Abstract: Elasticity is the essential property of cloud computing. As the name suggests, it constitutes the ability of a cloud system to adjust resource provisioning in relation to fluctuating workloads. There are two types of elasticity operations, vertical and horizontal. In this work, we are interested in horizontal scaling, which is ensured by two mechanisms; scaling in and scaling out. Following the sizing of the system, we can adopt scaling in the event of over-supply and scaling out in the event of under-supply. In this paper, we propose a formal model, based on temporized and colored Petri nets (TdCPNs), for the modeling of the duplication and the removal of a virtual machine from a server. This model is based on formal Petri Nets (PNs) modeling language. The proposed models are edited, verified, and simulated with two examples implemented in colored Petri nets (CPNs)tools, which is a modeling tool for colored and timed PNs.
Abstract: This paper develops a robust deadlock control technique for shared and unreliable resources in automated manufacturing systems (AMSs) based on structural analysis and colored Petri nets, which consists of three steps. The first step involves using strict minimal siphon control to create a live (deadlock-free) system that does not consider resource failure. The second step uses an approach based on colored Petri net, in which all monitors designed in the first step are merged into a single monitor. The third step addresses the deadlock control problems caused by resource failures. For all resource failures in the Petri net model a common recovery subnet based on colored petri net is proposed. The common recovery subnet is added to the obtained system at the second step to make the system reliable. The proposed approach is evaluated using an AMS from the literature. The results show that the proposed approach can be applied to an unreliable complex Petri net model, has a simpler structure and less computational complexity, and can obtain one common recovery subnet to model all resource failures.
Abstract: One major difficulty that faces developers of
concurrent and distributed software is analysis for concurrency based
faults like deadlocks. Petri nets are used extensively in the
verification of correctness of concurrent programs. ECATNets [2] are
a category of algebraic Petri nets based on a sound combination of
algebraic abstract types and high-level Petri nets. ECATNets have
'sound' and 'complete' semantics because of their integration in
rewriting logic [12] and its programming language Maude [13].
Rewriting logic is considered as one of very powerful logics in terms
of description, verification and programming of concurrent systems.
We proposed in [4] a method for translating Ada-95 tasking
programs to ECATNets formalism (Ada-ECATNet). In this paper,
we show that ECATNets formalism provides a more compact
translation for Ada programs compared to the other approaches based
on simple Petri nets or Colored Petri nets (CPNs). Such translation
doesn-t reduce only the size of program, but reduces also the number
of program states. We show also, how this compact Ada-ECATNet
may be reduced again by applying reduction rules on it. This double
reduction of Ada-ECATNet permits a considerable minimization of
the memory space and run time of corresponding Maude program.
Abstract: The UML modeling of complex distributed systems often is a great challenge due to the large amount of parallel real-time operating components. In this paper the problems of verification of such systems are discussed. ECPN, an Extended Colored Petri Net is defined to formally describe state transitions of components and interactions among components. The relationship between sequence diagrams and Free Choice Petri Nets is investigated. Free Choice Petri Net theory helps verifying the liveness of sequence diagrams. By converting sequence diagrams to ECPNs and then comparing behaviors of sequence diagram ECPNs and statecharts, the consistency among models is analyzed. Finally, a verification process for an example model is demonstrated.
Abstract: Colored Petri Nets (CPN) are very known kind of
high level Petri nets. With sound and complete semantics, rewriting
logic is one of very powerful logics in description and verification of
non-deterministic concurrent systems. Recently, CPN semantics are
defined in terms of rewriting logic, allowing us to built models by
formal reasoning. In this paper, we propose an automatic translation
of CPN to the rewriting logic language Maude. This tool allows
graphical editing and simulating CPN. The tool allows the user
drawing a CPN graphically and automatic translating the graphical
representation of the drawn CPN to Maude specification. Then,
Maude language is used to perform the simulation of the resulted
Maude specification. It is the first rewriting logic based environment
for this category of Petri Nets.
Abstract: One major difficulty that faces developers of
concurrent and distributed software is analysis for concurrency based
faults like deadlocks. Petri nets are used extensively in the
verification of correctness of concurrent programs. ECATNets are a
category of algebraic Petri nets based on a sound combination of
algebraic abstract types and high-level Petri nets. ECATNets have
'sound' and 'complete' semantics because of their integration in
rewriting logic and its programming language Maude. Rewriting
logic is considered as one of very powerful logics in terms of
description, verification and programming of concurrent systems We
proposed previously a method for translating Ada-95 tasking
programs to ECATNets formalism (Ada-ECATNet) and we showed
that ECATNets formalism provides a more compact translation for
Ada programs compared to the other approaches based on simple
Petri nets or Colored Petri nets. We showed also previously how the
ECATNet formalism offers to Ada many validation and verification
tools like simulation, Model Checking, accessibility analysis and
static analysis. In this paper, we describe the implementation of our
translation of the Ada programs into ECATNets.
Abstract: Wireless mobile communications have experienced
the phenomenal growth through last decades. The advances in
wireless mobile technologies have brought about a demand for high
quality multimedia applications and services. For such applications
and services to work, signaling protocol is required for establishing,
maintaining and tearing down multimedia sessions. The Session
Initiation Protocol (SIP) is an application layer signaling protocols,
based on request/response transaction model. This paper considers
SIP INVITE transaction over an unreliable medium, since it has been
recently modified in Request for Comments (RFC) 6026. In order to
help in assuring that the functional correctness of this modification is
achieved, the SIP INVITE transaction is modeled and analyzed using
Colored Petri Nets (CPNs). Based on the model analysis, it is
concluded that the SIP INVITE transaction is free of livelocks and
dead codes, and in the same time it has both desirable and
undesirable deadlocks. Therefore, SIP INVITE transaction should be
subjected for additional updates in order to eliminate undesirable
deadlocks. In order to reduce the cost of implementation and
maintenance of SIP, additional remodeling of the SIP INVITE
transaction is recommended.