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Versions: 00 01 02                                                      
JMAP                                                    B. Gondwana, Ed.
Internet-Draft                                                  Fastmail
Updates: 8620 (if approved)                                 12 July 2021
Intended status: Standards Track
Expires: 13 January 2022


                     JMAP Blob management extension
                      draft-gondwana-jmap-blob-02

Abstract

   The JMAP base protocol (RFC8620) provides the ability to upload and
   download arbitrary binary data via HTTP PUT and GET on defined
   endpoint.  This binary data is called a "Blob".

   This extension adds additional ways to create and access Blobs, by
   making inline method calls within a standard JMAP request.

   This extension also adds a reverse lookup mechanism to discover where
   blobs are referenced within other datatypes.

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 https://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 13 January 2022.

Copyright Notice

   Copyright (c) 2021 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 (https://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



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   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
   2.  Conventions Used In This Document . . . . . . . . . . . . . .   2
   3.  Blobs . . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Blob/set  . . . . . . . . . . . . . . . . . . . . . . . .   3
       3.1.1.  create  . . . . . . . . . . . . . . . . . . . . . . .   3
       3.1.2.  update  . . . . . . . . . . . . . . . . . . . . . . .   4
       3.1.3.  destroy . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Blob/get  . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.3.  Blob/lookup . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Security considerations . . . . . . . . . . . . . . . . . . .   7
   5.  IANA considerations . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  JMAP Capability registration for "blob" . . . . . . . . .   8
     5.2.  JMAP Error Codes Registration for "unknownDataType" . . .   8
     5.3.  Creation of "JMAP Datatypes" Registry . . . . . . . . . .   8
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   9
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Sometimes JMAP ([RFC8620]) interactions require creating a Blob and
   then referencing it.  In the same way that IMAP Literals ([RFC7888])
   were extended to reduce roundtrips for simple data, embedding simple
   small blobs into the JMAP method stream can reduce roundtrips.

   Likewise, when fetching an object, it can be useful to also fetch the
   raw content of that object without a separate roundtrip.

   Where JMAP is being proxied through a system which applies additional
   access restrictions, it can be useful to be able to see where a blob
   is referenced in order to decide whether to allow it to be
   downloaded.

2.  Conventions Used In This Document

   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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.



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3.  Blobs

   A blob is a sequence of zero or more octets.

   The JMAP base spec [RFC8210] defines the "Blob/copy" method, which is
   unchanged by this specfication.

3.1.  Blob/set

   This is a standard JMAP "set" method.

3.1.1.  create

   *Properties:*

   Any one of:

   *  data:asText: String|null

   *  data:asBase64: String|null

   *  data:asHex: String|null

   *  catenate: [SetObject] _list of octet sources in order_

   Also:

   *  type: String|null

   Result is:

   *  id: Id the blobId

   *  type: String|null _as given in the creation (if any); or detected
      from content; or null_

   *  size: UnsignedInt _as per RFC8620 - the size of the file in
      Octets_

   Any other properties identical to those that would be returned in the
   JSON response of the RFC8620 upload endpoint.

   SetObject:

   Any one of

   *  data:asText: String|null




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   *  data:asBase64: String|null

   *  data:asHex: String|null

   OR a blobId source:

   *  blobId: Id

   *  offset: UnsignedInt|null

   *  length: UnsignedInt|null

3.1.2.  update

   It is not possible to update a Blob, so any update will result in a
   "notUpdated" response.

3.1.3.  destroy

   If an uploaded Blob is not referenced by any persistent object, the
   server SHOULD destroy the object.  Some systems use a content-based
   ID for blobs, so the server MAY respond "destroyed" and yet that
   blobId still exist with the same content.

   Example:


























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   Method Call:

   [ "Blob/set", {
     "accountId" : "account1",
     "create" : {
       "1": {
         "data:asBase64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKA
                           AAAA1BMVEX/AAAZ4gk3AAAAAXRSTlN/gFy0ywAAAApJRE
                           FUeJxjYgAAAAYAAzY3fKgAAAAASUVORK5CYII=",
         "type" : "image/png"
       },
     },
   }, "R1" ]

   Response:

   [ "Blob/set", {
     "accountId" : "account1",
     "created" : {
       "1": {
         "id" : "G4c6751edf9dd6903ff54b792e432fba781271beb",
         "type" : "image/png",
         "size" : 95
       },
     },
   }, "R1" ]

3.2.  Blob/get

   A standard JMAP get.

   *Properties:*

   Any of

   *  data:asText

   *  data:asBase64

   *  data:asHex

   *  data _selects data:asText if the content is UTF-8, or
      data:asBase64_

   *  size

   If not given, returns "data" and "size".




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   QUESTION: do we want to add range operators?

   *  offset: UnsignedInt|null

   *  length: UnsignedInt|null

   Returns that range of octets (not characters!) from the blob.
   Alternative possible syntax - ranges within the properties, e.g:
   "data:asText:0:3000"

3.3.  Blob/lookup

   Given a list of blobIds, this method does a reverse lookup in each of
   the provided datatypes to find the list of Ids within that datatype
   which reference the provided blob.

   The definition of reference is somewhat loosely defined, but roughly
   means "you could discover this blobId by looking inside this object",
   for example if a Mailbox contains an Email which references the
   blobId, then it references that blobId.  Likewise for a Thread.

   *Parameters*

   *  accountId: "Id"

   The id of the account used for the call.

   *  datatypes: [String]

   A list of datatype names from the "JMAP Datatypes" registry for which
   "Can Reference Blobs" is "Yes".  The capability which defines each
   type must also be requested.

