RE: New web of things server projects

Dear Dave

For CoAP I would like to take advantage of the pub-sub mechanism that the IETF is working on, as a basis for the thing server to send notifications to other servers with proxies for the things that the CoAP server hosts.  I am chatting with some MQTT experts to ensure that we hit the ground running with the MQTT bindings.   A further challenge is the choice of binary encodings for messages.  Carsten Bormann of CoAP fame advocates CBOR, but other people are keen on EXI, which can offer superior compression based upon the data model.

I am getting more and more confused about what “Web” stands for in the W3C WoT activity. CoAP is a RESTful protocol that is built for transferring state of resources encoded as standard Internet Media Types. And it comes with a native support for asynchronous push notifications from the server. In what sense do we need a “binding” here?

Furthermore, why should we first constrain CoAP to the pub/sub pattern (which is very useful, IFF you want to explicitly build a pub/sub application, for instance to minimize the complexity for normally-off or mobile nodes) to then construct a binding on top to have RESTful interactions?

In my understanding, a binding for MQTT would be a REST gateway that uses the layered-system constraint to provide a REST interface on the one side and connect it to whatever system on the other side. Since MQTT does not have the notion of URIs and Content-Types, I agree that we need a binding here. However, in my understanding, these things then are MQTT things behind a gateway and not Web of Things servers.

The main problem I see with this development is that we say “hey, let’s build something easy with JSON,” but at the moment ignore a lot of complexity that will hit us once we reach critical mass. Then we will need to extend our simply world view and will eventually end up with CORBA/WS-* 2.0… The nice lesson about REST was that there are already a lot of mechanisms built into the protocol(s) to deal with this critical mass complexity of distributed systems; and we should use these mechanisms.

Best regards
Matthias