| Re: [m2m-iwg] M2M meta-model |
Hi, all. A few thoughts on the metamodel Wiki: - I would be explicit regarding date and datetime formats and wire formats. Since one of the goals of MQTT was to be efficient in terms of bandwidth, I would explore passing UTC-based long value representations of time on the wire, either nanoseconds since XXX or milliseconds since XXX. If you want the protocol to have a long life and broader applicability, I would support nanoseconds. Maybe have a two-part date format – a byte indicator of type (milliseconds, nanoseconds, or ISO 8601 string) followed by the data - Since it is now 2012, a “location” data type is a must, with a required latitude/longitude and optional elevation, units, speed, direction - The history/event policy should include change-based policies (deadbanding). These should include deadbanding by value, percentage of value, and time latency - Instead of “commands”, I’d suggest a more modern and broadly applicable term such as “services”, which imply bi-directionality (commands, queries, etc.) - If you’re going to be explicit about numeric types (integral vs floating), I would choose double and long, not double and integer, or at least support long also, as there are many use cases that require it - I’m not yet convinced that the device should be responsible for its ACL’s – that is a topic that should be discussed in the broader context of security - ACL’s should be applicable not only to data elements, but to all device functionality (data, service, events, device management tasks, etc.) - I’m curious why the protocol binding is at the data element level, and not the device level. That seems odd to me. - Data/service/event metadata should be extensible, and devices and applications should be allowed to add their own as needed for specific use cases. In ThingWorx, we name these a special type of metadata called “aspects” Best, Rick From: m2m-iwg-bounces@xxxxxxxxxxx [mailto:m2m-iwg-bounces@xxxxxxxxxxx] On Behalf Of Benjamin Cabé Hi all, As I mentioned during today's call, there's now a wiki page dedicated to M2M meta-model discussions http://wiki.eclipse.org/Machine-to-Machine/M2MIWG/M2M_meta-model . Please review the first version of requirements we've put there ; it is pretty well detailed in terms of data management, but it needs to be refined in terms of device management and ALM… Marco, Kai, (others?) we can discuss the meta-model in more details during a phone call, if needed. Also, we will provide a first implementation of this meta-model (in Ecore) in Koneki. Cheers! Benjamin — |