An Operational Semantics of Starlog

Lu, Lunjin; Cleary, John G.

doi:10.1007/10704567_18

Cited by 9 publications

(11 citation statements)

References 38 publications

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“…The purely declarative semantics of Dedalus, based on the reification of logical time into facts, are closer in spirit and interpretation to Statelog [29] and the languages proposed by Cleary and Liu [15,30,33] than to languages that admit procedural semantics to deal with update and deletion over time [12,16]. Previous work in temporal deductive databases attempted to compute finite representations for periodic phenomena [13]: we reuse many of these results in Dedalus.…”

Section: Related Workmentioning

confidence: 98%

Confluence Analysis for Distributed Programs: A Model-Theoretic Approach

Marczak¹,

Alvaro²,

Conway³

et al. 2011

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Building on recent interest in distributed logic programming, we take a model-theoretic approach to analyzing confluence of asynchronous distributed programs. We begin with a model-theoretic semantics for Dedalus and develop the concept of ultimate models to capture the non-deterministic eventual outcomes of distributed programs. After demonstrating the undecidability of checking confluence for Dedalus programs, we look for restricted sub-languages that guarantee confluence while providing adequate expressivity. We observe that a simple semipositive restriction called Dedalus + guarantees confluence while capturing PTIME, but demonstrate that the limited use of negation in Dedalus + makes certain simple and practical programs very difficult to express. To remedy this, we introduce Dedalus S , a restriction of Dedalus that allows a natural use of negation in the spirit of stratified negation, but retains the confluence of Dedalus + and similarly captures PTIME.

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Section: Related Workmentioning

confidence: 98%

Confluence Analysis for Distributed Programs: A Model-Theoretic Approach

Marczak¹,

Alvaro²,

Conway³

et al. 2011

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“…Timestamp unification and the infinite successor function serve as a monotonic, stratifying construct for treating isolation at its core: as a constraint on data dependencies. We were not the first to invent this idea (Starlog and Statelog have related constructs for time and state modification [51,42]). But we may be the most enthusiastic proponents of its utility for reasoning about parallel and distributed programming, and the role of time in computation.…”

Section: Embracing Time Evolving Statementioning

confidence: 99%

The declarative imperative

Hellerstein

2010

SIGMOD Rec.

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The rise of multicore processors and cloud computing is putting enormous pressure on the software community to find solutions to the difficulty of parallel and distributed programming. At the same time, there is more-and more varied-interest in data-centric programming languages than at any time in computing history, in part because these languages parallelize naturally. This juxtaposition raises the possibility that the theory of declarative database query languages can provide a foundation for the next generation of parallel and distributed programming languages.In this paper I reflect on my group's experience over seven years using Datalog extensions to build networking protocols and distributed systems. Based on that experience, I present a number of theoretical conjectures that may both interest the database community, and clarify important practical issues in distributed computing. Most importantly, I make a case for database researchers to take a leadership role in addressing the impending programming crisis. This is an extended version of an invited lecture at the ACM PODS 2010 conference [32].

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“…In contrast, languages proposed by Cleary and Liu [9,18,22] retain a purely logical interpretation by admitting temporal extensions into their syntax and interpreting assignment or update as a composite operation across timesteps [18] rather than as a primitive. We follow the latter approach, but differ in several significant ways.…”

Section: Updateable Statementioning

confidence: 99%

Dedalus: Datalog in Time and Space

Alvaro¹,

Marczak²,

Conway³

et al. 2009

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Recent research has explored using Datalog-based languages to express a distributed system as a set of logical invariants [2,19]. Two properties of distributed systems proved difficult to model in Datalog. First, the state of any such system evolves with its execution. Second, deductions in these systems may be arbitrarily delayed, dropped, or reordered by the unreliable network links they must traverse. Previous efforts addressed the former by extending Datalog to include updates, key constraints, persistence and events, and the latter by assuming ordered and reliable delivery while ignoring delay. These details have a semantics outside Datalog, which increases the complexity of the language or its interpretation, and forces programmers to think operationally. We argue that the missing component from these previous languages is a notion of time.In this paper we present Dedalus, a foundation language for programming and reasoning about distributed systems. Dedalus reduces to a subset of Datalog [30] with negation, aggregate functions, successor and choice, and admits an explicit representation of time into the logic language. We show that Dedalus provides a declarative foundation for the two signature features of distributed systems: mutable state, and asynchronous processing and communication. Given these two features, we address three important properties of programs in a domain-specific manner: a notion of safety appropriate to non-terminating computations, stratified monotonic reasoning with negation over time, and efficient evaluation over time via a simple execution strategy. We also provide conservative syntactic checks for our temporal notions of safety and stratification. Our experience implementing full-featured systems in variants of Datalog suggests that Dedalus is well-suited to the specification of rich distributed services and protocols, and provides both cleaner semantics and richer tests of correctness.

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An Operational Semantics of Starlog

Cited by 9 publications

References 38 publications

Confluence Analysis for Distributed Programs: A Model-Theoretic Approach

Confluence Analysis for Distributed Programs: A Model-Theoretic Approach

The declarative imperative

Dedalus: Datalog in Time and Space

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