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rfc:rfc7807

Internet Engineering Task Force (IETF) M. Nottingham Request for Comments: 7807 Akamai Category: Standards Track E. Wilde ISSN: 2070-1721 March 2016

                   Problem Details for HTTP APIs

Abstract

 This document defines a "problem detail" as a way to carry machine-
 readable details of errors in a HTTP response to avoid the need to
 define new error response formats for HTTP APIs.

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 5741.
 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/rfc7807.

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
 (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.

Nottingham & Wilde Standards Track [Page 1] RFC 7807 Problem Details March 2016

Table of Contents

 1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
 2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   3
 3.  The Problem Details JSON Object . . . . . . . . . . . . . . .   3
   3.1.  Members of a Problem Details Object . . . . . . . . . . .   5
   3.2.  Extension Members . . . . . . . . . . . . . . . . . . . .   6
 4.  Defining New Problem Types  . . . . . . . . . . . . . . . . .   6
   4.1.  Example . . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.2.  Predefined Problem Types  . . . . . . . . . . . . . . . .   8
 5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
 6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   6.1.  application/problem+json  . . . . . . . . . . . . . . . .   9
   6.2.  application/problem+xml . . . . . . . . . . . . . . . . .  10
 7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
   7.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
   7.2.  Informative References  . . . . . . . . . . . . . . . . .  12
 Appendix A.  HTTP Problems and XML  . . . . . . . . . . . . . . .  14
 Appendix B.  Using Problem Details with Other Formats . . . . . .  15
 Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  16
 Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1. Introduction

 HTTP [RFC7230] status codes are sometimes not sufficient to convey
 enough information about an error to be helpful.  While humans behind
 Web browsers can be informed about the nature of the problem with an
 HTML [W3C.REC-html5-20141028] response body, non-human consumers of
 so-called "HTTP APIs" are usually not.
 This specification defines simple JSON [RFC7159] and XML
 [W3C.REC-xml-20081126] document formats to suit this purpose.  They
 are designed to be reused by HTTP APIs, which can identify distinct
 "problem types" specific to their needs.
 Thus, API clients can be informed of both the high-level error class
 (using the status code) and the finer-grained details of the problem
 (using one of these formats).
 For example, consider a response that indicates that the client's
 account doesn't have enough credit.  The 403 Forbidden status code
 might be deemed most appropriate to use, as it will inform HTTP-
 generic software (such as client libraries, caches, and proxies) of
 the general semantics of the response.
 However, that doesn't give the API client enough information about
 why the request was forbidden, the applicable account balance, or how
 to correct the problem.  If these details are included in the

Nottingham & Wilde Standards Track [Page 2] RFC 7807 Problem Details March 2016

 response body in a machine-readable format, the client can treat it
 appropriately; for example, triggering a transfer of more credit into
 the account.
 This specification does this by identifying a specific type of
 problem (e.g., "out of credit") with a URI [RFC3986]; HTTP APIs can
 do this by nominating new URIs under their control, or by reusing
 existing ones.
 Additionally, problem details can contain other information, such as
 a URI that identifies the specific occurrence of the problem
 (effectively giving an identifier to the concept "The time Joe didn't
 have enough credit last Thursday"), which can be useful for support
 or forensic purposes.
 The data model for problem details is a JSON [RFC7159] object; when
 formatted as a JSON document, it uses the "application/problem+json"
 media type.  Appendix A defines how to express them in an equivalent
 XML format, which uses the "application/problem+xml" media type.
 Note that problem details are (naturally) not the only way to convey
 the details of a problem in HTTP; if the response is still a
 representation of a resource, for example, it's often preferable to
 accommodate describing the relevant details in that application's
 format.  Likewise, in many situations, there is an appropriate HTTP
 status code that does not require extra detail to be conveyed.
 Instead, the aim of this specification is to define common error
 formats for those applications that need one, so that they aren't
 required to define their own, or worse, tempted to redefine the
 semantics of existing HTTP status codes.  Even if an application
 chooses not to use it to convey errors, reviewing its design can help
 guide the design decisions faced when conveying errors in an existing
 format.

