Network Working Group J. Montoya
Internet-Draft May 05, 2020
Intended status: Informational
Expires: November 6, 2020
Profiled Hypertext Application Language
draft-montoya-phtal-01
Abstract
This document defines PHTAL, a generic representation format for
hypertext applications guided by REST constraints. PHTAL could be
compared to HTML without any graphical objectives.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Definitions and Terminology . . . . . . . . . . . . . . . 3
1.1.1. Terminology and Conformance Language . . . . . . . . 3
1.1.2. General . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
2. PHTAL Document . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Document description . . . . . . . . . . . . . . . . . . 4
2.1.1. Format . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.2. Schema . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Hypermedia as the engine of application state . . . . . . 4
2.2.1. Document root . . . . . . . . . . . . . . . . . . . . 5
2.2.2. Link Object . . . . . . . . . . . . . . . . . . . . . 7
2.2.3. Operation Object . . . . . . . . . . . . . . . . . . 9
2.2.4. HTTP Operation Object . . . . . . . . . . . . . . . . 11
2.2.5. Security Object . . . . . . . . . . . . . . . . . . . 12
2.2.6. Partial Object . . . . . . . . . . . . . . . . . . . 13
2.3. Self-descriptive messages . . . . . . . . . . . . . . . . 14
2.3.1. Linking to a profile . . . . . . . . . . . . . . . . 15
2.4. Code-On-Demand . . . . . . . . . . . . . . . . . . . . . 15
2.4.1. Script Object . . . . . . . . . . . . . . . . . . . . 16
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
3.1. application/phtal+xml . . . . . . . . . . . . . . . . . . 17
3.2. application/phtal+json . . . . . . . . . . . . . . . . . 19
4. References . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.1. Normative References . . . . . . . . . . . . . . . . . . 20
4.2. Informative References . . . . . . . . . . . . . . . . . 21
4.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 22
Appendix B. Frequently Asked Questions . . . . . . . . . . . . . 22
B.1. How can I submit comments or feedback to the editors? . . 22
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
This document defines PHTAL, a generic representation format for
hypertext applications guided by REST constraints. PHTAL could be
compared to HTML without any graphical objectives.
This document registers two media-type identifiers with the IANA:
"application/phtal+json" and "application/phtal+xml". This
registration is for community review and will be submitted to the
IESG for review, approval, and registration with IANA.
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1.1. Definitions and Terminology
1.1.1. Terminology and Conformance Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.1.2. General
Representational State Transfer, or *REST*, is an architectural style
for distributed hypermedia systems. Introduced and first defined in
2000 in Chapter 5, REST, of the doctoral dissertation "Architectural
Styles and the Design of Network-based Software Architecture" by Roy
Fielding.
*Hypermedia*, or hypertext, is defined by the presence of application
control information embedded within, or as a layer above, the
presentation of information. Hypermedia allows for a virtually
unbound network of resources while also guiding users through an
application as they navigate said relationships.
A *resource* is the intended conceptual target of a hypertext
reference.
*Representational state* indicates the current state of a requested
resource, the desired state for a requested resource, or the value of
some other resource, such as a representation of the input data
within a client's query form, or a representation of some error
condition for a response.
A *hyperlink* or link, is the representation of a virtual uni-
directional relationship between the context resource represented by
the document in which the link is found, and another resource. A
link consists of a hypertext reference, a hypermedia relationship
identifier, and communication protocol information.
A *hypertext reference* or href, is the target's Uniform Resource
Identifier.
A *hyperlink relationship*, also known as a link relation, identifies
the semantics behind a hyperlink.
*Application state* is the state of the user's application of
computing to a given task, controlled and stored by the user agent
and can be composed of representations from multiple servers.
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1.2. Motivation
The essential trade-off that REST makes when compared to an
architectural style like RPC is dynamic modifiability over
efficiency. Dynamic modifiability is the degree to which an
application can be changed without stopping and restarting the entire
system. This is what REST promises through the Uniform Interface,
and optionally Code-On-Demand, constraints.
Guided by these constraints PHTAL introduces generic but
comprehensive hypertext markup to enable application authors to
create evolvable and extensible applications, while spending most of
their descriptive efforts in defining application-specific
representations.
