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Versions: 00                                                            
CoRE Working Group                                            C. Bormann
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Informational                                A. Keranen
Expires: January 9, 2017                                        Ericsson
                                                           July 08, 2016


       The BLE (Bluetooth Low Energy) URI Scheme and Media Types
                     draft-bormann-t2trg-ble-uri-00

Abstract

   In addition to its use as a subnetwork layer for IP (e.g., via
   RFC 7668), in various IoT web applications Bluetooth Low Energy (BLE)
   can serve as a "local interconnect", connecting devices locally
   (i.e., not over IP) for use as a source of information and a target
   for actuation.  In order to fully use these capabilities in
   applications using web technologies, there is a need for a method for
   addressing the resources, i.e., a URI scheme, and definition of the
   representation of the data exchanged between the application and
   devices, i.e., media types.  This document is a straw man proposal
   for such a URI scheme and media types for interacting with the
   Bluetooth GAP and GATT protocols.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 9, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents



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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Access to local resources via Bluetooth Low Energy  . . . . .   3
   3.  Media types . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  application/ble-nodelist  . . . . . . . . . . . . . . . .   5
     3.2.  application/ble-gap-enablement  . . . . . . . . . . . . .   6
     3.3.  application/ble-gap-nameinfo  . . . . . . . . . . . . . .   6
     3.4.  application/ble-gatt-servicelist  . . . . . . . . . . . .   6
     3.5.  application/ble-gatt-characteristics  . . . . . . . . . .   6
   4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     4.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   In the context of the W3C Web of Things (WoT) Interest Group work,
   the need to address both resources connected over the Internet of
   Things and those connected over a "local interconnect" has been
   raised.  The present document is a straw man proposal for a URI
   format addressing the latter kind, using the example of the Bluetooth
   GAP and GATT protocols.

   The Bluetooth GAP and GATT REST API white papers [BT-GAP-REST]
   [BT-GATT-REST] describe how an HTTP gateway can be used for
   interacting with Bluetooth devices and their resources over the
   Internet, using HTTP.  If a Bluetooth device is IP-enabled (e.g.,
   [RFC7668]), also regular IP protocols (e.g., CoAP) and URI schemes
   can be used for end-to-end communication.  When a web application is
   running on a Bluetooth device, or the Bluetooth device is directly
   connected to the same device where the web application is running, IP
   communication is not always necessary but a mechanism for addressing
   the resources is still needed.  This document specifies a URI scheme
   for addressing such locally connected Bluetooth resources and
   functionality.

   In addition to locally connected resources, a BLE URI scheme can be
   used to address resources on a remote host that implements a proxy



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   supporting both the BLE scheme and another scheme that is possible to
   use over a network (e.g., HTTP or CoAP).

   The focus of this document is on interaction with the attributes and
   characteristics that would be exposed as resources for an IoT web
   application.  That is, functionality such as being able to create
   synchronous audio connection with a Bluetooth headset is out of
   scope.

   (Note that the version you are looking at is less than half-way
   complete.  We plan to fill in the rest of the proposal after
   receiving some initial feedback about the general approach.)

1.1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [RFC2119].

   GAP and GATT are protocols defined in [BTCorev4.2].

   Terminology for constrained nodes and constrained node networks can
   be found in [RFC7228].

   In this specification, the term "byte" is used in its now customary
   sense as a synonym for "octet".

   All multi-byte integers in this specification are interpreted in
   network byte order.

   Enabled nodes: Nodes that have been configures for automatic
   connection (and reconnection each time a connection is lost).

2.  Access to local resources via Bluetooth Low Energy

   For GAP, clients operating in the GAP Central and Observer roles
   [BTCorev4.2] are supported.  Security setup ("pairing") and the
   specifics of link encryption are out of scope for this version of the
   present document.  Specifically, there is an assumption that any
   necessary access control to nodes and resources on these nodes is
   performed when the URIs defined in this document are operated.

   The following URIs are predefined:







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    +------------------------+-------------------------+-----+--------+
    | URI                    | Semantics               | Op. | Result |
    +------------------------+-------------------------+-----+--------+
    | ble:/gap/nodes/passive | passive scan for nodes  | GET | (1)    |
    |                        |                         |     |        |
    | ble:/gap/nodes/active  | active scan for nodes   | GET | (1)    |
    |                        |                         |     |        |
    | ble:/gap/nodes/enabled | scan for enabled nodes  | GET | (1)    |
    |                        |                         |     |        |
    | ble:/gatt/nodes        | list of available nodes | GET | (2)    |
    +------------------------+-------------------------+-----+--------+

   The GAP operations return gap node links, operations on which are
   detailed below.  The implementation is free to choose the form of
   these node links, e.g. from the template "ble:/gap/node/{handle}".

     +---------------+-------------------------------+-----+--------+
     | URI           | Semantics                     | Op. | Result |
     +---------------+-------------------------------+-----+--------+
     | {node}        | Information about node {node} | GET | (1)    |
     |               |                               |     |        |
     | {node}/enable | Enablement of {node}          | PUT | (3)    |
     |               |                               |     |        |
     | {node}/name   | Name of {node}                | GET | (4)    |
     +---------------+-------------------------------+-----+--------+

   The above GATT operations return gatt node links, operations on which
   are detailed below.  Again, the implementation is free to choose the
   form of these node links, e.g. from the template "ble:/gatt/
   node/{handle}".  [[twotypes: Do we really need two types of node
   links or are the GAP and GATT ones possibly interchangeable?]]

