Content Negotiation by Profile

W3C First Public Working Draft

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Lars G. Svensson (Deutsche Nationalbibliothek)
Rob Atkinson (Metalinkage, Open Geospatial Consortium)
GitHub w3c/dxwg
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Ruben Verborgh


This document describes how Internet clients may negotiate for content provided by servers according to profiles. This is distinct from negotiating by Media Type or Language: the profile is expected to specify the content of information returned, which may be a subset of the information the responding server has about the requested resource, and may be structured in a specific way to meet interoperability requirements of a community of practice.

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at

This document was published by the Dataset Exchange Working Group as a First Public Working Draft. This document is intended to become a W3C Recommendation.

GitHub Issues are preferred for discussion of this specification. Alternatively, you can send comments to our mailing list. Please send them to (archives).

Please see the Working Group's implementation report.

Publication as a First Public Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

This document is governed by the 1 February 2018 W3C Process Document.

Overview of DXWG documents on profiles

This document is part of a set of documents on profiles, edited by the W3C Dataset Exchange Working Group (DXWG). Some of the documents are general while some are technology-specific:

1. Introduction

This section is non-normative.

Content delivered by dereferencing Internet identifiers can be negotiated for in different ways. When using the HTTP protocol [RFC7230], a client may set one or more headers:

However, clients have not had a defined way to negotiate for content based on its adherence to an information model - a standard, a specification or a profile - and this document addresses this functionality.

When online information about a resource adheres to one or more profiles, methods described here allow clients to list those profiles and request content according to one or more of them in order of preference. For example, information about an online book might adhere to the Dublin Core Terms [DCTERMS] metadata specification with each field of information, such as title, description, author etc., being defined and formatted according to various Dublin Core elements (dct:title, dct:description & dct:creator, respectively). Then, a request for the information about this book may ask for the list of profiles according to which the metadata is available, or it may ask specifically for a response adhering to the Dublin Core Terms. When no profile or an unsupported profile is requested, a server returns default content, that is, content conforming to the default profile supported by the server.

When selecting a content negotiation mechanism, an Internet client may use the HTTP protocol but it may also use other methods for providing instructions to a server, such as URI Query String Arguments (QSAs). QSAs are established as useful for humans and machines for situations where negotiation via HTTP is not practical, such as when manually entering requests into web browsers. This document also provides guidance for both HTTP and non-HTTP methods of content negotiation and ensures they all adhere to a single functional specification, ensuring their functional equivalency.

Guidance for the creation of profiles is provided in the [PROF-GUIDANCE] document created by the Dataset Exchange Working Group (DXWG).

Describing the parts of profiles and their relation to other profiles is the function of the Profiles Ontology [PROF-ONT], also produced by the DXWG.

2. Conformance

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY, MUST, MUST NOT, RECOMMENDED, and SHOULD are to be interpreted as described in [RFC2119].

For the purpose of compliance, the normative sections of this document are Section 3, Section 6, Section 7 and Section 8.

3. Definitions


An act of identifying something precisely or of stating a precise requirement. - Oxford English Dictionary

One form of a specification is a standard which is a "basis for comparison; a reference point against which other things can be evaluated" - [DCTERMS]


A named set of constraints on one or more identified base specifications, including the identification of any implementing subclasses of datatypes, semantic interpretations, vocabularies, options and parameters of those base specifications necessary to accomplish a particular function.

This definition includes what are often called "application profiles", "metadata application profiles", or "metadata profiles".

Source: deliberations of the DXWG. See ProfileContext wiki page.

A program that establishes a connection to a server for the purpose of sending one or more HTTP requests [RFC7230]
A program that accepts connections in order to service HTTP requests by sending HTTP responses. [RFC7230]
The entity that is identified by a URI. Familiar examples include an electronic document, an image, a source of information with a consistent purpose. [RFC3986]
Information that is supplied about a resource [RFC3986]
A message sent over the Internet, from a client to a server, for a information about a resource [RFC7230]
A message sent over the Internet, from a server to a client answering a request for information about a resource [RFC7230]
A short name identifying something, in the context of this document a profile
Issue 378: Complete list of definitionsprofile-negotiation

Feedback sought on any additional definitions we should include here to help with understanding this document.

