PROVIDING AGRICULTURAL MODELS WITH MEDIATED ACCESS TO HETEROGENEOUS WEATHER DATABASES
M. Laurenson, Takuji Kiura, S. Ninomiya · Applied Engineering in Agriculture · 2002
The Internet offers a convenient mechanism for delivering agricultural models to users. These models oftenrequire weather data, but weather databases accessible through the Internet differ greatly in their format and method ofaccess. As a result it is difficult to run models developed at one site using another sites data. A separate mediatorapplication, MetBroker, has been developed to provide agricultural models with consistent, rapid access to heterogeneousonline weather databases. Eleven weather data sources, including both filebased and relational databases, in sevencountries have been linked into the system and a number of weatherbased applications and applets now use this mechanismto access data. The system supports data retrieval from a single station or from all stations in a geographical region acrossmultiple databases. MetBroker stores metadata (data describing data) detailing each database, its stations, and their dataholdings, and provides this information to users in their preferred language. Client applications communicate with MetBrokerusing Java Remote Method Invocation, allowing data requests and query results to be encapsulated in data objects. Theperformance of the system over both dialup and Ethernetbased Internet connections is consistent with estimates based ondata volume and available bandwidth. The system demonstrates that a mediated architecture is a viable way to offer consistentaccess to a diverse range of databases containing similar kinds of data.