This document describes the Service Discovery architecture that we are proposing in the work-package SP3. Service Discovery Protocols provide a way for (software) clients to automatically discover available services (for example: printers, projectors) and for some advanced protocols to connect and use them in a transparent way. While being strongly connected to the other SPs/work-packages and most notably the SP1 and SP5, i.e. the demonstrators, it is designed to work in other settings. The foundations of this solution are its adaptability and its independence from the other services provided in the network in general, by any node (fixed/mobile or wired/wireless) or underlying layer (multicast routing, security): when they're available it can take advantage of them, but it is designed to function by building up and maintaining a relatively stable structure for Service Discovery where adhoc-specific but also standard Service Discovery Protocols and context information can be used by clients to find relevant services.