation choice to load database access modules as dynamically loaded libraries, which Sun was also the first to introduce. Sun engineers' original design of the configuration file and runtime loading of name service back-end libraries has withstood the test of time as operating systems have evolved and new name services are introduced. Over the years, programmers ported the NSS configuration file with nearly identical implementations to many other operating systems including FreeBSD, NetBSD, Linux, HP-UX, IRIX and AIX. More than two decades after the NSS was invented, GNU libc implements it almost identically. See also BSD Authentication Group (database) Name server Pluggable Authentication Modules External links Name Service Switch implementation in the GNU C Library NSS module supporting LDAP: nss_ldap Another NSS module supporting LDAP: nss-ldapd NSS module supporting AFS: nss_afs Unix Domain Name System Directory services