534 research outputs found
LTLf and LDLf Monitoring: A Technical Report
Runtime monitoring is one of the central tasks to provide operational
decision support to running business processes, and check on-the-fly whether
they comply with constraints and rules. We study runtime monitoring of
properties expressed in LTL on finite traces (LTLf) and in its extension LDLf.
LDLf is a powerful logic that captures all monadic second order logic on finite
traces, which is obtained by combining regular expressions and LTLf, adopting
the syntax of propositional dynamic logic (PDL). Interestingly, in spite of its
greater expressivity, LDLf has exactly the same computational complexity of
LTLf. We show that LDLf is able to capture, in the logic itself, not only the
constraints to be monitored, but also the de-facto standard RV-LTL monitors.
This makes it possible to declaratively capture monitoring metaconstraints, and
check them by relying on usual logical services instead of ad-hoc algorithms.
This, in turn, enables to flexibly monitor constraints depending on the
monitoring state of other constraints, e.g., "compensation" constraints that
are only checked when others are detected to be violated. In addition, we
devise a direct translation of LDLf formulas into nondeterministic automata,
avoiding to detour to Buechi automata or alternating automata, and we use it to
implement a monitoring plug-in for the PROM suite
OPR
The ability to reproduce a parallel execution is desirable for debugging and program reliability purposes. In debugging (13), the programmer needs to manually step back in time, while for resilience (6) this is automatically performed by the the application upon failure. To be useful, replay has to faithfully reproduce the original execution. For parallel programs the main challenge is inferring and maintaining the order of conflicting operations (data races). Deterministic record and replay (R&R) techniques have been developed for multithreaded shared memory programs (5), as well as distributed memory programs (14). Our main interest is techniques for large scale scientific (3; 4) programming models
Propagating Changes between Declarative and Procedural Process Models
Debatt protseduuriliste ja deklaratiivsete keelte eeliste ja puuduste üle erinevate kasutusjuhtude korral on olnud tuline. Protseduurilised keeled on sobivamad operatiivsete protsesside modelleerimiseks, deklaratiivsed keeli kasutatakse regulatsioonide/juhiste jaoks. Ometi tekib olukordi, kus on mõistlik kombineerida neid keeli, et saavutada parem tulemus. Selle asemel, et sundida modelleerijaid õppima uusi hübriidkeeli, peame me paremaks kahe spetsifikatsiooni eraldi hoidmist ja pakume välja viisi, kuidas protseduurilist mudelit automaatselt muuta nii, et see oleks kooskõlas deklaratiivsete reeglitega. Nõudlus sellise lahenduse jaoks tekib, näiteks kui organisatsioon peab muutma protsesse vastavalt muutuvatele välistele reeglitele. Üldiselt on nii võimalik ära kasutada deklaratiivsete keelte paindlikust ja hoida kõrgetasemelist tuge, mida pakuvad protseduurilised keeled. Lisaks, võrreldes originaalset ja parandatud mudelit, on võimalik selgelt näha reeglite mõju. Käesolevas lõputöös sõnastame me antud probleemi, loome teoreetilise vundamendi ja pakume välja olekumasinatel põhineva lahenduse, mida me võrdleme olemasolevate lahendustega mudelite parandamiseks ja protsesside avastamiseks.The debate on advantages and disadvantages of declarative versus procedural process modelling languages for different usage scenarios has been intense. Procedural languages are more suited for describing operational processes while declarative ones for expressing regulations/guidelines, and in many situations the need of combining the benefits of the two rises. Instead of forcing modellers to use a hybrid language, we envisage to keep the two specifications separate and propose a technique that automatically adapts procedural models so as to comply with sets of declarative rules. This not only fits scenarios where, e.g., company processes have to be modified according to changing external rules, but, more in general, it presents a way to take advantage of the flexibility of declarative while maintaining the high level of support provided by procedural languages. Furthermore, by comparing the original and the resulting procedural models, the impact of rules is clearly exposed. In this thesis, we frame the problem above by providing its theoretical characterisation and propose an automata-based solution, which is then evaluated against approaches leveraging state-of-the-art techniques for process discovery and model repair
Monotony in Service Orchestrations
Web Service orchestrations are compositions of different Web Services to form
a new service. The services called during the orchestration guarantee a given
performance to the orchestrater, usually in the form of contracts. These
contracts can be used by the orchestrater to deduce the contract it can offer
to its own clients, by performing contract composition. An implicit assumption
in contract based QoS management is: "the better the component services
perform, the better the orchestration's performance will be". Thus, contract
based QoS management for Web services orchestrations implicitly assumes
monotony. In some orchestrations, however, monotony can be violated, i.e., the
performance of the orchestration improves when the performance of a component
service degrades. This is highly undesirable since it can render the process of
contract composition inconsistent. In this paper we define monotony for
orchestrations modelled by Colored Occurrence Nets (CO-nets) and we
characterize the classes of monotonic orchestrations. We show that few
orchestrations are indeed monotonic, mostly since latency can be traded for
quality of data. We also propose a sound refinement of monotony, called
conditional monotony, which forbids this kind of cheating and show that
conditional monotony is widely satisfied by orchestrations. This finding leads
to reconsidering the way SLAs should be formulated
AUTOMATED PLANNING OF PROCESS MODELS: THE CONSTRUCTION OF SIMPLE MERGES
Business processes evolve dynamically with changing business demands. Because of these fast changes, traditional process improvement techniques have to be adapted and extended since they often require a high degree of manual work. To reduce this degree of manual work, the automated planning of process models is proposed. In this context, we present a novel approach for an automated construction of the control flow structure simple merge (XOR join). This accounts for a necessary step towards an auto-mated planning of entire process models. Here we build upon a planning domain, which gives us a general and formal basis to apply our approach independently from a specific process modeling lan-guage. To analyze the feasibility of our method, we mathematically evaluate the approach in terms of key properties like termination and completeness. Moreover, we implement the approach in a process planning software and apply it to several real-world processes
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