2. Requirements

 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 [RFC2119].

3. The Problem Details JSON Object

 The canonical model for problem details is a JSON [RFC7159] object.
 When serialized as a JSON document, that format is identified with
 the "application/problem+json" media type.

Nottingham & Wilde Standards Track [Page 3] RFC 7807 Problem Details March 2016

 For example, an HTTP response carrying JSON problem details:
 HTTP/1.1 403 Forbidden
 Content-Type: application/problem+json
 Content-Language: en
 {
  "type": "https://example.com/probs/out-of-credit",
  "title": "You do not have enough credit.",
  "detail": "Your current balance is 30, but that costs 50.",
  "instance": "/account/12345/msgs/abc",
  "balance": 30,
  "accounts": ["/account/12345",
               "/account/67890"]
 }
 Here, the out-of-credit problem (identified by its type URI)
 indicates the reason for the 403 in "title", gives a reference for
 the specific problem occurrence with "instance", gives occurrence-
 specific details in "detail", and adds two extensions; "balance"
 conveys the account's balance, and "accounts" gives links where the
 account can be topped up.
 The ability to convey problem-specific extensions allows more than
 one problem to be conveyed.  For example:
 HTTP/1.1 400 Bad Request
 Content-Type: application/problem+json
 Content-Language: en
 {
 "type": "https://example.net/validation-error",
 "title": "Your request parameters didn't validate.",
 "invalid-params": [ {
                       "name": "age",
                       "reason": "must be a positive integer"
                     },
                     {
                       "name": "color",
                       "reason": "must be 'green', 'red' or 'blue'"}
                   ]
 }
 Note that this requires each of the subproblems to be similar enough
 to use the same HTTP status code.  If they do not, the 207 (Multi-
 Status) [RFC4918] code could be used to encapsulate multiple status
 messages.

Nottingham & Wilde Standards Track [Page 4] RFC 7807 Problem Details March 2016

3.1. Members of a Problem Details Object

 A problem details object can have the following members:
 o  "type" (string) - A URI reference [RFC3986] that identifies the
    problem type.  This specification encourages that, when
    dereferenced, it provide human-readable documentation for the
    problem type (e.g., using HTML [W3C.REC-html5-20141028]).  When
    this member is not present, its value is assumed to be
    "about:blank".
 o  "title" (string) - A short, human-readable summary of the problem
    type.  It SHOULD NOT change from occurrence to occurrence of the
    problem, except for purposes of localization (e.g., using
    proactive content negotiation; see [RFC7231], Section 3.4).
 o  "status" (number) - The HTTP status code ([RFC7231], Section 6)
    generated by the origin server for this occurrence of the problem.
 o  "detail" (string) - A human-readable explanation specific to this
    occurrence of the problem.
 o  "instance" (string) - A URI reference that identifies the specific
    occurrence of the problem.  It may or may not yield further
    information if dereferenced.
 Consumers MUST use the "type" string as the primary identifier for
 the problem type; the "title" string is advisory and included only
 for users who are not aware of the semantics of the URI and do not
 have the ability to discover them (e.g., offline log analysis).
 Consumers SHOULD NOT automatically dereference the type URI.
 The "status" member, if present, is only advisory; it conveys the
 HTTP status code used for the convenience of the consumer.
 Generators MUST use the same status code in the actual HTTP response,
 to assure that generic HTTP software that does not understand this
 format still behaves correctly.  See Section 5 for further caveats
 regarding its use.
 Consumers can use the status member to determine what the original
 status code used by the generator was, in cases where it has been
 changed (e.g., by an intermediary or cache), and when message bodies
 persist without HTTP information.  Generic HTTP software will still
 use the HTTP status code.
 The "detail" member, if present, ought to focus on helping the client
 correct the problem, rather than giving debugging information.

