Invited Talk -- Contracts for BIP: Hierarchical Interaction Models for Compositional Verification -- Technical Session 1. Message Sequence Charts and SDL -- Thread-Based Analysis of Sequence Diagrams -- Recovering Repetitive Sub-functions from Observations -- Specification of Timed EFSM Fault Models in SDL -- Technical Session 2. Concurrency -- Coordination Via Types in an Event-Based Framework -- Exploring the Connection of Choreography and Orchestration with Exception Handling and Finalization/Compensation -- Towards Modal Logic Formalization of Role-Based Access Control with Object Classes -- Technical Session 3. Model Programs -- State Isomorphism in Model Programs with Abstract Data Structures -- Composition of Model Programs -- Technical Session 4. Theory -- New Bisimulation Semantics for Distributed Systems -- Event Correlation with Boxed Pomsets -- A Simple Positive Flows Computation Algorithm for a Large Subclass of Colored Nets -- Technical Session 5. Verification -- Improvements for the Symbolic Verification of Timed Automata -- The DHCP Failover Protocol: A Formal Perspective -- Verifying Erlang/OTP Components in ?CRL -- Technical Session 6. Model Checking -- Formal Analysis of Publish-Subscribe Systems by Probabilistic Timed Automata -- Testing Distributed Systems Through Symbolic Model Checking -- An Incremental and Modular Technique for Checking LTL?X Properties of Petri Nets -- Technical Session 7. Requirements and QoS -- Identifying Acceptable Common Proposals for Handling Inconsistent Software Requirements -- Formalization of Network Quality-of-Service Requirements -- Technical Session 8. Components -- Robustness in Interaction Systems -- Transactional Reduction of Component Compositions -- Specifying and Composing Interaction Protocols for Service-Oriented System Modelling.

These proceedings contain papers from the 27th FORTE conference. FORTE (Formal Techniques for Networked and Distributed Systems) is the joint int- national annual conference combining the former PSTV (Protocol Speci?cation Testing and Veri?cation) and former FORTE (Formal Description Techniques for Distributed Systems and Communication Protocols) conferences. The ?rst PSTV conference took place in 1981, and the ?rst FORTE took place in 1988. They were merged into one larger conference in 1996 and have run under the name of FORTE from 2001. The conference is a forum for presentation and d- cussion of the state of the art in theory, application, tools, and industrialization of formal methods. Over the years, FORTE has been held in numerous lo- tions, and this is re?ected by its recent history, with meetings in Pisa (Italy), Cheju Island(Korea),Houston(USA), Berlin(Germany),Madrid(Spain), Paris (France), Taiwan and now Tallinn, Estonia. FORTE was sponsored by Working Group 6.1 of Technical Committee 6 (TC6) of the InternationalFederation for Information Processing (IFIP). Indeed FORTE is one of the ?agship conferences of Working Group 6.1 (Architectures and Protocols for Distributed Systems), and covers many aspects of the main themes of WG6.1, namely, formal description techniques, open distributed s- tems, and quality of service. WG6.1 provided a Best Paper Award as well as funds to help student participation, and we are particularly grateful for this. The 27th FORTE conference was held during June 26-29, 2007, in Tallinn (Estonia), in the historical building of the Brotherhood of the Black Heads.