Architecture and performance of server-directed transcoding

ABSTRACT

Proxy-based transcoding adapts Web content to be a better match for client capabilities (such as screen size and color depth) and last-hop bandwidths. Traditional transcoding breaks the end-to-end model of the Web, because the proxy does not know the semantics of the content. Server-directed transcoding preserves end-to-end semantics while supporting aggressive content transformations.We show how server-directed transcoding can be integrated into the HTTP protocol and into the implementation of a proxy. We discuss several useful transformations for image content, and present measurements of the performance impacts. Our results demonstrate that server-directed transcoding is a natural extension to HTTP, can be implemented without great complexity, and can provide good performance when carefully implemented.

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.4 Distributed Systems
          Subjects: Client/server

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.2 Network Protocols

General Terms:
Design, Experimentation, Performance

Keywords:
HTTP, proxy, transcode, web