Nottingham & Wilde Standards Track [Page 5] RFC 7807 Problem Details March 2016

 Consumers SHOULD NOT parse the "detail" member for information;
 extensions are more suitable and less error-prone ways to obtain such
 information.
 Note that both "type" and "instance" accept relative URIs; this means
 that they must be resolved relative to the document's base URI, as
 per [RFC3986], Section 5.

3.2. Extension Members

 Problem type definitions MAY extend the problem details object with
 additional members.
 For example, our "out of credit" problem above defines two such
 extensions -- "balance" and "accounts" to convey additional, problem-
 specific information.
 Clients consuming problem details MUST ignore any such extensions
 that they don't recognize; this allows problem types to evolve and
 include additional information in the future.
 Note that because extensions are effectively put into a namespace by
 the problem type, it is not possible to define new "standard" members
 without defining a new media type.

4. Defining New Problem Types

 When an HTTP API needs to define a response that indicates an error
 condition, it might be appropriate to do so by defining a new problem
 type.
 Before doing so, it's important to understand what they are good for,
 and what's better left to other mechanisms.
 Problem details are not a debugging tool for the underlying
 implementation; rather, they are a way to expose greater detail about
 the HTTP interface itself.  Designers of new problem types need to
 carefully consider the Security Considerations (Section 5), in
 particular, the risk of exposing attack vectors by exposing
 implementation internals through error messages.
 Likewise, truly generic problems -- i.e., conditions that could
 potentially apply to any resource on the Web -- are usually better
 expressed as plain status codes.  For example, a "write access
 disallowed" problem is probably unnecessary, since a 403 Forbidden
 status code in response to a PUT request is self-explanatory.

Nottingham & Wilde Standards Track [Page 6] RFC 7807 Problem Details March 2016

 Finally, an application might have a more appropriate way to carry an
 error in a format that it already defines.  Problem details are
 intended to avoid the necessity of establishing new "fault" or
 "error" document formats, not to replace existing domain-specific
 formats.
 That said, it is possible to add support for problem details to
 existing HTTP APIs using HTTP content negotiation (e.g., using the
 Accept request header to indicate a preference for this format; see
 [RFC7231], Section 5.3.2).
 New problem type definitions MUST document:
 1.  a type URI (typically, with the "http" or "https" scheme),
 2.  a title that appropriately describes it (think short), and
 3.  the HTTP status code for it to be used with.
 Problem type definitions MAY specify the use of the Retry-After
 response header ([RFC7231], Section 7.1.3) in appropriate
 circumstances.
 A problem's type URI SHOULD resolve to HTML [W3C.REC-html5-20141028]
 documentation that explains how to resolve the problem.
 A problem type definition MAY specify additional members on the
 problem details object.  For example, an extension might use typed
 links [RFC5988] to another resource that can be used by machines to
 resolve the problem.
 If such additional members are defined, their names SHOULD start with
 a letter (ALPHA, as per [RFC5234], Appendix B.1) and SHOULD consist
 of characters from ALPHA, DIGIT ([RFC5234], Appendix B.1), and "_"
 (so that it can be serialized in formats other than JSON), and they
 SHOULD be three characters or longer.

4.1. Example

 For example, if you are publishing an HTTP API to your online
 shopping cart, you might need to indicate that the user is out of
 credit (our example from above), and therefore cannot make the
 purchase.

Nottingham & Wilde Standards Track [Page 7] RFC 7807 Problem Details March 2016

 If you already have an application-specific format that can
 accommodate this information, it's probably best to do that.
 However, if you don't, you might consider using one of the problem
 details formats -- JSON if your API is JSON-based, or XML if it uses
 that format.
 To do so, you might look for an already-defined type URI that suits
 your purposes.  If one is available, you can reuse that URI.
 If one isn't available, you could mint and document a new type URI
 (which ought to be under your control and stable over time), an
 appropriate title and the HTTP status code that it will be used with,
 along with what it means and how it should be handled.
 In summary: an instance URI will always identify a specific
 occurrence of a problem.  On the other hand, type URIs can be reused
 if an appropriate description of a problem type is already available
 someplace else, or they can be created for new problem types.

