Solid Protocol

This section is non-normative.

The Solid Protocol specification defines the following terms. These terms are referenced throughout this specification.

storage

A storage is a space of URIs that affords agents controlled access to resources.

Solid app

A Solid app is an application that reads or writes data from one or more storages.

URI

A Uniform Resource Identifier (URI) provides the means for identifying resources [RFC3986].

resource

A resource is the target of an HTTP request identified by a URI [RFC7231].

container resource

A container resource is a hierarchical collection of resources that contains other resources, including containers.

root container

A root container is a container resource that is at the highest level of the collection hierarchy.

resource metadata

Resource metadata encompasses data about resources described by means of RDF statements [RDF11-CONCEPTS].

agent

An agent is a person, social entity, or software identified by a URI; e.g., a WebID denotes an agent [WEBID].

owner

An owner is a person or a social entity that is considered to have the rights and responsibilities of a storage. An owner is identified by a URI, and implicitly has control over all resources in a storage. An owner is first set at storage provisioning time and can be changed.

origin

An origin indicates where an HTTP request originates from [RFC6454].

read operation

A read operation entails that information about a resource’s existence or its description can be known. [Source]

write operation

A write operation entails that information about resources can be created or removed. [Source]

append operation

An append operation entails that information can be added but not removed. [Source]

Prefixes and Namespaces

Prefix	Namespace	Description
rdf	http://www.w3.org/1999/02/22-rdf-syntax-ns#	[rdf-schema]
ldp	http://www.w3.org/ns/ldp#	[LDP]
solid	http://www.w3.org/ns/solid/terms#	Solid Terms
pim	http://www.w3.org/ns/pim/space#	Workspace Ontology
acl	http://www.w3.org/ns/auth/acl#	ACL Ontology
dcterms	http://purl.org/dc/terms/	[DC-TERMS]
stat	http://www.w3.org/ns/posix/stat	POSIX File Status

This section describes the conformance model of the Solid Protocol.

Normative and Informative Content

All assertions, diagrams, examples, and notes are non-normative, as are all sections explicitly marked non-normative. Everything else is normative.

The key words “MUST”, “MUST NOT”, “SHOULD”, and “MAY” are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

The key words “strongly encouraged”, “strongly discouraged”, “encouraged", “discouraged", “can", “cannot”, “could”, “could not”, “might”, and “might not” are used for non-normative content.

Specification Category

The Solid Protocol identifies the following Specification Category to distinguish the types of conformance: API, notation/syntax, set of events, processor behaviour, protocol.

Classes of Products

The Solid Protocol identifies the following Classes of Products for conforming implementations. These products are referenced throughout this specification.

Server

A server that builds on HTTP server [RFC7230] and [RFC7231] by defining media types, HTTP header fields, and the behaviour of resources, as identified by link relations.

Client

A client that builds on HTTP client [RFC7230], [RFC7231], and [FETCH] by defining behaviour in terms of fetching across the platform.

Interoperability

Interoperability of implementations for servers and clients is tested by evaluating an implementation’s ability to request and respond to HTTP messages that conform to this specification.

Servers MUST conform to HTTP/1.1 Message Syntax and Routing [RFC7230] and HTTP/1.1 Semantics and Content [RFC7231]. Servers SHOULD conform to HTTP/2 [RFC7540].

Servers SHOULD use TLS connections through the https URI scheme in order to secure the communication with clients. When both http and https URI schemes are supported, the server MUST redirect all http URIs to their https counterparts using a response with a 301 status code and a Location header.

Servers MUST conform to HTTP/1.1 Conditional Requests [RFC7232]. Servers SHOULD conform to HTTP/1.1 Caching [RFC7234]. Servers MAY conform to HTTP/1.1 Range Requests [RFC7233].

Servers MUST conform to HTTP/1.1 Authentication [RFC7235]. When a client does not provide valid credentials when requesting a resource that requires it (see WebID), servers MUST send a response with a 401 status code (unless 404 is preferred for security reasons).

Server MUST reject PUT, POST and PATCH requests without the Content-Type header with a status code of 400. [Source]

Clients MUST conform to HTTP/1.1 Message Syntax and Routing [RFC7230] and HTTP/1.1 Semantics and Content [RFC7231]. Clients MAY conform to HTTP/2 [RFC7540].

