The document discusses distributed systems and CORBA (Common Object Request Broker Architecture). It provides an overview of CORBA architecture including its object model, object request broker, interface definition language, client/server communication model using object references, and stubs and skeletons. It also compares CORBA to other distributed computing technologies like DCOM and discusses their similarities and differences.

1. Unit – 4

3. The Beginning: Monolithic Systems and Mainframes

4. The Revolution: Client/Server Architecture

5. The Evolution: Multitier Client/Server

34. Similarities between DCOM and CORBA Yes Yes Location Transparency Yes-OpenDoc Yes-OLE Compound document model Yes Yes Language independence CORBA IDL allows for separation of interface and implementation and provides a repository for storage of interfaces. Microsoft IDL allows for specification of interface and implementation and provides a repository for storage of interfaces. Interface similarities Formal: managed by the Object Management Group Recently made formal; managed by the Active Group, an Open Group affiliate Standards body Yes Yes Object Model CORBA DCOM Similarities

35. Differences between DCOM and CORBA Significant number of additional services, including query, trader, transactions, as well as facilities in the areas of information management and system management. Lastly, services in areas such as finance, distributed simulation, and computer integrated manufacturing ActiveX-interactive content standard Service differences Multi-vendor Single vendor; availability from other vendors expected Availability MVS, UNIX, Windows (all), Macintosh Windows NT; future support for Windows (all), Macintosh, UNIX, MVA Platforms Enterprise first; desktop second Desktop first; enterprise second Focus CORBA DCOM Differences

36. Differences between DCOM and CORBA Multiple Inheritance; interfaces are classes. Supports aggregation but not inheritance; interfaces are not classes. Interface Inheritance C++, Smalltalk, Ada95; JAVA and COBOL in process C, C++; working on JAVA, Visual Basic, Ada Language Binding Products since 1992; many services and facilities under construction NT shipped in 1996; decade-long evolution of OLE and COM products; most services and facilities under construction Maturity CORBA DCOM Differences

37. Value Basic Value Constructed Value Object Reference Primitive Types Integer Types Floating Point void Boolean Char & wchar Long & long long Float Double & Long Double Unsigned long & Unsigned long long Short & Unsigned short octet string