Source Code Verification for Embedded Systems using Prolog

System relevant embedded software needs to be reliable and, therefore, well tested, especially for aerospace systems. A common technique to verify programs is the analysis of their abstract syntax tree (AST). Tree structures can be elegantly analyzed with the logic programming language Prolog. Moreover, Prolog offers further advantages for a thorough analysis: On the one hand, it natively provides versatile options to efficiently process tree or graph data structures. On the other hand, Prolog's non-determinism and backtracking eases tests of different variations of the program flow without big effort. A rule-based approach with Prolog allows to characterize the verification goals in a concise and declarative way. In this paper, we describe our approach to verify the source code of a flash file system with the help of Prolog. The flash file system is written in C++ and has been developed particularly for the use in satellites. We transform a given abstract syntax tree of C++ source code into Prolog facts and derive the call graph and the execution sequence (tree), which then are further tested against verification goals. The different program flow branching due to control structures is derived by backtracking as subtrees of the full execution sequence. Finally, these subtrees are verified in Prolog. We illustrate our approach with a case study, where we search for incorrect applications of semaphores in embedded software using the real-time operating system RODOS. We rely on computation tree logic (CTL) and have designed an embedded domain specific language (DSL) in Prolog to express the verification goals.Comment: In Proceedings WLP'15/'16/WFLP'16, arXiv:1701.0014

Integration von Prolog und Java mit Hilfe der Connector Architecture CAPJa

Modern software is often realized as a modular combination of subsystems for, e. g., knowledge management, visualization, verification, or the interaction with users. As a result, software libraries from possibly different programming languages have to work together. Even more complex the case is if different programming paradigms have to be combined. This type of diversification of programming languages and paradigms in just one software application can only be mastered by mechanisms for a seamless integration of the involved programming languages. However, the integration of the common logic programming language Prolog and the popular object-oriented programming language Java is complicated by various interoperability problems which stem on the one hand from the paradigmatic gap between the programming languages, and on the other hand, from the diversity of the available Prolog systems. The subject of the thesis is the investigation of novel mechanisms for the integration of logic programming in Prolog and object–oriented programming in Java. We are particularly interested in an object–oriented, uniform approach which is not specific to just one Prolog system. Therefore, we have first identified several important criteria for the seamless integration of Prolog and Java from the object–oriented perspective. The main contribution of the thesis is a novel integration framework called the Connector Architecture for Prolog and Java (CAPJa). The framework is completely implemented in Java and imposes no modifications to the Java Virtual Machine or Prolog. CAPJa provides a semi–automated mechanism for the integration of Prolog predicates into Java. For compact, readable, and object–oriented queries to Prolog, CAPJa exploits lambda expressions with conditional and relational operators in Java. The communication between Java and Prolog is based on a fully automated mapping of Java objects to Prolog terms, and vice versa. In Java, an extensible system of gateways provides connectivity with various Prolog system and, moreover, makes any connected Prolog system easily interchangeable, without major adaption in Java.Moderne Software ist oft modular zusammengesetzt aus Subsystemen zur Wissensverwaltung, Visualisierung, Verfikation oder Benutzerinteraktion. Dabei müssen Programmbibliotheken aus möglicherweise verschiedenen Programmiersprachen miteinander zusammenarbeiten. Noch komplizierter ist der Fall, wenn auch noch verschiedene Programmierparadigmen miteinander kombiniert werden. Diese Art der Diversifikation an Programmiersprachen und –paradigmen in nur einer Software kann nur von nahtlosen Integrationsmechansimen für die beteiligten Programmiersprachen gemeistert werden. Gerade die Einbindung der gängigen Logikprogrammiersprache Prolog und der populären objektorientierten Programmiersprache Java wird durch zahlreiche Kompatibilitätsprobleme erschwert, welche auf der einen Seite von paradigmatischen Unterschieden der beiden Programmiersprachen herrühren und auf der anderen Seite von der Vielfalt der erhältlichen Prologimplementierungen. Gegenstand dieser Arbeit ist die Untersuchung von neuartigen Mechanismen für die Zusammenführung von Logikprogrammierung in Prolog und objektorienter Programmierung in Java. Besonders interessiert uns dabei ein objektorientierter, einheitlicher Ansatz, der nicht auf eine konkrete Prologimplementierung festgelegt ist. Aus diesem Grund haben wir zunächst wichtige Kriterien für die nahtlose Integration von Prolog und Java aus der objetorientierten Sicht identifziert. Der Hauptbeitrag dieser Arbeit ist ein neuartiges Integrationssystems, welches Connector Architecture for Prolog and Java (CAPJa) heißt. Das System ist komplett in Java implementiert und benötigt keine Anpassungen der Java Virtual Machine oder Prolog. CAPJa stellt einen halbautomatischen Mechanismus zur Vernetzung von Prolog Prädikaten mit Java zur Verfügung. Für kompakte, lesbare und objektorientierte Anfragen an Prolog nutzt CAPJa Lambdaausdrücke mit logischen und relationalen Operatoren in Java. Die Kommunikation zwischen Java und Prolog basiert auf einer automatisierten Abbildung von Java Objekten auf Prolog Terme, und umgekehrt. In Java bietet ein erweiterbares System von Schnittstellen Konnektivität zu einer Vielzahl an Prologimplmentierung und macht darüber hinaus jede verbundene Prologimplementierung einfach austauschbar, und zwar ohne größere Anpassung in Java

Seamless Cooperation of JAVA and PROLOG for Rule-Based Software Development

Abstract. Modern software often relies on the modular combination of several software subsystems, for instance rule-based subsystems for decision support, verification or knowledge management. Different software libraries in potentially different programming languages have to work together in just a single application. Even more complex is the case when different programming paradigms are combined. Such a diversification of programming languages and modules in just a single software application can only be mastered by smooth integration techniques that retain the power of different programming paradigms. Unfortunately, for the popular object-oriented programming language JAVA and the common logic programming language PROLOG occurring interoperability problems still are not solved sufficiently. To overcome various external and internal issues of former approaches we propose an intuitive and portable Connector Architecture for PROLOG and JAVA (CAPJA). A concise, extensible and independent communication layer with a pluggable interface system allows for a seamless integration of PROLOG programs in JAVA. Compared to former approaches we could reduce the code for the mere communication to a minimum. Several case studies with different PROLOG systems document not only the portability but the overall applicability of our approach