Source : Free On-Line Dictionary of Computing

Windows Open Service Architecture
     
         (WOSA) One of the mainstays
        of {Microsoft Windows}: the ethos of {abstraction} of core
        {services}.
     
        For each extension, Windows {Open} Services {Architecture}
        defines an {API} and an {SPI}, as well as a universal
        interface (usually placed in a single {DLL}) that both comply
        to.
     
        These then {transparent}ly let the {operating system} speak to
        {device drivers}, {database managers}, and other {low level}
        entities.
     
        These extensions include, among others, {ODBC} (called the
        "crowning jewel of WOSA"), {TAPI}, {WOSA/XFS}, {SAPI} and
        {MAPI}, and their supporting services, as well as the
        abstraction of access to {printers}, {modems}, and {networking
        services}, which run identically over {TCP/IP}, {IPX/SPX}, and
        {NetBEUI}.
     
        (2000-08-16)