The goal of the Searchable Product Archive and Discovery Engine (SPADE) is to provide a coherent system to manage the submission of, searching, and access to USArray and other data- and informational products, and to provide a uniform query mechanism that allows detailed queries by product-specific metadata.

A data product is, at one level, any encapsulated information derived or calculated from raw seismic or other data. At another level, a data product can be essentially anything, including derived information, images, station information, etc., and even raw data.

In SPADE, all products must be encoded in XML either explicitly using XML elements and attributes for the product parameters and values, or, in cases of binary data such as images or raw data, as Base64-encoded inline data or as attachments referenced from a "container" XML document.

Producers create and submit XML-encoded data products to the SPADE archive. Consumers query the system to find what products are available and access (download) the selected products. Consumers can access the system in several ways, including interactively through the Web and with stand-alone programs that communicate over the Internet using SOAP-based Web services and the SPADE Application Programming Interface (API).

The archive supports efficient queries across the product space. That is, a consumer may construct queries for each different product type by the metadata available for that product type. For instance, querying for Events must present an interface that includes (among other things) the ability to specify latitude, longitude, magnitude, depth, and a time range. Whereas, querying for some other product type may present an interface that specifies a completely or partially different set of parameters relevant to that particular product. In addition, queries can be constructed to search across product types by common metadata fields.

The result of a query is a list of products that match the query parameters. From this point, the query can be further refined, or the consumer can choose to view or download all or selected products from the query results. Downloading the selected products downloads the original XML documents and any associated attachments.

SPADE is structured such that new and as-yet unforeseen product types can be added to the archive with minimal effort. New product types will have to be registered with the system and will likely require a small amount of manual configuration. The system will also support the evolution of the definition of a product type, and therefore the evolution of the product's XML Schema, over time. In addition, the system supports product instance versioning, i.e., updating or replacing a submitted product with a newer, revised instance.

SPADE supports a Web services -based API to enable GUI and command-line client applications and a web browser-based interface for interactive queries.

SPADE query interface