A JEE RESTful service to access Conditions Data in ATLAS

Usage of Conditions Data in ATLAS is extensive for offline reconstruction and analysis (e.g.: alignment, calibration, data quality). The system is based on the LCG Conditions Database infrastructure, with read and write access via an ad hoc C++ API (COOL), a system which was developed before Run 1 data taking began. The infrastructure dictates that the data is organized into separate schemata (assigned to subsystems/groups storing distinct and independent sets of conditions), making it difficult to access information from several schemata at the same time. We have thus created PL/SQL functions containing queries to provide content extraction at multi-schema level. The PL/SQL API has been exposed to external clients by means of a Java application providing DB access via RESTful services, deployed inside an application server (JBoss WildFly). The services allow navigation over multiple schemata via simple URLs. The data can be retrieved either in XML or JSON formats, via simple clients (like curl or Web browsers).