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Internet Engineering Task Force (IETF)
Request for Comments: 8142
Category: Standards Track
ISSN: 2070-1721
S. Gillies
Mapbox
April 2017

GeoJSON Text Sequences

Abstract

This document describes the GeoJSON text sequence format and "application/geo+json-seq" media type. This format is based on JavaScript Object Notation (JSON) text sequences and GeoJSON, and it makes arbitrarily large geographic datasets incrementally parseable without restricting the form of GeoJSON texts within a sequence.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc8142.

Copyright Notice

Copyright © 2017 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 (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. Requirements Language ......................................2
   2. GeoJSON Text Sequence Format ....................................2
   3. Security Considerations .........................................3
   4. Interoperability Considerations .................................3
   5. IANA Considerations .............................................3
   6. References ......................................................4
      6.1. Normative References .......................................4
      6.2. Informative References .....................................5
   Author's Address ...................................................5

1. Introduction

Arbitrarily large sequences of values pose a problem for JavaScript Object Notation (JSON) [RFC7159] that is well explained in the motivation for JSON text sequences [RFC7464]. The GeoJSON format [RFC7946] faces the same kind of problem. Geographic datasets often run to the tens of thousands or millions of features. The problem is often amplified by the presence of large arrays of coordinates for each of the features.

This document describes a specialization of JSON text sequences. A GeoJSON text sequence is a document of arbitrarily large size containing one or more GeoJSON objects (e.g., multiple GeoJSON texts that can be produced and parsed incrementally) and not just a single GeoJSON FeatureCollection, Feature, or Geometry.

1.1. Requirements Language

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 [RFC2119].

2. GeoJSON Text Sequence Format

Defined in prose similar to the description of the JSON text sequence in [RFC7464], a GeoJSON text sequence is any number of GeoJSON [RFC7946] texts, each encoded in UTF-8 [RFC3629], preceded by one ASCII [RFC20] record separator (RS) character, and followed by a line feed (LF).

The GeoJSON text sequence format conforms to all the rules of [RFC7464] and adds the following constraint: each JSON text MUST contain a single GeoJSON object as defined in [RFC7946].

Heterogeneous sequences containing a mix of GeoJSON Geometry, Feature, and FeatureCollection objects are permitted. How producers and parsers of GeoJSON text sequences communicate rules for allowed GeoJSON types in exchanged sequences is not specified in this document.

3. Security Considerations

GeoJSON text sequences have no security considerations beyond those of JSON text sequences [RFC7464] and the GeoJSON format [RFC7946].

4. Interoperability Considerations

The advantage of using ASCII character RS "0x1e" to denote a text is that sequence producers and parsers need not enforce a canonical form of GeoJSON. Any valid GeoJSON, pretty-printed or compact, can be used in a GeoJSON text sequence.

A variety of parsers designed for newline-delimited sequences of compact JSON text are deployed on the internet today. While there is no canonical form for JSON texts, and pretty-printed and compact forms are equally valid, GeoJSON text sequences containing compact GeoJSON texts with no internal newlines are more interoperable with existing non-standardized parsers.

In a distributed system where order and exactly-once delivery of messages are difficult to achieve, GeoJSON text sequences that do not rely on order of texts for extra semantics are more interoperable than those that do.

5. IANA Considerations

The MIME media type for GeoJSON text sequences is "application/ geo+json-seq" (which uses the suffix established in [RFC8091]). IANA has registered it in the "Media Types" registry <https://www.iana.org/assignments/media-types/>. 

   Type name:  application
   
   Subtype name:  geo+json-seq
   
   Required parameters:  n/a
   
   Optional parameters:  n/a
   
   Encoding considerations:  binary
   
   Security considerations:  See Section 3 of RFC 8142
   Interoperability considerations:  See Section 4 of RFC 8142
   
   Published specification:  RFC 8142

Applications that use this media type: Geographic information 

      systems (GIS)

Additional information: 

      Deprecated alias names for this type:  n/a
      
      Magic number(s):  n/a
      
      File extension(s):  n/a
      
      Macintosh file type code(s):  n/a

Person to contact for further information: Sean Gillies 

      (sean.gillies@gmail.com)
   
   Intended usage:  COMMON
   
   Restrictions on usage:  none
   
   Author:  Sean Gillies (sean.gillies@gmail.com)
   
   Change controller:  IETF

6. References

6.1. Normative References

   [RFC20]    Cerf, V., "ASCII format for network interchange", STD 80,
              RFC 20, DOI 10.17487/RFC0020, October 1969,
              <http://www.rfc-editor.org/info/rfc20>.
   
   [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>.
   
   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <http://www.rfc-editor.org/info/rfc3629>.
   
   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <http://www.rfc-editor.org/info/rfc7159>.
   
   [RFC7464]  Williams, N., "JavaScript Object Notation (JSON) Text
              Sequences", RFC 7464, DOI 10.17487/RFC7464, February 2015,
              <http://www.rfc-editor.org/info/rfc7464>.
   
   [RFC7946]  Butler, H., Daly, M., Doyle, A., Gillies, S., Hagen, S.,
              and T. Schaub, "The GeoJSON Format", RFC 7946,
              DOI 10.17487/RFC7946, August 2016,
              <http://www.rfc-editor.org/info/rfc7946>.

6.2. Informative References

   [RFC8091]  Wilde, E., "A Media Type Structured Syntax Suffix for JSON
              Text Sequences", RFC 8091, DOI 10.17487/RFC8091, February
              2017, <http://www.rfc-editor.org/info/rfc8091>.

Author's Address

Sean Gillies
Mapbox 

   Email: sean.gillies@gmail.com
   URI:   http://sgillies.net