P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. "MT: A Toolset for Specifying and Analyzing Real-Time Systems," Real-Time System Symposium, Lake Buena Vista, FL, December 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....is extremely expensive, limiting the size of problems that can be handled. Discrete time is used by other tools such as [16, 28] The tool described in [28] also uses symbolic algorithms using BDDs. These tools, however, do not allow the quantitative analysis of systems as the proposed method. In [14] quantitative analysis is implemented, but with a more limited scope. Analytical methods for analyzing real time systems also exist, such as the rate monotonic scheduling theory [22, 19, 26] In this method a real time system is characterized by a set of periodic tasks, each having a period and ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: a toolset for specifying and analyzing real-time systems. In IEEE Real-Time Systems Symposium, 1993.

....languages for specifying and programming the system. These issues are important in order to manage the complexity of engineering increasingly large systems. Some of these issues, such as specification languages and verification, have already been addressed by the SARTOR project in the past [CHLR93] Our methodology pays attention to all these concerns, including the more pragmatic ones, while satisfying reasonable separation of concerns in the following issues: ffl Structural organization: both implementation based (mapping to a set of resources such as processors and network) and ....

....minor modifications. Modechart is a state based language designed for the specification of the behavior of real time systems. Modechart has been applied to a number of applications and a set of tools has been developed for editing, simulating, analyzing and implementing Modechart specifications [CHLR93, PMS95b] From the practical point of view, the concerns are suitability of the language for specification, programming and implementation of large scale real time systems. From the analytical point of view, the concerns are its formal semantics 11 and the suitability for formal analysis, as ....

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P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A.T. Rose. MT: A toolset for specifying and analyzing real--time systems. In Proceedings of the IEEE Real-Time Systems Symposium, pages 12--22. IEEE Computer Society, December 1993. 163

....The description of the system is then compiled into a state transition graph which can be analyzed using several methods. A symbolic model checker allows the verification of untimed properties expressed in CTL[15] Time bounded properties can be verified using RealTime CTL model checking[10]. In addition, algorithms derived from symbolic model checking are used to compute quantitative information about the model[1] The information produced allows the user to check the temporal correctness of the model: schedulability of the tasks of the system can be determined by computing their ....

....is extremely expensive, limiting the size of problems that can be handled. Discrete time is used by other tools such as[11,13,22] The tool described in[22] also uses symbolic algorithms using BDDs. These tools, however, do not allow the quantitative analysis of systems as the proposed method. In[10] quantitative analysis is implemented, but with a more limited scope. Analytical methods for analyzing real time systems also exist, such as the rate monotonic scheduling theory[16,17,21] In this method a real time system is characterized by a set of periodic tasks, each having a period and an ....

[Article contains additional citation context not shown here]

P. Clements, C. Heitmeyer, G. Labaw, and A. Rose. MT: a toolset for specifying and analyzing real-time systems. In IEEE Real-Time Systems Symposium, 1993.

....a discrete time tool, since this may simplify verification, speeding it up considerably and possibly enabling the analysis of larger systems. Discrete time is used by other tools such as [16, 31] These tools, however, do not allow the quantitative analysis of systems as the proposed method. In [13] quantitative analysis is implemented, but with a more limited scope. Dense time models allowing restricted quantitative analysis can be found in [18, 30, 14] Linear time temporal logics interpreted over both infinite paths and finite intervals have been introduced in [21, 22] However, they use ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: a toolset for specifying and analyzing real-time systems. In IEEE Real-Time Systems Symposium, 1993.

....Texas at Austin Austin, TX 78712 1188 Abstract The Modechart specification language is a formalism for the specification of real time systems. A toolset for specification, analysis and simulation for Modechart specifications exists for supporting the design and construction of real time systems [CHLR93]. This paper introduces a new tool in the the toolset: a compiler for a class of Modechart specifications, namely, that of deterministic system specifications, extended by a subclass of the non deterministic system specifications. The object code that the compiler generates is in ESTEREL, a member ....

