Network Data Access Research Articles

Developing service-oriented applications in a grid environment

The Open-source Project for a Network Data Access Protocol (OPeNDAP) software framework has evolved over the last 10 years to become a robust, high performance, service oriented architecture for the access and transport of scientific data from a broad variety of disciplines, over the Internet. Starting with version 4.0 of the server release, Hyrax, has at its core, the Back-End Server (BES). The BES offers ease of programming, extensibility and reliability al- lowing added functionality especially related to high- performance data Grids, that goes beyond its original goal of distributed data access. We present the fun- damentals of the BES server as a component based architecture, as well as our experiences using the BES

The DataNet partners: Sharing science, linking domains, curating data

AbstractThis panel introduces the first two DataNet partners funded through the National Science Foundation's Sustainable Digital Data Preservation and Access Network Partners (DataNet) solicitation (National Science Foundation, 2007). The first two of an expected five projects are The Data Conservancy: A Digital Research and Curation Virtual Organization, based at Johns Hopkins University (Sayeed Choudhury, PI), and DataONE: Observation Network for Earth, based at the University of New Mexico (William K. Michener, PI). Following a brief overview of NSF's DataNet vision and goals, each funded project will be introduced and positioned within the context of NSF's vision for the DataNet Partners. The next part of the panel will describe how information scientists and librarians are integrated into the projects, including research, educational, and service development objectives. The final part of the panel will discuss collaboration between the DataNet partners in order to serve as “elements of an interoperable data preservation and access network” (NSF, 2007).

MARINE ENVIRONMENT AND SECURITY FOR THE EUROPEAN AREA

In response to the joint European Commission and European Space Agency initiative to establish by 2008 a system for Global Monitoring for Environment and Security (GMES), the Marine Environment and Security for the European Area (MERSEA) Strand-1 Project was executed to assess and demonstrate the capacity of present monitoring and forecasting systems. The study area covered the North Atlantic, with its northwest European shelf seas, and the Mediterranean. By integrating of existing satellite observations with data from in situ measurement networks and ocean models, daily mean products and forecasts from four core data assimilation systems (10 km resolution) were compared and distributed through an Open-source Project for a Network Data Access Protocol (OPeNDAP) server from 1 June 2003 to 31 May 2004. Moreover, downscaling to high-resolution (1–5 km) models was used for specific applications to harmful algal bloom, eutrophication, and oil spill monitoring in the Baltic, North Sea, Irish Sea, Iberian coastal shelf seas, and the Aegean Sea. The lessons learned from this project are reported here.

Havana agents for comparison shopping and location-aware advertising in wireless mobile environments

Users of handheld wireless devices do not have the luxury to wade through pages and pages of information to find the products and services they need. In addition, the inconveniences of using the thumb controls on a cellular phone to navigate, along with the high costs of wireless data network access highlights the problems that wireless users face. The need for direct access to highly relevant, location-aware information with a minimal amount of browsing and a minimal amount of user input is what prompted us to investigate the feasibility of and development of a plan for deploying mobile agents to perform information filtering and retrieval on behalf of the users in a mobile commerce setting. In this paper, we discuss a novel mobile agent platform that can be used for comparison shopping in a mobile wireless environment, through which businesses can better understand and communicate with the mobile consumer. The proposed agent-based approach helps the end user reduce information overload by helping her filter out unnecessary information and only show information that is relevant; it provides novel ways for cellular service providers to compete, and businesses to acquire new customers. We will address the challenges associated with such an evolutionary approach, and provide some sample scenarios, along with an architectural design for the proposed system. A proof-of-concept prototype using Java RMI has been constructed as part of the Havana mobile agent platform.

NOMADS: A Climate and Weather Model Archive at the National Oceanic and Atmospheric Administration

An online archive of real-time and historical weather and climate model output and observational data is now available from the National Oceanic and Atmospheric Administration (NOAA). This archive, known as the NOAA National Operational Model Archive and Distribution System (NOMADS), was jointly initiated in 2001 by the National Climatic Data Center (NCDC), the National Centers for Environmental Prediction (NCEP), and the Geophysical Fluid Dynamics Laboratory (GFDL). At present, NOMADS provides access to real-time and historical 1) numerical weather prediction (NWP) model input and output, 2) GFDL's Coupled Global Climate Models (CGCM) output, 3) global and regional reanalysis from NCEP and the National Center for Atmospheric Research (NCAR), and 4) limited surface, upper-air, and satellite observational datasets from NCDC and NOAA's National Ocean Data Center (NODC) and Earth System Research Laboratory [formerly the Forecast System Laboratory (FSL)]. NOMADS is but one of many similar data services across the United States and abroad that are embracing and leveraging various pilot efforts toward distributed data access using agreed-to data transport and data format conventions. This allows for the interoperable access of various subsets of data across the Internet. These underlying community-driven agreements and the Open Source Project for a Network Data Access Protocol (OPeNDAP) data transport protocol form the core of NOMADS services as well as have the capability for “format neutral” access to data in many different formats and locations.

Wideband random access for the last mile

Data network access options available today employ either some variant of a narrowband connectionless ALOHA channel or a connection-oriented network architecture ill suited to the traffic characteristics of many data applications. But first-generation ALOHA is difficult to implement in networks operating at more than a few lens of kilobits. When connectionless access with aggregate data rates in the megabits are required it is possible to combine conventional ALOHA with the wide-bandwidth operation of spread spectrum to provide the high data rates required for today's applications. This combination is called spread ALOHA multiple access (SAMA).