An integrated system design for debugging distributed programs written in concurrent high-level languages is described. A variety of user-interface, monitoring, and analysis tools integrated around a uniform process model are provided. Because the tools are language-based, the user does not have to deal with low-level implementation details of distribution and concurrency, and instead can focus on the logic of the program in terms of language-level objects and constructs. The tools provide facilities for experimentation with process scheduling, environment simulation, and nondeterministic selections. Presentation and analysis of the program's behavior are supported by history replay, state queries, and assertion checking. Assertions are formulated in linear time temporal logic, which is a logic particularly well suited to specify the behavior of distributed programs. The tools are separated into two sets. The language-specific tools are those that directly interact with programs for monitoring of and on-line experimenting with distributed programs. The language-independent tools are those that support off-line presentation and analysis of the monitored information. This separation makes the system applicable to a wide range of programming languages. In addition, the separation of interactive experimentation from off-line analysis provides for efficient exploitation of both user time and machine resources. The implementation of a debugging facility for OCCAM is described.

Concert, a high-level-language approach to programming heterogeneous distributed systems, is described. The Concert model introduces a small set of language extensions into conventional procedural languages. These language extensions support a cooperative peer process model which addresses in the distributed environment the same issues addressed by language semantics in the conventional environment. The Concert implementation provides layered support for these language extensions, bridging a different source of heterogeneity at each layer. A prototype Concert system currently includes C programs running on OS/2 on multiple PS/2s communicating via calls with one another as well as with PL/I programs running on VM/370.>

An axiomatic semantic definition is given of the replacement model of exception handling in an expression-oriented language. These semantics require only two new proof rules for the most general case. An example is given of a program fragment using this model of exception handling, and these rules are used to verify the consistency of the fragment and its specification.

The authors introduce a new programming language concept, called typestate, which is a refinement of the concept of type. Whereas the type of a data object determines the set of operations over permitted on the object, typestate determines the subset of these operations which is permitted in a particular context. Typestate tracking is a program analysis technique which enhances program reliability by detecting at compile-time syntactically legal but semantically undefined execution sequences. These include reading a variable before it has been initialized and dereferencing a pointer after the dynamic object has been deallocated. The authors define typestate, give examples of its application, and show how typestate checking may be embedded into a compiler. They discuss the consequences of typestate checking for software reliability and software structure, and summarize their experience in using a high-level language incorporating typestate checking.

Optimistic Recovery is a new technique supporting application-independent transparent recovery from processor failures in distributed systems. In optimistic recovery communication, computation and checkpointing proceed asynchronously. Synchronization is replaced by causal dependency tracking , which enables a posteriori reconstruction of a consistent distributed system state following a failure using process rollback and message replay . Because there is no synchronization among computation, communication, and checkpointing, optimistic recovery can tolerate the failure of an arbitrary number of processors and yields better throughput and response time than other general recovery techniques whenever failures are infrequent.

We argue for the need of supporting a symmetric select construct, in which entry calls as well as accepts can be alternatives. We present several situations in which a symmetric select leads to a more natural programming style. We show that several semantic principles are violated by a nonsymmetric select, while being satisfied by a symmetric one. In particular, the suggested symmetric intertask communication mechanism is fully abstract and composable, and has a distributed termination rule which reduces the risk of deadlock. Our discussion is in terms of Ada™.

This paper presents a new model for exception handling, called the replacement model. The replacement model, in contrast to other exception-handling proposals, supports all the handler responses of resumption, termination, retry, and exception propagation, within both statements and expressions, in a modular, simple, and uniform fashion. The model can be embedded in any expression-oriented language and can also be adapted to languages which are not expression oriented with almost all the above advantages. This paper presents the syntactic extensions for embedding the replacement model into Algol 68 and its operational semantics. An axiomatic semantic definition for the model can be found in [27].

Article Free Access Share on An axiomatic treatment of exception handling Author: Shaula Yemini New York University New York UniversityView Profile Authors Info & Claims POPL '82: Proceedings of the 9th ACM SIGPLAN-SIGACT symposium on Principles of programming languagesJanuary 1982Pages 281–288https://doi.org/10.1145/582153.582183Published:25 January 1982Publication History 1citation276DownloadsMetricsTotal Citations1Total Downloads276Last 12 Months15Last 6 weeks0 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF