60197858
Self-Stabilizing Wormhole Routing on Ring Networks
Wormhole routing is most commonly used in parallel architectures in which messages are sent in small fragments, called flits. It is a lightweight and efficient method of routing messages between parallel processors. Self-stabilization is a technique that guarantees tolerance to transient faults (e.g., memory corruption or communication hazards) for a given protocol. Self-stabilization guarantees that the network recovers to a correct behavior in a finite amount of time, without the need for human intervention. Self-stabilization also guarantees the safety property, meaning that once the network is in a legitimate state, it will remain there until another fault occurs.
This paper presents the first self-stabilizing network algorithm in the wormhole routing model, using the unidirectional ring topology. Our solution benefits from wormhole routing by providing high throughput and low latency, and from self-stabilization by ensuring automatic resilience to all possible transient failures.
11950525
Anonymous publish/subscribe in P2P networks
One of the most important issues to deal with in peer-to-peer networks is how to disseminate information. In this paper, we use a completely new approach to solving the information dissemination problem. Our approach uses the publish/subscribe paradigm. The publish/subscribe method is the most inclusive strategy to establish communication between the information providers (publishers) and the information consumers (subscribers). We give a formal definition of publish/subscribe systems. We then use the publish/subscribe communication paradigm to design deterministic protocols (topic and content-based) for peer-to-peer networks. Our protocols are designed on top of an innovative information dissemination scheme, and can cope with the anonymity and mobility of both publishers and subscribers, weak-connectivity, and polarization, which are some of the characteristics of peer-to-peer networks. Moreover, in our solutions, every node could play a role of both publisher and subscriber The algorithms are designed completely independent of the underlying routing substrates. The key advantage of our protocols is that they are scalable without additional re-organization cost. To the best of our knowledge, this is the first time the content-based subscription has been addressed in peer-to-peer networks.
32186098
Buffer management in real-time active database systems
Real-time active database systems (RTADB) have attracted the attention of researchers in recent times. Such systems are envisioned as control systems for environments as diverse as process control, network management and automated financial trading. Sensors distributed throughout the system report the state of the system to the database. Unacceptable state reports typically results in corrective actions being triggered with deadlines. Thus RTADB's incorporate both real-time as well as active characteristics. We study buffer management in RTADB. Buffer management is recognized as not being a well studied area in real-time systems. As a result of our work, we postulate PAPER, a new buffer management scheme that relies on two strategies: prefetching and priority based buffer replacement. We report the result of studies of the performance of PAPER, as compared to that of existing buffer management algorithms. The insights derived from this paper impact both real-time database systems as well as real-time, active database systems.
2400545
Generating Boolean networks with a prescribed attractor structure
MOTIVATION
Dynamical modeling of gene regulation via network models constitutes a key problem for genomics. The long-run characteristics of a dynamical system are critical and their determination is a primary aspect of system analysis. In the other direction, system synthesis involves constructing a network possessing a given set of properties. This constitutes the inverse problem. Generally, the inverse problem is ill-posed, meaning there will be many networks, or perhaps none, possessing the desired properties. Relative to long-run behavior, we may wish to construct networks possessing a desirable steady-state distribution. This paper addresses the long-run inverse problem pertaining to Boolean networks (BNs).


RESULTS
The long-run behavior of a BN is characterized by its attractors. The rest of the state transition diagram is partitioned into level sets, the j-th level set being composed of all states that transition to one of the attractor states in exactly j transitions. We present two algorithms for the attractor inverse problem. The attractors are specified, and the sizes of the predictor sets and the number of levels are constrained. Algorithm complexity and performance are analyzed. The algorithmic solutions have immediate application. Under the assumption that sampling is from the steady state, a basic criterion for checking the validity of a designed network is that there should be concordance between the attractor states of the model and the data states. This criterion can be used to test a design algorithm: randomly select a set of states to be used as data states; generate a BN possessing the selected states as attractors, perhaps with some added requirements such as constraints on the number of predictors and the level structure; apply the design algorithm; and check the concordance between the attractor states of the designed network and the data states.


AVAILABILITY
The software and supplementary material is available at http://gsp.tamu.edu/Publications/BNs/bn.htm
7662147
Buffer management in real-time active database systems
Abstract Real-time, active database systems (RTADBSs) have attracted the attention of researchers in recent times. Such systems are envisioned as control systems for environments as diverse as process control, network management and automated financial trading. Sensors distributed throughout the system report the state of the system to the database. Unacceptable state reports typically result in corrective actions being triggered with deadlines. Thus RTADBSs incorporate both real-time as well as active characteristics. In this paper we study buffer management in RTADBSs. Buffer management is recognized as not being a well studied area in real-time systems. As a result of our work, we postulate (Prefetching Anticipatorily and Priority basEd Replacement) (PAPER), a new buffer management scheme that relies on two strategies: prefetching and priority based buffer replacement. We report the result of studies of the performance of PAPER, as compared to that of existing buffer management algorithms. The insights derived from this paper impact both real-time database systems as well as RTADBSs.
14006300
Abstraction and refinement in protocol derivation
Protocols may be derived from initial components by composition, refinement, and transformation. Adding function variables to a previous protocol logic, we develop an abstraction-instantiation method for reasoning about a class of protocol refinements. The main idea is to view changes in a protocol as a combination of finding a meaningful "protocol template" that contains function variables in messages, and producing the refined protocol as an instance of the template. Using higher-order protocol logic, we can develop a single proof for all instances of a template. A template can also be instantiated to another template, or a single protocol may be an instance of more than one template, allowing separate protocol properties to be proved modularly. These methods are illustrated using some challenge-response and key exchange protocol templates and an exploration of the design space surrounding JFK (just fast keying) and related protocols from the IKE (Internet key exchange) family, which produces some interesting protocols not previously studied in the open literature.
2213436
MANDATE: MAnaging Networks Using DAtabase TEchnology
There has been a growing demand for the development of tools to manage enterprise communication networks. A management information database is the heart of a network management system-it provides the interface between all functions of the network management system and, therefore, has to provide sophisticated functionality allied with high performance. The authors introduce the design of MANDATE (MAnaging Networks using DAtabase TEchnology), a proposed database system for effectively supporting the management of large enterprise networks. The MANDATE design makes a conscious attempt to take advantage of the special characteristics of network data and transactions, and of advances in database technology, to efficiently derive some of the required management functionality. >