   If a datatype is not known by the server or the associated capability
   has not been included then the server returns an "unknownDataType"
   error.

   *  ids: [Id]

   A list of blobId values to be looked for.

   *Response*

   *  list: [BlobInfo]

   A list of BlobInfo objects.

   *BlobInfo Object*



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   *  id: Id

   The Blob Identifier.

   *  datatypes: DataType[Id List]

   A map from datatype to list of Ids of that datatype (e.g. the
   datatype "Email" maps to a list of emailIds)

   e.g.

   [ "Blob/lookup", {
     "datatypes": ["Mailbox", "Thread", "Email"],
     "ids": ["Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",
             "G6f954bcb620f7f50fc8f21426bde3669da3d9067"]
   }, "R1" ]

   Response:

   [ "Blob/lookup", {
     "list": [
       {
         "id": "Gd2f81008cf07d2425418f7f02a3ca63a8bc82003",
         "datatypes": {
           "Mailbox": ["M54e97373", Mcbe6b662"],
           "Thread": ["T1530616e"],
           "Email": ["E16e70a73eb4", "E84b0930cf16"]
         }
       }
     ],
     "notFound": ["G6f954bcb620f7f50fc8f21426bde3669da3d9067"]
   }, "R1"]

4.  Security considerations

   TO BE IMPROVED:

   JSON parsers are not all consistent in handling non-UTF-8 data.  JMAP
   requires that all JSON data be UTF-8 encoded, so servers MUST either
   return "data:asBase64" or "isEncodingProblem: true" and modify the
   data to be UTF-8 safe.

   Servers MUST apply any access controls such that if the authenticated
   user would be unable to discover the blobId by making queries, then
   this fact can't be discovered via a Blob/lookup.  For example, if an
   Email exists in a Mailbox which the authenticated user does not have
   access to see, then that emailId MUST not be returned in a lookup for
   a blob which is referenced by that email.



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   If a blob is not visible to a user at all, then the server SHOULD
   return that blobId in the notFound array, however it may also return
   an empty list for each datatype, as it may not be able to know if
   other datatypes do reference that blob.

5.  IANA considerations

5.1.  JMAP Capability registration for "blob"

   IANA is requested to register the "blob" JMAP Capability as follows:

   Capability Name: urn:ietf:params:jmap:blob

   Specification document: this document

   Intended use: common

   Change Controller: IETF

   Security and privacy considerations: this document, Section XXX

5.2.  JMAP Error Codes Registration for "unknownDataType"

   IANA is requested to register the "unknownDataType" JMAP Error Code
   as follows:

   JMAP Error Code: unknownDataType

   Intended use: common

   Change Controller: IETF

   Reference: this document

   Description: The server does not recognise this data type, or the
   capability to enable it was not present.

5.3.  Creation of "JMAP Datatypes" Registry

   IANA is requested to create a new registry "JMAP Datatypes" with the
   initial content:










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   +================+=========+======+=====================================+=========+
   |Datatype name   |Can      |Can   |Capability                           |Reference|
   |                |Reference|use   |                                     |         |
   |                |Blobs    |for   |                                     |         |
   |                |         |State |                                     |         |
   |                |         |Change|                                     |         |
   +================+=========+======+=====================================+=========+
   |Core            |No       |No    |urn:ietf:params:jmap:core            |[RFC8620]|
   +----------------+---------+------+-------------------------------------+---------+
   |PushSubscription|No       |No    |urn:ietf:params:jmap:core            |[RFC8620]|
   +----------------+---------+------+-------------------------------------+---------+
   |Mailbox         |Yes      |Yes   |urn:ietf:params:jmap:mail            |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |Thread          |Yes      |Yes   |urn:ietf:params:jmap:mail            |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |Email           |Yes      |Yes   |urn:ietf:params:jmap:mail            |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |EmailDelivery   |No       |Yes   |urn:ietf:params:jmap:mail            |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |SearchSnippet   |No       |No    |urn:ietf:params:jmap:mail            |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |Identity        |No       |Yes   |urn:ietf:params:jmap:submission      |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |EmailSubmission |No       |Yes   |urn:ietf:params:jmap:submission      |[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |VacationResponse|No       |Yes   |urn:ietf:params:jmap:vacationresponse|[RFC8621]|
   +----------------+---------+------+-------------------------------------+---------+
   |MDN             |No       |No    |urn:ietf:params:jmap:mdn             |[RFC9007]|
   +----------------+---------+------+-------------------------------------+---------+

                                  Table 1

6.  Acknowledgements

   TBD

7.  Normative References

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

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.





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   [RFC8210]  Bush, R. and R. Austein, "The Resource Public Key
              Infrastructure (RPKI) to Router Protocol, Version 1",
              RFC 8210, DOI 10.17487/RFC8210, September 2017,
              <https://www.rfc-editor.org/info/rfc8210>.

8.  Informative References

   [RFC7888]  Melnikov, A., Ed., "IMAP4 Non-synchronizing Literals",
              RFC 7888, DOI 10.17487/RFC7888, May 2016,
              <https://www.rfc-editor.org/info/rfc7888>.

   [RFC8620]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July
              2019, <https://www.rfc-editor.org/info/rfc8620>.

   [RFC8621]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP) for Mail", RFC 8621, DOI 10.17487/RFC8621,
              August 2019, <https://www.rfc-editor.org/info/rfc8621>.

Author's Address

   Bron Gondwana (editor)
   Fastmail
   Level 2, 114 William St
   Melbourne  VIC 3000
   Australia

   Email: brong@fastmailteam.com
   URI:   https://www.fastmail.com






















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