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Serialisation of PXP DTDs
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Date: | 2008-10-24 (21:39) |
From: | Mauricio Fernandez <mfp@a...> |
Subject: | Re: [Caml-list] Re: Serialisation of PXP DTDs |
On Fri, Oct 24, 2008 at 11:11:10AM +0200, Mikkel Fahnøe Jørgensen wrote: > I guess this discussion is an overkill for the problem at hand, but > speaking of binary extensible protocols, have you looked at ASN.1? It > is an abstraction over any number of encodings. At least one binary > encoding has extension bits to allow future growth of object > collections and similar. Yes, I referred to it indirectly in my previous message. Indeed, ASN.1 supports disjoint unions ("tagged types") that would allow to extend a type. It is obviously possible to build extensible protocols with ASN.1, but if I understand it correctly, not all protocols expressed in ASN.1's abstract syntax are automatically extensible --- it requires some care when designing them (i.e., tagging). My main problem with ASN.1 is that even the distinguished encoding rules are fairly complex; also, explicit tagging results in relatively heavy serialization too. My protocol family is both substantially simpler and better adapted for extensibility. For example, the generic pretty-printer (able to decode any message) takes ~40 lines of code. -- Mauricio Fernandez - http://eigenclass.org