2. PHTAL Document
2.1. Document description
2.1.1. Format
All field names in the specification are *case sensitive*. This
includes all fields that are used as keys in a map, except where
explicitly noted that keys are *case insensitive*.
The schema exposes two types of fields: Fixed fields, which have a
declared name, and Patterned fields, which declare a regex pattern
for the field name.
Patterned fields MUST have unique names within the containing object.
2.1.2. Schema
In the descriptions that will follow, if a field is not explicitly
*REQUIRED* or described with a MUST or SHALL, it can be considered
OPTIONAL.
Machine readable mappings to XML and JSON are provided through the
appropriate schemas at http://www.phtal.org/xsd/phtal.xsd [1] and
http://www.phtal.org/json-schema/phtal.json [2], respectively.
2.2. Hypermedia as the engine of application state
The Uniform Interface constraint dictates that hypermedia must be the
engine of application state. This means that the state of the
application and its potential transitions are dictated by the
presence of hyperlinks and by the navigation of those links by an
user (human or automated). In order for users to traverse a selected
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relationship they depend on the server to provide communication
protocol instructions.
When servers provide control information at run-time instead of at
deploy-time, they retain control of their implementation space and
enable dynamic evolvability; they can change their implementation
without having to restart or deploy clients. Applications servers
are free to change their URI structure, they are free rearrange
resources into different servers, they are free introduce new links
that provide new features in existing representations, nothing will
break already deployed components as long as links are not broken.
2.2.1. Document root
The in-band elements defined by PHTAL aim to provide just what's
necessary for agents to evaluate the hyperlinks provided and invoke
the necessary operation to get the agent to the next application
state.
2.2.1.1. Fixed Fields
+------------+---------------+--------------------------------------+
| Name | Type | Description |
+------------+---------------+--------------------------------------+
| links | Map["string", | The links element is a map where the |
| | [Link Object | keys are hypermedia relationship |
| | (Section 2.2. | identifiers and the values are |
| | 2)]] | single or multiple Link elements. |
| | | The relationship identifier MUST be |
| | | a IANA registered relation type or |
| | | an URI that when dereferenced |
| | | resolves to an XREL |
| | | [I-D.draft-montoya-xrel-01] |
| | | document. |
| | | |
| operations | Map["string", | A map where the key is a protocol |
| | [Operation | identifier and the value is a |
| | Object (Secti | collection of Operation elements. |
| | on 2.2.3)]] | |
+------------+---------------+--------------------------------------+
The operations element MAY be included as part of an HTTP GET
response body, or as the response body to an HTTP OPTIONS, for
example.
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2.2.1.2. Examples
*JSON Representation Example*
{
"name": [
{
"use": "official",
"family": "Chalmers",
"given": [
"Peter",
"James"
]
}
],
"_links": {
"https://api-docs.myclinic.com/fhir/rel/encounter": [{
"href": "http://fhir.myclinic.com/Encounter/1234",
"operation": {
"HTTP": {
"method": "GET",
"produces": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Encounter\",
application/phtal+xml;profile=\"http://hl7.org/fhir/encounter.xsd\""
}
}
}]
},
"_operations": {
"HTTP": [{
"method": "PUT",
"consumes": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Encounter\",
application/phtal+xml;profile=\"http://hl7.org/fhir/encounter.xsd\""
"produces": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/OperationOutcome\",
application/phtal+xml;profile=\"http://hl7.org/fhir/operationoutcome.xsd\""
}]
}
}
*XML Representation Example*
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<Patient xmlns="http://hl7.org/fhir" xmlns:phtal="http://www.phtal.org">
<id value="example"/>
<name>
<use value="official"/>
<family value="Chalmers"/>
<given value="Peter"/>
<given value="James"/>