Clients MAY conform to HTTP/1.1 Conditional Requests [RFC7232]. Clients MAY conform to HTTP/1.1 Caching [RFC7234]. Clients MAY conform to HTTP/1.1 Range Requests [RFC7233].

Clients MUST conform to HTTP/1.1 Authentication [RFC7235] if it needs to access resources requiring authentication (see WebID). When a client receives a response with a 403 or 404 status code, the client MAY repeat the request with different credentials.

Clients MUST use the Content-Type HTTP header in PUT, POST and PATCH requests [RFC7231]. [Source]

The slash (/) character in the URI path indicates hierarchical relationship segments, and enables relative referencing [RFC3986]. The semantics of the slash character is shared by servers and clients. Paths ending with a slash denote a container resource. [Source]

If two URIs differ only in the trailing slash, and the server has associated a resource with one of them, then the other URI MUST NOT correspond to another resource. Instead, the server MAY respond to requests for the latter URI with a 301 redirect to the former. [Source]. Servers MUST authorize prior to this optional redirect. [Source].

This section is non-normative.

Servers should not re-use URIs, regardless of the mechanism by which resources are created. Certain specific cases exist where URIs may be reinstated when it identifies the same resource, but only when consistent with Web architecture’s URI persistence [WEBARCH]. [Source]

Servers MUST provide one or more storages. The storage resource (pim:Storage) is the root container for all of its contained resources (see Resource Containment).

When a server supports multiple storages, the URIs MUST be allocated to non-overlapping space.

Servers MUST advertise the storage resource by including the HTTP Link header with rel="type" targeting http://www.w3.org/ns/pim/space#Storage when responding to storage’s request URI.

Clients can determine a resource is of type storage by making an HTTP HEAD or GET request on the target URL, and checking for the Link header with rel="type" targeting http://www.w3.org/ns/pim/space#Storage.

Clients can determine the storage of a resource by moving up the URI path hierarchy until the response includes a Link header with rel="type" targeting http://www.w3.org/ns/pim/space#Storage.

Clients can discover a storage by making an HTTP GET request on the target URL to retrieve an RDF representation [RDF11-CONCEPTS], whose encoded RDF graph contains a relation of type http://www.w3.org/ns/pim/space#storage. The object of the relation is the storage (pim:Storage).

[Source] [Source]

Servers MUST include the Link header with rel="http://www.w3.org/ns/solid/terms#storageDescription" targeting the URI of the storage description resource in the response of HTTP GET, HEAD and OPTIONS requests targeting a resource in a storage.

Servers MUST include statements about the storage as part of the storage description resource.

Storage description statements include the properties:

rdf:type

A class whose URI is http://www.w3.org/ns/pim/space#Storage.

[Source].

Servers MUST keep track of at least one owner of a storage in an implementation defined way.

When a server wants to advertise the owner of a storage, the server MUST include the Link header with rel="http://www.w3.org/ns/solid/terms#owner" targeting the URI of the owner in the response of HTTP HEAD or GET requests targeting the root container.

[Source][Source][Source][Source]

Solid has the notion of containers to represent a collection of linked resources to help with resource discovery and lifecycle management.

There is a 1-1 correspondence between containment triples and relative reference within the path name hierarchy. [Source]. It follows that all resources are discoverable from a container and that it is not possible to create orphan resources. [Source]

The representation and behaviour of containers in Solid corresponds to LDP Basic Container and MUST be supported by server. [Source]

Servers can determine the value of the HTTP Last-Modified header field in response to HEAD and GET requests targeting a container based on changes to containment triples.

Contained Resource Metadata

Container descriptions are not limited to containment triples. To further support client navigation and application interaction, servers can include resource metadata about contained resources as part of the container description, as described below.

Servers SHOULD include resource metadata about contained resources as part of the container description, unless that information is inapplicable to the server.

Contained resource metadata statements include the properties:

rdf:type

A class whose URI is the expansion of the URI Template [RFC6570] http://www.w3.org/ns/iana/media-types/{+iana-media-type}#Resource, where iana-media-type corresponds to a value from the IANA Media Types [IANA-MEDIA-TYPES].

stat:size

A non-negative integer giving the size of the resource in bytes.

dcterms:modified

The date and time when the resource was last modified.

stat:mtime

The Unix time when the resource was last modified.

