Final Report : remove obsolete deps for LCFG client (274)

The Goal

The primary goal for this project was to remove the LCFG client dependency on obsolete W3C::SAX XML modules by switching to the XML::LibXML module which is based on libxml. The plan was to create a new object-oriented API for accessing and manipulating the profile/component/resource and packages information for an LCFG client profile. The intention being that, whilst initially the API would only be used for the rdxprof client process, it would be designed in such a way that it could be used by all LCFG software which needs to be able to read and write profile data in the various supported formats (both client and server side). Reducing the numerous separate implementations to a single code base would mean that as well as improving maintainability this would open the way to future new feature development since any new features would only need to be implemented once.

The Project

The Final Products

Other Benefits

Improvements to code quality
C is a lot less forgiving about vaguely defined behaviour than Perl so as part of the process of writing new C code many features needed to be better defined. This process also revealed a few bugs (that are now fixed) which could lead to corruption or misinterpretation of resource data on the client side.

Improvements to profile data quality
The testing phase uncovered many genuine bugs in various component schemas which are not being caught by the current LCFG compiler. In particular it has become clear that the resource tag validation in the LCFG server needs to be improved, of course, the hope would be that one day it will be converted to using the new core libraries.

Personal benefits
This project has given me many opportunities to enhance my programming knowledge and skills. I have gained a much deeper knowledge of the C programming language and have learnt a lot about combining C with Perl by using XS code. I have also learnt how to create parsers using the flex and bison tools. Along the way I have become familiar with tools such as valgrind which is used to check for memory leaks and the Coverity static analysis tool.

Bootstrapping improvements
Whilst porting some of the LCFG utilities (e.g. qxprof, qxpack) to the new libraries a number of circular build dependency issues were identified which make porting to new platforms difficult. To improve bootstrapping on new platforms (e.g. EL8) various scripts and Perl modules have been moved between packages.


-- StephenQuinney - 23 Nov 2017

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Topic revision: r2 - 23 Nov 2017 - 18:52:17 - StephenQuinney
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