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Versions: (draft-fge-json-schema-validation) 00 01

Internet Engineering Task Force                           A. Wright, Ed.
Internet-Draft
Intended status: Informational                                   G. Luff
Expires: October 17, 2017
                                                         H. Andrews, Ed.
                                                        Cloudflare, Inc.
                                                          April 15, 2017


 JSON Schema Validation: A Vocabulary for Structural Validation of JSON
                 draft-wright-json-schema-validation-01

Abstract

   JSON Schema (application/schema+json) has several purposes, one of
   which is JSON instance validation.  This document specifies a
   vocabulary for JSON Schema to describe the meaning of JSON documents,
   provide hints for user interfaces working with JSON data, and to make
   assertions about what a valid document must look like.

Note to Readers

   The issues list for this draft can be found at <https://github.com/
   json-schema-org/json-schema-spec/issues>.

   For additional information, see <http://json-schema.org/>.

   To provide feedback, use this issue tracker, the communication
   methods listed on the homepage, or email the document editors.

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 October 17, 2017.





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Copyright Notice

   Copyright (c) 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  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Terminology . . . . . . . . . . . . . . . . .   4
   3.  Interoperability considerations . . . . . . . . . . . . . . .   4
     3.1.  Validation of string instances  . . . . . . . . . . . . .   4
     3.2.  Validation of numeric instances . . . . . . . . . . . . .   4
     3.3.  Regular expressions . . . . . . . . . . . . . . . . . . .   4
   4.  General validation considerations . . . . . . . . . . . . . .   5
     4.1.  Keywords and instance primitive types . . . . . . . . . .   5
     4.2.  Validation of primitive types and child values  . . . . .   5
     4.3.  Constraints and missing keywords  . . . . . . . . . . . .   6
     4.4.  Keyword independence  . . . . . . . . . . . . . . . . . .   6
   5.  Meta-schema . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Validation keywords . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  multipleOf  . . . . . . . . . . . . . . . . . . . . . . .   6
     6.2.  maximum . . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.3.  exclusiveMaximum  . . . . . . . . . . . . . . . . . . . .   7
     6.4.  minimum . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.5.  exclusiveMinimum  . . . . . . . . . . . . . . . . . . . .   7
     6.6.  maxLength . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.7.  minLength . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.8.  pattern . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.9.  items . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     6.10. additionalItems . . . . . . . . . . . . . . . . . . . . .   8
     6.11. maxItems  . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.12. minItems  . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.13. uniqueItems . . . . . . . . . . . . . . . . . . . . . . .   9
     6.14. contains  . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.15. maxProperties . . . . . . . . . . . . . . . . . . . . . .   9
     6.16. minProperties . . . . . . . . . . . . . . . . . . . . . .   9
     6.17. required  . . . . . . . . . . . . . . . . . . . . . . . .  10
     6.18. properties  . . . . . . . . . . . . . . . . . . . . . . .  10



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     6.19. patternProperties . . . . . . . . . . . . . . . . . . . .  10
     6.20. additionalProperties  . . . . . . . . . . . . . . . . . .  11
     6.21. dependencies  . . . . . . . . . . . . . . . . . . . . . .  11
     6.22. propertyNames . . . . . . . . . . . . . . . . . . . . . .  11
     6.23. enum  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.24. const . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.25. type  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.26. allOf . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.27. anyOf . . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.28. oneOf . . . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.29. not . . . . . . . . . . . . . . . . . . . . . . . . . . .  13
   7.  Metadata keywords . . . . . . . . . . . . . . . . . . . . . .  13
     7.1.  definitions . . . . . . . . . . . . . . . . . . . . . . .  13
     7.2.  "title" and "description" . . . . . . . . . . . . . . . .  14
     7.3.  "default" . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.4.  "examples"  . . . . . . . . . . . . . . . . . . . . . . .  14
   8.  Semantic validation with "format" . . . . . . . . . . . . . .  14
     8.1.  Foreword  . . . . . . . . . . . . . . . . . . . . . . . .  14
     8.2.  Implementation requirements . . . . . . . . . . . . . . .  15
     8.3.  Defined formats . . . . . . . . . . . . . . . . . . . . .  15
       8.3.1.  date-time . . . . . . . . . . . . . . . . . . . . . .  15
       8.3.2.  email . . . . . . . . . . . . . . . . . . . . . . . .  15
       8.3.3.  hostname  . . . . . . . . . . . . . . . . . . . . . .  15
       8.3.4.  ipv4  . . . . . . . . . . . . . . . . . . . . . . . .  15
       8.3.5.  ipv6  . . . . . . . . . . . . . . . . . . . . . . . .  16
       8.3.6.  uri . . . . . . . . . . . . . . . . . . . . . . . . .  16
       8.3.7.  uri-reference . . . . . . . . . . . . . . . . . . . .  16
       8.3.8.  uri-template  . . . . . . . . . . . . . . . . . . . .  16
       8.3.9.  json-pointer  . . . . . . . . . . . . . . . . . . . .  16
   9.  Security considerations . . . . . . . . . . . . . . . . . . .  16
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     10.2.  Informative References . . . . . . . . . . . . . . . . .  17
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  19
   Appendix B.  ChangeLog  . . . . . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   JSON Schema can be used to require that a given JSON document (an
   instance) satisfies a certain number of criteria.  These criteria are
   asserted by using keywords described in this specification.  In
   addition, a set of keywords is also defined to assist in interactive
   user interface instance generation.

