I. Lee and V. Gehlot, "Language constructs for distributed real-time programming, " Proc Real-Time Systems Symposium, pp57-65, IEEE Computer Society Press, 1985.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of a system at the level of CA actions by means of both deadline and time triggered mechanisms. We will also represent temporal behaviour, where necessary, at the object and thread level. In this section we introduce a general framework that is an extension of the notion of a temporal scope [Lee Gehlot 1985][Burns Wellings 1997] Note that our model is more general than will often be needed, but is used here for expository proposes. We distinguish between time triggered and event triggered CA actions A time triggered temporal scope may have the following declaration: period T p , start[t0, t1] ....

I. Lee and V. Gehlot, "Language constructs for distributed real-time programming, " Proc Real-Time Systems Symposium, pp57-65, IEEE Computer Society Press, 1985.

....Shared Resources with Value Passing) This section presents the syntax and operational semantics of ACSR VP[2] which is an extension of ACSR. ACSR is a timed process algebra based on the synchronization model of CCS that includes features for representing synchronization, time, temporal scopes [9], resource requirements, and priorities. Although the time domain of ACSR can be either discrete [3] or dense [8] this paper uses discrete time exclusively since the systems we are modeling are typically scheduled using clocks with discrete granularities. Primitive actions consists of two kinds ....

I.Lee and V.Gehlot, Language Constructs for Distributed Real-Time Programming. In Proc. IEEE RealTime Systems Symposium, 1985.

....time of the method, and a set of temporal scopes, each of which defines absolute timing constraints on part of the method s execution. A temporal scope is usually represented by an absolute earliest start time, an absolute latest start time, and an absolute latest complete time (deadline) [Lee85]. This timing information is determined by the timing constraints imposed on the transaction that invokes the method. A method invocation also inherits a priority from the transaction that invokes it. Since each attribute of an object has fields representing value and timestamp, read and write ....

Lee, I., and Vijay Gehlot, "Language Constructs for Distributed Real-Time Programming," Proceedings of the 6th IEEE Real-Time System Symposium, December 1985.

....time to pass during the event occurrence. The Choice operator P Q represents possible executions either of the enabled processes may be chosen to execute. The operator PkQ is the parallel composition of P and Q. The Scope construct P 4 a t (Q; R; S) binds the process P by a temporal scope [LG85] and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [ f1g (i.e. t is either a non negative integer or infinity) The scope may be exited in a number of ways. First, if P successfully terminates before t time units by executing an event ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

.... either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope[14], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [f1g (i.e. t is either a non negative integer or infinity) P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....analysed are those that are relevant to the actual control path being studied. Many proposals express timing constraints as attributes of program blocks. For instance, the Distributed Programming System (DPS) uses temporal scopes which associate constraints with sequences of program statements [9]. Timing constraints can be placed on the starting and finishing time of code blocks and may refer to relative or absolute times. For example, a requirement that a sequence of statements A starts no earlier than absolute time T , and finishes no later than absolute time U , is expressed in DPS as ....

I. Lee and V. Gehlot. Language constructs for distributed real-time programming. In Proceedings of the IEEE Real-Time Systems Symposium, pages 57--66. IEEE, 1985.

....of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [6] of duration t, and incorporates both the features of timeouts and interrupts. The close operator, P ] I , produces a process that monopolizes the resources in I R. The restriction operator, PnF , limits the behavior of P by disallowing any externally observable events with labels in F . The ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . Note that in ACSR, execution of events can be interleaved while actions are executed synchronously by the processes in the parallel operator. The Scope construct P 4 (b;n) t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [20], and incorporates both the features of timeouts and interrupts. P executes for a maximum of t 2 NN [f1g time units. The scope may be exited in three ways. First, if P successfully terminates within time t by executing an event labeled with b, then control proceeds to the ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....nondeterminism either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope[8], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [f1g (i.e. t is either a non negative integer or infinity) P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....preference priority scheme is of less value. The lack of explicit deadline scheduling control in Ada requires that the run time scheduler assume the responsibility of deadline maintenance. Some real time languages which do provide such support include Real Time Euclid [KS86] PEARL [WW85] and DPS [LG85]. When using these languages, the run time scheduler is much easier to implement; in fact, such a scheduler may even utilize a static priority scheme. Once the deadlines associated with each process in a real time system have been determined, a schedule compatible with these deadlines must be ....