      +-----------------+----------------------------+-----+--------+
      | URI             | Semantics                  | Op. | Result |
      +-----------------+----------------------------+-----+--------+
      | {node}/services | Services offered by {node} | GET | (5)    |
      +-----------------+----------------------------+-----+--------+

   The above GATT operations return gatt service links, operations on
   which are detailed below.  Again, the implementation is free to
   choose the form of these node links, e.g. from the template
   "ble:/gatt/service/{nodehandle}/{servicehandle}".  [[nodesvsservices:
   In the current draft, it is not always clear whether a node leads to
   some resource or the client needs to go through a service to get
   there.  This needs to be clarified (or possibly unified).]]






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   +-------------------------------+--------------------+-----+--------+
   | URI                           | Semantics          | Op. | Result |
   +-------------------------------+--------------------+-----+--------+
   | {service}/secondaryservices   | Secondary services | GET | (5)    |
   |                               | for {service}      |     |        |
   |                               |                    |     |        |
   | {service}/characteristics     | Characteristics of | GET | (6)    |
   |                               | {service}          |     |        |
   |                               |                    |     |        |
   | {node}/{uuid}/characteristics | {uuid}             | GET | (6)    |
   |                               | Characteristics of |     |        |
   |                               | {node}             |     |        |
   +-------------------------------+--------------------+-----+--------+

      +-----+-------------------------------------------------------+
      |     | media type                                            |
      +-----+-------------------------------------------------------+
      | (1) | application/ble-nodelist+json or +cbor                |
      |     |                                                       |
      | (2) | application/ble-nodelist+json or +cbor, no attributes |
      |     |                                                       |
      | (3) | application/ble-gap-enablement+json or +cbor          |
      |     |                                                       |
      | (4) | application/ble-gap-nameinfo+json or +cbor            |
      |     |                                                       |
      | (5) | application/ble-gatt-servicelist+json or +cbor        |
      |     |                                                       |
      | (5) | application/ble-gatt-characteristics+json or +cbor    |
      +-----+-------------------------------------------------------+

3.  Media types

   The media types below are tentatively defined in CDDL, for both JSON
   (add +json) and CBOR (add +cbor) use.  Where the type "bytes" is used
   with JSON, the representation is a base64url [RFC4648] string.
   [[separatemediatypes: In the next version, we might possibly move to
   a single media type that has a choice between all these formats.]]

3.1.  application/ble-nodelist












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   nodelist = [* node]
   node = {
     href: text,  ; link to that specific node
     bdaddr: bdaddr,
     ? ad: attributelist, ; only for GAP use
   }

   bdaddr = bytes .size 6

   attributelist = [* attribute] ; could this be a map?
   attribute = [attributename, bytes]
   attributename = text

3.2.  application/ble-gap-enablement

   enablement = {
     enabled: bool,
     ? interval: uint,   ; define what unit
     ? latency: uint,    ; define what unit
   }

3.3.  application/ble-gap-nameinfo

   node = {
     href: text,  ; link to that specific node
     name: text,
   }

3.4.  application/ble-gatt-servicelist

   servicelist = [* service]
   service = {
     href: text,
     uuid: uuid,
   }

   uuid = bytes .size 16

3.5.  application/ble-gatt-characteristics












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   characteristics = [* characteristic]
   characteristic = {
     href: text,  ; link for this characteristic
     properties: properties,
   }

   properties = bytes .bits property
   property = &(
   Broadcast: 0
   Readable: 1
   Writable-with-no-response: 2
   Writable: 3
   Notify: 4
   Indicate: 5
   Authenticated-signed-write: 6
   Extended-property-available: 7
   )

4.  References

4.1.  Normative References

   [BT-GAP-REST]
              Bluetooth Special Interest Group, Internet Working Group,
              "GAP REST API White Paper", April 2014,
              <https://www.bluetooth.com/develop-with-bluetooth/white-
              papers>.

   [BT-GATT-REST]
              Bluetooth Special Interest Group, Internet Working Group,
              "GATT REST API White Paper", April 2014,
              <https://www.bluetooth.com/develop-with-bluetooth/white-
              papers>.

   [BTCorev4.2]
              Bluetooth Special Interest Group, "Bluetooth Core
              Specification Version 4.2", December 2014,
              <https://www.bluetooth.org/en-us/specification/adopted-
              specifications>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
              RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.







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4.2.  Informative References

   [RFC4648]  Josefsson, S., "The Base16, Base32, and Base64 Data
              Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
              <http://www.rfc-editor.org/info/rfc4648>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228, DOI 10.17487/
              RFC7228, May 2014,
              <http://www.rfc-editor.org/info/rfc7228>.

   [RFC7668]  Nieminen, J., Savolainen, T., Isomaki, M., Patil, B.,
              Shelby, Z., and C. Gomez, "IPv6 over BLUETOOTH(R) Low
              Energy", RFC 7668, DOI 10.17487/RFC7668, October 2015,
              <http://www.rfc-editor.org/info/rfc7668>.

Authors' Addresses

   Carsten Bormann
   Universitaet Bremen TZI
   Postfach 330440
   Bremen  D-28359
   Germany

   Phone: +49-421-218-63921
   Email: cabo@tzi.org


   Ari Keranen
   Ericsson
   Jorvas  02420
   Finland

   Email: ari.keranen@ericsson.com

















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