....use of hierarchical graphical formalisms to extend conventional state transition diagrams. However, the semantics of Modechart is defined axiomatically in terms of RTL (Real Time Logic [JM86] which is a logic especially amenable to reasoning about the absolute timing of events. A set of tools [CHLR93] has been developed for the specification and analysis of real time systems within the SARTOR environment, to which we now add implementation capabilities. In this paper we describe a compiler for the class of deterministic Modechart programs and a subset of the class of non deterministic ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A.T. Rose. "MT:A Toolset for Specifying and Analyzing Real--Time Systems ". In Proceedings of the IEEE Real-Time Systems Symposium, pages 12--22, December 1993.

....happened concurrently in the system at time t. Modechart does not have built in constructs to explicitly express run time resource requirements. However, some run time resource requirements may be encoded in Modechart through the enabling conditions. For an example, the reader is referred to [CHLR93] where part of a missile system along with the operating system are modeled in Modechart. In this example, the scheduler part of the operating system is encoded as a mode that executes in parallel along with the missile system application. The scheduler mode is itself a parallel mode where ....

....to add the notion of prioritized modes. STARTOR and MT are two toolsets that have been built based on Modechart. STARTOR [HL91] is an experimental toolset to build and prove properties about hard real time software and is based on Modechart to describe the functional view of the software. MT [CHLR93, RPC94] is another toolset that has been developed for the specification, verification, and simulation of real time systems using a subset of Modechart. In MT, one can write a Modechart specification and an RTL formula that describes system properties, such as safety properties, and automatically ....

P.C. Clements, C.L. Heitmeyer, B.G. Labaw, and A. T. Rose. Mt: A toolset for specifying and analyzing real-time systems. In Proc. of the Real-Time Systems Symposium, pages 12--22, Raleigh-Durham, North Carolina, December 1-3 1993.

....instant that the predicate changes values it is considered both true and false. As a result, if MOVEUP were not split into two modes, setting APP to false would both cause the gate to begin to move up, and then immediately start down. 13.5. 2 HARM Mailbox The HLCS (Harm Low Cost Seeker) system [18] is an attempt to design a low cost guidance package for the HARM (High speed Anti Radiation Missile) an anti radar missile. Included in the project is an attempt to design a new avionics package. The Naval Research Laboratory has used Modechart to model this system [19] The next two examples ....

....process, many of these algorithms have been implemented in the tools XMCVFY and XSVT, which allow users to generate computation graphs and simulation verification graphs for a subset of Modechart, and evaluate various queries using the graphs. The first of these tools is part of the MT toolset [18], developed by Dr. Aloysius Mok s Real Time Systems group at the University of Texas at Austin, together with Connie Heitmeyer s group at the Naval Research Laboratory. 15.2 Related Work Formal specification and verification techniques for real time systems is an area of active research. This ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proc. IEEE Real-Time Systems Symposium, December 1993.

....the specification, validating expectations about typical behaviors, and verifying the correctness of the specification over all behaviors. More detailed information about the Modechart specification language can be found in [JLM88] and [JM94] Simulating Modechart specifications is covered in [CHLR93]. The theoretical framework for the verifier is in [JS88] and [Stu90] Finally, RPC94] is a detailed user s guide for the Modechart Toolset. In the introduction, a methodology was proposed envisioning specification, verification and validation as a collaborative process involving the user and ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proc. IEEE Real-Time Systems Symposium, December 1993.

....languages for specifying and programming the system. These issues are important in order to manage the complexity of engineering increasingly large systems. Some of these issues, such as specification languages and verification, have already been addressed by the SARTOR project in the past [4]. Our methodology pays attention to all these concerns, including the more pragmatic ones, while satisfying reasonable separation of concerns in the following issues: ffl Structural organization: both architecture based (mapping to a set of resources such as processors and network) and ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. Rose. MT: A toolset for specifying and analyzing real--time systems. In Proceedings of the IEEE Real-Time Systems Symposium, pages 12--22. IEEE Computer Society, December 1993.