   This specification will use the terminology defined by the JSON
   Schema core [json-schema] specification.




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2.  Conventions and Terminology

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

   This specification uses the term "container instance" to refer to
   both array and object instances.  It uses the term "children
   instances" to refer to array elements or object member values.

   Elements in an array value are said to be unique if no two elements
   of this array are equal [json-schema].

3.  Interoperability considerations

3.1.  Validation of string instances

   It should be noted that the nul character (\u0000) is valid in a JSON
   string.  An instance to validate may contain a string value with this
   character, regardless of the ability of the underlying programming
   language to deal with such data.

3.2.  Validation of numeric instances

   The JSON specification allows numbers with arbitrary precision, and
   JSON Schema does not add any such bounds.  This means that numeric
   instances processed by JSON Schema can be arbitrarily large and/or
   have an arbitrarily long decimal part, regardless of the ability of
   the underlying programming language to deal with such data.

3.3.  Regular expressions

   Two validation keywords, "pattern" and "patternProperties", use
   regular expressions to express constraints.  These regular
   expressions SHOULD be valid according to the ECMA 262 [ecma262]
   regular expression dialect.

   Furthermore, given the high disparity in regular expression
   constructs support, schema authors SHOULD limit themselves to the
   following regular expression tokens:

      individual Unicode characters, as defined by the JSON
      specification [RFC7159];

      simple character classes ([abc]), range character classes ([a-z]);

      complemented character classes ([^abc], [^a-z]);




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      simple quantifiers: "+" (one or more), "*" (zero or more), "?"
      (zero or one), and their lazy versions ("+?", "*?", "??");

      range quantifiers: "{x}" (exactly x occurrences), "{x,y}" (at
      least x, at most y, occurrences), {x,} (x occurrences or more),
      and their lazy versions;

      the beginning-of-input ("^") and end-of-input ("$") anchors;

      simple grouping ("(...)") and alternation ("|").

   Finally, implementations MUST NOT take regular expressions to be
   anchored, neither at the beginning nor at the end.  This means, for
   instance, the pattern "es" matches "expression".

4.  General validation considerations

4.1.  Keywords and instance primitive types

   Most validation keywords only constrain values within a certain
   primitive type.  When the type of the instance is not of the type
   targeted by the keyword, the validation succeeds.

   For example, the "maxLength" keyword will only restrict certain
   strings (that are too long) from being valid.  If the instance is a
   number, boolean, null, array, or object, the keyword passes
   validation.

4.2.  Validation of primitive types and child values

   Two of the primitive types, array and object, allow for child values.
   The validation of the primitive type is considered separately from
   the validation of child instances.

   For arrays, primitive type validation consists of validating
   restrictions on length with "minItems" and "maxItems", while "items"
   and "additionalItems" determine which subschemas apply to which
   elements of the array.  In addition, "uniqueItems" and "contains"
   validate array contents as a whole.

   For objects, primitive type validation consists of validating
   restrictions on which and how many properties appear with "required",
   "minProperties", "maxProperties", "propertyNames", and the string
   array form of "dependencies", while "properties",
   "patternProperties", and "additionalProperties" determine which
   subschemas apply to which object property values.  In addition, the
   schema form of "dependencies" validates the object as a whole based
   on the presence of specific property names.



