The Unidata community of over 160 universities is building a system for disseminating near real-time earth observations via the Internet. Unlike other systems, which are based on data centers where the information can be accessed, Unidata Internet Data Distribution (IDD) is designed so a university can request that certain data sets be delivered to computers at their site as soon as they are available from the observing system. The IDD system also allows any site with access to specialized observations to inject the dataset into the IDD for delivery to other interested sites.
Unidata Local Data Manager (LDM) is a collection of cooperating programs that select, capture, manage, and distribute arbitrary data products. The system is designed for event-driven data distribution of the kind used in the Unidata Internet Data Distribution project.
The Unidata IDD has been in operation on a 24x7 basis since 1995, when it replaced a real-time data delivery system that used a sideband on satellite TV broadcasts. The satellite delivery system required that user sites pay a subscription fee and have a special receiver to decode the data stream. The switch to IDD did away with the subscription fee and the need for a special receiver, which made it possible for many more sites to receive a greatly expanded menu of data streams. The reach of the IDD has been expanded internationally and it is now being used to ship real time data in all directions to virtually every continent on the globe.