Issue 537: Harmonise definitions across Profile docsprofile-descriptionprofile-guidanceprofile-negotiation

Currently the definitions sections for the Guidance & Ontology docs need updating and the Conneg doc is updated but now different and probably needs further updating.

We need to solicit feedback in the FPWDs on the granularity of definitions and, when we have a result, ensure that the same definitions are used in all 3 docs.

4. Motivation

This section is non-normative.

In many cases, there are several ways to describe a resource within the scope of a single Media Type. For instance, XML documents, while conforming to the text/xml Media Type, may adhere to one of several DTDs or XML Schemas. RDF documents, with a choice of Media Type serializations such as text/turtle, application/rdf+xml and others, have a large number of vocabularies (classes and properties) available to use for their content's information model. When a client initiates a request for an Internet resource, such as an HTTP GET to retrieve a resource or an HTTP PUT to create or replace a resource, the client and server must have a standardized way to exchange information on how the transmitted resource will be structured according to DTDs, XML Schema, vocabularies or other standards, specifications or profiles. When using non-HTTP content negotiation, various methods such as URIs with Query String Arguments have been implemented previously, such as the OAI-PMH [OAI-PMH] and OGC's CSW [CSW] protocols.

This document describes content negotiation based on profiles using HTTP protocol. It introduces HTTP headers and non-HTTP methods, such as via QSAs, and defines a general QSA Application Programming Interface (API).

This section is non-normative.

The standardization of the content-negotiation HTTP headers is the purview of the IETF. A first proposal for an Internet Draft for Negotiating Profiles in HTTP [PROF-IETF] is available but has not yet been submitted to the IETF. The current version of the IETF draft (-00) is expected to be completely re-written in parallel work with this document and should not be seen as anything but work-in-progress.

Issue 380: Remove text in favour of full reference to final IETF docprofile-negotiation

The Internet-Draft for the registration of Accept-Profile and Content-Profile is currently work-in progress. When that work is completed, the above text will be adjusted accordingly or deleted.

Issue 382: Reference previous HTTP Accept workprofile-negotiation

Previous uses of Accept-* headers or other HTTP headers for this use will be listed and discussed here.

Issue 383: Reference previous Alternate Views workprofile-negotiation

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

Issue 516: Refer to OAI-PMH as an implementation of QSAprofile-negotiation

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

Issue 384: Reference the LDPprofile-negotiation

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

6. Abstract Model

This section describes an abstract conceptual model for content negotiation by profile, independent of any realizations of it within a specific environment.

6.1 Context

All content negotiation takes place between a client and a server over the Internet with the former requesting a representation of a resource or a resource's metadata through a request and receiving it via a response. In some cases, a server may have to make a request of a client and receive a response.

An Internet resource may have many aspects over which a client/server pair of agents might negotiate for content. These aspects are to be treated independently so content negotiation for a resource involving negotiation by profile and any other aspects of a resource will not affect each other. For this reason, other than a directive to maintain independence, no further discussion of negotiation by profile and the relations to other forms of negotiation are given. Specific realizations might require special handling of profile and other forms of negotiation.

A client requesting the representation of a resource conforming to a profile MUST identify the resource by a Uniform Resource Identifier (URI) [RFC3986] and MUST identify a profile either by a URI or a token that unambiguously identifies the profile for the server within that request/response session.

In this abstract model, we don't assume any specifics about client, server, resource, metadata, request or response.

Issue 391: Profile version representation by identifierprofile-negotiation

if we use URIs for profiles but the profile definition changes, how will clients know? Do we need to make strong statements about versions and URI uniqueness?

6.2 Requests and Responses

There are two main types of request that a client might make of a server regarding content negotiation by profile. A client wishing to negotiate for content via a profile adhering to this specification MUST be able to implement these two request types.

  1. list profiles
    a client requests the list of URIs of profiles for which a server is able to deliver conformant resources
  2. get resource by profile
    a client requests a representation of the requested resource represented conforming to a particular profile

A third request type is given that is expected not to apply to all realizations of this abstract model and not all clients adhering to this specification need implement it.