</name>
<phtal:link rel="https://api-docs.myclinic.com/fhir/rel/encounter">
<phtal:href>http://fhir.myclinic.com/Encounter/1234</phtal:href>
<phtal:operation protocol="HTTP">
<phtal:method>GET</phtal:method>
<phtal:produces>application/phtal+json;profile="http://hl7.org/fhir/json-schema/Encounter",
application/phtal+xml;profile="http://hl7.org/fhir/encounter.xsd"
</phtal:produces>
</phtal:operation>
</phtal:link>
<phtal:operation protocol="HTTP">
<phtal:method>PUT</phtal:method>
<phtal:consumes>application/phtal+json;profile="http://hl7.org/fhir/json-schema/Encounter",
application/phtal+xml;profile="http://hl7.org/fhir/encounter.xsd"
</phtal:consumes>
<phtal:produces>application/phtal+json;profile="http://hl7.org/fhir/json-schema/OperationOutcome",
application/phtal+xml;profile="http://hl7.org/fhir/operationoutcome.xsd"
</phtal:produces>
</phtal:operation>
</Patient>
2.2.2. Link Object
2.2.2.1. Fixed Fields
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+---------------+---------------+-----------------------------------+
| Name | Type | Description |
+---------------+---------------+-----------------------------------+
| href | "string" | *REQUIRED* The link's target |
| | | resource. The href property MUST |
| | | be a URI [RFC3986] or a URI |
| | | Template [RFC6570]. |
| | | |
| uriParameters | Map["string", | A map where the keys are the |
| | "string"] | names of the variables in the |
| | | href property when it is an URI |
| | | Template, and the values are URIs |
| | | that resolve to a document that |
| | | appropriately describes the |
| | | format and semantics of the |
| | | variables, e.g.: a DTD, XSD, JSON |
| | | Schema, RAML Data Type, OpenAPI |
| | | schema, etc. |
| | | |
| operation | Map["string", | The protocol specific operation |
| | Operation | for traversing this link. There |
| | Object (Secti | SHOULD NOT be two operations for |
| | on 2.2.3)] | the same protocol. |
| | | |
| partial | Partial | A partial representation of the |
| | Object (Secti | target resource. |
| | on 2.2.6) | |
+---------------+---------------+-----------------------------------+
When the operation element is not present the client SHOULD assume
that the required operation is an HTTP GET.
2.2.2.2. Examples
*JSON Representation Example*
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{
"href": "http://fhir.myclinic.com/Patient/{id}/{?_pretty,_elements}",
"uriParameters": {
"id": "https://api-docs.myclinic.com/fhir/patientId.raml",
"_pretty": "https://api-docs.myclinic.com/fhir/parameters/_pretty.raml",
"_elements": "https://api-docs.myclinic.com/fhir/parameters/_elements.raml"
},
"operation": {
"HTTP": {
"method": "GET",
"produces": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Encounter\",
application/phtal+xml;profile=\"http://hl7.org/fhir/encounter.xsd\""
}
}
}
*XML Representation Example*
<phtal:link rel="https://api-docs.myclinic.com/fhir/rel/encounter">
<phtal:href>http://fhir.myclinic.com/Patient/{id}/{?_pretty,_elements}</phtal:href>
<phtal:uriParameter profile="https://api-docs.myclinic.com/fhir/patientId.raml">id</phtal:uriParameter>
<phtal:uriParameter profile="https://api-docs.myclinic.com/fhir/parameters/_pretty.raml">_pretty</phtal:uriParameter>
<phtal:uriParameter profile="https://api-docs.myclinic.com/fhir/parameters/_elements.raml">_elements</phtal:uriParameter>
<phtal:operation protocol="HTTP">
<phtal:method>GET</phtal:method>
<phtal:produces>application/phtal+json;profile="http://hl7.org/fhir/json-schema/Encounter",
application/phtal+xml;profile="http://hl7.org/fhir/encounter.xsd"
</phtal:produces>
</phtal:instructions>
</phtal:link>
2.2.3. Operation Object
The most important element that PHTAL representations provide is the
operation element. This element instructs the agent on how to
interact with a resource through a particular communication protocol.
This allows the server to control its own URI space and the clients
to be undisrupted when URI changes are made or new representation or
protocol support is added.
Identifying protocol specific instructions allows servers to separate
communication protocols from resource identification. This is
consistent with the URI specification [RFC3986] and allows PHTAL to
support arbitrary protocols.
