Nianen Chen

Checkpoint Interval and System's Overall Quality for Message Logging-Based Rollback and Recovery in Distributed and Embedded Computing

In distributed environment, message logging based checkpointing and rollback recovery is a common... more In distributed environment, message logging based checkpointing and rollback recovery is a commonly used approach for providing distributed systems with fault tolerance and synchronized global states. Clearly, taking more frequent checkpointing reduces system recovery time in the presence of faults, and hence improves the system availability; however, more frequent checkpointing may also increase the probability for a task to miss its deadlines or prolong its execution time in faultfree scenarios. Hence, in distributed and real-time computing, the system's overall quality must be measured by a set of aggregated criteria, such as availability, task execution time, and task deadline miss probability. In this paper, we take into account state synchronization costs in the checkpointing and rollback recovery scheme and quantitatively analyze the relationships between checkpoint intervals and these criteria. Based on the analytical results, we present an algorithm for finding an optimal checkpoint interval that maximizes system's overall quality.

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A Non-Intrusive Approach to Enhance Legacy Embedded Control Systems with Cyber Protection Features

Springer eBooks, 2009

Architecture Support for Behavior-based Adaptive Checkpointing

Journal of Software, Feb 1, 2008

Checkpointing is a commonly used approach to provide system fault-tolerance. However, using a con... more Checkpointing is a commonly used approach to provide system fault-tolerance. However, using a constant checkpointing frequency may compromise the system's overall performance when there are multiple types of QoS requirements involved. Hence, it is important that the checkpointing frequency is customizable and runtime adaptable. However, for open distributed and embedded applications, often there is a large number of entities involved in an application and these entities may join or leave the system frequently. The scale and the dynamicity make it difficult to apply the adaptive checkpointing strategy unless we have a model that encapsulates the issues within a well-defined structure and further shields complexity from application developers. In this paper, we introduce a behavior-based adaptive checkpointing approach for open systems and present an architecture support to optimize system's overall performance through using adaptive checkpointing frequencies.

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Using a role-based coordination model to achieve adaptive and quantifiable dependability for open distributed embedded systems

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The role of roles in supporting reconfigurability and fault localizations for open distributed and embedded systems

ACM Transactions on Autonomous and Adaptive Systems, Sep 1, 2007

One of the main characteristics of open distributed embedded systems is that the involved entitie... more One of the main characteristics of open distributed embedded systems is that the involved entities are often very dynamic-different individual entities may join or leave the systems frequently. Therefore, systems built of these dynamic entities must be runtime reconfigurable. In addition, large classes of open embedded systems often have high availability and dependability requirements. However, the openness makes these requirements more difficult to achieve and the system more vulnerable to attacks. This article presents a coordination model, the Actor, Role and Coordinator (ARC) model, that aims to support reconfigurability and fault localization for open distributed embedded software systems. In particular, the actor model is used to model concurrent embedded entities, while the system's reconfigurability and dependability requirements are encapsulated within coordination objects: roles and coordinators, and are achieved through coordination among the actors. Roles, as a key thrust in the ARC model not only represent an abstraction for a set of behaviors shared by This article is based on the paper "Reconfigurable Coordination Model for Dynamic Autonomous Real-Time Systems" by Shangping Ren, Limin Shen, and Jeffrey Tsai, which appears in the Proceedings of the IEEE International Conference on Sensor Networks, Ubiquitous, and Trustworthy Computing, 60-67.

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Profit and penalty aware (PP-aware) scheduling for tasks with variable task execution time

As computing devices and the Internet technology advances, real-time on-line services are emergin... more As computing devices and the Internet technology advances, real-time on-line services are emerging. Different from traditional real-time applications for which the scheduling objective is to meet task deadlines, the optimization goal for on-line service systems is to maximize profit obtained through providing timely services. For this class of applications, there are two distinctive characteristics: (1) tasks, i.e., client requests, are

1 Checkpointing Implementation for Real-time and Fault Tolerant Applications on RTAI

Checkpointing Rollback Recovery protocol is often used to provide fault tolerance for real-time a... more Checkpointing Rollback Recovery protocol is often used to provide fault tolerance for real-time applications. However, existing checkpointing implementations support only non-real-time applications as the checkpointing overhead is usually not deterministic. In this paper, we present an implementation of the checkpointing scheme with the Real-Time Application Interface (RTAI) supported by Linux, where services provided by the real-time operating system makes the checkpointing overhead, including the time to place a checkpoint and the time to recover the system from a failure, predictable.

