Advanced querying for future directory enabled applications 1

With the growth of the Internet, directory softwares have recently proliferated. The Lightweight Directory Access Protocol (LDAPv3 [18]) is the standard, proposed by the Internet Engineering Task Force (IETF [9]) for modelling and querying network directory information, as well as accessing network directory services. More recently, several extensions have been proposed to the directory model to widen its application field. Indeed, future directory-based applications, known as Directory Enabled Networks (DEN) applications [3], use directories in a way far more complicated than existing ones. Notably, these applications have more complex query needs and LDAP query language must be extended to exploit the directory model extensions engendered by these new applications. In this paper, we present DQL (Directory Query Language), a high-level declarative language to query extended LDAP directories. As opposed to the LDAP query language, based on a protocol approach, DQL relies on databases and distributed systems technologies to offer more flexibility and interactivity. DQL extends LDAP query language with path expressions retrieval while keeping its semantics fully compliant with LDAP protocol. In addition, DQL’s query evaluator introduces the concept of partial query results which is important to query distributed directories, especially in Internet environments where some servers may often be down or unreachable.