Search

This paper describes two-fold approach towards utilizing Triple Modular Redundancy (TMR) in Wireless Adhoc Network (AdocNet). A distributed checkpointing and recovery protocol is proposed. The protocol eliminates useless checkpoints and helps in selecting only dependent processes in the concerned checkpointing interval, to recover. A process starts recovery from its last checkpoint only if it finds that it is dependent (directly or indirectly) on the faulty process. The recovery protocol also prevents the occurrence of missing or orphan messages. In AdocNet, a set of three nodes (connected to each other) is considered to form a TMR set, being designated as main, primary and secondary. A main node in one set may serve as primary or secondary in another. Computation is not triplicated, but checkpoint by main is duplicated in its primary so that primary can continue if main fails. Checkpoint by primary is then duplicated in secondary if primary fails too.

Background Since the declaration of COVID-19 as a global pandemic by the World Health Organization, the disease has gained momentum with every passing day. Various private and government sectors of different countries allocated funding for research in multiple capacities. A significant portion of efforts has been devoted to information technology and service infrastructure development, including research on developing intelligent models and techniques for alerts, monitoring, early diagnosis, prevention, and other relevant services. As a result, many information resources have been created globally and are available for use. However, a defined structure to organize these resources into categories based on the nature and origin of the data is lacking. Objective This study aims to organize COVID-19 information resources into a well-defined structure to facilitate the easy identification of a resource, tracking information workflows, and to provide a guide for a contextual dashboard design and development. Methods A sequence of action research was performed that involved a review of COVID-19 efforts and initiatives on a global scale during the year 2020. Data were collected according to the defined structure of primary, secondary, and tertiary categories. Various techniques for descriptive statistical analysis were employed to gain insights into the data to help develop a conceptual framework to organize resources and track interactions between different resources. Results Investigating diverse information at the primary, secondary, and tertiary levels enabled us to develop a conceptual framework for COVID-19–related efforts and initiatives. The framework of resource categorization provides a gateway to access global initiatives with enriched metadata, and assists users in tracking the workflow of tertiary, secondary, and primary resources with relationships between various fragments of information. The results demonstrated mapping initiatives at the tertiary level to secondary level and then to the primary level to reach firsthand data, research, and trials. Conclusions Adopting the proposed three-level structure allows for a consistent organization and management of existing COVID-19 knowledge resources and provides a roadmap for classifying future resources. This study is one of the earliest studies to introduce an infrastructure for locating and placing the right information at the right place. By implementing the proposed framework according to the stated guidelines, this study allows for the development of applications such as interactive dashboards to facilitate the contextual identification and tracking of interdependent COVID-19 knowledge resources.

Model-driven development is a pragmatic approach to software development that embraces domain-specific languages (DSLs), where models correspond to DSL programs. A distinguishing feature of model-driven development is that clients of a model can select from an open set of alternative semantics of the model by applying different model transformation. However, in existing model-driven frameworks, dependencies between models, model transformations, and generated code artifacts are either implicit or globally declared in build scripts, which impedes modular reasoning, separate compilation, and programmability in general.We propose the design of a new module system that incorporates models and model transformations as modules. A programmer can apply transformations in import statements, thus declaring a dependency on generated code artifacts. Our design enables modular reasoning and separate compilation by preventing hidden dependencies, and it supports mixing modeling artifacts with conventional code artifacts as well as higher-order transformations. We have formalized our design and the aforementioned properties and have validated it by an implementation and case studies that show that our module system successfully integrates model-driven development into conventional programming languages.