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4.3.  Constraints and missing keywords

   Each JSON Schema validation keyword adds constraints that an instance
   must satisfy in order to successfully validate.

   Validation keywords that are missing never restrict validation.  In
   some cases, this no-op behavior is identical to a keyword that exists
   with certain values, and these values are noted where known.

4.4.  Keyword independence

   Validation keywords typically operate independently, without
   affecting each other's outcomes.

   For schema author convenience, there are some exceptions:

      "additionalProperties", whose behavior is defined in terms of
      "properties" and "patternProperties"; and

      "additionalItems", whose behavior is defined in terms of "items".

5.  Meta-schema

   The current URI for the JSON Schema Validation is <http://json-
   schema.org/draft-06/schema#>.

6.  Validation keywords

   Validation keywords in a schema impose requirements for successful
   validation of an instance.

6.1.  multipleOf

   The value of "multipleOf" MUST be a number, strictly greater than 0.

   A numeric instance is valid only if division by this keyword's value
   results in an integer.

6.2.  maximum

   The value of "maximum" MUST be a number, representing an inclusive
   upper limit for a numeric instance.

   If the instance is a number, then this keyword validates only if the
   instance is less than or exactly equal to "maximum".






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6.3.  exclusiveMaximum

   The value of "exclusiveMaximum" MUST be number, representing an
   exclusive upper limit for a numeric instance.

   If the instance is a number, then the instance is valid only if it
   has a value strictly less than (not equal to) "exclusiveMaximum".

6.4.  minimum

   The value of "minimum" MUST be a number, representing an inclusive
   upper limit for a numeric instance.

   If the instance is a number, then this keyword validates only if the
   instance is greater than or exactly equal to "minimum".

6.5.  exclusiveMinimum

   The value of "exclusiveMinimum" MUST be number, representing an
   exclusive upper limit for a numeric instance.

   If the instance is a number, then the instance is valid only if it
   has a value strictly greater than (not equal to) "exclusiveMinimum".

6.6.  maxLength

   The value of this keyword MUST be a non-negative integer.

   A string instance is valid against this keyword if its length is less
   than, or equal to, the value of this keyword.

   The length of a string instance is defined as the number of its
   characters as defined by RFC 7159 [RFC7159].

6.7.  minLength

   The value of this keyword MUST be a non-negative integer.

   A string instance is valid against this keyword if its length is
   greater than, or equal to, the value of this keyword.

   The length of a string instance is defined as the number of its
   characters as defined by RFC 7159 [RFC7159].

   Omitting this keyword has the same behavior as a value of 0.






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6.8.  pattern

   The value of this keyword MUST be a string.  This string SHOULD be a
   valid regular expression, according to the ECMA 262 regular
   expression dialect.

   A string instance is considered valid if the regular expression
   matches the instance successfully.  Recall: regular expressions are
   not implicitly anchored.

6.9.  items

   The value of "items" MUST be either a valid JSON Schema or an array
   of valid JSON Schemas.

   This keyword determines how child instances validate for arrays, and
   does not directly validate the immediate instance itself.

   If "items" is a schema, validation succeeds if all elements in the
   array successfully validate against that schema.

   If "items" is an array of schemas, validation succeeds if each
   element of the instance validates against the schema at the same
   position, if any.

   Omitting this keyword has the same behavior as an empty schema.

6.10.  additionalItems

   The value of "additionalItems" MUST be a valid JSON Schema.

   This keyword determines how child instances validate for arrays, and
   does not directly validate the immediate instance itself.

   If "items" is an array of schemas, validation succeeds if every
   instance element at a position greater than the size of "items"
   validates against "additionalItems".

   Otherwise, "additionalItems" MUST be ignored, as the "items" schema
   (possibly the default value of an empty schema) is applied to all
   elements.

   Omitting this keyword has the same behavior as an empty schema.








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6.11.  maxItems

   The value of this keyword MUST be a non-negative integer.

   An array instance is valid against "maxItems" if its size is less
   than, or equal to, the value of this keyword.

6.12.  minItems

   The value of this keyword MUST be a non-negative integer.

   An array instance is valid against "minItems" if its size is greater
   than, or equal to, the value of this keyword.

   Omitting this keyword has the same behavior as a value of 0.

6.13.  uniqueItems

   The value of this keyword MUST be a boolean.

   If this keyword has boolean value false, the instance validates
   successfully.  If it has boolean value true, the instance validates
   successfully if all of its elements are unique.

