Internet-Draft JMAP Portability Extensions February 2024
Baum & Happel Expires 22 August 2024 [Page]
Intended Status:
Standards Track
J.M. Baum, Ed.
H.J. Happel, Ed.

JMAP Migration and Portability Extensions


JMAP (RFC8620) is a generic, efficient, mobile friendly and scalable protocol that can be used for data of any type. This makes it a good fit for migrations or data portability use cases. This extension adds additional features useful (but not limited to) those use cases.

It adds a feature exposing details about the product, backend and environment of a JMAP server.

It also adds a data model for extending the JMAP Response with log messages, particularly helpful for debugging.

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

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 22 August 2024.

Table of Contents

1. Introduction

Every server-side software has its own quirks. For example, a JMAP server might only have partially implemented the JMAP standard or design decisions might have been taken that let the server deviate from what is actually required by [RFC8620]. Servers might also have unintended bugs or have certain restrictions that are not sufficiently reflected by their list of supported server capabilities.

JMAP as a protocol for data migration and portability targets a large variety of pre-existing systems. Especially legacy systems often come with a lot of constraints that may prohibit them from fully complying with the JMAP standard. Interoperable clients that aim to have a successful structured data exchange with such "unique" servers need to handle these quirks with workarounds on the client-side. Clients only want to apply special workarounds in situations where they are truly necessary. This is typically done by identifying which server-side software they are communicating with.

JMAP does not provide a standardized way to retrieve an identifier of the product that is residing on the server side. Due to the lack of standardization clients are left to identify misbehaving servers by error-prone means. Examples are checking against a list of known URLs or checking known unique responses, typically only sent by certain products. This makes identifying products time-consuming and brittle.

Related functionality in other standards are the PRODID property in iCalendar [RFC5545] and vCard [RFC6350], which allows identifying the product that produced the files. ManageSieve [RFC5804] and JMAP Sieve [I-D.ietf-jmap-sieve] define an implementation property, which allows identifying the Sieve implementation.

Additionally, server-side logs are very valuable to analyze issues a client may run into. Usually, logs are either stored locally on the instances or sent to a dedicated logging server. However, data migrations often take place in constrained environments under which access to server-side logs is limited. JMAP can be leveraged to supply log messages along-side the usual data exchange. This also removes the need to operate a separate logging infrastructure or have dedicated channels for log messages.

1.1. 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.

The definitions of JSON keys and datatypes in the document follow the conventions described in the core JMAP specification [RFC8620].

1.2. Addition to the capabilities object

The capabilities object is returned as part of the JMAP Session object; see [RFC8620], Section 2. This document defines two additional capability URIs.

1.2.1. urn:ietf:params:jmap:core:backendinfo

This extension defines one additional urn:ietf:params:jmap:core:backendinfo server capability that provides details about the product, backend and environment.

The value of this property in the JMAP Session capabilities property is an object that MUST contain the following information on server capabilities:

  • apiBackend: SoftwareInfo|null Information on the JMAP API backend component.
  • product: SoftwareInfo|null Information on the overall application or product.
  • environment: String|null Information on the environment the software is running in.

A SoftwareInfo object has the following properties:

  • name: String The JMAP API backend software.
  • version: String|null The software version.

This extension does not add anything to the account's accountCapabilities property.

Here is an example JSON snippet:

  "capabilities": {
    "urn:ietf:params:jmap:core:backendinfo": {
      "apiBackend": {
        "name": "OpenXPort/Horde",
        "version": "1.0.0"
      "product": {
        "name": "Horde Webmailer",
        "version": "1.0.0"
      "environment": {
        "name": "PHP",
        "version": "5.5"

1.2.2. urn:ietf:params:jmap:debug

Represents support for the logs property in the JMAP method response (defined in RFC8620 Section 3.4) and the "problem details" types (defined in RFC8620 Section 3.6.1) using the LogLine data type.

The value of this property in the JMAP Session and account's capabilities property is an empty object.

2. Structured Data Exchange Extension

The Response object as well as all "problem details" objects will be extended via:

A LogLine object has the following properties:

An example list of logs sent alongside a response to Core/echo would look like:

  "logs" : [
      "file" : "Logger.php",
      "level" : "info",
      "line" : 32,
      "message" : "Array Logger has been successfully initialized",
      "timestamp" : "2022-01-18T10:26:56+01:00"
      "file" : "ErrorHandler.php",
      "level" : "warning",
      "line" : 52,
      "message" : "fopen(bridge.php):
        failed to open stream: No such file or directory",
      "timestamp" : "2022-01-18T10:26:56+01:00"
  "methodResponses" : [

3. Security considerations

All security considerations of JMAP [RFC8620] apply to this specification.

Log messages might contain sensitive user data as well as detailed information about the system on which an API server has been installed. Appropriate measures must be taken to restrict access to JMAP Debug to trusted parties only.

4. IANA considerations

4.1. JMAP Capability Registration for "backendinfo"

IANA will register the "backendinfo" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:backendinfo

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, Section 3.

4.2. JMAP Capability registration for "debug"

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

Capability Name: urn:ietf:params:jmap:debug

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, Section 3.

4.3. JMAP Datatype Registration for "LogLine"

IANA will register the "LogLine" Data Type as folows:

Type Name: "LogLine"

Can reference blobs: No

Can use for state change: No

Capability: urn:ietf:params:jmap:debug

Reference: this document

5. Acknowledgements

Bron Gondwana, Neil Jenkins, Alexey Melnikov, Ken Murchison, Robert Stepanek and the JMAP working group at the IETF.

6. Normative References

Murchison, K., "JMAP for Sieve Scripts", Work in Progress, Internet-Draft, draft-ietf-jmap-sieve-19, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Desruisseaux, B., Ed., "Internet Calendaring and Scheduling Core Object Specification (iCalendar)", RFC 5545, DOI 10.17487/RFC5545, , <>.
Melnikov, A., Ed. and T. Martin, "A Protocol for Remotely Managing Sieve Scripts", RFC 5804, DOI 10.17487/RFC5804, , <>.
Perreault, S., "vCard Format Specification", RFC 6350, DOI 10.17487/RFC6350, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Jenkins, N. and C. Newman, "The JSON Meta Application Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, , <>.

Authors' Addresses

Joris Baum (editor)
Alter Schlachthof 57
76137 Karlsruhe
Hans-Joerg (editor)
Alter Schlachthof 57
76137 Karlsruhe