Virtual Observatory

[27]  A virtual observatory (VxO) a term now appearing within the scientific data community is a distributed software system that allows users to find, access, and use resources from a collection of data repositories and service providers. A virtual observatory can provide either metadata or data services and is typically focused on presenting the collection of data, metadata and functional services to a given set of customers bound by a common interest. The virtual observatory is an implementation of what is typically called service oriented architecture (SOA) bound by a common theme.

[28]  Within the environmental community it is envisioned that using the VxO domain scientists will be able to:

Figure 7
[29]  As shown in Figure 7 the virtual observatory consists of a number of services built around a community based core.

[30]  Because SPIDR is built around the Grid core it is easily adaptable to support the VxO infrastructure. SPIDR itself has been chosen as the basis of or a component of a number of virtual observatories. An example is the Virtual Radiation Belt Observatory (ViRBO) which is focused on the physics and phenomena surrounding the high energy particle belts surrounding the Earth and provides data from satellites and models covering the region.

[31]  In order to meet the "spirit'' of a VxO, a system must encompass certain functionality. For example in the workflow component a system must:

[32]  The SPIDR interface meets all of these criteria by using the Jakarta Struts framework to define workflow. This makes it possible to easily create multiple systems views focused on a particular user skill level (e.g. novice, advanced, admin) or discipline (e.g. geomagnetic, iononspheric, cosmic rays) without having to rewrite code. The interface can largely be adapted by editing XML documents from the Struts workflow configuration.

[33]  Another element to a VxO is the Application Interface, here the system must provide:

[34]  Obviously many of these items map directly to the Grid paradigm basically making any VxO an implementation of Grid. It is likely that as both progress there will be a merging in several key areas and particularly in environmental science related activities.


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