   Omitting this keyword has the same behavior as a value of false.

6.14.  contains

   The value of this keyword MUST be a valid JSON Schema.

   An array instance is valid against "contains" if at least one of its
   elements is valid against the given schema.

6.15.  maxProperties

   The value of this keyword MUST be a non-negative integer.

   An object instance is valid against "maxProperties" if its number of
   properties is less than, or equal to, the value of this keyword.

6.16.  minProperties

   The value of this keyword MUST be a non-negative integer.

   An object instance is valid against "minProperties" if its number of
   properties is greater than, or equal to, the value of this keyword.

   Omitting this keyword has the same behavior as a value of 0.



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6.17.  required

   The value of this keyword MUST be an array.  Elements of this array,
   if any, MUST be strings, and MUST be unique.

   An object instance is valid against this keyword if every item in the
   array is the name of a property in the instance.

   Omitting this keyword has the same behavior as an empty array.

6.18.  properties

   The value of "properties" MUST be an object.  Each value of this
   object MUST be a valid JSON Schema.

   This keyword determines how child instances validate for objects, and
   does not directly validate the immediate instance itself.

   Validation succeeds if, for each name that appears in both the
   instance and as a name within this keyword's value, the child
   instance for that name successfully validates against the
   corresponding schema.

   Omitting this keyword has the same behavior as an empty object.

6.19.  patternProperties

   The value of "patternProperties" MUST be an object.  Each property
   name of this object SHOULD be a valid regular expression, according
   to the ECMA 262 regular expression dialect.  Each property value of
   this object MUST be a valid JSON Schema.

   This keyword determines how child instances validate for objects, and
   does not directly validate the immediate instance itself.  Validation
   of the primitive instance type against this keyword always succeeds.

   Validation succeeds if, for each instance name that matches any
   regular expressions that appear as a property name in this keyword's
   value, the child instance for that name successfully validates
   against each schema that corresponds to a matching regular
   expression.

   Omitting this keyword has the same behavior as an empty object.








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6.20.  additionalProperties

   The value of "additionalProperties" MUST be a valid JSON Schema.

   This keyword determines how child instances validate for objects, and
   does not directly validate the immediate instance itself.

   Validation with "additionalProperties" applies only to the child
   values of instance names that do not match any names in "properties",
   and do not match any regular expression in "patternProperties".

   For all such properties, validation succeeds if the child instance
   validates against the "additionalProperties" schema.

   Omitting this keyword has the same behavior as an empty schema.

6.21.  dependencies

   This keyword specifies rules that are evaluated if the instance is an
   object and contains a certain property.

   This keyword's value MUST be an object.  Each property specifies a
   dependency.  Each dependency value MUST be an array or a valid JSON
   Schema.

   If the dependency value is a subschema, and the dependency key is a
   property in the instance, the entire instance must validate against
   the dependency value.

   If the dependency value is an array, each element in the array, if
   any, MUST be a string, and MUST be unique.  If the dependency key is
   a property in the instance, each of the items in the dependency value
   must be a property that exists in the instance.

   Omitting this keyword has the same behavior as an empty object.

6.22.  propertyNames

   The value of "propertyNames" MUST be a valid JSON Schema.

   If the instance is an object, this keyword validates if every
   property name in the instance validates against the provided schema.
   Note the property name that the schema is testing will always be a
   string.

   Omitting this keyword has the same behavior as an empty schema.





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6.23.  enum

   The value of this keyword MUST be an array.  This array SHOULD have
   at least one element.  Elements in the array SHOULD be unique.

   An instance validates successfully against this keyword if its value
   is equal to one of the elements in this keyword's array value.

   Elements in the array might be of any value, including null.

6.24.  const

   The value of this keyword MAY be of any type, including null.

   An instance validates successfully against this keyword if its value
   is equal to the value of the keyword.

6.25.  type

   The value of this keyword MUST be either a string or an array.  If it
   is an array, elements of the array MUST be strings and MUST be
   unique.

   String values MUST be one of the six primitive types ("null",
   "boolean", "object", "array", "number", or "string"), or "integer"
   which matches any number with a zero fractional part.

   An instance validates if and only if the instance is in any of the
   sets listed for this keyword.

6.26.  allOf

   This keyword's value MUST be a non-empty array.  Each item of the
   array MUST be a valid JSON Schema.

   An instance validates successfully against this keyword if it
   validates successfully against all schemas defined by this keyword's
   value.

