A control barrier includes a barrier wall having a front face and an opposing back face each extending between a top end and an opposing bottom end, a first recess being formed on the front face at the bottom end of the barrier wall. One technique identifies candidate matches between document sub-strings and database members utilizing signatures. As a result, implantation can occur immediately after the cleaningpreparation process without the contamination potential of exposure of the wafer to an external environment. Responsive to a request that causes the first resource to be served to a client from a server in a domain associated with the first content provider, a CDN server is identified in the domain associated with the shared CDN to serve the second resource to the client.