....on Real Time Logic (RTL) JM86] are assertions that have to be met at runtime. The constraints are monitored at run time as new events are generated, and are examined to detect violations. The approach in [JRR94] has been used to check the simulation of an executable specification in [RS94] [CHLR93], and [Jah95] Features in [JM86] have also been folded into an application development language in [GKS95] where the authors extend C with RTL like mechanisms for specifying and (run time) monitoring of timing constraints. An abstract model for performance visualization of complex systems that ....

P. Clements, C. Heitmeyer, B. Labaw, and A. Rose, "MT: A Toolset for Specifying and Analyzing Real-Time Systems", Proceedings of The IEEE Real-Time Systems Symposium, 12-22, December, 1993.

....are satisfied by the model, without providing any quantitative information. Other SMC based techniques have been extended to deal with real time systems [13, 30] but only determine if the properties are satisfied by the model, or provide limited quantitative information about the system [14]. Some verification tools adopt a continuous time approach [1, 21] contrary to Verus, which uses discrete time. Although continous time approach allows a more accurate measurement of time, it demands a larger space to represent the model. This demand makes modeling complex systems very ....

P. Clements, C. Heitmeyer, G. Labaw, and A. Rose. MT: a toolset for specifying and analyzing real-time systems. In IEEE Real-Time Systems Symp., 1993.

....graphical formalisms to extend conventional state transition diagrams. Modechart adds absolute and relative timing semantics to Statecharts transitions. A set of tools has been developed for the specification, analysis and implementation of real time systems within the Modechart framework [Clements et al. 1993, Puchol et al. 1995] Modechart specifications are made up of modes and transitions. Modes can be thought of as hierarchical partitions of the state space, and can be combined by using parallel or serial composition. The most basic modes are called atomic modes. A serial relationship among ....

Clements, P. C., Heitmeyer, C. L., Labaw, B. G., and Rose, A. (1993). MT: A toolset for specifying and analyzing real--time systems. In Proceedings of the IEEE Real-Time Systems Symposium, pp. 12--22.

....and software developers, and is easy to use and modify. The initial language lacked an underlying formal semantics. A number of semantics have been proposed [5, 30, 26, 54, 62] some of which became bases of tools performing consistency and completeness checks [31] and enabling simulations [21, 55] of requirements. In this section we briefly describe SCR behavioral requirements and environmental assumptions. A more formal description can be found in [31] The SCR model is used to specify reactive systems. The environment contains monitored and controlled variables. Monitored variables are ....

P. Clements, C. Heitmeyer, B. Labaw, and A. Rose. "MT: A Toolset for Specifying and Analyzing Real-time Systems". In Proceedings of Real-Time Systems Symposium, Raleigh, NC, December 1993.

....time interval, as indicated above, the theorem proving component of the SDE was used to prove that selected portions of the requirements held for all constant values and for all times. 4. Related Work A number of other development environments are available for other specification languages. MT [Clements et al. 1993] is an integrated development environment for the Modechart language, which incorporates components similar to those of the SDE. It includes the ability to hierarchically traverse specifications and invoke the editor on the displayed portion. MT s Consistency and Completeness Checker is similar in ....

Clements, P.C., C.L. Heitmeyer, B.G. Labaw, and A.T. Rose (1993), "MT: A Toolset for Specifying and Analyzing Real-Time Systems," Proceedings of the Real-Time Systems Symposium, IEEE Computer Society Press, Los Alamitos, CA, pp. 12-22.

....might be possible to encode the run time resource requirements with the functional requirements in these languages as events or boolean conditions, the resulting specification may be complex and hard to modify. For an example, the reader is referred to the description of the Modechart toolset MT [7] where several tasks of a missile system are modeled together with a cpu allocation. Further, the above languages lack an equivalence relation that can be used to verify the correctness of a specification with respect to another, e.g. expressing system requirements. 6.2 The Production Cell Among ....

