QtCS 2017 CoAP

CoAP Client

• Contribution consists of CoAP client
  • Supports PUT/GET/POST/DELETE
    • Not yet FETCH/PATCH (RFC 8132)
  • Supports Blockwise transfer
  • Supports Notification (QCoapReply::notified signal, QCoapClient::cancelObserve())
  • Partially supports multicast
    • Sending on multicast works and works for receiving one reply
    • Currently does not work with receiving multiple replies
• API is modelled after QNAM but does not use it
  • QCoapClient, QCoapRequest, QCoapReply
• No DTLS support yet (see network discussion)
• API does support IETF-style resource discovery (multicast GET to /.well-known/core)
  • QCoapClient::discover, QCoapDiscoveryReply
  • API needs a little work:
    • signal and parameters
    • discover() should be able to send on both IPv4 and v6 multicast, without the user hardcoding anything
    • building of query parameters (QUrlQuery?)
• Add a method to QCoapClient and QNetworkAccessManager: setDeleteOnFinished / setAutoDeleteReplies
  • Defaults to false on QNAM, defauts to true here
• No CoAP+TCP plans yet

Testing

• Once we have CoAP server support, we can test client against server
• Inadviseable to run a CoAP server on the Qt network test server
  • Network too unstable already in TCP, probably a horrible idea to use it with UDP
• We should run a local server on the testing VM
  • Californium is Java
  • We may need to write something with libcoap (C)

CoAP server

We will need it. For example, all OCF devices are both clients and servers.

DTLS

• DTLS support needs to be added to QtNetwork or it will be too difficult
  • We just need to design it so that it will work for both the CoAP client and server

CBOR

We would like to have CBOR support in QtCore.

• Would the API be part of QJsonDocument or separate (but looking like it)?
  • Thiago's gut feeling is that making it part of QJsonDocument will make it too constrained for future uses (Example: COSE uses integer keys in maps, not strings)
• Volunteers to work with Thiago on doing this
  • Witekio people
  • Frederik
  • Shawn
  • Alejandro Exojo