The dcterms:modified value of a contained resource corresponds with the Last-Modified header value of the contained resource. If one were to perform HEAD or GET requests on the URI of the contained resource at the time of the HTTP message’s generation, then a response with the 200 status code including the Last-Modified header would indicate the same date and time.

Note: Contained Resource Metadata Considerations

The generation of contained resource metadata may be inapplicable to some servers, for example, when that information does not exist or is expensive to determine.

Contained resource metadata is protected by the server.

[Source] [Source] [Source]

Solid has the notion of auxiliary resources to provide supplementary information such as descriptive metadata, authorization conditions, data shape constraints, digital rights or provenance record about a given resource (hereafter referred as the subject resource), and affects how resources and others associated with it are processed, served or interpreted.

Servers MUST support auxiliary resources defined by this specification and manage the association between a subject resource and auxiliary resources. When a subject resource is deleted its auxiliary resources are also deleted by the server (Server Deleting Auxiliary Resources).

Auxiliary resources are represented as RDF documents [RDF11-CONCEPTS]. HTTP interactions on auxiliary resources are subject to the requirements as per Reading and Writing Resources.

This specification defines the following types of auxiliary resources:

• Web Access Control
• Description Resource

Servers MUST advertise auxiliary resources associated with a subject resource by responding to HEAD and GET requests by including the HTTP Link header with the rel parameter [RFC8288].

Clients can discover auxiliary resources associated with a subject resource by making an HTTP HEAD or GET request on the target URL, and checking the HTTP Link header with the rel parameter [RFC8288].

Auxiliary Type	Link Relation	Definitions
Web Access Control	acl	[WAC]
Description Resource	describedby	[POWDER-DR]

Web Access Control

An auxiliary resource of type Web Access Control provides access control description of a subject resource (Web Access Control).

Description Resource

An auxiliary resource of type Description Resource provides a description of a subject resource.

Servers MUST NOT directly associate more than one description resource to a subject resource.

When an HTTP request targets a description resource, the server MUST apply the authorization rule that is used for the subject resource with which the description resource is associated.

Clients can discover resources that are described by description resources by making an HTTP HEAD or GET request on the target URL, and checking the HTTP Link header with a rel value of describes (inverse of the describedby relation) [RFC6892].

When creating new resources, servers can determine an effective request URI’s type by examining the URI path ending (URI Slash Semantics).

When a successful PUT or PATCH request creates a resource, the server MUST use the effective request URI to assign the URI to that resource.

When a successful POST request creates a resource, the server MUST assign a URI to that resource. Servers MAY allow clients to suggest the URI of a resource created through POST, using the HTTP Slug header as defined in [RFC5023].

[Source][Source].

Servers MUST support the HTTP GET, HEAD and OPTIONS methods [RFC7231] for clients to read resources or to determine communication options. [Source]

Servers MUST indicate the HTTP methods supported by the target resource by generating an Allow header field in successful responses.

When responding to authorized requests, servers MUST indicate supported media types in the HTTP Accept-Patch [RFC5789], Accept-Post [LDP] and Accept-Put [The Accept-Put Response Header] response headers that correspond to acceptable HTTP methods listed in Allow header value in response to HTTP GET, HEAD and OPTIONS requests.

[Source] [Source] [Source]

Servers MUST support the HTTP PUT, POST and PATCH methods [RFC7231]. [Source] [Source]

Servers MUST create intermediate containers and include corresponding containment triples in container representations derived from the URI path component of PUT and PATCH requests. [Source]

Servers MUST allow creating new resources with a POST request to URI path ending /. Servers MUST create a resource with URI path ending /{id} in container /. Servers MUST create a container with URI path ending /{id}/ in container / for requests including the HTTP Link header with rel="type" targeting a valid LDP container type. [Source] [Source]

When a POST method request targets a resource without an existing representation, the server MUST respond with the 404 status code. [Source]

When a PUT or PATCH method request targets an auxiliary resource, the server MUST create or update it. When a POST method request with the Slug header targets an auxiliary resource, the server MUST respond with the 403 status code and response body describing the error. [Source]

Servers MUST NOT allow HTTP PUT or PATCH on a container to update its containment triples; if the server receives such a request, it MUST respond with a 409 status code. [Source]

Servers MUST NOT allow HTTP POST, PUT and PATCH to update a container’s resource metadata statements; if the server receives such a request, it MUST respond with a 409 status code. [Source]

Servers MAY use the HTTP ETag header with a strong validator for RDF bearing representations in order to encourage clients to opt-in to using the If-Match header in their requests.

