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Quick history:
SOM 1.0 - came out with OS/2 2.0 and used to build WorkPlaceShell
SOM 2.0 - aligned with CORBA 1.1, used CORBA IDL and added DSOM.
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
- IDL compiler is a C++ program rather than a SOM based framework. This solves a chicken-and-egg problem.
- Assembler is not used for thunking, somResolve() uses macros and apply/dispatch stubs.
- Some components are just hollow stubs, such as SOMP.
- Some components are not fully functional, eg somossvr.
- You can have both C and C++ header files generated. The choice of 'somcorba' or 'somstars' comes from managing the 'SOMSTAR' macro.
- 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