Strong Dependencies between Software Components Pietro Abate：（软件组件之间的依赖性很强Pietro减弱）.pdfVIP

Strong Dependencies between Software Components Pietro Abate Jaap Boender abate@pps.jussieu.fr Jaap.Boender@pps.jussieu.fr ` Universite Paris Diderot, PPS UMR 7126, Paris, France Roberto Di Cosmo Stefano Zacchiroli roberto@ zack@pps.jussieu.fr Abstract Within FOSS distributions, software components are managed as packages [6]. Packages are described Component-based systems often describe context re- with meta-information, which include complex inter- quirements in terms of explicit inter-component dependen- relationships describing the static requirements to run prop- cies. Studying large instances of such systems—such as free erly on a target system. Requirements are expressed in and open source software (FOSS) distributions—in terms terms of other packages, possibly with restrictions on the of declared dependencies between packages is appealing. desired versions. Both positive requirements (dependen- It is however also misleading when the language to express cies) and negative requirements (conflicts) are usually al- dependencies is as expressive as boolean formulae, which lowed. is often the case. In such settings, a more appropriate no- Example 1.1. An excerpt of the inter-package relationships tion of component dependency exists: strong dependency. of the postfix Internet mail transport agent in Debian This paper introduces such notion as a first