P.C. Clements, C.L. heitmeyer, B.G. Labaw, and A. T. Rose. Mt: A toolset for specifying and analyzing real-time systems. In Proc. of IEEE Real-Time Systems Symposium, pages 12--22, Raleigh-Durham, North Carolina, December 1-3 1993.

....cannot all be known a priori. The work is important to us though in that it defines a class of constraints specifiable and monitorable by our tool. The Monitoring and Assertion tool (MAC) 4] is a formal analysis technique for monitoring symbolic execution traces generated by the Modechart Toolset [5]. It provides a mechanism for evaluating properties of the system on a particular execution trace. Leveson s work in the early 1980 s [21] is early recognition of the need for run time checking for hazard prevention. Her synchronous approach, though, requires embedding constraints in the ....

....added initially. Language oriented tasks in addition to implementing the complier include exploring the specification of hazards that occur over time (e.g. temperature rising too fast) We are also comparing SafeTQuel to specification languages suitable for safety critical systems (e.g. MT [5] and RSML [20] This comparison will establish the suitability of a query language for constraint specification. 6.2 Future Work There are several avenues of long term pursuit. We would like to apply hazard detection to a virtual environment, where hazards still have meaning though in a less ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proceedings IEEE Real-Time Systems Symposium, December 1993.

....reasoning about the absolute timing of events. The second is an operational semantics [13] which captures a more computational and intuitive approach to the language. A set of tools has been developed for the specification, analysis and implementation of real time systems within this framework [14, 15]. Modechart specifications are made up of modes and transitions. Modes can be thought of as hierarchical partitions of the state space, and can be combined by using parallel or serial composition. The most basic modes are called atomic modes. A serial relationship among several modes indicates ....

P.C. Clements, C. L. Heitmeyer, B. G. Labau, and A. T. Rose, "MT: A toolset for specifying and analyzing real-time systems", IEEE Real-Time Systems Symposium, December 1993.

....it might be possible to encode the run time resource requirements as boolean conditions using formalisms without explicit notions of resources, the resulting specification is often complex and hard to modify. For an example, the reader is referred to the description of the Modechart toolset MT [5] where several tasks of a missile system are modeled together with a cpu allocation. In addition, the development of the GCSR language is motivated by two other concerns: one is to support the modular, hierarchical, and thus, scalable specification of real time systems; the other is to benefit ....

P.C. Clements, C.L. Heitmeyer, B.G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proc. of the RealTime Systems Symposium, pages 12--22, RaleighDurham, North Carolina, December 1-3 1993.

....of real time programs. Such questions may include minimum and maximum delays between events in the program, as well as questions about the concurrency behavior of the program (e.g. freedom from deadlock and absence of starvation) To date, very few tools exist that can answer these questions [8, 9, 21, 22, 35]. All existing approaches and the corresponding tools are very sensitive to program size, due to the computational complexity of the analysis. Our approach to the analysis of real time programs uses a timed extension of Petri nets, which we call a Simple Time Petri net (or STP net) for modeling ....

....then T 1 is blocked for at most d time units. If T 2 does not accept the call within this time, then T 1 s call is canceled, and T 1 executes the delay alternative instead. Figure 2 shows a net fragment illustrating our modeling of timed entry calls. Each place is labeled by a t 1 [10] t 2 [8] t 5 [0] t 6 [0] t 4 [0] t 3 [0] p 6 p 3 p 7 p 1 p 2 p 5 p 4 p 8 p 10 p 9 Figure 2: STP net fragment modeling Ada timed entry call statement. place name, and each transition is labeled by a transition name, followed by a static firing delay in square brackets. Places p 1 , p 2 , and p 3 represent ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proceedings Real-Time Systems Symposium, pages 12--22. IEEE, December 1993.