4.2. Predefined Problem Types

 This specification reserves the use of one URI as a problem type:
 The "about:blank" URI [RFC6694], when used as a problem type,
 indicates that the problem has no additional semantics beyond that of
 the HTTP status code.
 When "about:blank" is used, the title SHOULD be the same as the
 recommended HTTP status phrase for that code (e.g., "Not Found" for
 404, and so on), although it MAY be localized to suit client
 preferences (expressed with the Accept-Language request header).
 Please note that according to how the "type" member is defined
 (Section 3.1), the "about:blank" URI is the default value for that
 member.  Consequently, any problem details object not carrying an
 explicit "type" member implicitly uses this URI.

5. Security Considerations

 When defining a new problem type, the information included must be
 carefully vetted.  Likewise, when actually generating a problem --
 however it is serialized -- the details given must also be
 scrutinized.
 Risks include leaking information that can be exploited to compromise
 the system, access to the system, or the privacy of users of the
 system.

Nottingham & Wilde Standards Track [Page 8] RFC 7807 Problem Details March 2016

 Generators providing links to occurrence information are encouraged
 to avoid making implementation details such as a stack dump available
 through the HTTP interface, since this can expose sensitive details
 of the server implementation, its data, and so on.
 The "status" member duplicates the information available in the HTTP
 status code itself, thereby bringing the possibility of disagreement
 between the two.  Their relative precedence is not clear, since a
 disagreement might indicate that (for example) an intermediary has
 modified the HTTP status code in transit (e.g., by a proxy or cache).
 As such, those defining problem types as well as generators and
 consumers of problems need to be aware that generic software (such as
 proxies, load balancers, firewalls, and virus scanners) are unlikely
 to know of or respect the status code conveyed in this member.

6. IANA Considerations

 This specification defines two new Internet media types [RFC6838].

6.1. application/problem+json

 Type name:  application
 Subtype name:  problem+json
 Required parameters:  None
 Optional parameters:  None; unrecognized parameters should be ignored
 Encoding considerations:  Same as [RFC7159]
 Security considerations:  see Section 5 of this document
 Interoperability considerations:  None
 Published specification:  RFC 7807 (this document)
 Applications that use this media type:  HTTP
 Fragment identifier considerations:  Same as for application/json
    ([RFC7159])

Nottingham & Wilde Standards Track [Page 9] RFC 7807 Problem Details March 2016

 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 and email address to contact for further information:
    Mark Nottingham <mnot@mnot.net>
 Intended usage:  COMMON
 Restrictions on usage:  None.
 Author:  Mark Nottingham <mnot@mnot.net>
 Change controller:  IESG

6.2. application/problem+xml

 Type name:  application
 Subtype name:  problem+xml
 Required parameters:  None
 Optional parameters:  None; unrecognized parameters should be ignored
 Encoding considerations:  Same as [RFC7303]
 Security considerations:  see Section 5 of this document
 Interoperability considerations:  None
 Published specification:  RFC 7807 (this document)
 Applications that use this media type:  HTTP
 Fragment identifier considerations:  Same as for application/xml (as
    specified by Section 5 of [RFC7303])

Nottingham & Wilde Standards Track [Page 10] RFC 7807 Problem Details March 2016

 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 and email address to contact for further information:
    Mark Nottingham <mnot@mnot.net>
 Intended usage:  COMMON
 Restrictions on usage:  None.
 Author:  Mark Nottingham <mnot@mnot.net>
 Change controller:  IESG

7. References

7.1. 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>.
 [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>.
 [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
            Specifications: ABNF", STD 68, RFC 5234,
            DOI 10.17487/RFC5234, January 2008,
            <http://www.rfc-editor.org/info/rfc5234>.
 [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>.
 [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Message Syntax and Routing",
            RFC 7230, DOI 10.17487/RFC7230, June 2014,
            <http://www.rfc-editor.org/info/rfc7230>.

