This volume contains the proceedings of TESTCOM/FATES 2008, a joint c- ference of two communities: TESTCOM was the 20th edition of the IFIP TC6/ WG6.1 International Conference on Testing of Communicating Systems and FATESwasthe8theditionoftheInternationalWorkshoponFormalApproaches to Testing of Software. TESTCOM/FATES 2008 was held at the Campus In- vation Center in Tokyo, Japan during June 10-13, 2008. Testing is one of the most important techniques for validating and che- ing the correctness of communication and software systems. Testing, however, is also a laborious and very cost-intensive task during the development process of such systems. TESTCOM is a series of international conferences addressing the problemsoftestingcommunicatingsystems,including communicationprotocols, services, distributed platforms, and middleware. FATES is a series of inter- tional workshopsdiscussing the challengesof using rigorousand formal methods for testing software systems in general. TESTCOM/FATES aims at being a - rum for researchers, developers, and testers to review, discuss, and learn about new approaches,concepts, theories, methodologies,tools, and experiences in the ?eld of testing of communicating systems and software. TESTCOM has a long history. Previously it was called the International Workshop on Protocol Test Systems (IWPTS) and changed its name to the - ternationalWorkshoponTestingofCommunicatingSystem(IWTCS)later.The previous conferences were held in Vancouver, Canada (1988); Berlin, Germany (1989);McLean,USA (1990);Leidschendam,TheNetherlands(1991);Montr´ eal, Canada (1992); Pau, France (1993); Tokyo, Japan (1994); Evry, France (1995); Darmstadt,Germany(1996);Cheju Island,Korea(1997);Tomsk,Russia(1998); Budapest, Hungary (1999); Ottawa, Canada (2000); Berlin, Germany (2001); Sophia Antipolis, France (2002); Oxford, UK (2004); Montr´ eal, Canada (2005); New York, USA (2006) and Tallinn, Estonia (2007).
