With large number of datasets now available through the Web, data-sharing ecosystems such as the Web Observatory have emerged. The Web Observatory provides an active decentralised ecosystem for datasets and applications based on a number Web Observatory sites, each of which can run in a different administrative domain. On a Web Observatory site users can publish and securely access datasets across domains via a harmonised API and reverse proxies for access control. However, that API provides a different interface to that of the databases on which datasets are stored and, consequently, existing applications that consume data from specific databases require major modification to be added to the Web observatory ecosystem. In this paper we propose a lightweight architecture called Porter Proxy to address this concern. Porter Proxy exposes the same interfaces as databases as requested by the users while enforcing access control. Characteristics of the proposed Porter Proxy architecture are evaluated based on adversarial scenario-handling in Web Observatory eco-system.