6.27.  anyOf

   This keyword's value MUST be a non-empty array.  Each item of the
   array MUST be a valid JSON Schema.

   An instance validates successfully against this keyword if it
   validates successfully against at least one schema defined by this
   keyword's value.




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6.28.  oneOf

   This keyword's value MUST be a non-empty array.  Each item of the
   array MUST be a valid JSON Schema.

   An instance validates successfully against this keyword if it
   validates successfully against exactly one schema defined by this
   keyword's value.

6.29.  not

   This keyword's value MUST be a valid JSON Schema.

   An instance is valid against this keyword if it fails to validate
   successfully against the schema defined by this keyword.

7.  Metadata keywords

7.1.  definitions

   This keyword's value MUST be an object.  Each member value of this
   object MUST be a valid JSON Schema.

   This keyword plays no role in validation per se.  Its role is to
   provide a standardized location for schema authors to inline JSON
   Schemas into a more general schema.

   As an example, here is a schema describing an array of positive
   integers, where the positive integer constraint is a subschema in
   "definitions":


   {
       "type": "array",
       "items": { "$ref": "#/definitions/positiveInteger" },
       "definitions": {
           "positiveInteger": {
               "type": "integer",
               "exclusiveMinimum": 0
           }
       }
   }









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7.2.  "title" and "description"

   The value of both of these keywords MUST be a string.

   Both of these keywords can be used to decorate a user interface with
   information about the data produced by this user interface.  A title
   will preferably be short, whereas a description will provide
   explanation about the purpose of the instance described by this
   schema.

7.3.  "default"

   There are no restrictions placed on the value of this keyword.

   This keyword can be used to supply a default JSON value associated
   with a particular schema.  It is RECOMMENDED that a default value be
   valid against the associated schema.

7.4.  "examples"

   The value of this keyword MUST be an array.  There are no
   restrictions placed on the values within the array.

   This keyword can be used to provide sample JSON values associated
   with a particular schema, for the purpose of illustrating usage.  It
   is RECOMMENDED that these values be valid against the associated
   schema.

   Implementations MAY use the value of "default", if present, as an
   additional example.  If "examples" is absent, "default" MAY still be
   used in this manner.

8.  Semantic validation with "format"

8.1.  Foreword

   Structural validation alone may be insufficient to validate that an
   instance meets all the requirements of an application.  The "format"
   keyword is defined to allow interoperable semantic validation for a
   fixed subset of values which are accurately described by
   authoritative resources, be they RFCs or other external
   specifications.

   The value of this keyword is called a format attribute.  It MUST be a
   string.  A format attribute can generally only validate a given set
   of instance types.  If the type of the instance to validate is not in
   this set, validation for this format attribute and instance SHOULD
   succeed.



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8.2.  Implementation requirements

   Implementations MAY support the "format" keyword.  Should they choose
   to do so:

      they SHOULD implement validation for attributes defined below;

      they SHOULD offer an option to disable validation for this
      keyword.

   Implementations MAY add custom format attributes.  Save for agreement
   between parties, schema authors SHALL NOT expect a peer
   implementation to support this keyword and/or custom format
   attributes.

8.3.  Defined formats

8.3.1.  date-time

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   date representation as defined by RFC 3339, section 5.6 [RFC3339].

8.3.2.  email

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   Internet email address as defined by RFC 5322, section 3.4.1
   [RFC5322].

8.3.3.  hostname

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   representation for an Internet host name, as defined by RFC 1034,
   section 3.1 [RFC1034].

8.3.4.  ipv4

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   representation of an IPv4 address according to the "dotted-quad" ABNF
   syntax as defined in RFC 2673, section 3.2 [RFC2673].




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8.3.5.  ipv6

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   representation of an IPv6 address as defined in RFC 2373, section 2.2
   [RFC2373].

8.3.6.  uri

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   URI, according to [RFC3986].

8.3.7.  uri-reference

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   URI Reference (either a URI or a relative-reference), according to
   [RFC3986].

8.3.8.  uri-template

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   URI Template (of any level), according to [RFC6570].

8.3.9.  json-pointer

   This attribute applies to string instances.

   A string instance is valid against this attribute if it is a valid
   JSON Pointer, according to [RFC6901]

9.  Security considerations

   JSON Schema validation defines a vocabulary for JSON Schema core and
   concerns all the security considerations listed there.