Nottingham & Wilde Standards Track [Page 11] RFC 7807 Problem Details March 2016

 [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
            Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
            DOI 10.17487/RFC7231, June 2014,
            <http://www.rfc-editor.org/info/rfc7231>.
 [W3C.REC-xml-20081126]
            Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
            F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
            Edition)", W3C Recommendation REC-xml-20081126, November
            2008, <http://www.w3.org/TR/2008/REC-xml-20081126>.

7.2. Informative References

 [ISO-19757-2]
            International Organization for Standardization,
            "Information Technology --- Document Schema Definition
            Languages (DSDL) --- Part 2: Grammar-based Validation ---
            RELAX NG", ISO/IEC 19757-2, 2003.
 [RFC4918]  Dusseault, L., Ed., "HTTP Extensions for Web Distributed
            Authoring and Versioning (WebDAV)", RFC 4918,
            DOI 10.17487/RFC4918, June 2007,
            <http://www.rfc-editor.org/info/rfc4918>.
 [RFC5988]  Nottingham, M., "Web Linking", RFC 5988,
            DOI 10.17487/RFC5988, October 2010,
            <http://www.rfc-editor.org/info/rfc5988>.
 [RFC6694]  Moonesamy, S., Ed., "The "about" URI Scheme", RFC 6694,
            DOI 10.17487/RFC6694, August 2012,
            <http://www.rfc-editor.org/info/rfc6694>.
 [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
            Specifications and Registration Procedures", BCP 13,
            RFC 6838, DOI 10.17487/RFC6838, January 2013,
            <http://www.rfc-editor.org/info/rfc6838>.
 [RFC7303]  Thompson, H. and C. Lilley, "XML Media Types", RFC 7303,
            DOI 10.17487/RFC7303, July 2014,
            <http://www.rfc-editor.org/info/rfc7303>.
 [W3C.REC-html5-20141028]
            Hickson, I., Berjon, R., Faulkner, S., Leithead, T.,
            Navara, E., O'Connor, E., and S. Pfeiffer, "HTML5", W3C
            Recommendation REC-html5-20141028, October 2014,
            <http://www.w3.org/TR/2014/REC-html5-20141028>.

Nottingham & Wilde Standards Track [Page 12] RFC 7807 Problem Details March 2016

 [W3C.REC-rdfa-core-20130822]
            Adida, B., Birbeck, M., McCarron, S., and I. Herman, "RDFa
            Core 1.1 - Second Edition", W3C Recommendation
            REC-rdfa-core-20130822, August 2013,
            <http://www.w3.org/TR/2013/REC-rdfa-core-20130822>.
 [W3C.REC-xml-stylesheet-20101028]
            Clark, J., Pieters, S., and H. Thompson, "Associating
            Style Sheets with XML documents 1.0 (Second Edition)", W3C
            Recommendation REC-xml-stylesheet-20101028, October 2010,
            <http://www.w3.org/TR/2010/REC-xml-stylesheet-20101028>.

Nottingham & Wilde Standards Track [Page 13] RFC 7807 Problem Details March 2016

Appendix A. HTTP Problems and XML

 Some HTTP-based APIs use XML [W3C.REC-xml-20081126] as their primary
 format convention.  Such APIs can express problem details using the
 format defined in this appendix.
 The RELAX NG schema [ISO-19757-2] for the XML format is as follows.
 Keep in mind that this schema is only meant as documentation, and not
 as a normative schema that captures all constraints of the XML
 format.  Also, it would be possible to use other XML schema languages
 to define a similar set of constraints (depending on the features of
 the chosen schema language).
    default namespace ns = "urn:ietf:rfc:7807"
    start = problem
    problem =
      element problem {
        (  element  type            { xsd:anyURI }?
         & element  title           { xsd:string }?
         & element  detail          { xsd:string }?
         & element  status          { xsd:positiveInteger }?
         & element  instance        { xsd:anyURI }? ),
        anyNsElement
      }
    anyNsElement =
      (  element    ns:*  { anyNsElement | text }
       | attribute  *     { text })*
 The media type for this format is "application/problem+xml".
 Extension arrays and objects are serialized into the XML format by
 considering an element containing a child or children to represent an
 object, except for elements that contain only child element(s) named
 'i', which are considered arrays.  For example, the example above
 appears in XML as follows:

