Transformer meta-components are one of the building blocks that are provided by the OBS
Framework. They are introduced to automate the tailoring process whereby the assets
provided by the framework are modified to match the needs of a target application (see
the framework development
process). More specifically, transformer meta-components can automatically modify
the source code of an existing component to endow it with some new application-specific
property or behaviour.
In the OBS Framework, tranformer meta-components are implemented as aspect
programs (see here for an introduction
to aspect oriented programming) using the XWeaver aspect
language and aspect weaver. XWeaver is an extensible, customizable and minimally
intrusive aspect weaver that is specifically aimed at qualifiable applications. The mode
of operation of the generator meta-components is illustrated in the
figure: The code modification process is
driven by a set of specifications that are expressed in an XML document. These
specifications describe a modification to be performed upon the code of some existing
building blocks. The XWeaver aspect weaver takes these specifications and the existing
building blocks as inputs and generates the modified building blocks as output.
The development of the transformer meta-components for the OBS Framework is currently under
way and will be described in a future release of the framework.