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2.2.3.1. Fixed Fields
+----------------+----------------+---------------------------------+
| Name | Type | Description |
+----------------+----------------+---------------------------------+
| method | "string" | Instructs the agent what |
| | | protocol specific method to use |
| | | when interacting with the |
| | | identified resource. The |
| | | default value is whatever |
| | | protocol specific method |
| | | results in information |
| | | retrieval, eg. HTTP GET. |
| | | |
| produces | "string" | Indicates to the client what |
| | | media types the server supports |
| | | as response content to |
| | | following the current link. It |
| | | MUST be a media range and |
| | | parameters according to Section |
| | | 5.3.2 'Accept' of the HTTP |
| | | Specification [RFC7231]. |
| | | |
| consumes | "string" | Indicates to the client what |
| | | media types the server supports |
| | | as request content to following |
| | | the current link. It MUST be a |
| | | media range and parameters |
| | | according to Section 5.3.2 |
| | | 'Accept' of the HTTP |
| | | Specification [RFC7231]. |
| | | |
| requestContent | "boolean" | Indicates to the client whether |
| | | a request content is required |
| | | or not for the following the |
| | | current link. The default value |
| | | is "false". |
| | | |
| onInvoke | EventAttribute | Script function which is to be |
| | | executed when this operation is |
| | | invoked. |
+----------------+----------------+---------------------------------+
The quality weight parameters MAY be used in the "consumes" and
"produces" properties to indicate to the client which media types are
preferred, possibly allowing the client to know when a known media
type has been superseded and a new one is preferred.
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2.2.3.2. Examples
*JSON Representation Example*
{
"method": "POST",
"consumes": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Appointment\"",
"produces": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/OperationOutcome\"",
"requestContent": true,
"onInvoke": "..."
}
*XML Representation Example*
<phtal:operation protocol="HTTP" onInvoke="...">
<phtal:consumes>application/phtal+xml;profile="http://hl7.org/fhir/appointment.xsd"
</phtal:consumes>
<phtal:produces>application/phtal+xml;profile="http://hl7.org/fhir/operationoutcome.xsd"
</phtal:produces>
<phtal:requestContent>true</phtal:requestContent>
</phtal:operation>
2.2.4. HTTP Operation Object
The HTTP Operation element is an extension of the Operation element
specifically for interactions using the HTTP [RFC7231] protocol.
2.2.4.1. Added Properties
+----------+---------------+----------------------------------------+
| Name | Type | Description |
+----------+---------------+----------------------------------------+
| security | [Security | An array of Security elements, the |
| | Object (Secti | operation can be authenticated by any |
| | on 2.2.5)] | of the specified security schemes. |
| | | |
| headers | Map["string", | A map where the keys are the names of |
| | "string"] | the HTTP headers to be sent and the |
| | | values are URIs that resolve to a |
| | | document that appropriately describes |
| | | the format and semantics of the |
| | | variables, e.g.: a DTD, XSD, JSON |
| | | Schema, RAML Data Type, OpenAPI |
| | | schema, etc. |
+----------+---------------+----------------------------------------+
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2.2.4.2. Examples
*JSON Representation Example*
{
"method": "POST",
"consumes": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Appointment\"",
"produces": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/OperationOutcome\"",
"requestContent": true,
"security": {
"https://api-docs.myclinic.com/fhir/security/basicAuth": [],
"https://api-docs.myclinic.com/fhir/security/oauth2.0": [
"appointment:write"
]
},
"headers": {
"trace-id": "https://api-docs.myclinic.com/fhir/traceId.raml"
}
}
*XML Representation Example*
<phtal:operation protocol="HTTP">
<phtal:consumes>application/phtal+xml;profile="http://hl7.org/fhir/appointment.xsd"
</phtal:consumes>
<phtal:produces>application/phtal+xml;profile="http://hl7.org/fhir/operationoutcome.xsd"
</phtal:produces>
<phtal:requestContent>true</phtal:requestContent>
<phtal:security scheme="https://api-docs.myclinic.com/fhir/security/basicAuth">
<phtal:scope>appointment:write</phtal:scope>
</phtal:security>
<phtal:security scheme="https://api-docs.myclinic.com/fhir/security/oauth2.0"/>
</phtal:operation>
2.2.5. Security Object
2.2.5.1. Patterned Fields
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+---------+------------+--------------------------------------------+
| Field | Type | Description |
| Pattern | | |
+---------+------------+--------------------------------------------+
| {name} | ["string"] | Each name MUST resolve to an OpenAPI 3.1 |
| | | Spec [OAS] Security Scheme declaration. If |
| | | the security scheme is of type "oauth2" or |
| | | "openIdConnect", then the value is a list |
| | | of scope names required for the execution. |
| | | For other security scheme types, the array |
| | | MUST be empty |
+---------+------------+--------------------------------------------+
2.2.6. Partial Object
Partial representation of the linked resource.