I. Lee and V. Gehlot. "Language Constructs for Distributed Real-Time Programming," Proceedings of the Real-Time Systems Symposium, San Diego, CA, Dec 1985, pp 57-66.

....the paper and reports on our current research within the ACSR paradigm. II. Formalism A. ACSR ACSR (Algebra of Communicating Shared Resources) is a timed process algebra based on the synchronization model of CCS that includes features for representing synchronization, time, temporal scopes [20], resource requirements, and priorities. Although the time domain of ACSR can be either discrete [19] or dense [5] this paper and the GCSR XVERSA toolset use discrete time exclusively. The ACSR paradigm is based on the view that a real time system consists of a set of communicating processes that ....

....The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . Note that in ACSR, execution of events can be interleaved while actions are executed synchronously by the processes in the parallel operator. The Scope construct P 4 b t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [20], and incorporates both the features of timeouts and interrupts. P executes for a maximum of t 2 NN [ f1g time units. The scope may be exited in three ways. First, if P successfully terminates within time t by executing an event labeled with b, then control proceeds to the ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....Divergent paths represent alternative computation paths allowed for the system. 2. 2 ACSR ACSR (Algebra of Communicating Shared Resources) is a timed process algebra based on the synchronization model of CCS that includes features for representing synchronization, time, temporal scopes [9], resource requirements, and priorities. The ACSR paradigm is based on the view that a real time system consists of a set of communicating processes that execute on a finite set of serially reusable resources and synchronize with one another through communication channels. The use of shared ....

....The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . Note that in ACSR, execution of events can be interleaved while actions are executed synchronously by the processes in the parallel operator. The Scope construct P 4 b t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [9], and incorporates both the features of timeouts and interrupts. P executes for a maximum of t 2 NN [f1g time units. The scope may be exited in three ways. First, if P successfully terminates within time t by executing an event labeled with b, then control proceeds to the ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [LG85], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 D T . P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within time t by executing an event labeled with a, then control ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....Divergent paths represent alternative computation paths allowed for the system. 2. 2 ACSR ACSR (Algebra of Communicating Shared Resources) is a timed process algebra based on the synchronization model of CCS that includes features for representing synchronization, time, temporal scopes [9], resource requirements, and priorities. The ACSR paradigm is based on the view that a real time system consists of a set of communicating processes that execute on a finite set of serially reusable resources and synchronize with one another through communication channels. The use of shared ....

....The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . Note that in ACSR, execution of events can be interleaved while actions are executed synchronously by the processes in the parallel operator. The Scope construct P4 b t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [9], and incorporates both the features of timeouts and interrupts. P executes for a maximum of t 2 NN [ f1g time units. The scope may be exited in three ways. First, if P successfully terminates within time t by executing an event labeled with b, then control proceeds to the exceptionhandler ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....schedulability analysis. DICON DPS satisfies every requirement listed in the previous section for real time programming languages so let us look at it in further detail. 3. 3 DICON DPS Language Model DPS (distributed programming system) and DICON (distributed configuration specification language) [Lee85] fulfill all the criteria listed for real time languages. DICON is a very high level specification language and DPS provides a supporting environment and tools package for developing and running DICON programs. DICON defines distributed static processes that declare how they should be activated. ....

I. Lee, V. Gehlot. Language Constructs for Distributed Real Time Programming. Proceedings of the IEEE 1985 Real Time Systems Symposium, 1985, pp 57-66.

....like the strong choice) and therefore it loses the higher level constructs such as timeout. 3 ACSR Actions The Algebra of Communicating Shared Resources is a timed process algebra based on the synchronization model of CCS and that includes features for representing dense time, temporal scopes [7], resources, and priorities. ACSR uses two distinct types of actions to model computation: time and resource consuming actions, called timed actions, and instantaneous actions, called events. 3.1 Resource Consuming and Timed Actions A system in ACSR is composed of a finite set of serially ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE RealTime Systems Symposium, 1985.

