Using an Actor Framework for Scientific Computing: Opportunities and Challenges

We examine the challenges and advantages of using an actor framework for programming and execution of scientific workflows. The following specific topics are studied: implementing workflow semantics and typical workflow patterns in the actor model, parallel and distributed execution of workflow activities using actors, leveraging event sourcing as a novel approach for workflow state persistence and recovery, and applying supervision as a fault tolerance model for workflows. In order to practically validate our research, we have created Scaflow, an Akka-based programming library and workflow execution engine. We study an example workflow implemented in Scaflow, and present experimental measurements of workflow persistence overhead

Serverless Computing for Scientific Applications

Serverless computing has become an important model in cloud computing and influenced the design of many applications. Here, we provide our perspective on how the recent landscape of serverless computing for scientific applications looks like. We discuss the advantages and problems with serverless computing for scientific applications, and based on the analysis of existing solutions and approaches, we propose a science-oriented architecture for a serverless computing framework that is based on the existing designs. Finally, we provide an outlook of current trends and future directions

Database Replication for Disconnected Operations with Quasi Real-Time Synchronization

Database replication is a way to improve system throughput or achieve high availability. In most cases, using an active-active replica architecture is efficient and easy to deploy. Such a system has CP properties (from the CAP theorem: Consistency, Availability and network Partition tolerance). Creating an AP (available and partition tolerant) system requires using multi-primary replication. This approach, because of many difficulties in implementation, is not widely used. However, deployment of CCDB (experiment conditions and calibration database) needs to be an AP system in two locations. This necessity became an inspiration to examine the state-of-the-art in this field and to test the available solutions. The tests performed evaluate the performance of the chosen replication tools: Bucardo and EDB Replication Server. They show that the tested tools can be successfully used for continuous synchronization of two independent database instances

AUTOMATIC PROXY GENERATION AND LOAD-BALANCING-BASED DYNAMIC CHOICE OF SERVICES

The paper addresses the issues of invoking services from within workflows which are becoming an increasingly popular paradigm of distributed programming. The main idea of our research is to develop a facility which enables load balancing between the available services and their instances. The system consists of three main modules: a proxy generator for a specific service according to its interface type, a proxy that redirects requests to a concrete instance of the service and load-balancer (LB) to choose the least loaded virtual machine (VM) which hosts a single service instance. The proxy generator was implemented as a bean (in compliance to EJB standard) which generates proxy according to the WSDL service interface description using XSLT engine and then deploys it on a GlassFish application server using GlassFish API, the proxy is a BPEL module and load-balancer is a stateful Web Service

A Platform for Collaborative e-Science Applications

Abstract A novel, holistic, approach to scientific investigations should, besides analysis of individual phenomena, integrate different, interdisciplinary sources of knowledge about a complex system to obtain a deep understanding of the system as a whole. This innovative way of research, recently called system-level science [1], requires advanced software environments to support collaborating research groups. Most problem-solving environments and virtual laboratories In the ViroLab project The Virtual Laboratory (see The Experiment Planning Environment supports rapid experiment plan development while the Experiment Management Interface enables loading and execution of experiments. The Experiment Repository developers and published for future use. The virtual laboratory engi Operation Invoker which instantiates grid object repr operation invocations. The GridSpace Applic load balancing on computational servers. The Data Access Service remote databases located in research institutions and Fig. 1. Architecture of the Virtual Laboratory The provenance approach in the ViroLab virtual laboratory ontology-based semantic modeling, monitoring of infrastructure, and database technologies, in order to coll the execution of experiments, represent it in a meaningful way, repository. In the ViroLab project, this virtual laboratory is used to plan and virological experiments, with various types of analysis of as the calculation of drug resistance, querying historical and about experiments, a drug resistance system based on the Retrogram been applied to other application domains, such as comparison, data mining using the Weka library, series of Gaussian application on the EGEE infrastructure. computer science classes. We have developed an environment for collaborative planning, execution of e-Science applications. It facilitates fast, close cooperation and users so it may be used by groups of experts running In-silico experiments undergo frequent changes, this platform encourages quick, agile simulation software releasing