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This is an old revision of the document!

Quick history:

  • SOM 1.0 - came out with OS/2 2.0 and used to build WorkPlaceShell. It includes only SOMObject, SOMClass and SOMClsMgr classes.
  • SOM 2.0 - aligned with CORBA 1.1, used CORBA IDL and added DSOM. SOM Compiler was reworked and Emitter Framework was added.
  • SOM 2.1
  • SOM adopted by Apple to move OpenDoc from C++ to a language neutral framework.
  • SOM 3.0 - added IIOP support, referencing counting for SOMObject and more CORBA frameworks

SOM was available on OS/2 2.0 upwards, Windows NT, AIX 4, OS/390 and OS/400.

Why somFree?

This project provides a clean-room implementation of the major SOM components and is built to be very portable. The name comes from the method used to delete a SOMObject.

Main differences from IBM SOM

  1. IDL compiler is a C++ program rather than a SOM based framework. This solves a chicken-and-egg problem.
  2. Assembler is not used for thunking, somResolve() uses macros and apply/dispatch stubs.
  3. Some components are just hollow stubs, such as SOMP.
  4. Some components are not fully functional, eg somossvr.
  5. You can have both C and C++ header files generated. The choice of 'somcorba' or 'somstars' comes from managing the 'SOMSTAR' macro.
  6. No security functions implemented.

Changes

Changes from original somFree compiler:

  • Most of internal structures now also present as in old IBM SOM 2.1 NT Toolkit.
  • New emitters:
    • LNK - Open Watcom WLink support.
    • DUMP - displays structures, available to emitter.
    • PAS - Pascal client support.
    • IPAS - Pascal implementation classes support.
  • SOM Compiler library now mostly documented.
  • SOMLINK style functions for most of SOM Compiler library added.
  • Emitters now IBM SOM 2.1 and IBM SOM 3.0 compatible without recompilation.
  • somFree Compiler supports IBM SOM 2.1, IBM SOM 3.0, and somFree 1.0 emitters.
  • somtShowEntry function outputs more info.
  • Undocumented SOMTTypes now documented.
  • SOMIPC now supports IDL 4.2 specification.
  • CORBA C Language Mapping Specification 1.0 now supported by default instead of CORBA 1.1 C Language mapping.
  • Added support of OIDL files