My thoughts on the platform abstractions layer is as follows.  Note that I 
will initially focus on the client-side of things, but I hope to also 
eventually get to the server side to see what needs to be abstracted.

Just to level-set, the goal is to attempt to concentrate as much as 
possible any platform differences in one area - code will be located in 
the platforms/ directory.  There occasionally will be times when this 
cannot be done, but hopefully those occasions will be few and any 
platform-specific code changes required outside of platforms/ directory 
will be minimal. 

I have initially identified several areas that need to be abstracted:  DLL 
loading, mutex, socket, and obtaining OS errors.  There may be more (such 
as event log for FFDC kinds of stuff - on Unix maybe syslog() will be 
used, on windows to the event log), but that will be identified and done 
later.

The idea is to have classes for the various platform-specific stuff.  The 
header files and default implementation would be in platforms/ directory 
as follows:

platforms/AxisPsLibraryLoader.hpp 
platforms/AxisPsLibraryLoader.cpp
platforms/AxisPsMutex.hpp
platforms/AxisPsMutex.cpp
platforms/AxisPsSocket.hpp
platforms/AxisPsSocket.cpp
platforms/AxisPsOSError.hpp
platforms/AxisPsOSError.cpp

The default implementation of these classes will be patterned after Unix 
and packaged in a DLL/share library called, for lack of a better name, 
axis_platformservices.so.   The AXIS engine will need to link to this 
DLL/shared library and thus it will need to be created first prior to 
creating any other DLLs/shared libraries.

The implementation code for other platforms will be in each platform 
directory.  For example, OS/400 will need to have its own 
AxisPsLibraryLoader.cpp file so one will be located as follows:

platforms/os400/AxisPsLibraryLoader.cpp

When building the  axis_platformservices DLL/shared library, which files 
are build is dependent on the platform.  For example, OS/400 would build 
everything in platforms/os400/ and would also build 
platforms/AxisPsMutex.cpp, platforms/AxisPsSocket.cpp and 
platforms/AxisPsOSError.cpp. 

The creation of the classes and implementation will be done as part of 
stage one.  I will also attempt to modify the ant build scripts to build 
the DLL/shared library.  However, I have no expertise with makefiles so 
someone would need to do that.  Stage one would just be putting the stuff 
in CVS and for all of you to look at and comment on.  Everything should 
still build as it does now.

Stage two would be to change the Axis engine to use the above classes and 
link to the service program.  Again, someone would need to volunteer to 
update makefiles.  At this point in time the ant build would work but the 
make would fail unless someone updates the makefile.

For stage three, if we still want to go to APR, the default implementation 
can be changed to use the APR APIs, and if a platform wants to go that way 
they can, otherwise, a platform can still have its own implementation of 
the classes.  This will protect platforms that may not have all the APR 
APIs, or do not have APR at all.

So what do you think? 



Nadir K. Amra

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