PEP 347

Pegasus Enhancement Proposal (PEP) 347

PEP#: 347

PEP Type: Functional

Title: Separate internal modules from current libpegcommon library

Version: 1.1

Created: 2nd March 2009

Authors: Thilo Boehm

Status: Approved

Version History:

Version	Date	Author	Change Description
0.1	18 March 2009	Thilo Boehm	Initial Submission
0.2	20 March 2009	Thilo Boehm	Discussion Arch Call 03/19 Drop the extra include path Still name finding of the new library Define criteria to identify modules for new library
1.0	27 March 2009	Thilo Boehm	Final version for ballot
1.1	16 April 2009	Thilo Boehm	Approved version, including final comments.

Abstract:

This PEP proposes to separate internal used modules, not using the external interface or dependent modules, from the current libpegcommon library in to a new separate library to reduce the size of the libpegcommon, allow to add internal only classes with out interfering the external interface, and moderate the degree to which internal classes are included in an SDK library.

1. Definition of the Problem

Historically the Pegasus common library libpegcommon has become the home of all kinds of commonly used functions and classes in OpenPegasus. This includes classes which are part of the external interface defined in PEP#344 as well as classes used internally for the implementation of the cimserver, not meant for usage by any external project.

The mixture of internal and external interfaces as well as the overall size of the common library has become a major concern. Keep on adding new function to libpegcommon unnecessarily grows the size of client applications and further raises the risk of breaking the external interfaces or unintended use of internal only functions by exploiting client applications or C++ CIM Providers.

2. Proposed Solution

To reduce the size of the common library, enable OpenPegasus to add internal only classes with out extending the libpegcommon, and to lower the risk of breaking the external interfaces while implementing enhancements for OpenPegasus, a new library should be created for OpenPegasus. The new library should contain as many of the internal only classes from libpegcommon as possible. New functions/classes, not meant for external use should also go to this new library.

To be able to change the internals without changing the external interface the current libpegcommon has to be split into two libraries.
But the interfaces are so interweaved, that it is not easy to split such that the external interfaces are not broken.

This PEP proposes a start by migrating modules from the libpegcommon into a separate library.

The proposed name for the new library is libpeggeneral and resides in pegasus/src/Pegasus/General

The selection criteria for modules to be moved from libpegcommon to libpeggeneral is that these modules are not used directly or indirectly by the external interface.
The rationale for this criteria is, not to break the SDK and linkage on any platforms.

The modules of the new library are only used by server provided tools and server internal libraries.

The build order is first build libpegcommon then build libpeggeneral.
libpeggeneral can be linked to libpegcommen to resolve its dependencies but not vice versa.
libpegclient is only linked to libpegcommen.

This is the list identified modules of libpegcommon for libpeggeneral library:

CIMError.cpp	SetFileDescriptorToEBCDICEncoding.h	IndicationFormatter.h
CIMError.h	MofWriter.cpp	IndicationFormatter.cpp
DynamicLibrary.cpp	MofWriter.h	SSLContextManager.cpp
DynamicLibrary.h	OptionManager.cpp	SSLContextManager.h
DynamicLibraryPOSIX.cpp	OptionManager.h	Stopwatch.cpp
DynamicLibraryWindows.cpp	PropertyAccessor.cpp	Stopwatch.h
	PropertyAccessor.h

Testing

All corresponding tests are moved to src/Pegasus/General/tests

This is the list of tests to be move from Pegasus/Common/tests to Pegasus/General/tests:

CIMError

DynamicLibrary

IndicationFormatter

OptionManager

Stopwatch

ToMof

Implementation

The necessary changes to establish libpeggeneral is done in 2 Steps.
The 2 Steps should be done very closely not to cause a NbaT break.

The changes are done on the head of CVS.

Step1

In step1 only the movement of the files is done.
A script will be provided with the neccesarry CVS commands to delete the files from /directories from src/Pegasus/Common and create the files in src/Pegasus/General.
The delete/create steps are committed with the appropriate comment, where the files is moved to/where it comes from.

Step 2

In step 2 the necessary changes to the files are done to reflect the movement of the files into libpeggeneral.

Schedule

OpenPegasus 2.10

Appendix

During doing analyzes for this PEP some general findings are made.
These findings are will be filed as separate Bugs independent from this PEP:

Finding 1

CIMNamedUnchecked.h is still part of the libpegcommon. It was replaced by CIMNameCast.h ( Bug# 8097 ).
This finding has been resolved with Bug# 8468

Finding 2

The following modules are only used with in the Repository. So they have to be part of the lippegrepository.

AutoStreamer.cpp	AutoStreamer.h	BinaryStreamer.cpp	BinaryStreamer.h
Packer.cpp	Packer.h	XmlStreamer.cpp	XmlStreamer.h
ObjectStreamer.h

Finding 3

QueryExpressionRep.h & QueryExpressionRep.cpp should be part of libpegqueryexpression:

Three modules are using this class:
Pegasus/Server/CIMOperationRequestDispatcher and Pegasus/WQL/WQLQueryExpressionRep
But Pegasus/ProviderManager2/QueryExpressionFactory is not.

Future Work

There is still potential in the libpegcommon for modules to be moved to libpeggeneral but this needs rework of other modules.

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