  1. list profiles tokens
    a client requests the list of tokens that the server uses for profiles and for which the server is able to deliver resource representations that conform to the profile. The server also provides a mapping from tokens to profile URIs

A server adhering to this specification MUST respond to each request with the following responses. The first two types are required, handling the third depends on the realization environment.

  1. list profiles
    a server responds to a client with the list of profile URIs for the profiles for which it is able to deliver conformant resource representations
  2. get resource by profile
    a server responds with either a specific profile for a resource conforming to a requested profile identified by the client or it responds with a default profile
  3. list profiles tokens
    a server responds with the list of profile tokens for which it is able to deliver conformant resource representations and the mapping of the tokens to profile URIs.
Issue 587: Consider merging 'list profiles' & 'list profiles tokens' functionsprofile-negotiation

It might be possible to have a single function, list profiles in place of the currently proposed 2: list profiles & list profiles tokens.

Two factors at least need to be considered:

  1. whether all Realizations can support a single function
  • we suspect that HTTP cannot support delivery of a dictionary
  1. whether it's clearest expressed as one or two functions
  • this is qualitative thing

More detailed descriptions of these requests and their responses are given next.

6.2.1 list profiles

A client wishes to know for which profiles a server is able to deliver conformant representations of a resource. The content of the list can be known either before a request for a particular resource representation is made or it is known after an initial request for a resource representation is made.

The list profiles request MUST be either an independent request or part of another realization's request.

The list profiles request MAY result in a response in one of a number of structures or formats provided that the profiles representations conforming to the request are unambiguously identified either by URI or a token mappable to a URI.

A server MUST NOT list profiles that resource representations conform to if it is unable to deliver those representations when presented with a get resource by profile request.

6.2.2 get resource by profile

The most basic request of content negotiation by profile is for a client to request a representation of a resource that is claimed to conform to a profile.

A client executing a get resource by profile request MUST identify the profile with either a URI or a token mappable to a URI.

A client executing a get resource by profile MAY request a resource representation conforming to one of any number of profiles with its preference expressed in a some form of list ordering.

Issue 588: "get resource by profile" should indicate profile appliedprofile-negotiation

Extracted from Jaroslav's comments in Issue #569.

6.2.3 list profiles tokens

A client/server pair of agents MAY refer to profiles by identifiers other than URIs, token, as long as both the client and server are able to deterministically map that token to a profile's URI. This is due to the known requirement for profiles to be able to be referred to within other URIs, such as those of resources and other situations where referring to the profile itself by a URI is not possible.

A server responding to a list profiles tokens request MUST provide token/URI mappings that list tokens and URIs, either of which can be used for get resource by profile requests within the same realization.

7. Realizations

This section describes realizations of the abstract model in multiple implementation domains.

7.1 Hypertext Transfer Protocol Headers

A realization of the Abstract Model using Hypertext Transfer Protocol (HTTP) headers is presented here. This implementation is based on HTTP content negotiation and uses two new HTTP headers, Accept-Profile and Content-Profile that are to be defined in an upcoming Internet-Draft [PROF-IETF].

Issue 500: Specify the order in which content negotiation is performedprofile-negotiation

It would appear that it will necessary to negotiate for profile before language or content-type. Memento specifies that time-based negotiation MUST take place before any other negotiation.

7.1.1 list profiles

Listing profiles for a resource using HTTP can be done in two ways. Using HTTP OPTIONS

The use of HTTP OPTIONS is discouraged since the responses are not cacheable.

The first one is to issue an OPTIONS request against the resource. In this case a server implementing content negotiation by profile SHOULD return a Content-Profile header listing all profiles the requested resource conforms to.

Example 1: Using HTTP OPTIONS to list available profiles
OPTIONS /some/resource HTTP/1.1


HTTP/1.1 200 OK
Content-Profile: urn:example:profile:1;q=0.8,;q=0.5
[More headers for this resource]

7.1.2 get resource by profile

Getting a resource representation conforming to a specific profile is done by issuing an HTTP GET request against the resource and specifying the desired profile URI in an Accept-Profile header. It is possible to specify a range of acceptable profile URIs and also to indicate preferences by using quality indicators (q-values).

