In the case of the Internet the gateway functionality is needed to maintain interoperability with the current WWW software. This structure is reminiscent of how global naming services are organised. A WWW browser always connects to a local WWW server for locally maintained information, or to a local cache server for outside information. Cache servers buffer retrieved documents so that frequently referred information tends to move closer to the users. Both WWW servers and caches can be replicated in order to improve availability and performance.
Replication is necessary at least in the cache servers forming the backbone network.
The new WWW servers and cache servers communicate using an enhanced hypertext transfer protocol that is designed for the efficient transfer of hypermedia information. The protocol might, for instance, support multicasting cache invalidation messages and updates of frequently referred documents to the backbone cache servers. While an infrastructure based on caching proxies does not make sense in this context, some level of integration between the two worlds can still be envisioned. For instance, a person's home page might contain a hypertext link that, when clicked, tries to establish a video-call to that person's video phone. In this way, real-time services could be invoked from an information browsing service.