2.2.6.1. Fixed Fields
+------+----------+-------------------------------------------------+
| Name | Type | Description |
+------+----------+-------------------------------------------------+
| type | "string" | Identifies the media type that describes the |
| | | partial representation. |
| | | |
| data | Any | The actual partial representation content. |
+------+----------+-------------------------------------------------+
Partial content SHOULD NOT be considered full representations even if
their contents happen to be complete. It is RECOMMENDED partial
representations provide just enough information for agents to be able
to discern which link they want to follow and SHOULD NOT be used as
mechanism to batch interactions.
In the case of XML it is the content of the "partial" element, in
JSON it is the value of a "data" property.
2.2.6.2. Examples
*JSON Representation Example*
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{
"type": "application/phtal+json;profile=\"http://hl7.org/fhir/json-schema/Encounter\"",
"data": {
"status": "in-progress",
"class": {
"system": "http://terminology.hl7.org/CodeSystem/v3-ActCode",
"code": "IMP",
"display": "inpatient encounter"
}
}
}
*XML Representation Example*
<phtal:partial profile="application/phtal+xml;profile=\"http://hl7.org/fhir/json-schema/Encounter\"">
<Encounter xmlns="http://hl7.org/fhir">
<status value="in-progress"/>
<class>
<system value="http://terminology.hl7.org/CodeSystem/v3-ActCode"/>
<code value="IMP"/>
<display value="inpatient encounter"/>
</class>
</Encounter>
</phtal:partial>
2.3. Self-descriptive messages
The Uniform Interface constraint also dictates that messages must be
self-descriptive. This is achieved by message metadata, of which
content type metadata is a vital part. The purpose of content type
metadata in web interactions is not only to indicate representation
format or schema, but the sender's preferred interpretation of that
format, an application-specific format.
By making use of media type parameters, PHTAL representations allow
participants to retain the ability to signal their preferred
interpretation of a message. Message authors only have to identify
the document that defines the application-specific format of their
representation and attach it to an otherwise generic PHTAL
representation.
When web participants identify an application-specific format in
metadata they promote visibility and evolvability. Intermediaries
(i.e., proxies and gateways) are able to accurately and more
efficiently perform significant functions such as encapsulating
legacy services, and enhancing client functionality.
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2.3.1. Linking to a profile
To indicate their preferred interpretation of a PHTAL representation,
the sender SHOULD include a "profile" media type parameter. The
profile parameter SHOULD be a dereferenceable URI that resolves to a
document that describes the format and semantics of the resource
representation, e.g.: a DTD, XSD, JSON Schema, RAML Data Type,
OpenAPI schema, etc..
For example consider the following interactions:
POST http://www.example.com/some-identifier
Content-Type: application/json
Accept: application/json
200 OK
Content-Type: application/json
This interaction can only be accurately interpreted to mean that the
client requested "http://www.example.com/some-identifier" to process
an "application/json" request and it successfully responded with an
"application/json" response. "application/json" offers intermediaries
no semantic information about the content of the message besides how
it's (de)serialized.
POST http://www.example.com/some-identifier
Content-Type: application/phtal+json;profile="http://hl7.org/fhir/json-schema/Appointment"
Accept: application/phtal+json;profile="http://hl7.org/fhir/json-schema/OperationOutcome"
200 OK
Content-Type: application/phtal+json;profile="http://hl7.org/fhir/json-schema/OperationOutcome"```
In contrast, this second interaction is perfectly clear. The client
requested "http://www.example.com/some-identifier" to process a
clinical Appointment request and it successfully responded with an
OperationOutcome response that details the results of the processing.
Intermediaries are able to parse and manipulate the message, perhaps
defaulting values of the appointment request, or adding and/or
removing links from the response, or maybe redirecting the message to
different resources based on the profile information.
