Software architecture is important for large systems in which it is the main means for among other things, controlling complexity. Current ideas on software architectures were not available more than ten years ago. Software developed at that time has been deteriorating from an architectural point of view over the years, as a result of adaptations made in the software because of changing system requirements. Parts of the old software are nevertheless still being used in new product lines. To make changes in that software, like adding features, it is imperative to first adapt the software to accommodate those changes. Architecture improvement of existing software is therefore becoming more and more important. The paper describes a two-phase process for software architecture improvement, which is the synthesis of two research areas: the architecture visualisation and analysis area of Philips Research, and the transformation engines and renovation factories area of the University of Amsterdam. Software architecture transformation plays an important role, and is to our knowledge a new research topic. Phase one of the process is based on Relation Partition Algebra (RPA). By lifting the information to higher levels of abstraction and calculating metrics over the system, all kinds of quality aspects can be investigated. Phase two is based on formal transformation techniques on abstract syntax trees. The software architecture improvement process allows for a fast feedback loop on results, without the need to deal with the complete software and without any interference with the normal development process.

When a compiler is designed carefully, it is possible to extract its grammar. We reengineer the extracted grammar to one that is geared towards reengineering. From this reengineering grammar we generate an architecture called a software renovation factory. This includes: generic analysis and transformation functionality and a native pattern language using the concrete syntax of the language for which the renovation is necessary. Moreover, we generate the grammar in HTML format so that reengineers can quickly understand the language. We applied our approach successfully to an exceptionally complex and large proprietary language. Our approach enables rapid development of software renovation factories. We believe that our approach can partly solve the lack of Year 2000 tool support for many languages.

Discusses tools that aid in the development, assessment and reengineering of language descriptions (i.e. syntactic descriptions of a language). We develop assessment tools that give an indication as to what is wrong with an existing language description, and give hints towards its correction. From a correct and complete language description, it is possible to generate a parser, a manual and online documentation. The parser is geared towards reengineering purposes, but is also used to parse the examples that are contained in the documentation. The reengineered language description is a basic ingredient for a reengineering factory that can manipulate this language. The described tool support can also be used to develop a language standard without syntax errors in the language description and its code examples.

Abstract. In the process-algebraic verification of systems with three or more components put in parallel, alphabet axioms are considered to be useful. These are rules that exploit the information about the alphabets of the processes involved. The alphabet of a process is the set of actions it can perform. In this paper, we extend μCRL (a formal proof system for ACP τ + data) with such axioms. The alphabet axioms that are added to the proof theory are completely formal and therefore highly suited for computer-checked verification. This is new compared to previous papers where the formulation of alphabet axioms relies for a considerable amount on informal data parameters and implicit (infinite) set theory.

Abstract. This paper is supplementary to [KoS98]. It illustrates by means of examples the use of alphabet axioms as presented in [KoS98]. Furthermore a brief overview of μCRL [GrP94] and its proof theory [GrP93] are added.