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Checkpointing Implementation for Real-time and Fault Tolerant Applications on RTAI

A Role-Based Coordination Model and its Realization

Informatica (slovenia), 2008

This paper presents a framework to support Open Distributed and Embedded (ODE) application develo... more This paper presents a framework to support Open Distributed and Embedded (ODE) application development based on the Actor-Role-Coordinator (ARC) model. The ARC model is a role-based coordination model developed to address three main concerns inherent in an ODE system: dynamicity, scalability, and stringent QoS requirements. It treats an ODE system as a composition of concurrent computation and coerced coordination. In particular, the ARC model uses concurrent objects that communicate with each other through asynchronous messages, i.e., actors, to model the concurrent computation of an ODE system, while the system's QoS requirements are mapped to coordination constraints. Coordination entities, i.e., roles and coordinators, impose coordination constraints on concurrent actors transparently through message interceptions and manipulations. In the ARC model, roles provide actor behavior abstractions for coordinators and coordinators are responsible for coordinating roles. In addition, a role also has local coordination responsibilities among actors belonging to that role. This coordination is called intra-role coordination which complements the inter-role coordination performed by the coordinators. In other words, under the ARC model, an ODE application is modeled by three orthogonal layers: computation, intrarole coordination and inter-role coordination. This separation not only improves software modularity and reusability, but also allows different levels of compositions. Our experiments show that the model scales well as the number of entities involved in the system increases, and that the performance overhead introduced by the external coordination layers is limited. Povzetek: Opisano je ogrodje za model aktor-vloga-koordinator (ARC).

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A Workflow-Based Non-intrusive Approach for Enhancing the Survivability of Critical Infrastructures in Cyber Environment

Third International Workshop on Software Engineering for Secure Systems (SESS'07: ICSE Workshops 2007), 2007

The focus of this paper is on vulnerabilities which exist in Supervisory Control and Data Acquisi... more The focus of this paper is on vulnerabilities which exist in Supervisory Control and Data Acquisition (SCADA) systems. Cyber attacks targeting weaknesses in these systems can seriously degrade the survivability of a critical system. Detailed here is a non-intrusive approach for improving the survivability of these systems without interruption of their normal process flow. In a typical SCADA system, unsafe conditions are avoided by including interlocking logic code on the base system. This prevents conflicting operations from starting at inappropriate times, and provides corrective action or graceful shutdown of the system when a potentially unsafe condition is detected. If this code or these physical devices are manipulated remotely, the system can fail with unpredictable results. In the proposed approach, a workflow is constructed on a system outside of the attack path and separate from the process under control. The workflow is a combination of the functional behavior of a SCADA system and a model generated by cyber attack scenarios in that system. A cause and effect relationship of commands processed by the SCADA system is simulated in the workflow to help detect malicious operations. The workflow will then contain functional and survivability knowledge of the underlying system. Failures induced by the introduction of malicious logic will be predicted by simulating the fault in the workflow. Modeling these modes of failure will be valuable in implementing damage control. This model is event driven and conducts simulation externally, hence does not interfere with normal functionality of the underlying systems.

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A Non-Intrusive Approach to Enhance Legacy Embedded Control Systems with Cyber Protection Features

Machine Learning in Cyber Trust, 2009

Using a role-based coordination model to achieve adaptive and quantifiable dependability for open distributed embedded systems

Companion to the 21st ACM SIGPLAN conference on Object-oriented programming systems, languages, and applications - OOPSLA '06, 2006

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Building a Coordination Framework to Support Behavior-Based Adaptive Checkpointing for Open Distributed Embedded Systems

2007 40th Annual Hawaii International Conference on System Sciences (HICSS'07), 2007

Checkpointing is a commonly used approach to provide fault-tolerance and improve system dependabi... more Checkpointing is a commonly used approach to provide fault-tolerance and improve system dependability. However, using a constant and pre- configured checkpointing frequency may compromise other QoS criteria when there are resource and timing constraints. The frequency of checkpointing should be based on the importance of corresponding entities&#39; behaviors and should also be runtime adaptable. The paper presents a behavior-based coordination

Checkpoint Interval and System's Overall Quality for Message Logging-Based Rollback and Recovery in Distributed and Embedded Computing

2009 International Conference on Embedded Software and Systems, 2009

In distributed environment, message logging based checkpointing and rollback recovery is a common... more In distributed environment, message logging based checkpointing and rollback recovery is a commonly used approach for providing distributed systems with fault tolerance and synchronized global states. Clearly, taking more frequent checkpointing reduces system recovery time in the presence of faults, and hence improves the system availability; however, more frequent checkpointing may also increase the probability for a task to miss its deadlines or prolong its execution time in faultfree scenarios. Hence, in distributed and real-time computing, the system's overall quality must be measured by a set of aggregated criteria, such as availability, task execution time, and task deadline miss probability. In this paper, we take into account state synchronization costs in the checkpointing and rollback recovery scheme and quantitatively analyze the relationships between checkpoint intervals and these criteria. Based on the analytical results, we present an algorithm for finding an optimal checkpoint interval that maximizes system's overall quality.

