Full Abstraction at Package Boundaries of Object-Oriented Languages

Verifying backwards compatibility of object-oriented libraries using Boogie

“…In this subsection, we shortly introduce the formal model from [35]. We start with a standard small-step operational semantics (similar to FJ [20]) that reduces configurations ζ which consist of heap and stack.…”

“…In this section, we give an informal introduction to the fully abstract trace-based semantics that is formalized in [35]. In our approach, the denotation of a library, which are sets of packages that consist of classes and interfaces, is expressed by the interactions between code belonging to the library and code belonging to (program) contexts.…”

“…In previous work [35], we have given a fully abstract trace-based semantics for class libraries of a sequential object-oriented programming language with the typical OO features, namely interfaces, classes, inheritance and subtyping. To model encapsulation aspects, we considered a package system which allows package-local types.…”

“…In order to focus on verification aspects, we use the sound and complete method from [35] for reasoning about backwards compatibility of class libraries that we developed specifically for this task at hand. To simplify the presentation and the formal model in this paper, we focus on (contextual) equivalence, which is the symmetric version of backwards compatibility.…”

Game Semantic Analysis of Equivalence in IMJ

“…Contextual equivalence is well known to pose a challenge to automated verification due to quantification over contexts. The quest for obtaining more direct methods of attack on the problem in the Java setting has underpinned a great deal of semantic research, mainly using operational approaches [1,7,8,6,16], but this did not lead to decision procedures. In our case, the potential for automation stems from the compositionality of the underlying semantics, which allows for a compositional translation of terms into automata in the decidable cases.…”