Re: [TF-AP] FYI - HTTP Web Push protocol

Hi Michael,

Comments inline below.

> On 5 Aug 2015, at 14:57, Michael Koster <michaeljohnkoster@gmail.com> wrote:
> 
> Hi Dave,
> 
> I reviewed the webpush draft 2 weeks ago in Prague and hope to align CoAP Pub-Sub with webpush patterns and architecture as much as is practical. 
> 
> Webpush has a good mapping to REST principles and some interesting reliability features, but as I recall there is not a keep-alive ping function. I believe webpush depends on existing methods for TCP (really TLS) firewall traversal.
> 
> Firewall traversal seems to be a cross layer issue of sorts, between the application and the transport. Maybe there is something in HTTP/2 that addresses this?

That is what I am expecting and need to check.

Another thing to look at is the corresponding W3C work on a Web Push API.

> 
> I haven’t seen much discussion of the firewall problem in the WoT IG. What’s the position or expectation?

It is definitely something for us to discuss.  Currently many IoT devices register with a cloud based server via an outbound connection through the Firewall/NAT to that server.  Sending notifications from the Cloud to devices within the Firewall/NAT is a bit of a challenge.  Establishing an outbound session that then allows the cloud server to push notifications to the device works reasonably well modulo the time out and closed connection issue.

Other approaches involve the use of a hub as a router for incoming notifications, where the hub has the duty of establishing a communication path through the Firewall.  There is a role for devices that combine the role of a home hub and Firewall for a more integrated approach to security.

A challenge for the Web of Things Framework is enabling a server within the Firewall to register a proxy on a server in the cloud, where the things being proxied are exposed as public URLs tied to the cloud server.  I have been thinking about a server API to support this and hope to provide a demo for the Sapporo meeting.

Best regards,
    Dave


> 
> Best regards,
> 
> Michael
> 
> 
> On Aug 5, 2015, at 4:31 AM, Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>> wrote:
> 
>> The IETF webpush WG seems relevant to the binding of the web of things data model to HTTP, and is analogous to the CoAP OBSERVE mechanism.  In essence, a client subscribes to events that are then pushed to it via HTTP 2 server push. I haven’t looked at the details, but suspect this includes provision for keep alive messages to ensure that a Firewall/NAT doesn’t block the server push messages.
>> 
>> Webpush WG: https://datatracker.ietf.org/wg/webpush/documents/ <https://datatracker.ietf.org/wg/webpush/documents/>
>> 
>> One of the recent drafts is: "Generic Event Delivery Using HTTP Push”
>> 
>>    draft-ietf-webpush-protocol-00,  published 20 July 2015
>> ]  https://datatracker.ietf.org/doc/draft-ietf-webpush-protocol/?include_text=1 <https://datatracker.ietf.org/doc/draft-ietf-webpush-protocol/?include_text=1>
>> 
>> —
>>    Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>
>> 
>> 
>> 
> 

—
   Dave Raggett <dsr@w3.org <mailto:dsr@w3.org>>