@prefix solid: <http://www.w3.org/ns/solid/terms#>.
@prefix ex: <http://www.example.org/terms#>.

_:rename a solid:InsertDeletePatch;
  solid:where   { ?person ex:familyName "Garcia". };
  solid:inserts { ?person ex:givenName "Alex". };
  solid:deletes { ?person ex:givenName "Claudia". }.

Servers MUST support the HTTP DELETE method [RFC7231]. [Source] [Source]

When a DELETE request targets storage’s root container or its associated ACL resource, the server MUST respond with the 405 status code. Server MUST exclude the DELETE method in the HTTP response header Allow in response to requests to these resources [RFC7231]. [Source]

When a contained resource is deleted, the server MUST also remove the corresponding containment triple. [Source]

When a contained resource is deleted, the server MUST also delete the associated auxiliary resources (see the Auxiliary Resources section).

When a DELETE request targets a container, the server MUST delete the container if it contains no resources. If the container contains resources, the server MUST respond with the 409 status code and response body describing the error. [Source]

This section is non-normative.

The server might perform additional actions, as described in the normative references like [RFC7231]. For example, the server could perform additional cleanup tasks for resources it knows are no longer referenced or have not been accessed for some period of time, and so on.

Subsequent GET requests to the deleted resource usually result in a 404 or 410 status code, although HTTP allows others. [Source] [Source]

When a server creates a resource on HTTP PUT, POST or PATCH requests such that the request’s representation data encodes an RDF document [RDF11-CONCEPTS] (as determined by the Content-Type header), the server MUST accept GET requests on this resource when the value of the Accept header requests a representation in text/turtle or application/ld+json [Turtle] [JSON-LD11]. [Source] Source] [Source] [Source]

When a PUT, POST, PATCH or DELETE method request targets a representation URL that is different than the resource URL, the server MUST respond with a 307 or 308 status code and Location header specifying the preferred URI reference. [Source]

This section is non-normative.

Servers are encouraged to publish any constraints on clients’ ability to create or update resources by adding a Link header with an appropriate context URI, a link relation of http://www.w3.org/ns/ldp#constrainedBy, and a target URI identifying a set of constraints [RFC8288], to responses to requests that fail due to violation of those constraints. The same Link header can be provided in other responses.

Servers are encouraged to use the URIs of the constraints that are defined by specifications or other constraint URIs within its authority depending on the request's semantics on a target resource.

Constraints are intended to be protected and persistent resources and therefore cannot be modified by clients. To facilitate better client interactions, it is encouraged to express constraints in RDF.

[Source]

Entities in a Solid ecosystem use the Solid Notifications Protocol to communicate about changes affecting a resource.

Servers MUST conform to the Solid Notifications Protocol [SOLID-NOTIFICATIONS-PROTOCOL] by implementing the Resource Server to enable clients to discover subscription resources and notification channels available to a given resource or storage.

Servers MUST conform to the Solid Notifications Protocol [SOLID-NOTIFICATIONS-PROTOCOL] by implementing the Subscription Server to process and produce instructions for subscription requests.

Servers MUST conform to the Solid Notifications Protocol [SOLID-NOTIFICATIONS-PROTOCOL] by implementing the Notification Sender to produce and send messages to a Notification Receiver.

Servers MUST conform to the Solid Notifications Protocol [SOLID-NOTIFICATIONS-PROTOCOL] by implementing the Notification Receiver to receive and process messages that conform to a notification channel type.

The following is non-normative.

The Solid WebSockets API (Unofficial Draft) [SOLID-WEBSOCKETS-API] has been the common notification protocol for many years. That draft does not include an authentication mechanism, and therefore this Protocol has transitioned to require the Solid Notifications Protocol.

Existing client and server implementations should begin providing support for the new notification protocol while supporting backwards compatibility, as appropriate.

A server MUST implement the CORS protocol [FETCH] such that, to the extent possible, the browser allows Solid apps to send any request and combination of request headers to the server, and the Solid app can read any response and response headers received from the server. If the server wishes to block access to a resource, this MUST NOT happen via CORS but MUST instead be communicated to the Solid app in the browser through HTTP status codes such as 401, 403, or 404 [RFC7231].

