Three-valued asynchronous distributed runtime verification

Scheffel, Torben; Schmitz, Malte

doi:10.1109/memcod.2014.6961843

Cited by 22 publications

(18 citation statements)

References 11 publications

(22 reference statements)

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“…We also highlight that the mentioned approaches [3,5,8], and other works [11,26,27] do in effect introduce a decentralized specification. These approaches define separate monitors with different specifications, typically consisting of splitting the formula into subformulae.…”

Section: Related Workmentioning

confidence: 78%

On the Monitoring of Decentralized Specifications

El-Hokayem

Falcone

2020

ACM Trans. Softw. Eng. Methodol.

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We define two complementary approaches to monitor decentralized systems. The first relies on those with a centralized specification, i.e, when the specification is written for the behavior of the entire system. To do so, our approach introduces a data-structure that i) keeps track of the execution of an automaton, ii) has predictable parameters and size, and iii) guarantees strong eventual consistency. The second approach defines decentralized specifications wherein multiple specifications are provided for separate parts of the system. We study decentralized monitorability, and present a general algorithm for monitoring decentralized specifications. We map three existing algorithms to our approaches and provide a framework for analyzing their behavior. Lastly, we introduce our tool, which is a framework for designing such decentralized algorithms, and simulating their behavior.

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Section: Related Workmentioning

confidence: 78%

On the Monitoring of Decentralized Specifications

El-Hokayem

Falcone

2020

ACM Trans. Softw. Eng. Methodol.

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“…Multi-valued Semantics. Multi-valued semantics for temporal logics are widely used in runtime verification, see for example, [Bauer and Falcone 2016;Bauer et al 2011;Mostafa and Bonakdarbour 2015;Scheffel and Schmitz 2014]. Their semantics extend the classical LTL semantics by also assigning non-Boolean truth values to finite prefixes of infinite words [Bauer et al 2010].…”

Section: Related Workmentioning

confidence: 99%

“…Since their LTL variant only has temporal connectives that refer to the past, only safety properties are expressible. Scheffel and Schmitz [2014] extend this work to handle also some liveness properties by working with a richer fragment of LTL that includes temporal connectives that refer to the future. The algorithm by Bauer and Falcone [2016] assumes a lock-step semantics and thus only applies to synchronous systems.…”

Section: Related Workmentioning

confidence: 99%

Runtime Verification over Out-of-order Streams

Basin

Klaedtke²,

Zălinescu

2019

ACM Trans. Comput. Logic

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We present an approach for verifying systems at runtime. Our approach targets distributed systems whose components communicate with monitors over unreliable channels, where messages can be delayed, reordered, or even lost. Furthermore, our approach handles an expressive specification language that extends the real-time logic MTL with freeze quantifiers for reasoning about data values. The logic's main novelty is a new three-valued semantics that is well suited for runtime verification as it accounts for partial knowledge about a system's behavior. Based on this semantics, we present online algorithms that reason soundly and completely about streams where events can occur out of order. We also evaluate our algorithms experimentally. Depending on the specification, our prototype implementation scales to out-of-order streams with hundreds to thousands of events per second.First, note that as (0,1] β is syntactic sugar for tU (0,1] β, we can ignore the continuation subformulas in the propositional formulas, since they simplify to t. Furthermore, note that θ w (Ψ α, J 1 ,[x →d ] w ) has only one anchor subformula (different from a propositional constant), since α's temporal constraint (0, 1] is unsatisfiable for J 1 , that is, θ w (mc J 1 , J 1 (0,1] ) = f and hence θ w (β J 1 , J 1 ,[x →d ] ) ≡ f. Finally, note that for β and J 2 , we have the two propositions βLemma 4.1 for MTL carries over to MTL ↓ and its propositional formulas Ψ γ , J,ν w . Lemma 5.2. The following two statements hold.(1) If w, j, ν |≈ γ ∈ 2, then θ w (Ψ γ , J,ν w ) ≡ w, j, ν |≈ γ . ) depends on ψ J,ν , for some K and µ ∈ val w (γ , K) , for ψ φ, with the parent formula γ . Recall that a propositional formula Ψ depends on the proposition p if [p → t](Ψ) [p → f](Ψ). Example 5.5. We revisit Example 5.1 with the formula ↓ r x . α and the observation w = J 0 , ([ ], [ ]) J 1 , ([ ], [r → d]) J 2 , ([ ], [ ]) . Recall that α = (0,1] β, with β = p(x), J 0 = [0, τ ), J 1 = {τ }, and J 2 = (τ , ∞). We have the following relevant valuations.val w (↓ r x . α, J 0 ) = {[ ]} val w (↓ r x . α, J 1 ) = {[ ]} val w (↓ r x . α, J 2 ) = {[ ]} val w (α, J 0 ) = {[ ]} val w (α, J 1 ) = {[x → d]} val w (α, J 2 ) = {[ ]} val w (β, J 0 ) = {[ ]} val w (β, J 1 ) = {[ ]} val w (β, J 2 ) = {[ ], [x → d]}

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“…In runtime verification it is not usual to distinguish between inputs and outputs, since their observation makes them events of the same nature, and therefore it is difficult to compare the work from that area with ours. While some work has investigated asynchronous runtime monitoring [10,41], the problems considered in this context are different: this line of work does not distinguish between input and output and does not explore potential reorderings of traces. Instead, it looks at the situation in which the monitor and system do not synchronise on actions: actions engaged in by the system might instead be recorded and analysed later.…”

Section: Related Workmentioning

confidence: 99%

“…The idea is that if we observe an action that does not match our property (because it was observed before it was expected by the property) then we can later cancel this occurrence with the complement of the observed action. Similarly, the interleavings considered in the last known position mechanism [41] could also be used to deduct the reorderings allowed by a certain property.…”

Section: Related Workmentioning

confidence: 99%

A tool supported methodology to passively test asynchronous systems with multiple users

Merayo

Hierons

Núñez

2018

Information and Software Technology

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Context: Testing usually involves the interaction of the tester with the system under test. However, there are many situations in which this interaction is not feasible and so one requires a passive approach in which the system is analysed to look for failures or unexpected behaviours. The entities of a complex system usually communicate in an asynchronous manner and this complicates the testing tasks since the observed order of events need not be the same as the order in which the events were produced. In previous work, we presented a formal passive testing theory for a single user and system communicating through an asynchronous channel. We were able to check that a trace generated by the system satisfies a given property. Objective: This papers extends our work, for detecting potential intrusions and unexpected behaviours, to the case where many users simultaneously communicate with a central server. We evaluate the practical value of the theoretical framework with a non-trivial system. Method: We developed a novel complete theoretical framework to analyse asynchronous systems with multiple users. All the algorithms are fully implemented. Experiments were performed over the Nextcloud platform to show the applicability of our framework. The experiments include an attack so that actual vulnerabilities could be revealed. Results: The application of our methodology, supported by a tool fully implementing it, was able to reveal a vulnerability in the WebDAV protocol running on Nextcloud. Conclusion: The extension of our previous work is not only useful from a theoretical point of view but also increases the applicability of the original work. We are now able to analyse systems where the interaction with different users can lead to unexpected behaviours. We have been able to find a vulnerability in a real system, showing the usefulness of our work.

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Three-valued asynchronous distributed runtime verification

Cited by 22 publications

References 11 publications

On the Monitoring of Decentralized Specifications

On the Monitoring of Decentralized Specifications

Runtime Verification over Out-of-order Streams

A tool supported methodology to passively test asynchronous systems with multiple users

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