A scalable, deployable, heterogeneous internet directory service.

Abstract

The Internet is in need of a comprehensive directory service. From finding people and documents to providing location-independent links on the World Wide Web, an Internet directory service holds the promise of making the Internet a more manageable place. Despite several efforts in this area, no comprehensive widely-accepted service yet exists. We present a scalable, heterogeneous directory service, that is integrated with the existing Internet infrastructure, increasing its chances for acceptance and deployment. The system consists of two parts, a global framework capable of incorporating multiple underlying local directory services, and an optimized local service to which we hope sites will migrate. The global framework is a unique amalgamation of diverse and proven existing technologies, designed with flexibility, performance and ease of deployment in mind. The Domain Name System (DNS) is used for naming and navigation. Multiple underlying local directory services are supported through the use of Uniform Resource Locators (URLs) and a new DNS directory exchange (DX) record. Wide-area searching across many servers is supported efficiently through the use of distributed indexing. The local service is based on the Lightweight Directory Access Protocol (LDAP), originally developed as a low-cost front end to the X.500 directory. LDAP has been extended to function as a stand-alone system that can participate in our global framework, better fit the Internet environment, and support wide-area searching via distributed indexing. This makes our system highly compatible with, but not tied to X.500. The system has been implemented and found to perform well, serving as a testbed for directory service problem investigation. Our implementation includes two servers, a client library, clients, and various tools for creating and maintaining a directory and distributed indexes. We have defined a client Application Program Interface (API) for accessing the directory, and several supporting systems to help client developers. We present the design and implementation of our system, performance and scaling analysis, comparisons to other systems, and prospects for future deployment.