Concretely, whenever a server receives an HTTP request containing a valid Origin header [RFC6454], the server MUST respond with the appropriate Access-Control-* headers as specified in the CORS protocol [FETCH]. In particular, the server MUST set the Access-Control-Allow-Origin header to the valid Origin value from the request and list Origin in the Vary header value. The server MUST make all used response headers readable for the Solid app through Access-Control-Expose-Headers (with the possible exception of the Access-Control-* headers themselves). A server MUST also support the HTTP OPTIONS method [RFC7231] such that it can respond appropriately to CORS preflight requests.

Careful attention is warranted, especially because of the many edge cases. For instance, servers SHOULD explicitly enumerate all used response headers under Access-Control-Expose-Headers rather than resorting to *, which does not cover all cases (such as credentials mode set to include). Servers SHOULD also explicitly list Accept under Access-Control-Allow-Headers, because values longer than 128 characters (not uncommon for RDF-based Solid apps) would otherwise be blocked, despite shorter Accept headers being allowed without explicit mention.

A WebID is an HTTP URI denoting an agent, for example a person, organisation, or software [WEBID]. When a WebID is dereferenced, server provides a representation of the WebID Profile in an RDF document [RDF11-CONCEPTS] which uniquely describes an agent denoted by a WebID. WebIDs are an underpinning component in the Solid ecosystem and are used as the primary identifier for users and applications.

The Solid OpenID Connect (Solid OIDC) specification defines how resource servers verify the identity of relying parties and end users based on the authentication performed by an OpenID provider [SOLID-OIDC].

This section is non-normative.

The Solid ecosystem initially relied on WebID-TLS for authenticated resource access [WEBID-TLS]. The current recommendation for authentication relies on Solid-OIDC (Solid-OIDC). Implementations can use WebID-TLS just as any other mechanism as an additional authentication method.

Web Access Control (WAC) is a decentralized cross-domain access control system providing a way for Linked Data systems to set authorization conditions on HTTP resources using the Access Control List (ACL) model. Server manages the association between a resource and an ACL resource with the acl Link Relation, and applies the authorization conditions on requested operations. Authorizations are described using the ACL ontology to express and determine access privileges of a requested resource. Applications can discover authorization rules associated with a given resource, and to control such rules, as directed by an agent.

Clients MUST conform to the Web Access Control specification [WAC].

[Source] [Source] Source] Source]

Access Control Policy (ACP) is a language for describing, controlling, and granting access to resources. Authorizations are described using the ACL ontology to express and determine access privileges of a requested resource.

Clients MUST conform to the Access Control Policy specification [ACP].

[Source]

The Accept-Put Response Header

This specification introduces a new HTTP response header Accept-Put used to specify the document formats accepted by the server on HTTP PUT requests. It is modelled after the Accept-Patch header defined in [RFC5789] and the Accept-Post header defined in [LDP].

The syntax for Accept-Put, using the ABNF syntax defined in Section 1.2 of [RFC7231], is:

Accept-Put = "Accept-Put" ":" # media-range

The Accept-Put header specifies a comma-separated list of media ranges (with optional parameters) as defined by [RFC7231], Section 5.3.2. The Accept-Put header, in effect, uses the same syntax as the HTTP Accept header minus the optional accept-params BNF production, since the latter does not apply to Accept-Put.

The presence of the Accept-Put header in response to any method is an implicit indication that PUT is allowed on the resource identified by the request URI. The presence of a specific document format in this header indicates that that specific format is allowed on PUT requests to the resource identified by the request URI.

IANA Registration Template:

The Accept-Put response header must be added to the permanent registry (see [RFC3864]).

Header field name

Accept-Put

Applicable Protocol

HTTP

Author/Change controller

W3C Solid Community Group

Specification document

This specification

This section is non-normative.

While this section attempts to highlight a set of security considerations, it is not a complete list. Implementers are urged to seek the advice of security professionals when implementing mission critical systems using the technology outlined in this specification.

Implementations are subject to the same security considerations that are found in HTTP/1.1 [RFC7230] and [RFC7231].

