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There can be only one! The future of Application Layer Protocols

There can be only one! The future of Application Layer Protocols. Henrik Frystyk Nielsen. Purpose of this Talk. Convergence of Application level Protocols …and the emergence of the Big Hammer Protocol with the small heart Similar to what is happening to XML Working towards a framework

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There can be only one! The future of Application Layer Protocols

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  1. There can be only one!The future of Application Layer Protocols Henrik Frystyk Nielsen

  2. Purpose of this Talk • Convergence of Application level Protocols • …and the emergence of the Big Hammer Protocol with the small heart • Similar to what is happening to XML • Working towards a framework • Avoiding flag days • What a Framework Doesn’t Solve • Distributed Extensibility vs. interoperability There can be only one

  3. HTTP/1.1 - The Big Fire Fighter • Main purpose was to fix three problems • Provide a semantically well-defined caching model • Support vanity hostnames • Limiting waste of TCP connections • Criteria for solutions was that the user would see a clear win • People need personal incentives to change • Implementors need clear market benefit to implement • Goal was Achieved - deployment is underway • Performance has improved a lot There can be only one

  4. Hmm, but how do we Extend it? • Extensibility wasn’t part of the basic 1.1 package • HTTP is not a centrally controlled protocol • Has maybe never been • It’s extended by everybody for any possible purpose • No structured way of extending HTTP • Extend and hope for the best! • Layering is implicit - looks and feels like hairball • No explicit type information • Using POST as a tunnel mechanism • Reducing HTTP to a byte transport There can be only one

  5. HTTP at the Center of the Typhoon • Clear tendency in protocol design from... • Similar protocols with different background (IMAP etc.), to • Protocols that are largely copying HTTP(RTSP, SIP etc.), to • Protocols that use HTTP POST (IPP etc.), to • Protocols that copy pieces for easier integration with HTTP (TIP etc.), to • Actual HTTP extensions (DAV etc.) There can be only one

  6. But Why Only One? • The Convergence is inevitable! • Application layer protocol development is driven by application programmers • They don’t want to have different protocol engines for highly related tasks • Users don’t want to know the difference • Interested in getting my job done • Don’t want to get stopped by error messages: I can’t talk to that guy! • Shared Platform (not necessarily interoperability) There can be only one

  7. But Why HTTP? • Has a lot of flexibility for “creative” usage • Many interactions are not defined in the HTTP/1.1 spec • For example, is end-to-end really end-to-end? • Often enough to get the work done • Few are interested in the beauty of solutions • But stretching the limits of its extensibility • Interactions are becoming more and more complex • Interoperability at stake! • We need a more powerful framework! There can be only one

  8. HTTP - the Next Generation • The generic application level protocol • A simple, extensible framework • Protocols become Profiles • Explicit Layering and modularization • Break up the big “lump” style 1.x messages • Extensibility at the core • Lessons from our HTTP/PEP/Mandatory work • Not quite RPC, not quite messages • Who cares? There can be only one

  9. What a Framework Doesn’t Solve • Will distributed extensibility lead to chaos? • How do extensions coexist? • Two extensions land on the same agent - can they speak, are they orthogonal or do they conflict? • Central Registration has its place • Extension Policing required • Granularity of Extensions Important • Will probably be lumped together in bigger packets There can be only one

  10. More Information on the Web • HTTP-NG Project • HTTP-NG Activity • HTTP-NG Working Groups (W3C Members only) • HTTP/1.x Overview • W3C Member Site • W3C There can be only one

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