Example 3: Requesting a representation conforming to a specific profile using HTTP headers
GET /a/resource HTTP/1.1
Accept: text/turtle;q=0.8, application/xml;q=0.5
Accept-Profile: urn:example:profile:1;q=1.0,urn:example:profile:2;q=0.6
[more request headers]


HTTP/1.1 200 OK
Content-Type: text/turtle
Content-Profile: urn:example:profile:1
[more response headers]

Having performed content negotiation and returned a resource representation, it is RECOMMENDED that the server also include a Link header indicating the availability of alternate resources encoded in other media types and conforming to other profiles, as described above.

7.1.3 list profiles tokens

Currently, there is no proposed way to implement this function using HTTP.

7.2 URI Query String Arguments

Issue 544: Query string implementation of profile selectionprofile-negotiation

There is a question within the working group regarding the advisability of specifying an alternative method of content negotiation conducted via query strings rather than HTTP headers. We have a requirement to show how datasets with different profiles can be made discoverable by humans, but there is disagreement whether this requirement extends to implementing the same negotiation scheme used in HTTP headers.

Many systems use query string argument (QSA) to control profiles of representations to be returned - even when not using this terminology. whilst much of this is ad-hoc, standard API specifications may include canonical parameter names for these concepts. The specification proposed here is a recommendation in the absence of an alternative. The implication however is that a canonical means to discover mappings between other APIs and the Abstract Model is required.

Issue 538: QSA Profile Conneg realisation must support QSA discoveryprofile-negotiation

If the QSA realisation of the profile conneg Abstract Model ( doesn't mandate the use of particular QSA keys (such as _profile & _mediatype) then it needs to provide a way for users to discover what QSA keys are used.

A Query String Argument (QSA) realization of the Abstract Model is presented here. Unlike the HTTP realization, which is the subject of an independent document [PROF-IETF], this realization is fully specified here and this document is considered normative for the QSA realization. This realization does not preclude other QSA specifications for profile and content negotiation.

A query string is a part of a URI which assigns values to specified parameters. QSAs are commonly used within web browsers by humans and in other client/server situations to deliver extra information to a server.

Key naming

When content negotiation by profile is to take place using QSAs, the requests and responses of the Abstract Model MUST be implemented. However there is some flexibility in how this may be done: QSA key/value pairs must be implemented but the specific key terms may be changed. In this realization, _profile and _mediatype are used to indicate a single profile or a list of preference-ordered profiles or Media types respectively with profiles or Media Types indicated by either URI or token.

Note: Current use of tokens for negotiation by Media Type

Currently, the convention in HTTP content negotiation by media type uses tokens for Media Types, such as text/html or application/ld+json with the tokens registered at IANA's Media Types list.

There is no proposal yet to create a central register of profiles as this is thought by the authors to be un-sustainable in the long-term, given the likely numbers of profiles to be established.

For this reason, the QSA realization allows either URIs or tokens for profiles to be used and it is expected, though not mandated here, that QSA realizations will also allow URIs or tokens for Media Types and other content negotiation dimensions, such as language. There are already several initiatives that have created URIs for Media Types based on the IANA register's tokens.

Resource URI

Resource URIs for which QSA-based profile negotiation is taking place MUST NOT themselves be QSA values of other resource URIs in any QSA-based realization. Such mechanics may be used but must be transparent to the realization's client applications.

Example 4: Resource URIs must not, themselves, be parameters of other URIs
For the representation of Resource X, according to Profile Y, in Media Type Z:

GET /single/endpoint?resource= HTTP/1.1

GET /resource/X?_profile=Y&_mediatype=Z HTTP/1.1

7.2.1 list profiles

A QSA with a fixed value MUST be supported by a server to allow a client to make a list profiles request.

Issue 589: Consider not using _profile QSA key for _profile=listprofile-negotiation

a dedicated parameter may by used (_list), e.g. allowing for listing of profile (_list=profile) or media type (_list=media-type)

Extracted from Jaroslav's edits: Issue #569

The QSA key/value pair _profile=list SHOULD be used however the server MAY make available an equivalent pair as long as this is discoverable. This is to cater for APIs that alreadly implement a similar function using QSA key/value pairs such as _view=alternates.

