Re: [iot-sp] LWM2M protocol adapter prototype

[Dejan Bosanac <dejanb@xxxxxxxxxxxx>]

Just a couple of thoughts from me.

The job of the IoT Connector is to provide the nice programming model for the IoT use cases (telemetry, provisioning, etc.) for a heterogenous (and large) devices environment. So, in my view this is something that needs to be defined on the northbound of the connector. People tend to prefer reactive/asynchronous APIs these days, but if there’s a need, the synchronous style API can be created as well (at least for certain cases). Then connector needs to translate that to whatever protocol/semantics devices use. And that’s the job of Protocol Adapters. So the adapter is just a one piece in the whole picture and it’s not where we should be solving “application developer” view of the system. 

For example, Eclipse Kura already uses MQTT topics for all use cases (http://eclipse.github.io/kura/ref/mqtt-namespace.html). So if some devices are connected through Kura, we need to provide that conversion from MQTT to RPC world on the northbound. 

In my opinion, the messaging is a good fit for this intermediate layer, as it provides many benefits, like decoupling, flexibility in terms of scalability, routing, security, etc.

TLDR version; I agree that we need to provide an easy and natural model for developers using IoT Connector. We should do that with a proper design of API(s) on the northbound. The job of the connector and adapters then is to translate that API to the real world of various devices and gateways.

On Tue, Dec 8, 2015 at 10:17 PM, David Ingham <dingham@xxxxxxxxxx> wrote:

I think the Spring documentation you referenced is based on AMQP 0.9.1 as it talks about “exchanges” and “queues” neither of which are part of the AMQP 1.0 spec.

 

Anyway, all that said, I think the interesting technical question here is what form the higher-level protocol messages take between the protocol adaptors and the IoT Connector which is I think the point you were getting at too.

 

From: iot-sp-bounces@xxxxxxxxxxx [mailto:iot-sp-bounces@xxxxxxxxxxx] On Behalf Of Scott Lewis
Sent: 08 December 2015 21:08
To: iot-sp@xxxxxxxxxxx
Subject: Re: [iot-sp] LWM2M protocol adapter prototype

 

On 12/8/2015 12:48 PM, David Ingham wrote:

<stuff deleted>

Thanks I understand that Dave.  But my point was that AMQP basically implements queues and topics for the model of inter-process interaction. 

[DBI] No, AMQP 1.0 has no notion of queues and topics, it has a notion of 1-way Links.

All I meant to say was that the typical communication model exposed to the programmer is queues and topics.   I understand that 1 way-links may lie underneath in AMQP, but for this discussion that doesn't much matter to me at the moment.

However, if you feel their explanation is incorrect, feel free to correct the folks behind this article:  https://spring.io/understanding/AMQP

<stuff deleted>

As one whose implemented RPC over AMQP and other messaging impls (e.g. [1]), it hasn't been my experience that layering non-trivial RPC on async messaging is as simple as you implying.  Particularly when one considers service-and-distribution-level issues in addition to transport-level protocol differences [2].

 

[DBI] I agree that implementing RPC over AMQP 0.x, JMS and other queuing systems isn’t trivial. Doing request/response over a pair of AMQP 1.0 Links is different.

Indeed it is.  I would argue that generally what people are 'looking for' is closer to RPC than it is req/resp over a link.  Granted not true for all use cases, but generally true I would say.   That's why I'm asking the following...

>My follow-up question really is:   what thinking is currently happening WRT this mapping between IoT >communication needs (e.g. provisioning) and these abstractions (e.g. async/sync, point vs. multipoint, reliable vs. >unreliable, rpc, events, etc).

Thanks,

Scott

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Regards
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Dejan Bosanac
about.me/dejanb