Instructions: Linking of shared oracle libraries !!!

	After I responded to an article about shared libraries and
	Oracle databases, I have received multiple requests for 
	scripts I used for linking of libraries.

	I have linked shared libraries for Oracle V7 on Alpha OSF/1 1.2,
	Oracle V6 on AIX 3.2 and ICL SVR4. First two ones have been working
	without problems (OSF/1 version for about two months and
	AIX version more than year) but ICL version was unstable
	(but the problem is in operating system, not in shared library
	itself). Outside of Unix world, I have also linked a
	shared Oracle library in VAX/VMS environment (which is much
	better than partial solution provided by Oracle).

	Since my AIX script seemed to be a little out-of-date for newer 
	Oracle versions, I'll try to give instructions for linking
	libraries instead of posting a script which won't work.

	The procedure for linking a shared oracle library for AIX 3.2 is:

	1) Find out library names that are normally required to link
	   Oracle programs (something link liboracle.a, libsqlnet.a,
	   libtcp.a, osntab.o, libsql14.a etc ...). 

	2) Find out function names required by Pro*C programs. You can
	   do this by examining precompiled .c files or taking a
	   look on sqlcpr.h header file distributed with oracle.
	   (I think that all functions in sqlcpr.h are not required
	   by Pro*C programs, so examining precompiled files might
	   be better choice, if you have time for it).

	3) Create an export file for shared library. The file should
	   contain function names found in step 2, one function name
	   at each row. Name this file "ora.exp".

	4) Link shared library with following command:

		ld -T512 -H512 -bE:ora.exp -bM:SRE -o oralib_shr.o \
			oracle_libraries_found_in_step_1 -lc

	   This will create "oralib_shr.o", which is your new shared
	   oracle library for linking programs. You can create an archive
	   library from it (if you want) with "ar -cr libora.a oralib_shr.o".
	
	5) Test application by linking it with shared library instead
	   of original oracle libraries. 

	In AIX, you can run into following problems:

		- Unresolved functions
		- Unresolved variables

		References to unresolved functions like ".appfo",
		".iapprs" and "iapprval" are caused by including
		"sqlgt2" and "sqlpf2" in your orelib.exp file.
		Remove this and error will go away.

		Reference to unresolved variable "p_xargv" can be
		removed by creating a small C source file which
		contains

			int	p_xargv;

		and linking it into your shared library with oracle libraries.

	These errors can occur, becouse linkers are more picky about input
	files when linking shared libraries. However, in most cases there
	are workarounds (or kludges) to get around them. Don't give up
	too easily !!

	Then the OSF/1 case:
	

	1) Same as in AIX.

	2) Create a C file (name it dummy.c) containing:

		dummy ()

		{
			sqlcex ();
			sqlald ();
			sqlclu ();
		}
	
	   This file is needed just to force OSF/1 linker to include 
	   all necessary functions from archive libraries. 

	3) Compile dummy.c with "cc -c dummy.c"

	4) Link shared library with command:

		ld -shared -check_registry /usr/shlib/so_locations \


			   -update_registry /usr/local/lib/so_locations \


			   -no_archive -o libora.so \


			   dummy.o \
			   oracle_libraries_found_in_step_1 \


			   -lm -lc


			
	Maybe there is a nicer way to tell which functions must be 
	included into shared library than using a dummy.c but I could
	not get things working in any other way. The so_locations -files
	are important if you want to use OSF/1 "quickstart" feature to
	speed up program start-up times.

	Remember that Oracle can find it hard to support you if you use
	shared libraries built yourself. So far, we here have had absolutely
	no problems and I seriously recommend using of shared libraries
	on all platforms you can since it radically cuts down software
	development time by reducing linking times.

	We use also HP-UX here, but linking of shared libraries is not possible
	on it, becouse the software should have been compiled with
	special option (+z or +Z) to be compatible with shared libraries
	(shame on you, HP !!).


	Speedy linkings, 
				Ari
---
	Ari Suutari			ari_at_tahko.lpr.carel.fi
	Carelcomp Oy
	Lappeenranta
	FINLAND