2.4. Code-On-Demand
In order to further promote modifiability of a system REST defines
code-on-demand as an optional constraint. An optional constraint
would observe desired behavior where supported, but with the
understanding that it may not be the general case. Code-on-demand is
a style of code mobility in which the processing logic is moved from
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the server into the client, thus providing dynamic extensibility;
functionality can be added to a deployed component without impacting
the rest of the system.
Ultimately, application servers may prefer if legacy clients could
adapt to new representations or communication protocols instead of
having to support overloaded versions of a feature. At the cost of
visibility, code-on-demand allows application servers to re-program a
deployed component to support new features, thus freeing the server
from the responsibility of maintaining backwards compatibility.
It's worthy to mention other advantages of code-on-demand outside of
modifiability. Scalability of the server is improved, since it can
off-load work to the client. User-perceived performance and
efficiency are enhanced when the code can adapt its actions to the
client's environment and interact with the user locally rather than
through remote interactions.
Very similar to HTML's script element PHTAL provides ways to embed
code into its representations.
2.4.1. Script Object
A script element is equivalent to the script element in HTML and thus
is the place for scripts (e.g., ECMAScript). Any functions defined
within any script element have a "global" scope across the entire
current document.
TODO: Consider what to include about DOM and Events.
2.4.1.1. Fixed Fields
+--------+----------+-----------------------------------------------+
| Name | Type | Description |
+--------+----------+-----------------------------------------------+
| type | "string" | *REQUIRED* Identifies the media type that |
| | | describes the script content. |
| | | |
| source | "string" | An URI that references the script's content. |
| | | |
| data | "string" | The actual contents of the script. It is |
| | | mutually exclusive with the source property. |
+--------+----------+-----------------------------------------------+
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2.4.1.2. Examples
*JSON Representation Example*
{
"_scripts": [{
"type": "text/javascript",
"source": "http://fhir.myclinic.com/scripts/patientScript"
},
{
"type": "text/javascript",
"data": "..."
}]
}
*XML Representation Example*
<Patient xmlns="http://hl7.org/fhir" xmlns:phtal="http://www.phtal.org">
<phtal:script type="text/javascript" src="http://fhir.myclinic.com/scripts/patientScript"/>
<phtal:script type="text/javascript">
<![CDATA[
function foo(evt) {
...
}
]\]>
</phtal:script>
</Patient>
3. IANA Considerations
This specification establishes two media types: 'application/
phtal+xml' and 'application/phtal+json'
3.1. application/phtal+xml
*Type name:* application
*Subtype name:* phtal+xml
*Required parameters:* none
*Optional parameters:*
*charset:* This parameter has identical semantics to the charset
parameter of the 'application/xml' media type as specified in
[RFC7303].
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*profile:* A dereferenceable URI that resolves to a document that
describes the format and semantics of the resource representation,
e.g.: a DTD, XSD, RAML Data Type, OpenAPI schema, etc.. A profile
must not change the semantics of the resource representation when
processed without profile knowledge, so that clients both with and
without knowledge of a profiled resource can safely use the same
representation. The profile parameter may also be used by clients
to express their preferences in the content negotiation process.
*Encoding considerations:*
*binary:* Same as encoding considerations of application/xml as
specified in [RFC7303].
*Security considerations:*
This format shares security issues common to all XML content
types. The security issues of [RFC7303], section 10, should be
considered.
Several PHTAL elements may cause arbitrary URIs to be referenced.
In this case, the security issues of [RFC3986], section 7, should
be considered.
In common with HTML, PHTAL documents may reference external
scripting language media. Scripting languages are executable
content. In this case, the security considerations in the Media
Type registrations for those formats shall apply.
*Interoperability considerations:* none
*Fragment identifier considerations:*
*Published specification:* This Document
*Applications that use this media type:* Various
*Additional information:*
*magic number(s):* none
*file extensions:* .xml
*macintosh type file code:* TEXT
*object idenfiers:* none
*Person to contact for further information:*
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*Name:* Jose Montoya
*Email:* jam01@protonmail.com
*Intended usage:* Common
*Author/change controller:* Jose Montoya
3.2. application/phtal+json
*Type name:* application
*Subtype name:* phtal+json
*Required parameters:* none
*Optional parameters:*
*profile:* A dereferenceable URI that resolves to a document that
describes the format and semantics of the resource representation,
e.g.: a JSON Schema, RAML Data Type, OpenAPI schema, etc.. A
profile must not change the semantics of the resource
representation when processed without profile knowledge, so that
clients both with and without knowledge of a profiled resource can
safely use the same representation. The profile parameter may
also be used by clients to express their preferences in the
content negotiation process.