Servers are strongly discouraged from assuming that HTTP request headers’ field-values are valid or non-malicious. Servers are strongly encouraged to sanitize requests before processing them or incorporating them in messages sent to others. Servers are encouraged to reject bad requests that conflict with this specification's normative requirements. Servers are encouraged to restrict untrusted requests. Servers are encouraged to apply normalization and canonicalization algorithms where applicable. Servers are encouraged to take measures to mitigate potential timing attacks attempting to discover resource existence even if requesting agent has no access to the resource(s). Servers are strongly discouraged from exposing information beyond the minimum amount necessary to enable a feature.

Servers are strongly discouraged from assuming that the user agent is a regular Web browser, even when requests contain familiar values in headers such as User-Agent or Origin. Such an assumption could lead to incorrect conclusions about the security model of the application making the request, since the request might actually come from a non-browser actor unaffected by browser security constraints.

Servers disable all cross-origin protections in browsers because resource access is governed explicitly by the Authorization component. As such, servers cannot rely on browser-based cross-origin protection mechanisms for determining the authentication status or representation of a resource. In particular, servers are strongly encouraged to ignore HTTP cookies from untrusted origins. Additional security measures can be taken to prevent metadata in error responses from leaking. For instance, a malicious application could probe multiple servers to check whether the response status code is 401 or 403, or could try to access an error page from an intranet server within the user agent’s private network to extract company names or other data. To mitigate this, when a request from an untrusted Origin arrives, the server may want to set the status code of error responses to 404 and/or anonymize or censor their contents.

Servers are encouraged to use TLS connections to protect the contents of requests and responses from eavesdropping and modification by third parties. Unsecured TCP connections without TLS may be used in testing environments or when the server is behind a reverse proxy that terminates a secure connection.

This section is non-normative.

Privacy is one of the ethical values that underpin the web. To empower people with needs to have strong privacy protections with respect to information flows, implementers as well as developers of specifications in the Solid ecosystem are encouraged to consider privacy-related design choices as per W3C Privacy Principles [PRIVACY-PRINCIPLES].

Servers are encouraged to use authorization techniques to prevent unwanted access to resources, rather than depending on the relative obscurity of their resource names.

Identifiable Information

In order to prevent leakage of non-resource data, servers are strongly discouraged from including identifiable information in error responses.

This section is non-normative.

We acknowledge the diversity of people using the Web, anyone that may create or use information. Our aim is to have inclusive designs for wide range of people and their abilities. This section details general accessibility considerations to take into account for Web content accessibility, accessible applications, authoring tools, and accessible user agents that uses this specification.

Web Content Accessibility: As with implementation of any Web standard or protocol, ignoring accessibility issues makes information unusable by a large subset of the population. It is strongly encouraged to follow accessibility guidelines and standards, such as the W3C Accessibility Guidelines [WCAG-3.0] to cover an array of recommendations to make content accessible to a wider range of people regardless of any disability, limitation, or sensitivity. It is also strongly encouraged to follow the guidance of Making content usable for people with cognitive and learning disabilities [COGA-USABLE].

Accessible Applications: To help assistive technologies to provide a consistent user interface and understanding of the objects, it is strongly encouraged to follow the Accessible Rich Internet Applications [WAI-ARIA-1.2] recommendations. To enable semantic navigation, styling and interactive features in context of digital publishing, it is encouraged to follow the Digital Publishing WAI-ARIA Module 1.0 [DPUB-ARIA-1.0]. To support structured graphics such as charts, graphs, technical drawings and scientific diagrams, to assistive technologies in order improve accessibility of graphics or diagrams through detailed annotations, it is encouraged to follow the WAI-ARIA Graphics Module [GRAPHICS-ARIA-1.0].

Authoring Tool Accessibility: To contribute to the proliferation of Web content that is accessible to a broad range of people, it is strongly encouraged to follow the Authoring Tool Accessibility Guidelines [ATAG20] in the design of authoring tools to support the production of accessible content through accessible user interfaces.

User Agent Accessibility Guidelines: To support the general principles for the development of accessible user agents, i.e., any software that retrieves, renders and facilitates end-user interaction with web content, it is strongly encouraged to follow the User Agent Accessibility Guidelines [UAAG20].

This section is non-normative.