This paper describes two-fold approach towards utilizing Triple Modular Redundancy (TMR) in Wireless Adhoc Network (AdocNet). A distributed checkpointing and recovery protocol is proposed. The protocol eliminates useless checkpoints and helps in selecting only dependent processes in the concerned checkpointing interval, to recover. A process starts recovery from its last checkpoint only if it finds that it is dependent (directly or indirectly) on the faulty process. The recovery protocol also prevents the occurrence of missing or orphan messages. In AdocNet, a set of three nodes (connected to each other) is considered to form a TMR set, being designated as main, primary and secondary. A main node in one set may serve as primary or secondary in another. Computation is not triplicated, but checkpoint by main is duplicated in its primary so that primary can continue if main fails. Checkpoint by primary is then duplicated in secondary if primary fails too., Comment: International Journal of UbiComp (IJU), Vol.6, No.4, October 2015

In this paper we present an application of the MATINE method for investigating dependencies in antivirus (AV) software and some vulnerabilities arising from these dependencies. Previously, this method has been effectively used to find vulnerabilities in network protocols. Because AV software is as vulnerable as any other software and has a great security impact, we decided to use this method to find vulnerabilities in AV software. These findings may have implications to critical infrastructure, for the use of AV is often considered obligatory. The results were obtained by gathering semantic data on AV vulnerabilities, analyisis of the data and content analysis of media follow-up. The results indicate, that different aspects of AV software should be observed in the context of critical infrastructure planning and management.

In today’s Configuration Management system, it becomes extremely necessary to be able to support multiple projects, branches and versions of the source code. As an institution’s build system becomes more complex, management of the source code becomes very time-consuming and complex if the build system is not mature enough. This puts pressure on several entities, especially the build and release management teams, as well as the quality assurance and product testing teams. This thesis introduces a technique to obtain dependency information from build systems, mapping executables to source files and analyzing their dependencies. Dependency information can be used to reduce the testing effort, automate the entire sustaining production process (service packs and patches) to customers, prevent test escapes, highlight the relationships between various components of a system as well as provide product and system model views of the internal representation of a product’s architecture. This thesis proposes a method to gather dependency information of a system by extracting certain metadata from executables. After some in-depth research, we identified that source files can be initially injected with certain information that remains embedded in it even after a system has been built into executables. This information can also be extracted and compiled to create dependency information that maps executables, static and dynamic shared libraries as well as software and enterprise archives to the source files that were used to build them

Dependency tracking between communicating tasks is an important concept in backward error recovery for parallel applications. One can extend the traditional dependence tracking model for message passing systems to track dependencies between shared memory and task private states for shared memory applications. The objective of this paper is to analyze the issues generated by locks and barriers in parallel applications so that we can checkpoint tasks at any time (even when holding or waiting for locks and barriers). In particular we attempt to extend earlier dependency tracking mechanisms to locks and barriers. We address both coordinated and uncoordinated checkpointing schemes.

Backward error recovery involving checkpointing and restart of tasks is an important component of any system providing fault tolerance to applicati- ons distributed over a network. A central problem to checkpointing and recovery is the ability to track dependencies and arrive at a consistent global checkpoint. Traditionally literature treats one of either distributed shared memory (DSM) or message passing as the interprocess communication mechanism when considering the issue of fault tolerance. This paper describes preliminary investigation into common mechanisms that can be implemented to support a wide variety of protocols in both shared memory and message passing systems. In effect it can be used in a system that combines both these IPC mechanisms.

Current cluster architectures provide the ideal environment to run federations of main-memory database systems (FMMDBs). In FMMDBs, data resides in the main memory of the federation servers. FMMDBs significantly improve performance by avoiding I/O during the execution of read operations. To maximize the performance of update transactions as well, some applications recur to deferred disk writes. This means that update transactions commit before their modifications are written on stable storage and durability must be ensured outside the database. While deferred disk writes in centralized MMDBs relax the durability property of transactions only, in FMMDBs transaction atomicity may be also violated in case of failures. We address this issue from the perspective of log-based rollback-recovery in distributed systems and provide an efficient solution to the problem. Besides presenting a mechanism to ensure atomicity in FMMDBs, the paper bridges the gap between rollback-recovery in message-passing distributed systems and distributed transaction processing, and shows how results developed in the first context can be exploited in the second.