....diagrams. Modechart adds absolute and relative timing semantics to Statecharts transitions. Its semantics is defined in terms of RTL (Real Time Logic [JM86] which is a logic especially amenable to reasoning about the absolute timing of events. A set of tools has been developed [CHLR93] for the specification and analysis of real time systems within this framework. Modechart specifications are made up of modes and transitions. Modes can be thought of as hierarchical partitions of the state space, and can be combined by using parallel or serial composition. The basic modes are ....

P.C. Clements, C. L. Heitmeyer, B. G. Labau, and A. T. Rose. MT: A toolset for specifying and analyzing realtime systems. IEEE Real-Time Systems Symposium, December 1993.

....obtuse descriptions, and this has impeded their application within industrial settings, and 2) their manual application to realistic problems is time consuming and error prone. As a result, many formalisms have adopted graphical notation [15] 17] 27] and are supported by automated tools [9] [10], 12] 21] 25] 26] that perform tasks such as syntax checking, semantic equivalences (e.g. CWB[9] for CCS) or pre orders checking (e.g. FDR [12] for CSP) model checking (e.g. MT [10] for Modecharts and the TTM RTTL verifier[25] and interactive execution. To avoid the mathematical ....

.... many formalisms have adopted graphical notation [15] 17] 27] and are supported by automated tools [9] 10] 12] 21] 25] 26] that perform tasks such as syntax checking, semantic equivalences (e.g. CWB[9] for CCS) or pre orders checking (e.g. FDR [12] for CSP) model checking (e.g. MT [10] for Modecharts and the TTM RTTL verifier[25] and interactive execution. To avoid the mathematical notation and facilitate the use of ACSR by practitioners that are not necessarily experts in process algebras, we have developed the Graphical Communicating Shared Resources (GCSR) 4] language. ....

P.C. Clements, C.L. Heitmeyer, B.G. Labaw, and A. T. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proc. of the IEEE RealTime Systems Symposium, pages 12--22, RaleighDurham, North Carolina, December 1-3 1993.

....difficulties can be avoided by performing monitoring and assertion checking in the context of a simulation of the behavior of the system under development. In this paper, we describe the incorporation of a monitoring and assertion checking tool into the Modechart Toolset. The Modechart Toolset (MT)[4] is a collection of integrated tools developed by the Naval Research Laboratory together with researchers from the University of Texas to address these challenges. MT supports the formal specification of real time behavior for distributed systems in a language called Modechart [5] and formal ....

P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose, "MT: A toolset for specifying and analyzing real-time systems," in Proc. IEEE Real-Time Systems Symposium, December 1993.

....coverage, determinism, and other application independent properties. The next step is to symbolically execute the specification, using a simulator, to ensure that it captures the developer s intent; the simulator can be run either manually, or automatically using an input script (see, e.g. [3]) In the later stages of requirements, the developer uses mechanical support to analyze the specification for application properties. Initially, he extracts a small subset with fixed parameters and only a few states from the specification and uses a model checker. This may be repeated, each time ....

P. Clements, C. Heitmeyer, B. Labaw, and A. Rose. MT: A toolset for specifying and analyzing real-time systems. In Proc., Real-Time Systems Symp., Raleigh, NC, December 1993.

....for readability. The Modechart development and analysis environment A suite of software engineering environment tools to facilitate use of the Modechart language is under development at the University of Texas at Austin [7] as well as at the U. S. Naval Research Laboratory in Washington [1] 2] [3]. A software engineer will have at his or her disposal the following major facilities available under the Modechart environment: a sophisticated graphical user interface for entering a modechart, displaying it, searching it, navigating through it, modifying it, and analyzing it [4] a ....

Clements, P., C. Heitmeyer, B. Labaw, and A. Rose, "MT: A Toolset for Specifying and Analyzing Real-Time Systems", Proceedings, 1993 Real-Time Systems Symposium, Durham, NC, December 1993.

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P. C. Clements, C. L. Heitmeyer, B. G. Labaw, and A. T. Rose. "MT: A Toolset for Specifying and Analyzing Real-Time Systems," Real-Time System Symposium, Lake Buena Vista, FL, December 1990.

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