VO Architecture
A car is complicated under the hood, but driving it is simple. This is our vision in creating the Virtual Observatory.
In astronomical analysis packages such as IRAF and IDL, astronomers select building blocks, and build up analysis tools from them. In the VO, the methodology will be much the same, except that the building blocks will be web services that may be running on remote computers.
In these packages, there are core components that form a foundation for higher level functionality, for example, reading a FITS file or coadding images. The VO follows exactly the same model, but what is new is the shift to the world of distributed data. The data is so large that it is no longer possible to simply download all of it, and it is difficult to find the relevant data. The data will no longer be copied to a workstation, but
rather the computing moves to the data.
Therefore the corresponding core components for the VO are:
- finding what data is available (through the VO registry)
- getting access to that data (images, catalogs, and spectra) through simple requests.
We have set out to build the simplest services first, to make it easy for people to publish and discover data, and to use these services.
We hope for a network effect: the paradigm changes when most data is published in VO-compliant form, and most people are using VO protocols. The big data providers are exposing data through VO protocols, and we provide a means for smaller datasets to be published as VO-compliant.
While these changes are occuring "under the hood", the paradigm of building an analysis as connected components will remain much the same—but the components will now be spread all over the world.
The computational components will be built as "web services"—a wide-ranging industry standard—that allows remote functionality to be available as if it were local. These services carry a "self-description" of their functionality, and the VO projects are adding further astronomy-specific description—the area of sky that a survey covers for example.
For a more detailed description of the NVO architecture, see http://www.ivoa.net/Documents/latest/IVOArch.html