RMI vs. CORBA • RMI – Java-only distributed object model – relatively simple to use • especially if already familiar with Java – software needed is free – new so lacks maturity • but had knowledge of CORBA • many RMI designers participated in the design of CORBA • CORBA – language independent distributed object model • but nearly all CORBA development is done in C++ – relatively complex to use – software needed to use is expensive • but the price of OrbixWeb has been dropped to $799 – spec. has been maturing for several years • Object Management Group (OMG) – started in 1989 – over 600 member companies • many capabilities have been defined – naming service, automated launching of servers, timeouts, transactions, ... – vendors haven’t implemented the complete set of defined object services • switching between ORB vendors can require major codemodification. Non-OO Approaches To Distributed Processing • Remote Procedure Call (RPC) – allows invocation of remote functions – biggest drawback is that it’s not OO • Sockets – allow data transfer using of application specific protocols • example - cash register system – 1 = purchase – 2 = return – 3 = exchange – different data must be sent for each – the data transferred can indicate what should be done on the server – error prone due to assumptions about what types of data will be sent and received (protocol)

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