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Adaptive optimal checkpoint interval and its impact on system's overall quality in soft real-time applications

Proceedings of the 2009 ACM symposium on Applied Computing, 2009

Soft real-time systems often have to consider both timing and probabilistic fault-tolerance requi... more Soft real-time systems often have to consider both timing and probabilistic fault-tolerance requirements. When checkpointing techniques are used for fault tolerance purposes, the checkpointing frequency unyieldingly affects the system&amp;#x27;s overall quality measured by an integrated value of system QoS properties, such as availability, task execution time, and task deadline miss probability. In this paper, we first formally analyze the relationships between checkpoint interval and system availability, task execution time, and task deadline miss probability, respectively by considering a Poisson probabilistic fault model. We further define the system&amp;#x27;s overall quality as a weighted sum of these three QoS measures, from which an optimization problem is formulated to decide the checkpoint interval that maximizes system&amp;#x27;s overall quality. Also presented in the paper are a prototype implementation of a framework that allows adaptive checkpointing and a set of experiments executed upon the framework that further validate our analytical results.

Profit and penalty aware (PP-aware) scheduling for tasks with variable task execution time

Proceedings of the 2010 ACM Symposium on Applied Computing, 2010

As computing devices and the Internet technology advances, real-time on-line services are emergin... more As computing devices and the Internet technology advances, real-time on-line services are emerging. Different from traditional real-time applications for which the scheduling objective is to meet task deadlines, the optimization goal for on-line service systems is to maximize profit obtained through providing timely services. For this class of applications, there are two distinctive characteristics: (1) tasks, i.e., client requests, are

Architecture Support for Behavior-based Adaptive Checkpointing

Journal of Software, 2008

Checkpointing is a commonly used approach to provide system fault-tolerance. However, using a con... more Checkpointing is a commonly used approach to provide system fault-tolerance. However, using a constant checkpointing frequency may compromise the system's overall performance when there are multiple types of QoS requirements involved. Hence, it is important that the checkpointing frequency is customizable and runtime adaptable. However, for open distributed and embedded applications, often there is a large number of entities involved in an application and these entities may join or leave the system frequently. The scale and the dynamicity make it difficult to apply the adaptive checkpointing strategy unless we have a model that encapsulates the issues within a well-defined structure and further shields complexity from application developers. In this paper, we introduce a behavior-based adaptive checkpointing approach for open systems and present an architecture support to optimize system's overall performance through using adaptive checkpointing frequencies.

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The Actor Role Coordinator Implementation Developer's Manual

The role of roles in supporting reconfigurability and fault localizations for open distributed and embedded systems

ACM Transactions on Autonomous and Adaptive Systems, 2007

One of the main characteristics of open distributed embedded systems is that the involved entitie... more One of the main characteristics of open distributed embedded systems is that the involved entities are often very dynamic—different individual entities may join or leave the systems frequently. Therefore, systems built of these dynamic entities must be runtime reconfigurable. In addition, large classes of open embedded systems often have high availability and dependability requirements. However, the openness makes these requirements more difficult to achieve and the system more vulnerable to attacks. This article presents a coordination model, the Actor, Role and Coordinator (ARC) model, that aims to support reconfigurability and fault localization for open distributed embedded software systems. In particular, the actor model is used to model concurrent embedded entities, while the system's reconfigurability and dependability requirements are encapsulated within coordination objects: roles and coordinators, and are achieved through coordination among the actors. Roles, as a key ...

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Actors, Roles and Coordinators — A Coordination Model for Open Distributed and Embedded Systems

Lecture Notes in Computer Science, 2006

This paper presents a coordination model, the Actor, Role and Coordinator (ARC) model, to address... more This paper presents a coordination model, the Actor, Role and Coordinator (ARC) model, to address three main concerns inherent in a pervasive Open Distributed and Embedded (ODE) system: dynamicity, scalability, and stringent QoS requirements. The model treats a pervasive ODE system as a composition of concurrent computation and coerced coordination. In particular, concurrent computation is modeled as Actors, while coerced

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