*Encoding considerations:* binary
*Security considerations:*
This media type shares security issues common to all JSON content
types. The security issues of [RFC8259], section 6, should be
considered.
Several PHTAL elements may cause arbitrary URIs to be referenced.
In this case, the security issues of [RFC3986], section 7, should
be considered.
In common with HTML, PHTAL documents may reference external
scripting language media. Scripting languages are executable
content. In this case, the security considerations in the Media
Type registrations for those formats shall apply.
*Interoperability considerations:* none
*Fragment identifier considerations:* none
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*Published specification:* This Document
*Applications that use this media type:* Various
*Additional information:*
*magic number(s):* none
*file extensions:* .json
*macintosh type file code:* TEXT
*object idenfiers:* none
*Person to contact for further information:*
*Name:* Jose Montoya
*Email:* jam01@protonmail.com
*Intended usage:* Common
*Author/change controller:* Jose Montoya
4. References
4.1. Normative References
[I-D.draft-montoya-xrel-01]
Montoya, J., "Extended Link Relationships", draft-montoya-
xrel-01 (work in progress), October 2019.
[OAS] OpenAPI Initiative, a Linux Foundation Collaborative
Project, "OpenAPI Specification", n.d.,
<https://github.com/OAI/OpenAPI-Specification/blob/v3.1.0-
dev/versions/3.1.0.md>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://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,
<https://www.rfc-editor.org/info/rfc3986>.
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[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012,
<https://www.rfc-editor.org/info/rfc6570>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[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,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7303] Thompson, H. and C. Lilley, "XML Media Types", RFC 7303,
DOI 10.17487/RFC7303, July 2014,
<https://www.rfc-editor.org/info/rfc7303>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
4.2. Informative References
[I-D.draft-handrews-json-schema-hyperschema-01]
Andrews, H. and A. Wright, "JSON Hyper-Schema: A
Vocabulary for Hypermedia Annotation of JSON", draft-
handrews-json-schema-hyperschema-01 (work in progress),
January 2018.
[I-D.draft-kelly-json-hal-08]
Kelly, M., "JSON Hypertext Application Language", draft-
kelly-json-hal-08 (work in progress), May 2016.
[REST] Fielding, R., "Architectural Styles and the Design of
Network-based Software Architectures", Ph.D. Dissertation,
University of California, Irvine, 2000,
<http://www.ics.uci.edu/~fielding/pubs/dissertation/
fielding_dissertation.pdf>.
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[W3C.hydra]
Lanthaler, M., "A Vocabulary for Hypermedia-Driven Web
APIs", 2018, <http://www.hydra-cg.com/spec/latest/core/>.
[W3C.TAG.role-media-types]
Fielding, R. and I. Jacobs, "Role of Internet Media
Types", 2001, <https://www.w3.org/2001/tag/doc/mime-
respect-20130422#media-type>.
4.3. URIs
[1] http://www.phtal.org/xsd/phtal.xsd
[2] http://www.phtal.org/json-schema/phtal.json
[3] https://github.com/phtal-org/internet-draft-phtal/issues
[4] https://phtal-org.github.io/internet-draft-phtal/
Appendix A. Acknowledgments
Thanks to Mike Kelly, Henry Andrews, Marcus Lanthaler, Mike Amundsen,
Stu Charlton, and Jeff Michaud for their contributions in this space
even if not directly related to PHTAL.
Appendix B. Frequently Asked Questions
B.1. How can I submit comments or feedback to the editors?
The issues list for this draft can be found at https://github.com/
phtal-org/internet-draft-phtal/issues [3]. For additional
information, see https://phtal-org.github.io/internet-draft-phtal/
[4].
To provide feedback, use this issue tracker, the communication
methods listed on the homepage, or email the document editors.
Author's Address
Jose Montoya
Email: jam01@protonmail.com
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