ADL software provides a distributed searching mechanism for geospatially referenced data collections. Distributed means you can search different types of databases at different locations. ADL software has the ability to use existing metadata. ADL defines a general architecture that makes it possible to use with a wide variety of databases, often without changing the content or information within the database.

The ADL architecture is centered around a middleware server that provides multiple clients with a uniform view of multiple heterogeneous collection servers. The ADL search buckets are the principal mechanism by which this uniform view is achieved:

• Clients formulate queries in terms of collection-neutral search buckets.
• The middleware server translates and forwards queries to the collection servers.
• Collections servers are responsible for evaluating the queries in ways that are meaningful for their respective collections.