....or like Q. The choice is made based on the first execution steps of P and Q. The construct PkQ represents the parallel composition of the two processes P and Q whereby they may proceed independently or may synchronize. The Scope construct P 4 a t (Q; R; S) binds the process P by a temporal scope [Lee85], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [ f1g (i.e. t is either a non negative integer or infinity) The scope may be exited in a number of ways. First, if P successfully terminates before t time units by executing an event ....

I. Lee and V. Gehlot. Language constructs for distributed real-time programming. In Proc. of Real-Time Systems Symposium (RTSS' 85), 1985.

....external event, without aborting the entire task. Ada is the first language proposed for international standardization to provide such a construct, though several languages have previously provided features limiting statement level constructs to specific amounts of real or execution time [3, 5, 9, 10]. The syntax of the asynchronous select statement is select triggering statement [ triggered statements ] then abort abortable part end select; The triggering statement specifies the event that will abort the abortable part. It can be either an entry call or a delay statement. Either of ....

Insup Lee and Vijay Gehlot. Language constructs for distributed real-time programming. In Proceedings of the Real-Time Systems Symposium, San Diego, California, December 1985.

.... implementations[50] the runtime adjustment of individual object parameters[56] or of structural properties of sets of communicating objects[1] Compiler based techniques for runtime configuration have included the dynamic synthesis of program code[46] and the re direction of procedure calls[40]. Our research builds on and partly extends past work in configurable systems. Our aim is not to explore specific configuration techniques, but instead, to attain improved performance in parallel programs by giving programmers user or kernel level libraries with which they may construct ....

I. Lee and V. Gehlot. Language constructs for distributed real-time programming. In Proc. of the 6th Real-Time Systems Symposium, San Diego, CA, pages 57--66. IEEE, Dec. 1985.

..... code code A code . code . end milestone milestone milestone milestone Figure 1 Milestone in a task 3. THE APPROACH To provide a more adequate environment for real time systems a possible approach is to express those constraints directly in the structure of the program [4, 5, 6, 7]. The rationale for such an approach is that efficiency in producing the results depends basically on the time constraints involved; and that the amount of resources available in the system may be changed during the execution (due to maintenance or a fault) This time constraints specification ....

I. Lee and V. Gehlot, "Language Constructs for Distributed Real-Time Programming ", Proceedings Real-Time Systems Symposium, San Diego, California, pp. 5766 (December 1985).

....P Q represents nondeterminism either of the processes may be chosen to execute, subject to the constraints of the environment and preemption relation. The operator PkQ is the parallel composition of P and Q. The Scope construct P 4 a t (Q; R; S) binds the process P by a temporal scope [22], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [ f1g (i.e. t is either a non negative integer or infinity) P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....nondeterminism either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope[20], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [f1g (i.e. t is either a non negative integer or infinity) P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, pages 57--66. IEEE Computer Society Press, December 1985.

....of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [LG85], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 D T . P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within time t by executing an event labeled with a, then control ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . Note that in ACSR, execution of events can be interleaved while actions are executed synchronously by the processes in the parallel operator. The Scope construct P4 b t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [8], and incorporates both the features of timeouts and interrupts. P executes for a maximum of t 2 NN [ f1g time units. The scope may be exited in three ways. First, if P successfully terminates within time t by executing an event labeled with b, then control proceeds to the success handler ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....for the next cycle. After the process gets access to the resource, it lowers its priority. The lowest priority process, P [0] cannot decrease its priority any further, while P [5] cannot increase it. The Scope construct P 4 a t (Q; R; S) binds the execution of process P by a temporal scope [34], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t is either a non negative integer or infinity. The scope may be exited in a number of ways. First, if P successfully terminates before t time units by executing an output event labeled with a, then ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proceedings of IEEE Real-Time Systems Symposium, 1985.

