Re: [core] [Dots] Large asynchronous notifications under DDoS: New BLOCK Option?

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Hi Achim, 

One clarification question:

>             +--------->|   GET /path/ctrl Token 0xf1 { NonBlock2
> 1/0/1024 NonBlock2 2/0/1024 }

Do existing CoAP implementations (libcoap, for example) support GETs with a payload?

Cheers,
Med

> -----Message d'origine-----
> De : Achim Kraus [mailto:[e-mail]]
> Envoyé : mercredi 8 avril 2020 20:56
> À : Jon Shallow; BOUCADAIR Mohamed TGI/OLN; [e-mail];
> [e-mail]; [e-mail]
> Objet : Re: [core] [Dots] Large asynchronous notifications under DDoS:
> New BLOCK Option?
> 
> Hi Jon,
> 
> let me try to demonstrate, how “application layer framing” could look
> like:
> 
> > New CoAP Option NONBLOCK2 equivalent to BLOCK2, but does not rely on
> client doing GET to get the next block synchronously. >
> >
> >         CLIENT      SERVER
> >           |          |
> >           +--------->|   GET /path Token 0xf0 Observe 0 NonBlock2
> 0/0/1024
> >           |          |
> >           |<---------+   2.05 Token 0xf0 Observe 1234 NonBlock2
> 0/1/1024
> >           |          |
> >           |<---------+   2.05 Token 0xf0 Observe 1234 NonBlock2
> 1/1/1024
> >           |          |
> >           |<---------+   2.05 Token 0xf0 Observe 1234 NonBlock2
> 2/1/1024
> >           |          |
> >           |<---------+   2.05 Token 0xf0 Observe 1234 NonBlock2
> 3/0/1024
> Do these messages in the application layer -> encode the messages =>
> put
> the encoded message as payload for ordinary notifies:
> 
>           CLIENT      SERVER
>             |          |
>             +--------->|   GET /path Token 0xf0 Observe 0 NonBlock2
> 0/0/1024
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1234 { 2.05 Token
> 0xf0 Observe abc NonBlock2 0/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1235 { 2.05 Token
> 0xf0 Observe abc NonBlock2 1/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1236 { 2.05 Token
> 0xf0 Observe abc NonBlock2 2/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1237 { 2.05 Token
> 0xf0 Observe abc NonBlock2 3/0/1024 }
> 
> The outer notifies will be processed as usual, the application block
> logic is yours.
> 
> Observe triggered
>             |<---------+   2.05 Token 0xf0 Observe 1238 { 2.05 Token
> 0xf0 Observe abd NonBlock2 0/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1239 { 2.05 Token
> 0xf0 Observe abd NonBlock2 1/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1240 { 2.05 Token
> 0xf0 Observe abd NonBlock2 2/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1241 { 2.05 Token
> 0xf0 Observe abd NonBlock2 3/0/1024 }
> 
> Observe triggered
>             |<---------+   2.05 Token 0xf0 Observe 1238 { 2.05 Token
> 0xf0 Observe abd NonBlock2 0/1/1024 }
>             |          |
>             |  X<------+   2.05 Token 0xf0 Observe 1239 { 2.05 Token
> 0xf0 Observe abd NonBlock2 1/1/1024 }
>             |          |
>             |  X<------+   2.05 Token 0xf0 Observe 1240 { 2.05 Token
> 0xf0 Observe abd NonBlock2 2/1/1024 }
>             |          |
>             |<---------+   2.05 Token 0xf0 Observe 1241 { 2.05 Token
> 0xf0 Observe abd NonBlock2 3/0/1024 }
> 
> 
> Client realises blocks are missing and asks for the missing ones in
> one go
> 
>             +--------->|   GET /path/ctrl Token 0xf1 { NonBlock2
> 1/0/1024 NonBlock2 2/0/1024 }
>             |          |
>             |  X<------+   2.05 Token 0xf0 Observe 1242 { 2.05 Token
> 0xf0 Observe abd NonBlock2 1/1/1024 }
>             |          |
>             |<...------+   2.05 Token 0xf0 Observe 1243 { 2.05 Token
> 0xf0 Observe abd NonBlock2 2/1/1024 }
> 
> Get final missing block
>             +--------->|   GET /path/ctrl Token 0xf2 { / NonBlock2
> 1/0/1024 }
>             |          |
>             |<...------+   2.05 Token 0xf0 Observe 1244 { 2.05 Token
> 0xf0 Observe abd NonBlock2 1/1/1024 }
> 
> 
> That should be not considered as "precise description of the
> application
> layer framing". It should just give a first impression, how coap
> standards could be used, and the specific stuff could be move to the
> application layer (reusing coap again).
> 
> best regards
> Achim