Nottingham & Wilde Standards Track [Page 14] RFC 7807 Problem Details March 2016

 HTTP/1.1 403 Forbidden
 Content-Type: application/problem+xml
 Content-Language: en
 <?xml version="1.0" encoding="UTF-8"?>
 <problem xmlns="urn:ietf:rfc:7807">
   <type>https://example.com/probs/out-of-credit</type>
   <title>You do not have enough credit.</title>
   <detail>Your current balance is 30, but that costs 50.</detail>
   <instance>https://example.net/account/12345/msgs/abc</instance>
   <balance>30</balance>
   <accounts>
     <i>https://example.net/account/12345</i>
     <i>https://example.net/account/67890</i>
   </accounts>
 </problem>
 Note that this format uses an XML namespace.  This is primarily to
 allow embedding it into other XML-based formats; it does not imply
 that it can or should be extended with elements or attributes in
 other namespaces.  The RELAX NG schema explicitly only allows
 elements from the one namespace used in the XML format.  Any
 extension arrays and objects MUST be serialized into XML markup using
 only that namespace.
 When using the XML format, it is possible to embed an XML processing
 instruction in the XML that instructs clients to transform the XML,
 using the referenced XSLT code [W3C.REC-xml-stylesheet-20101028].  If
 this code is transforming the XML into (X)HTML, then it is possible
 to serve the XML format, and yet have clients capable of performing
 the transformation display human-friendly (X)HTML that is rendered
 and displayed at the client.  Note that when using this method, it is
 advisable to use XSLT 1.0 in order to maximize the number of clients
 capable of executing the XSLT code.

Appendix B. Using Problem Details with Other Formats

 In some situations, it can be advantageous to embed problem details
 in formats other than those described here.  For example, an API that
 uses HTML [W3C.REC-html5-20141028] might want to also use HTML for
 expressing its problem details.
 Problem details can be embedded in other formats either by
 encapsulating one of the existing serializations (JSON or XML) into
 that format or by translating the model of a problem detail (as
 specified in Section 3) into the format's conventions.

Nottingham & Wilde Standards Track [Page 15] RFC 7807 Problem Details March 2016

 For example, in HTML, a problem could be embedded by encapsulating
 JSON in a script tag:
        <script type="application/problem+json">
          {
           "type": "https://example.com/probs/out-of-credit",
           "title": "You do not have enough credit.",
           "detail": "Your current balance is 30, but that costs 50.",
           "instance": "/account/12345/msgs/abc",
           "balance": 30,
           "accounts": ["/account/12345",
                        "/account/67890"]
          }
        </script>
 or by inventing a mapping into RDFa [W3C.REC-rdfa-core-20130822].
 This specification does not make specific recommendations regarding
 embedding problem details in other formats; the appropriate way to
 embed them depends both upon the format in use and application of
 that format.

Acknowledgements

 The authors would like to thank Jan Algermissen, Subbu Allamaraju,
 Mike Amundsen, Roy Fielding, Eran Hammer, Sam Johnston, Mike McCall,
 Julian Reschke, and James Snell for review of this specification.

Authors' Addresses

 Mark Nottingham
 Akamai
 Email: mnot@mnot.net
 URI:   https://www.mnot.net/
 Erik Wilde
 Email: erik.wilde@dret.net
 URI:   http://dret.net/netdret/

Nottingham & Wilde Standards Track [Page 16]

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