Subject: [dtn] AMP comment on ADM derived/custom data types

From: Brian Sipos <[email-masked]>
Date: Wed, 30 Mar 2016 21:01:15 +0000

This is a comment against "draft-birrane-dtn-amp-02".

I feel like having the AMP spec be protocol and ADM spec (YANG) be data model allows a good separating of concerns. The AMP can stay coherent, minimal, and necessary. The ADM can be arbitrarily expressive, as far as using subtyping to specialize (e.g. GUAGE or COUNTER subtypes) or using grouping or lists/tables to compose larger data sets. This is similar to SNMP use of primitive encoding forms in the protocol and textual conventions in MIB data models. To this end, it may be useful to have a statement in the AMP frontmatter about the distinction between the AMP-specified encoding types vs. ADM-specified value semantics.

My goal for AMP-encoded messages would to at least allow for "blind" decoding in the sense of being able to pull apart an encoded message without knowing its data model/schema. This is purely for the sake of generic test/diagnostic tools and having been bitten by schema-dependence of ASN.1 and similar binary forms. Even if application-specific data stays encoded as a BLOBs, at least the first-level supporting structure of control+parameters or report+entries. This would guarantee some amount of utility from basic protocol-level tooling (i.e. Wireshark decoder, scapy protocol module). I think the current spec is very close already.