-The Austin Protocol Compiler presents a protocol specification language called the Timed Abstract Protocol (TAP) notation. This book will finally close the communication gap between the protocol verifiers and the protocol implementers.

The TAP notation uses two types of semantics: an abstract semantics that appeals to the protocol verifiers and a concrete semantics which appeals to the protocol implementers. The Austin Protocol Compiler illustrates that the two types of semantics of TAP are equivalent. Thus, the correctness of TAP specification of some protocol, that is established based on the abstract semantics of TAP, is maintained when this specification is implemented based on concrete semantics of TAP. The equivalence between the abstract and concrete semantics of TAP suggests the following three-step method for developing a correct implementation of a protocol in this book:

1. Specify the protocol using the TAP notation.

2. Verify the correctness of the specification based on the abstract semantics of TAP

3. Implement the specification based on the concrete semantics of TAP

   For step 3, this book introduces the Austin Protocol Compiler (APC) that takes as input, a TAP specification of some protocol, and produces as output C-code that implements this protocol based on the concrete semantics of TAP.

   The Austin Protocol Compiler is designed for a professional audience composed of protocol designers, verifiers, reviewers and implementers. This volume is also suitable for graduate-level students in computer science and electrical engineering.

   Zusammenfassung
   There are two groups of researchers who are interested in designing network protocols and who cannot (yet) effectively communicate with one another c- cerning these protocols. The first is the group of protocol verifiers, and the second is the group of protocol implementors. The main reason for the lack of effective communication between these two groups is that these groups use languages with quite different semantics to specify network protocols. On one hand, the protocol verifiers use specification languages whose semantics are abstract, coarse-grained, and with large atom- ity. Clearly, protocol specifications that are developed based on such semantics are easier to prove correct. On the other hand, the protocol implementors use specification languages whose semantics are concrete, fine-grained, and with small atomicity. Protocol specifications that are developed based on such - mantics are easier to implement using system programming languages such as C, C++, and Java. To help in closing this communication gap between the group of protocol verifiers and the group of protocol implementors, we present in this monograph a protocol specification language called the Timed Abstract Protocol (or TAP, for short) notation. This notation is greatly influenced by the Abstract Protocol Notation in the textbook Elements of Network Protocol Design, written by the second author, Mohamed G. Gouda. The TAP notation has two types of sem- tics: an abstract semantics that appeals to the protocol verifiers and a concrete semantics thatappeals to the protocol implementors group.

   Inhalt
   Network Protocols.- The Timed Abstract Protocol Notation.- Execution Models of Network Protocols.- Equivalence of Execution Models.- Preserving Fairness.- The Austin Protocol Compiler.- Two Examples.- A DNS Server.- Concluding Remarks.