The complete request for the profiles to which a resource's representations conform can be communicated in a single URI like thus:

Example 5: Requesting a list of profiles for a resource by QSA
GET /a/resource?_profile=list HTTP/1.1

where /a/resource is the URI of the resource for which the list of available profiles is requested

A client making this request MAY negotiate for particular formats of the response by using a QSA equivalent to the HTTP Accept header to indicate a Media Type. A server SHOULD implement a _mediatype QSA for this but MAY implement an alternative, such as _format as long as this is dicoverable,

An example profile listing for a resource in HTML would look like:

Example 6: Requesting a list of profiles for a resource by QSA in HTML
GET /a/resource?_profile=list&_mediatype=text/html HTTP/1.1

7.2.2 get resource by profile

Issue: To be completed

Expressing profile preference

A server implementing profile listing for resources SHOULD allow the requester to indicate preferences. This SHOULD be done by allowing the QSA indicating the desired profile, usually _profile, to have a comma-separated list as its value so, for a client desiring representations of /a/resource according to profiles with tokens aaa, bbb & ccc we have:

Example 7: Requesting a list of profiles for a resource by QSA in HTML
GET /a/resource?_profile=aaa,bbb,ccc HTTP/1.1

Servers MAY support any combination of profile URIs or tokens for this (e.g. aaa,,bbb). However, in this situation, profile URIs containing commas must escape them.

Similarly, a server implementing multiple Media Type return formats for profile listing SHOULD allow a client to specify a preference order for Media Types and also for other dimensions of content negotiation, such as language. When using a QSA-only API, Media Type preferences (and language and others in a similar fashion) MAY be specified in a comma-separated list form, most preferred to least such that a client requesting profil

7.2.3 list profiles tokens

Issue: To be completed

8. Test Suites

This section includes links to software tools to be used for testing the adherence of implementations to the realizations given in this document.

Apache JMeter

An Apache JMeter implementation of a test suite is maintained at:

Issue 385: Complete Links to Test Suitesprofile-negotiation

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

9. Implementations

This section is non-normative.

This section includes implementations of the realizations given in this document and their conformance test results. The tools used for conformance testing are listed in the section above.

Issue 467: Model implementation reporting as done in SHACLprofile-descriptionprofile-negotiation

The SHACL Recommendation contains a link to an SHACL Test Suite and Implementation Report that we should emulate to implementations.

10. Security and Privacy

This section is non-normative.

The use of HTTP to negotiate and transport implies that all privacy and security issues that are relevant for that protocol are also relevant for profile negotiation. E. g., information such as user agent, accept-headers, IP address etc. can potentially be used as identifying information, and particularly, the IP address adds information about geolocation and institutional membership. Apart from that, there are no known security or privacy impacts of this feature.

For a more complete view of those issues, cf. the Privacy and Security Questionnaire for this deliverable.

A. Appendices

A.1 Requirements

This section lists, and then addresses, individual requirements that the Dataset Exchange Working Group considered important for content negotiation by profile.


Responses to individual requirement Issues listed here are, at the time of the First Public Working Draft of this document, for demonstration only; to indicate the logic of answers to individual requirements.

These requirement responses may not survive in their current form in later drafts of this document nor may individual listings of requirements; they may be subsumed into the flowing txt of the document.

Profile definition [RPFDF]

Create a sufficiently wide definition of an application profile to address declaration of interoperability profiles data may conform to, and through this mechanism provide the means for DCAT instances and collections to also declare the profiles of DCAT they conform to.

These Use case specific requirements apply to the required scope of this definition. Where appropriate these are also captured as additional requirements.