.... either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [15], and incorporates the features of both timeouts and interrupts. We call t the time bound, where t 2 Z Z [ f1g. P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within time t by executing an event labeled with a, then ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....algebras with either value passing or dynamic priorities. 3 ACSR with Value Passing 3. 1 Syntax ACSR (Algebra of Communicating Shared Resources) is a timed process algebra based on the synchronization model of CCS that includes features for representing synchronization, time, temporal scopes [LG85], resource requirements, and priorities. Although the time domain of ACSR can be either discrete [LBGG94] or dense [BG94] this paper uses discrete time exclusively since the systems we are modeling are typically scheduled using clocks with discrete granularities. The domain of time is therefore ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....resources allotted to E, and J R is a set of the resource allotted to F . In the case where I J 6= E and F may be able to share certain resources. But as we have stated, such resource sharing must be interleaved. The Scope construct E4 B t (F; G; H) binds the term E by a temporal scope (Lee and Gehlot, 1985), and it incorporates both the features of timeouts and interrupts. We call t the time bound and B the termination control, where t 2 NN [ f1g (i.e. t is either a positive integer or infinity) and B = f p g or B = While E is executing we say that the scope is active. The scope can be ....

Lee, I., and Gehlot, V. (1985), Language constructs for distributed real-time programming, in "Proc. IEEE Real-Time Systems Symposium," IEEE Computer Society Press, Los Alamitos.

....under grant number N00014 89 J 1040 and by a Graduate Research Fellowship from the Clare Boothe Luce Foundation. 1 Introduction Timing constraints for real time systems are typically expressed with respect to processing, for example, period, release time, and deadline of a task, and delay [12, 16, 17]. These constraints are often applied in the context of designs based on periodic processing. Working with timing constraints only for processing, however, complicates some aspects of real time system design. Data dependencies between processes with different periods lead to timing interactions ....

....damage assessment (fault containment) 3) recovery, and (4) repair and return to service. Timing fault detection has been an active research issue in real time systems. Mechanisms for the expression and monitoring of constraints on program execution time have been widely investigated, e.g. in [5, 12, 16, 17, 21, 23]. These mechanisms in isolation provide only for timing error detection, and this detection is localized to the erroneous process where a timing exception is typically raised. No inherent assistance is provided for damage assessment, recovery, or return to service. Periodic objects extend the ....

Lee, Insup, and Vijay Gehlot, "Language Constructs for Distributed Real-Time Programming, " Proc. of the Real-Time Systems Symposium, IEEE Comp. Soc. Press, 1985, pp. 57-66.

....nondeterminism either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope[15], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 Z Z [ f1g. P executes for a maximum of t time units. The scope may be exited in a number of ways. First, if P successfully terminates within time t by executing an event labeled with a, then ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

.... either of the processes may be chosen to execute, subject to the event offerings and resource limitations of the environment. The operator P 1 kP 2 is the concurrent execution of P 1 and P 2 . The Scope construct P 4 a t (P 1 ; P 2 ; P 3 ) binds the process P by a temporal scope [16], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 DT . P executes for a maximum of t time units. The scopemay be exited in a number of ways. First, if P successfully terminates within time t by executing an event labeled with a, then control ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

....time to pass during the event occurrence. The Choice operator P Q represents possible executions either of the enabled processes may be chosen to execute. The operator PkQ is the parallel composition of P and Q. The Scope construct P 4 a t (Q; R; S) binds the process P by a temporal scope [12], and incorporates both the features of timeouts and interrupts. We call t the time bound, where t 2 NN [ f1g (i.e. t is either a non negative integer or infinity) The scope may be exited in a number of ways. First, if P successfully terminates before t time units by executing an event ....

I. Lee and V. Gehlot. Language Constructs for Distributed Real-Time Programming. In Proc. IEEE Real-Time Systems Symposium, 1985.

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I. Lee and V. Gehlot, Language constructs for distributed real-time programming, Proc. Real-Time Systems Symposium, pp. 57--66, San Diego, California, December 1985.

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I. Lee and V. Gehlot, "Language Constructs for Distributed Real-Time Programming", Proceedings of the 1985 Real-Time Systems Symposium, pp 57-66, IEEE Computer Society Press, 1985.

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I. Lee and V. Gehlot. Language constructs for distributed real-time programming. In Proc. of the 6th Real-Time Systems Symposium, San Diego, CA, pages 57--66. IEEE, Dec. 1985.

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