The Raincore Distributed Session Service for Networking Elements

Motivated by the explosive growth of the Internet, we study efficient and fault-tolerant distributed session layer protocols for networking elements. These protocols are designed to enable a network cluster to share the state information necessary for balancing network traffic and computation load among a group of networking elements. In addition, in the presence of failures, they allow network traffic to fail-over from failed networking elements to healthy ones. To maximize the overall network throughput of the networking cluster, we assume a unicast communication medium for these protocols. The Raincore Distributed Session Service is based on a fault-tolerant token protocol, and provides group membership, reliable multicast and mutual exclusion services in a networking environment. We show that this service provides atomic reliable multicast with consistent ordering. We also show that Raincore token protocol consumes less overhead than a broadcast-based protocol in this environment in terms of CPU task-switching. The Raincore technology was transferred to Rainfinity, a startup company that is focusing on software for Internet reliability and performance. Rainwall, Rainfinity’s first product, was developed using the Raincore Distributed Session Service. We present initial performance results of the Rainwall product that validates our design assumptions and goals

Computing in the RAIN: a reliable array of independent nodes

The RAIN project is a research collaboration between Caltech and NASA-JPL on distributed computing and data-storage systems for future spaceborne missions. The goal of the project is to identify and develop key building blocks for reliable distributed systems built with inexpensive off-the-shelf components. The RAIN platform consists of a heterogeneous cluster of computing and/or storage nodes connected via multiple interfaces to networks configured in fault-tolerant topologies. The RAIN software components run in conjunction with operating system services and standard network protocols. Through software-implemented fault tolerance, the system tolerates multiple node, link, and switch failures, with no single point of failure. The RAIN-technology has been transferred to Rainfinity, a start-up company focusing on creating clustered solutions for improving the performance and availability of Internet data centers. In this paper, we describe the following contributions: 1) fault-tolerant interconnect topologies and communication protocols providing consistent error reporting of link failures, 2) fault management techniques based on group membership, and 3) data storage schemes based on computationally efficient error-control codes. We present several proof-of-concept applications: a highly-available video server, a highly-available Web server, and a distributed checkpointing system. Also, we describe a commercial product, Rainwall, built with the RAIN technology

Rigorous Design of Fault-Tolerant Transactions for Replicated Database Systems using Event B

System availability is improved by the replication of data objects in a distributed database system. However, during updates, the complexity of keeping replicas identical arises due to failures of sites and race conditions among conflicting transactions. Fault tolerance and reliability are key issues to be addressed in the design and architecture of these systems. Event B is a formal technique which provides a framework for developing mathematical models of distributed systems by rigorous description of the problem, gradually introducing solutions in refinement steps, and verification of solutions by discharge of proof obligations. In this paper, we present a formal development of a distributed system using Event B that ensures atomic commitment of distributed transactions consisting of communicating transaction components at participating sites. This formal approach carries the development of the system from an initial abstract specification of transactional updates on a one copy database to a detailed design containing replicated databases in refinement. Through refinement we verify that the design of the replicated database confirms to the one copy database abstraction

The Development of an Integrated Anger Management Protocol

This thesis describes the rationale for and development of an anger management protocol that can be used with middle and high school students. The protocol is based primarily on the anger management work of Goldstein (1999) and Larson and Lochman (2002) integrated with the Holarchichal Model of Executive Functions (McCloskey, 2008). The protocol also integrates the Collaborative and Proactive Solutions model of Greene and Ablon (2001) and mediated learning principles. This integrated anger management protocol primarily draws upon internally based executive function interventions involving goal-setting and increasing self-awareness and self-realization. This thesis discusses the methodologies in developing the protocol, a program overview and rationale for included protocol items, and a discussion chapter including reflections on the protocol development process, potential contributions to the field, future research direction, and protocol limitations

Design of a shared whiteboard component for multimedia conferencing

This paper reports on the development of a framework for multimedia applications in the domain of tele-education. The paper focuses on the protocol design of a specific component of the framework, namely a shared whiteboard application. The relationship of this component with other components of the framework is also discussed. A salient feature of the framework is that it uses an advanced ATM-based network service. The design of the shared whiteboard component is considered representative for the design as a whole, and is used to illustrate how a flexible protocol architecture utilizing innovative network functions and satisfying demanding user requirements can be developed

The Effectiveness of a Computer-Assisted, Cognitive-Behavior Program for Treating Anxiety Symptoms in Children with Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a complex and multifaceted, neurodevelopmental disorder that severely impacts children and families across a variety of settings. Prevalence rates of ASD are continuing to increase rapidly, with sizeable intervention and treatment costs placed on families and society. Further complicating the matter, many individuals with ASD also evidence co-occurring anxiety symptoms or disorders and tend to be at a higher risk for developing such problems when compared to other clinical populations or typically developing children. This study investigated the effectiveness of a computer-assisted CBT program, Camp Cope-A-Lot (CCAL), in regards to reducing anxiety symptoms in four participants diagnosed with ASD. Data from quantitative measures revealed inconsistent results, yet informal, qualitative feedback from parents as well as information from the researcher’s observations and progress notes appeared more promising for use of the CCAL intervention for this population of children