https://www.dagstuhl.de/20481

November 22 – 27 , 2020, Dagstuhl Seminar 20481

Principles of Contract Languages

Organizers

Dilian Gurov (KTH Royal Institute of Technology – Kista, SE)
Reiner Hähnle (TU Darmstadt, DE)
Marieke Huisman (University of Twente – Enschede, NL)
Giles Reger (University of Manchester, GB)

For support, please contact

Simone Schilke for administrative matters

Michael Gerke for scientific matters

Documents

Dagstuhl Seminar Schedule (Upload here)

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Motivation

Formal, precise analysis of non-trivial software is a task that necessarily must be decomposed. The arguably most important composition principle in programming is the procedure (function, method, routine) call. For this reason it is natural to decompose the analysis of a program along its call structure. Decomposition in this context means to replace a procedure call with a declarative description, possibly an approximation, of the call's effect. In his seminal work on runtime verification in Eiffel, Bertrand Meyer suggested to use the metaphor of a contract between the user (caller) and implementor (callee) for such a description.

Contracts continue to be a central element in run-time (dynamic) analysis. In the last two decades they also became the dominant decomposition approach in deductive verification and are realized in all major software verification systems. More recently, software contracts are increasingly used in test case generation and model checking. Furthermore, programming languages such as "Racket" were designed with a notion of contract. Contract-based specification languages are available for mainstream programming languages, notably JML for "Java" and ACSL/ACSL++ for "C"/"C++".

However, there is considerable fragmentation concerning terminology, basic principles, expressivity, and usage of contracts in different research communities. Therefore, this Dagstuhl Seminar aims to convene researchers working with contracts in static verification, runtime verification, as well as testing, with the goal of creating a unified view on software contracts.

The seminar will address the following topics and questions:

  • What are the fundamental aspects of contracts for software development?
  • What format or structure should contracts have?
  • How expressive does a contract language need to be?
  • How do contract formats depend on their use cases?
  • How should contracts be composed and decomposed?
  • How can contracts be used for documentation, testing and verification?
  • How can a unified view on contracts help integrating static and dynamic techniques?
  • How can contracts support agile software development?
  • How should contracts be refined upon a failed verification attempt?

The format of the seminar will be as follows. Each day will be dedicated to a specific topic and will consist, in the morning, of one or two tutorials that make a general overview of the topic, followed by short technical talks. During the afternoon, we will have brief pitches from participants to spark off discussions in groups on important questions raised in the morning. The day will be wrapped up by a plenary discussion in which the groups will present a summary of their findings.

Motivation text license
  Creative Commons BY 3.0 DE
  Dilian Gurov, Reiner Hähnle, Marieke Huisman, and Giles Reger

Classification

  • Semantics / Formal Methods
  • Software Engineering
  • Verification / Logic

Keywords

  • Software contract
  • Software specification
  • Static verification
  • Run-time verification

Documentation

In the series Dagstuhl Reports each Dagstuhl Seminar and Dagstuhl Perspectives Workshop is documented. The seminar organizers, in cooperation with the collector, prepare a report that includes contributions from the participants' talks together with a summary of the seminar.

 

Download overview leaflet (PDF).

Publications

Furthermore, a comprehensive peer-reviewed collection of research papers can be published in the series Dagstuhl Follow-Ups.

Dagstuhl's Impact

Please inform us when a publication was published as a result from your seminar. These publications are listed in the category Dagstuhl's Impact and are presented on a special shelf on the ground floor of the library.