  1. Clarify any relationship between profiles and validation languages
  2. Profiles have URI identifiers that resolve to more detailed descriptions
  3. Each application profile needs to be documented, preferably by showing/reusing what is common across profiles
  4. Profiles should provide both machine and human readable views.
  5. Profiles may inherit clauses from one or more parent profiles
  6. Profiles must support a view that includes all inherited constraints clearly identifying the parent profile the constraint is defined in.
  7. Profiles may be used to describe the metadata standard a description conforms to, the standards to which the resource described (e.g. dataset) and the standards each distribution conforms to.
  8. Conceptually, profiles can extend other vocabularies or profiles, or can be refinements of other vocabularies or profiles (#ID37)
  9. Responses can conform to multiple, modular profiles (#ID3)

Related requirements: Profile representation [RPFRP] Profile negotiation [RPFN] Profiles listing [RPFL] 
Related use cases: Detailing and requesting additional constraints (profiles) beyond content types [ID2] Responses can conform to multiple, modular profiles [ID3] Discover available content profiles [ID5] Description of dataset compliance with standards [ID43] Profile relation to validation [ID48] 


Profiles listing [RPFL]

Create a way to list the profiles implemented by a dataset or a specific distribution

Some subset of profile metadata that can be included in a DCAT context should have a canonical set of properties recommended. Initial requirements are 1) short definition 2) input and editing guidance. Links should be consistent with#RPFRP

Related requirements: Profile definition [RPFDF] Profile negotiation [RPFN] Profile representation [RPFRP] 
Related use cases: Profile support for input functions [ID46] 


This requirement is addressed by suggesting how an Internet resource in general, rather than specifically a dcat:Dataset or dcat:Distribution should list profiles it implements. A DCAT- specific solution should not be any different from the general case.

Profile definition and constraints on properties are not addressed here. See [PROF-GUIDANCE].

This requirement is taken to mean "create a way to list the profiles implemented by a Internet resource for humans and machines to use". For the former (humans), the options are:

  • discovery via HTML representation
    • see [PROF-GUIDANCE]
    • an approach suggested is to provide an alternate view resource for the original resource located at RESOURCE_URI + ?_view=alternates which lists, at a minimum, the profiles, media types (formats) & languages available, as per the alternate views guidance.
Issue 392: Clarify how to refer to alternates view methodology for profile negprofile-negotiation

This issue was created in the Conneg by Profile document and is listed in it. Once consensus on addressing it is reached here in comments below, the results will be added to the document and the issue closed.

The Use Case Web browser navigation of profile information is recorded but no DXWG method is yet proposed. In prior art, the so-called alternates view method is listed. This method is not yet aligned with the IETF proposal.

For the latter (machines):

  • discovery via HTTP
    • see [PROF-IETF]
    • HTTP mechanics are described that allow clients to negotiate with servers for profile listings
  • discovery via RDF graph
Issue 393: Clarify if DCAT's use of ProfileDescdcatprofile-guidance

Is DCAT expecting to implement a profile of ProfileDesc or a DCAT-aligned set of terminology or will it follow the vocabulary as-is?

In the draft version of the conneg document, the Requirement #73 is answered by addressing the general case (profile listing of a resource) and then notes are given on the DCAT-specific answer given that the Requirement gives DCAT listing of profiles as the motivation.

If DCAT is to adopt the general, ProfileDesc mechanics of profile listing, no special menthoin needs to be made.

If DCAT is to adopt specialised terminology (profileing ProfileDesc) then what reference, if any from DCAT to ProfileDesc needs to be made?

Profile negotiation [RPFN]

Create a way to negotiate choice of profile between clients and servers

Related requirements: Profile definition [RPFDF] 
Related use cases: Detailing and requesting additional constraints (profiles) beyond content types [ID2] Standard APIs for metadata profile negotiation [ID30] 


This requirement is the focus of the IETF RFC in the DXWG Family of Documents [PROF-IETF].

In summary, a series of new HTTP headers are added to the HTTP specification allowing for HTTP negotiation via profile in a manner similar to negotiation via Media Type or Language.

Usage notes [RUN]

Ability to provide information on how to use the data.

Should this also apply to specific distributions?

Related requirements: Profiles listing [RPFL] Dataset aspects [RDSAT] Dataset publications [RDSP] 
Related use cases: Common requirements for scientific data [ID9] 


Issue 217: Responses can conform to multiple, modular profiles (UC 5.3)f2f3profile-guidanceprofile-negotiationrequirement


Issue 261: Define conneg interaction with media types that have a profile paramprofile-negotiationrequirementrequires discussion

Some media types already have a profile parameter, such as JSON-LD. The profile negotiation deliverable should define how conflicts between it's syntax and profiles specified in the media type are handled.