   JSON Schema validation allows the use of Regular Expressions, which
   have numerous different (often incompatible) implementations.  Some
   implementations allow the embedding of arbitrary code, which is
   outside the scope of JSON Schema and MUST NOT be permitted.  Regular
   expressions can often also be crafted to be extremely expensive to




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   compute (with so-called "catastrophic backtracking"), resulting in a
   denial-of-service attack.

10.  References

10.1.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [json-schema]
              "JSON Schema: A Media Type for Describing JSON Documents",
              draft-wright-json-schema-00 (work in progress), October
              2016.

10.2.  Informative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <http://www.rfc-editor.org/info/rfc1034>.

   [RFC2373]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 2373, DOI 10.17487/RFC2373, July 1998,
              <http://www.rfc-editor.org/info/rfc2373>.

   [RFC2673]  Crawford, M., "Binary Labels in the Domain Name System",
              RFC 2673, DOI 10.17487/RFC2673, August 1999,
              <http://www.rfc-editor.org/info/rfc2673>.

   [RFC3339]  Klyne, G. and C. Newman, "Date and Time on the Internet:
              Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
              <http://www.rfc-editor.org/info/rfc3339>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.

   [RFC6570]  Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
              and D. Orchard, "URI Template", RFC 6570,
              DOI 10.17487/RFC6570, March 2012,
              <http://www.rfc-editor.org/info/rfc6570>.







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   [RFC6901]  Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
              "JavaScript Object Notation (JSON) Pointer", RFC 6901,
              DOI 10.17487/RFC6901, April 2013,
              <http://www.rfc-editor.org/info/rfc6901>.

   [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>.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <http://www.rfc-editor.org/info/rfc5322>.

   [ecma262]  "ECMA 262 specification", <http://www.ecma-
              international.org/publications/files/ECMA-ST/
              Ecma-262.pdf>.



































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Appendix A.  Acknowledgments

   Thanks to Gary Court, Francis Galiegue, Kris Zyp, and Geraint Luff
   for their work on the initial drafts of JSON Schema.

   Thanks to Jason Desrosiers, Daniel Perrett, Erik Wilde, Ben Hutton,
   Evgeny Poberezkin, Brad Bowman, Gowry Sankar, Donald Pipowitch, and
   Dave Finlay for their submissions and patches to the document.

Appendix B.  ChangeLog

   [[CREF1: This section to be removed before leaving Internet-Draft
   status.]]

   draft-wright-json-schema-validation-01

      *  Standardized on hyphenated format names ("uriref" becomes "uri-
         ref")

      *  Add the formats "uri-template" and "json-pointer"

      *  Changed "exclusiveMaximum"/"exclusiveMinimum" from boolean
         modifiers of "maximum"/"minimum" to independent numeric fields.

      *  Split the additionalItems/items into two sections

      *  Reworked properties/patternProperties/additionalProperties
         definition

      *  Added "examples" keyword

      *  Added "contains" keyword

      *  Allow empty "required" and "dependencies" arrays

      *  Fixed "type" reference to primitive types

      *  Added "const" keyword

      *  Added "propertyNames" keyword

   draft-wright-json-schema-validation-00

      *  Added additional security considerations

      *  Removed reference to "latest version" meta-schema, use numbered
         version instead




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      *  Rephrased many keyword definitions for brevity

      *  Added "uriref" format that also allows relative URI references

   draft-fge-json-schema-validation-01

      *  Initial draft.

      *  Salvaged from draft v3.

      *  Redefine the "required" keyword.

      *  Remove "extends", "disallow"

      *  Add "anyOf", "allOf", "oneOf", "not", "definitions",
         "minProperties", "maxProperties".

      *  "dependencies" member values can no longer be single strings;
         at least one element is required in a property dependency
         array.

      *  Rename "divisibleBy" to "multipleOf".

      *  "type" arrays can no longer have schemas; remove "any" as a
         possible value.

      *  Rework the "format" section; make support optional.

      *  "format": remove attributes "phone", "style", "color"; rename
         "ip-address" to "ipv4"; add references for all attributes.

      *  Provide algorithms to calculate schema(s) for array/object
         instances.

      *  Add interoperability considerations.

Authors' Addresses

   Austin Wright (editor)

   EMail: aaa@bzfx.net


   Geraint Luff

   EMail: luffgd@gmail.com





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   Henry Andrews (editor)
   Cloudflare, Inc.

   EMail: henry@cloudflare.com















































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