Adaptability of content and software to the needs of target audiences helps towards accessibility. The mechanisms to cater information and interfaces so that people from any culture, region, or language preference can participate better. Towards this end, it is strongly encouraged to apply the recommendations and best practices of W3C Internationalization Activity. For example, content authors can:

• include links to navigate to different languages of the content;
• declare the base language of a document, indicate multiple languages and their directional flow – to help with translations;
• use Unicode character encoding, e.g., UTF-8, in data forms and text to ensure correct effects;
• check and minimise inappropriate cultural bias, and improve translatability;
• restrict markup use to structure and semantics.

This section is non-normative.

These questions provide an overview of security and privacy considerations for this specification as guided by [SECURITY-PRIVACY-QUESTIONNAIRE].

What information might this feature expose to Web sites or other parties, and for what purposes is that exposure necessary?

There are no known security impacts of the features in this specification.

Do features in your specification expose the minimum amount of information necessary to enable their intended uses?

Yes.

How do the features in your specification deal with personal information, personally-identifiable information (PII), or information derived from them?

Access to a resource is only granted to authorized agents. HTTP request payloads can contain any data including that which identifies or refers to the user of the application. Meaningful consent to any personal data that applications include is extended by the client to the server.

How do the features in your specification deal with sensitive information?

The features do not require obtaining or exposing sensitive information.

Do the features in your specification introduce new state for an origin that persists across browsing sessions?

No.

Do the features in your specification expose information about the underlying platform to origins?

No.

Does this specification allow an origin to send data to the underlying platform?

No. Resources are described within the framework of HTTP, where some kinds of resources are required to be RDF documents. Servers might be able to redirect to other resources, e.g., the https: URLs to file:, data:, or blob: URLs, but no behaviour is defined by this specification.

Do features in this specification allow an origin access to sensors on a user’s device

No.

What data do the features in this specification expose to an origin? Please also document what data is identical to data exposed by other features, in the same or different contexts.

No detail about another origin’s state is exposed. As the association between a resource and its auxiliary resource is at the discretion of the server, they can be on different origins (URI Origin). When a server participates in the CORS protocol [FETCH], HTTP requests from different origins may be allowed. This feature does not add any new attack surface above and beyond normal CORS requests, so no extra mitigation is deemed necessary.

Do features in this specification enable new script execution/loading mechanisms?

No.

Do features in this specification allow an origin to access other devices?

No.

Do features in this specification allow an origin some measure of control over a user agent’s native UI?

No.

What temporary identifiers do the features in this specification create or expose to the web?

None.

How does this specification distinguish between behaviour in first-party and third-party contexts?

Inapplicable.

How do the features in this specification work in the context of a browser’s Private Browsing or Incognito mode?

No different than browser’s 'normal' state.

Does this specification have both "Security Considerations" and "Privacy Considerations" sections?

Yes, in Security Considerations and Privacy Considerations.

Do features in your specification enable origins to downgrade default security protections?

No.

How does your feature handle non-"fully active" documents?

Inapplicable.

This section is non-normative.

These questions provide an overview of ethical considerations and societal impact as guided by [SOCIETAL-IMPACT-QUESTIONNAIRE].

What kinds of activities do you anticipate your specification becoming a critical part of?

..

What kinds of activities could your specification become a part of that you are not designing for?

..

What risks do you see in features of your specification being misused, or used differently from how you intended?

..

Can users of the Web Platform choose not to use features of your specification?

..

What groups of people are excluded from using features of your specification?

..

What effect may features of your specification have on minority groups?

..

What are the power dynamics at play in implementations of your specification?

..

What points of centralization does your feature bring to the web platform?

..

To what extent do the features in your specification impact the natural environment?

..

What is the expected lifetime of your specification feature(s)?

..

Have you completed the Security & Privacy Self-review Questionnaire?

Yes, in Security Considerations and Privacy Considerations.

• Amend language, document details, and markup.
• Add Change Log.
• Update References.
• Change requirement for server including Accept-* headers in OPTIONS * to OPTIONS.
• Add requirements for server auxiliary resources management and link auxiliary type.
• Constrain server requirement for Allow methods to successful responses.
• Update current copyright year.
• Add advisement for privacy principles.
• Add requirements for storage description: discovery, resource, statements.
• Add requirement for Solid Notifications Protocol.
• Remove the term data pod and add definition of storage.
• Add Constraints and Problem Details.
• Add consideration for restricting untrusted requests.
• Update Conformance to add Normative and Information Content, Class of Products, Specification Category, Interoperability.
• Update Security and Privacy Review.
• Add requirements for Access Control Policy.