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An Executable Semantics for a Formalized Data Flow Diagram Specification Language
, 1993
"... While traditional Data Flow Diagrams (DFDs) are popular, they lack the formality needed in a good specification technique. We provide an executable semantics for a subset of RTSPECS, a formalization of DFDs, using the programming language Standard ML. RTSPECS is a formal notation for specifying con ..."
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Cited by 7 (5 self)
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While traditional Data Flow Diagrams (DFDs) are popular, they lack the formality needed in a good specification technique. We provide an executable semantics for a subset of RTSPECS, a formalization of DFDs, using the programming language Standard ML. RTSPECS is a formal notation for specifying concurrent and realtime software that relies on modelbased specification of abstract datatypes. Processes are specified using assertions rather than algorithms. Because our semantics of RTSPECS is written in SML, it is also an interpreter, yielding a directly executable specification language.
Formalized Data Flow Diagrams and Their Relation to Other Computational Models
, 1996
"... One approach to the formalization of Data Flow Diagrams (DFD's) is presented by Coleman ([Col91], [CB94]) and Leavens, et al., [LWBL96]. These Formalized Data Flow Diagrams (FDFD's) can be viewed as another model of computation. This paper contains an analysis of the computational power of these FDF ..."
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Cited by 3 (3 self)
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One approach to the formalization of Data Flow Diagrams (DFD's) is presented by Coleman ([Col91], [CB94]) and Leavens, et al., [LWBL96]. These Formalized Data Flow Diagrams (FDFD's) can be viewed as another model of computation. This paper contains an analysis of the computational power of these FDFD's. We first consider the issue whether certain features of FDFD's affect their computational power. A Reduced Data Flow Diagram (RDFD) is an FDFD with no stores, finite domains for flow values, and no facility for testing for empty flows, but it may contain persistent flows. An RDFD without persistent flows is called a persistent flowfree Reduced Data Flow Diagram (PFFRDFD). We show that PFFRDFD's are Turing equivalent. The other features of FDFD's only add to the expressive power of FDFD's ([SB96]). Therefore, any FDFD can be expressed as an PFFRDFD. Our proof that PFFRDFD's are Turing equivalent procedes as follows. We first show that any RDFD can be simulated by a FIFO Petri N...
Timed Data Flow Diagrams
, 1996
"... Data Flow Diagrams (DFD's) are widely used in industry to express requirements specifications. However, as used in practice, there has been no precise semantics for DFD's, let alone an incorporation of a model of time. In this paper, we augment the Formalized Data Flow Diagrams (FDFD's) defined in [ ..."
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Cited by 2 (2 self)
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Data Flow Diagrams (DFD's) are widely used in industry to express requirements specifications. However, as used in practice, there has been no precise semantics for DFD's, let alone an incorporation of a model of time. In this paper, we augment the Formalized Data Flow Diagrams (FDFD's) defined in [LWBL96] by adding a deterministic (or stochastic) time behavior for the consumption of values from inflows to processes and the production of values to the outflows from processes. We call our new FDFD model Timed (or Stochastic) Data Flow Diagrams (TDFD's or SDFD's). We identify two factors in determining how time can affect the choice of how an FDFD can change state. The first factor has to do with when the decision is made as to which state transition will be next occur. The two possibilities are a Preselection Policy and a Race Policy. The other timing factor is the past history of an FDFD execution. We identify three alternatives: Resampling, Work Age Memory, and Enabling Age Memory...
NonAtomic Components of Data Flow Diagrams: Stores, Persistent Flows, and Tests for Empty Flows
, 1996
"... It has been shown in [SB96] that a particular subclass of Formalized Data Flow Diagrams (FDFD's) is Turing equivalent. We call this Turing equivalent subclass of FDFD's persistent flowfree Reduced Data Flow Diagrams (PFFRDFD's). PFFRDFD's do not contain persistent flows, reference only values ..."
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Cited by 1 (1 self)
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It has been shown in [SB96] that a particular subclass of Formalized Data Flow Diagrams (FDFD's) is Turing equivalent. We call this Turing equivalent subclass of FDFD's persistent flowfree Reduced Data Flow Diagrams (PFFRDFD's). PFFRDFD's do not contain persistent flows, reference only values whose types have finite domains, and have enabling conditions that contain no tests for empty flows. In addition, FDFD's do not contain (direct) representations of stores. This raises the question whether any of these common features of traditional Data Flow Diagrams elevates the expressive power of FDFD's, or whether the various subclasses have the same expressive power as FDFD's with these features. This paper addresses this issue of whether persistent flows, arbitrary domains, tests for empty flows or stores are essential features with respect to the expressive power of Formalized Data Flow Diagrams. 2 1.1 Introduction Traditional Data Flow Diagrams (DFD's) are probably the most widely...
Subclasses of Formalized Data Flow Diagrams: Monogeneous, Linear, and Topologically Free Choice RDFD's
, 1996
"... Formalized Data Flow Diagrams (FDFD's) and, especially, Reduced Data Flow Diagrams (RDFD's) are Turing equivalent ([SB96a]). Therefore, no decidability problem can be solved for FDFD's in general. However, it is possible to define subclasses of FDFD's for which decidability problems can be answered. ..."
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Cited by 1 (1 self)
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Formalized Data Flow Diagrams (FDFD's) and, especially, Reduced Data Flow Diagrams (RDFD's) are Turing equivalent ([SB96a]). Therefore, no decidability problem can be solved for FDFD's in general. However, it is possible to define subclasses of FDFD's for which decidability problems can be answered. In this paper we will define certain subclasses of FDFD's, which we call Monogeneous RDFD's, Linear RDFD's, and Topologically Free Choice RDFD's. We will show that two of these three subclasses of FDFD's can be simulated via isomorphism by the correspondingly named subclasses of FIFO Petri Nets. It is known that isomorphisms between computation systems guarantee the same answers to corresponding decidability problems (e. g., reachability, deadlock, liveness) in the two systems ([KM82]). This means that problems where it is known that they can (not) be solved for a subclass of FIFO Petri Nets it follows immediately that the same problems can (not) be solved for the correspondingly named subc...
Stochastic Analysis of Periodic Timed Data Flow Diagrams with Markovian Transition Times
, 1996
"... Timed (or Stochastic) Data Flow Diagrams (TDFD's or SDFD's) introduced in [SB96b] are an extension of the Formalized Data Flow Diagrams, defined in [LWBL96]. This extension allows us to assess the quantitative behavior (e. g., performance, throughput, average load of a bubble, etc.) as well as the q ..."
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Timed (or Stochastic) Data Flow Diagrams (TDFD's or SDFD's) introduced in [SB96b] are an extension of the Formalized Data Flow Diagrams, defined in [LWBL96]. This extension allows us to assess the quantitative behavior (e. g., performance, throughput, average load of a bubble, etc.) as well as the qualitative behavior (e. g., deadlock, reachability, termination, finiteness, liveness, etc.), eventually depending on different types of transition times, for the system modeled through the TDFD. In this paper, we consider Markovian transition times for the consumption of inflow items and for the production of items on the outflow. Moreover, we require the TDFD to be periodic and irreducible and it must have a finite reachability set. For these models, we have been able to apply an aggregation principle of [Sch84], extended for periodic Markov chains by [Woo93], to efficiently determine stationary probabilities, expected waiting times, and limiting process probabilities. 2 1.1 Introduc...