For example, a server would need to deterministically handle:

GET /foo/bar HTTP/1.1

Accept: application/ld+json;profile=""

(edited to fix header name)


Issue 263: IETF submission must not include query param pattern requirementsprofile-negotiationrequirementrequires discussion

I believe that any submission to the IETF for the processing rules around content negotiation for profiles that includes query parameters as a mechanism rather than the proposed Accept-Profile header will be rejected, as it conflicts with base W3C and IETF architectural constraints.

In particular:

Extensions MUST NOT constrain the format or semantics of queries.

Meaning that we must not say that uses of _view or _format or _profile or similar have special semantics.

The query component contains non-hierarchical data that, along with data in the path component (Section 3.3), serves to identify a resource [...]

Meaning that the query parameter is included in the URI for determining the identity of the resource. Thus foo?_profile=p1 is a different resource (in RDF terms) from foo or foo?_profile=p2. This would make it not content negotiation at all, just separate resources.

Content negotiation refers to the practice of making available multiple representations via the same URI.

Combined with the above, makes _profile not count as "content negotiation", as the URI is different because the query component of the URI is part of the opaque URI string.

And etc. I'm sure that @RubenVerborgh can provide further supporting documents.

This is NOT to say that the WG cannot specify such an approach, but that it must be separate from the formal content negotiation deliverable.

This is an expansion of #74 (comment), and proposed clarification as to the scope.


The IETF submission in the DXWG Family of Documents [PROF-IETF] does not address content negotiaiton by profile query param patterns: it is limited to HTTP specification-based negotiation only.

Recommendations for content negotiation by profile via query param patterns (Query String Arguments) are given in the Profile Guidance [PROF-GUIDANCE] document where an API for this is defined.

Issue 264: Metadata about server profile support can be used for discovery and mediated traversal via content negotiation. [ID5] (5.5)profile-guidanceprofile-negotiationrequirementrequires discussion

Entered from Google Doc


Issue 265: Enable the ability to negotiate the data profile via http, similar to the negotiation of data formats today. [ID30] (5.30)plenary-approvedprofile-guidanceprofile-negotiationrequirementrequires discussion

Entered from Google Doc


This requirement is met by [PROF-IETF].




(assuming wording of "a profile must have an identifier")

Profiles must be identified by an HTTP URI.

Short codes (tokens) for profiles that map to HTTP URIs for them may be used in systems that ensure the tokens map deterministically. This allows for the use of simple strings in places where URIs are impractical yet preserves the guarantee that every profile has an HTTP URI.




This requirement is met by [PROF-ONT].


This requirement is met by [PROF-IETF].


A.2 Issue Summary

A.3 Additional Issues

This section will be removed in a later version of this document.

Additional Issues related to this document and not yet placed within it are listed at the:

B. References

B.1 Normative references

DCMI Metadata Terms. Dublin Core metadata initiative.14 June 2012. DCMI Recommendation. URL:
Profile Guidance. 2018-12-31. W3C Editor's Draft. URL:
Negotiating Profiles in HTTP. Lars G. Svensson; Ruben Verborgh.2017-10-24. IETF Internet Draft. URL:
Profile Descriptions ontology. 2018-09-23. W3C Editor's Draft. URL:
Key words for use in RFCs to Indicate Requirement Levels. S. Bradner. IETF. March 1997. Best Current Practice. URL:
Uniform Resource Identifier (URI): Generic Syntax. T. Berners-Lee; R. Fielding; L. Masinter. IETF. January 2005. Internet Standard. URL:
Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing. R. Fielding, Ed.; J. Reschke, Ed.. IETF. June 2014. Proposed Standard. URL:

B.2 Informative references

Catalogue Services 3.0 - General Model. Douglas Nebert; Uwe Voges; Lorenzo Bigagli. OGC. 10 June 2016. URL:
The Open Archives Initiative Protocol for Metadata Harvesting. Carl Lagoze; Herbert Van de Sompel; Michael Nelson; Simeon Warner. OAI. 8 January 2015. URL: