Activity Streams (http://activitystrea.ms) J. Snell
Internet-Draft IBM
Intended status: Standards Track M. Marum
Expires: November 14, 2014 SugarCRM
May 13, 2014
JSON Activity Streams 2.0 - Action Handlers
draft-snell-activitystreams-actions-06
Abstract
This specification defines Action Handlers for use with the Activity
Streams 2.0 format.
Author's Note
Note that this document is a work-in-progress draft specification
that does not yet represent a "standard". It is the intention of
this specification to propose a few new ideas and openly solicit
feedback on their definition and use. While this document might
eventually evolve into an RFC the ideas described herein have not yet
been broadly implemented and have definitions that will evolve
through successive iterations of this draft.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 14, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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described in the Simplified BSD License.
Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Action Handlers . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Content Security Policy . . . . . . . . . . . . . . . . . 6
3. HTTP Action Handler . . . . . . . . . . . . . . . . . . . . . 8
4. View Action Handler . . . . . . . . . . . . . . . . . . . . . 11
5. Embed Action Handler . . . . . . . . . . . . . . . . . . . . 14
6. Intent Action Handler . . . . . . . . . . . . . . . . . . . . 17
7. Using "service" and "application" objects as action handlers 17
8. HTML Form Objects . . . . . . . . . . . . . . . . . . . . . . 18
9. Typed Payload Objects . . . . . . . . . . . . . . . . . . . . 19
10. URL Template Objects . . . . . . . . . . . . . . . . . . . . 20
11. Parameters Object . . . . . . . . . . . . . . . . . . . . . . 21
11.1. The Parameter Object . . . . . . . . . . . . . . . . . . 22
11.2. Using UrlTemplate and TypedPayload objects as parameter
descriptions . . . . . . . . . . . . . . . . . . . . . . 26
12. Authentication Object . . . . . . . . . . . . . . . . . . . . 27
13. Styles Object . . . . . . . . . . . . . . . . . . . . . . . . 28
14. Security Considerations . . . . . . . . . . . . . . . . . . . 30
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
16. Normative References . . . . . . . . . . . . . . . . . . . . 30
Appendix A. Using Action Handlers From Other Vocabularies . . . 31
A.1. Schema.org Actions Proposal . . . . . . . . . . . . . . . 31
A.2. Google's "Actions in the Inbox" . . . . . . . . . . . . . 31
A.3. Mixing Vocabularies . . . . . . . . . . . . . . . . . . . 32
A.4. Example Drawing From Multiple Vocabularies . . . . . . . 33
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
1. Overview
The Activity Streams 2.0 [I-D.snell-activitystreams] specification
introduces the notion of "actions" that can be associated with
objects. Using the "actions" property described in Sections 3.6 and
3.6.1 of the Activity Streams 2.0 document, the producer of an object
can declare a specific set of verbs appropriate for the object and
map each of those to one or more objects ("action handlers") or
resources capable of "carrying out" the verb. This document expands
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on that mechanism by defining and describing a core set of action
handler object types.
2. Action Handlers
An action handler is an Activity Streams 2.0 object whose objectType
and member properties instruct a consuming application how to carry
out the verb the action handler has been associated with. For
instance, given the following example:
{
"objectType": "note",
"displayName": "Title of the note",
"content": "This is a simple note.",
"actions": {
"share": {
"objectType": "ViewActionHandler",
"url": "http://example.org/share",
"target": "_blank"
},
"like": {
"objectType": "EmbedActionHandler",
"mediaType": "text/plain",
"content": "Hello World"
}
}
}
The "note" object has two declared actions, "share" and "like". Each
of those is associated with one action handler object. The "share"
action has a action handler of type "ViewActionHandler", while the
"like" action has an "EmbedActionHandler".
As illustrated in the example, action handlers are represented as
Activity Streams 2.0 objects. All such objects share a common set of
base member properties as defined in the following table:
+----------+-----------------------------+--------------------------+
| Property | Value | Description |
+----------+-----------------------------+--------------------------+
| confirm | Boolean | True if the consuming |
| | | application ought to |
| | | seek confirmation prior |
| | | to using the action |
| | | handler to carry out |
| | | it's associated action. |
| | | Defaults to False. |
| context | JSON Object | Contextual information |
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| | | associated with the |
| | | action handler, |
| | | represented as a JSON |
| | | Object without any |
| | | particular structure. |
| | | How the context is used |
| | | is dependent entirely on |
| | | the action handler |
| | | definition and on how a |
| | | consuming application |
| | | chooses to implement the |
| | | action handler. |
| expects | Link Value | For action handlers with |
| | [I-D.snell-activitystreams] | a distinct input |
| | | requirement (e.g. |
| | | HttpActionHandler), the |
| | | expects property |
| | | provides a description |
| | | of the expected input. |
| | | The value is expressed |
| | | as either a String |
| | | containing a fully |
| | | qualified IRI, an |
| | | Activity Stream Object, |
| | | or an Array of IRI's or |
| | | Objects. When multiple |
| | | values are provided, |
| | | they MUST be considered |
| | | as mutually exclusive |
| | | alternatives. |
| returns | Link Value | For action handlers with |
| | [I-D.snell-activitystreams] | a distinct output, the |
| | | returns property |
| | | provides a description |
| | | of the expected output. |
| | | The value is expressed |
| | | as either a String |
| | | containing a fully |
| | | qualified IRI, an |
| | | Activity Stream Object, |
| | | or an Array of IRI's or |
| | | Objects. When multiple |
| | | values are provided, |
| | | they MUST be considered |
| | | as mutually exclusive |
| | | alternatives. |
| auth | Authentication Value | For action handlers with |
| | (Section 12) | specific authentication |
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| | | requirements, the "auth" |
| | | property provides |
| | | information about the |
| | | specific authentication |
| | | mechanisms supported. |
| requires | Link Value | An optional Link Value |
| | [I-D.snell-activitystreams] | whose value(s) describe |
| | | features or behaviors an |
| | | implementation MUST |
| | | support in order to |
| | | carry out the action. |
| | | Requirements are |
| | | designed to be |
| | | intentionally open-ended |
| | | and will vary depending |
| | | on specific Action |
| | | Handler type. Any |
| | | implementation that does |
| | | not support any |
| | | specified required |
| | | feature MUST ignore the |
| | | Action Handler. |
| prefers | Link Value | An optional Link Value |
| | [I-D.snell-activitystreams] | whose value(s) describe |
| | | features or behaviors an |
| | | implementation SHOULD |
| | | support in order to |
| | | carry out the action. |
| | | Requirements are |
| | | designed to be |
| | | intentionally open-ended |
| | | and will vary depending |
| | | on specific Action |
| | | Handler type. Any |
| | | implementation that does |
| | | not support any |
| | | specified preferred |
| | | feature MAY ignore the |
| | | feature. |
+----------+-----------------------------+--------------------------+
This specification defines four specific base types of action
handler:
o The HTTP Action Handler (Section 3),
o The View Action Handler (Section 4),
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o The Embed Action Handler (Section 5), and
o The Intent Action Handler (Section 6).
Implementations are free to use Activity Stream objects of any
objectType as an action handler. Consuming applications MAY ignore
any object it encounters that use objectTypes that are not recognized
or supported as action handlers. Alternatively, the consuming
application MAY treat such objects as implied Intent Action Handlers
(Section 6).
Multiple independent action handlers can be associated with any
single verb using a JSON Array. The ordering of objects within such
an array is not considered to be significant.
For example, in the following, the "share" action has two associated
action handlers:
{
"objectType": "event",
"displayName": "Party!",
"content": "We're going to party like it's 1999!",
"id": "urn:example:events:123",
"actions": {
"share": [
{
"objectType": "HttpActionHandler",
"method": "POST",
"url": "http://example.org/share-this/123",
"returns": {
"objectType": "TypedPayload",
"mediaType": "text/html"
}
},
{
"objectType": "EmbedActionHandler",
"mediaType": "text/html",
"content": "<div>...</div>"
}
]
}
}
2.1. Content Security Policy
Note that all Action Handler types are subject to any relevant active
Content Security Policy [W3C.WD-CSP11-20140211], or CSP, that is in-
scope for the context in which the Action Handler is being invoked.
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The specific CSP directive that applies to a particular action
handler type may vary depending on the Action Handler's objectType.
Because the successful application of the Content Security Policy
depends on the ability to determine the Origin [RFC6454] with which
content is associated, the following rules for determining the origin
for an Action Handler apply:
If the Action Handler contains a "url" property, and that property
is being used to invoke the handler, the URL specified is used to
establish the origin as defined in [RFC6454], Section 4.
Otherwise, the Origin is derived from the Base URI of the Action
Handler as determined by following the guidelines specified in
Section 6.1 of the JSON-LD specification
[W3C.REC-json-ld-20140116].
For instance, the example below illustrates an HTTP response carrying
an Activity Streams object with three separate Action Handlers, each
with a distinct Origin:
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HTTP/1.1 200 OK
Content-Type: application/activity+json
Content-Location: http://example.net/baz
{
"objectType": "note",
"content": "This is a simple note",
"actions": {
"view": {
{
"objectType": "ViewActionHandler",
"url": "http://example.org/foo"
},
{
"objectType": "EmbedActionHandler",
"content": "<div>This is fun</div>",
"@context": {
"@base": "https://example.com:8443/bar"
}
},
{
"objectType": "IntentActionHandler",
"context": {
"a": "b",
"b": "c"
}
}
}
}
}
The Origin for the "ViewActionHandler" is determined to be "http://
example.org:80"; the Origin for the "EmbedActionHandler" is "http://
example.com:8443"; and the Origin for the "IntentActionHandler" is
"http://example.net".
3. HTTP Action Handler
An HTTP Action Handler describes an HTTP request/response flow used
to carry out an action. It is identified using an objectType value
of "HttpActionHandler".
The defining characteristic of the HttpActionHandler is that the the
HTTP request and response flow occur independently of any browser or
navigation context. In other words, invocation of the handler MUST
NOT directly cause the user agent to navigate to or visually display
the results of the HTTP request. This makes the HttpActionHandler
suited primarily for RESTful API style operations in much the same
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way that a web application developer would use the XMLHttpRequest
object.
+----------+------------------------+-------------------------------+
| Property | Value | Description |
+----------+------------------------+-------------------------------+
| url | Link Value | Specifies the HTTP or HTTPS |
| | | URL to which the HTTP request |
| | | is directed. |
| method | HTTP Method String | The HTTP method to use. |
| | (e.g. "GET", "POST", | Defaults to "GET" |
| | "PUT", etc) | |
+----------+------------------------+-------------------------------+
For example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"share": {
"objectType": "HttpActionHandler",
"url": "http://example.org/foo",
"method": "POST"
}
}
}
In the Activity Streams 2.0 format, the "url" property is defined as
a "Link Value", this means that it is possible for the value of the
"url" property to be an Activity Stream object that a consuming
application can use to resolve the actual target URL. This
specification defines a new UrlTemplate (Section 10) objectType
specifically intended for such use.
The UrlTemplate object can be used within an HTTP Action Handler, for
instance, whenever carrying out the HTTP request requires the
construction of a new URL that includes variable parameters:
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{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"review": {
"objectType": "HttpActionHandler",
"url": {
"objectType": "UrlTemplate",
"template": "http://example.org/note/123{?rating}",
"parameters": {
"rating": {
"displayName": "Rating",
"maxInclusive": 5,
"minInclusive": 1,
"type": "unsignedInt"
}
}
},
"method": "POST"
}
}
}
If the HTTP request requires an input payload, the HttpActionHandler
object can contain an "expects" property. The value of "expects" is
an Activity Streams 2.0 "Link Value" represented either as a simple
JSON string containing a fully qualified IRI, an Activity Stream
object, or an array of IRI's or Objects. This specification defines
a new HtmlForm (Section 8) objectType to be used whenever the input
of the HTTP request is an HTML Form POST. A new TypedPayload
(Section 9) objectType is defined for use whenever the input is an
arbitrary MIME media type.
For example, the following describes an HTML Form post with a single
"foo" parameter submitted using the "application/x-www-form-
urlencoded" format:
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{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"share": {
"objectType": "HttpActionHandler",
"method": "POST",
"url": "http://example.org/foo",
"expects": {
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"foo": {
"type": "string",
"displayName": "Foo Property"
}
}
}
}
}
}
When a Content Security Policy is in effect, invocation of the HTTP
Action Handler is always governed by the "connect-src" directive
defined in Section 3.2.5.3 of [W3C.WD-CSP11-20140211]. Further, when
the HTTP Action Hander specifies any method other than "GET", and the
input when invoking the action handler is an HTML Form, the handler
is additionally governed by the CSP "form-action" directive
(Section 3.2.5.6).
4. View Action Handler
The View Action Handler describes an action that causes either an
existing or new browser context to be navigated to the identified
resource. It is specified using an objectType value of
"ViewActionHandler".
ViewActionHandler is roughly equivalent to the HTML anchor tag in
that invocation of the handler causes the user agent to navigate to
the identified resource. Unlike the anchor tag, however, the
ViewActionHandler can specify the HTTP method, input payload and
expected output.
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+----------+---------------+----------------------------------------+
| Property | Value | Description |
+----------+---------------+----------------------------------------+
| url | Link Value | Specifies the HTTP or HTTPS URL to |
| | | which the HTTP request is directed. |
| method | HTTP Method | The HTTP method to use. Defaults to |
| | String (e.g. | "GET" |
| | "GET", | |
| | "POST", | |
| | "PUT", etc) | |
| target | Browsing | Specifies the Browsing Context Name or |
| | Context Name | keyword, as defined by |
| | or Keyword | [W3C.CR-html5-20140429], that will be |
| | | used when the action handler is |
| | | invoked. |
| sandbox | HTML5 | An optional string specifying HTML5 |
| | "sandbox" | [W3C.CR-html5-20140429] sandbox |
| | restrictions | restrictions that ought to be applied |
| | | to the content referenced by the "url" |
| | | property. |
+----------+---------------+----------------------------------------+
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "ViewActionHandler",
"url": "http://example.org/foo",
"target": "_new"
}
}
}
As a shortcut, ViewActionHandlers that use the "GET" method can be
specified using a JSON string containing the absolute URL. For
instance:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": "http://example.org/foo"
}
}
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In such cases, the "target" property is assumed to be unspecified.
If the intended HTTP request uses the GET method, and the target URL
is to be constructed by expanding a URL Template, the UrlTemplate
object itself can be used directly as the action handler.
In other words, the following example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "ViewActionHandler",
"method": "GET",
"url": {
"objectType": "UrlTemplate",
"template": "http://example.org/note/{noteid}",
"parameters": {
"noteid": {
"type": "nonNegativeInteger",
"totalDigits": 5
}
}
}
}
}
}
Can, instead, be specified as:
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{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "UrlTemplate",
"template": "http://example.org/note/{noteid}",
"parameters": {
"noteid": {
"type": "nonNegativeInteger",
"totalDigits": 5
}
}
}
}
}
When a Content Security Policy is in effect, View Action Handlers are
subject to the same processing requirements as HTML anchor and form
elements. For instance, the "child_src" directive governs whether or
not the View Action Handler is permitted to create nested or
auxiliary browsing contexts, while the "form_action" directive
governs a View Action Handler that uses any method other than "GET"
and whose input is an HTML Form.
5. Embed Action Handler
An Embed Action Handler defines static or dynamic content to be
visually rendered to carry out an action. Examples of embeds can
include static HTML, images, videos, gadgets and applications. It is
identified using an objectType value of "EmbedActionHandler".
The defining characteristic that differentiates an Embed Action
Handler from a View Action Handler is that the former always implies
the use of the current browsing context and that content is expected
to be displayed inline as embedded content (similar to the way HTML5
img, audio, video and iframe tags are handled).
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+-----------+--------------+----------------------------------------+
| Property | Value | Description |
+-----------+--------------+----------------------------------------+
| url | Link Value | The URL from which to retrieve the |
| | | content for this embed. |
| content | String | The character based "static" content |
| | | to be embeded. The "mediaType" |
| | | parameter specifies the MIME media |
| | | type of the content. |
| mediaType | MIME Media | The MIME Media Type of the embedded |
| | Type | content. |
| style | Styles | Visual CSS styling hints to apply to |
| | Object | the element containing the embedded |
| | (Section 13) | content. |
| preview | Link Value | A reference to a "preview" |
| | | representation of the embedded |
| | | content. Typically, this would a URL |
| | | to a thumbnail or screenshot image of |
| | | the content. |
| sandbox | HTML5 | An optional string specifying HTML5 |
| | "sandbox" | [W3C.CR-html5-20140429] sandbox |
| | restrictions | restrictions that ought to be applied |
| | | to the content referenced by the "url" |
| | | property. |
+-----------+--------------+----------------------------------------+
In the following example, the "view" action is associated with an
"EmbedActionHandler" containing a static fragment of HTML markup:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "EmbedActionHandler",
"content": "<div>This is some bit of embedded HTML</div>",
"mediaType": "text/html",
"style": {
"height": "100px",
"width": "100px",
"box-shadow": "10px 10px 5px #888888"
},
"displayName": "Some embedded content",
"preview": "http://example.org/preview/123.jpg"
}
}
}
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Alternatively, the embedded content can be referenced by URL:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "EmbedActionHandler",
"url": "http://example.org/foo",
"mediaType": "text/html"
}
}
}
The mediaType parameter specifies the type of content to be embedded.
Consuming applications MAY ignore Embed Action Handlers that specify
unrecognized or unsupported mediaTypes.
Example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "EmbedActionHandler",
"url": "http://example.org/foo.mpg",
"mediaType": "video/mpeg"
}
}
}
Exactly how the content referenced by the Action Handler is embedded
and displayed is dependent on the implementation and may vary by
content type. For instance, an implementation invoking an Embed
Action Handler that references an image resource (e.g. "image/png")
might use the HTML5 img tag to embed the content.
When a Content Security Policy is in effect, the specific directives
that apply will be entirely dependent on the type of content being
embedded and how the implementation chooses to embed it. For
instance, embedded image resources will be governed by the
"image_src" directive while embedded video will be governed by the
"media_src" directive. Please refer to the Content Security Policy
[W3C.WD-CSP11-20140211] specification for a detailed explanation of
each of the directives that may apply.
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6. Intent Action Handler
An Intent Action Handler provides a generic way for the publisher of
an Activity object to tell the consuming application to figure out
how to handle the action on it's own. The consumer can, for
instance, pass the object off to some other native platform
application. It is identified using an objectType value of
"IntentActionHandler".
For example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"share": {
"objectType": "IntentActionHandler",
"displayName": "Share This",
"context": {
"foo": "ABC",
"bar": 123
}
}
}
}
Whether and how the Intent Action Handler is invoked is dependent
entirely on the implementation. Regardless of how the handler is
invoked, the implementation MUST, at a minimum, pass the value of the
"context" property along.
7. Using "service" and "application" objects as action handlers
The "service" and "application" object are existing objectTypes
defined by the Activity Streams 1.0 core schema. While these objects
were not originally designed to be used as action handlers, they can
be. Specifically, the "service" objectType can be used when the
action is to be carried out using some specific third party service
interface; the "application" objectType can be used when the action
is to be carried out by deferring some some specific native platform
application. When such objectTypes are used as actions handlers,
they are to be treated as specializations of Intent Action Handler.
For example:
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{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"share": {
"objectType": "service",
"displayName": "My Sharing Service",
"url": "http://share.example.org/api"
},
"save": {
"objectType": "application",
"displayName": "Read this later!",
"platform": "android",
"id": "123",
"url": "http://play.google.com/..."
}
}
}
8. HTML Form Objects
+------------+----------------+-------------------------------------+
| Property | Value | Description |
+------------+----------------+-------------------------------------+
| mediaType | MIME Media | Defaults to "application/x-www- |
| | Type | form-urlencoded" |
| parameters | Parameters | Defines the HTML form parameters. |
| | Object | |
| | (Section 11) | |
+------------+----------------+-------------------------------------+
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For example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"review": {
"objectType": "ViewActionHandler",
"method": "POST",
"target": "_new",
"url": "http://example.org/foo",
"expects": {
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"foo": {
"displayName": "Foo",
"type": "string",
"placeholder": "Foo"
},
"bar": {
"type": "string",
"value": "Provided Value"
}
}
}
}
}
}
Is roughly equivalent to the following HTML form:
<form method="post" action="http://example.org/foo" target="_new">
<label for="foo">Foo:</label>
<input id="foo" name="foo" type="input" placeholder="Foo" />
<input name="bar" type="hidden" value="Provided Value" />
<input type="submit" />
</form>
9. Typed Payload Objects
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+-----------+-----------------------------+-------------------------+
| Property | Value | Description |
+-----------+-----------------------------+-------------------------+
| mediaType | MIME Media Type | The MIME Media Type of |
| | | the Payload |
| type | Type Value | An optional Type Value |
| | [I-D.snell-activitystreams] | that describes the |
| | | payloads semantic type. |
| schema | Link Value | An optional Link Value |
| | [I-D.snell-activitystreams] | whose value(s) describe |
| | | the structure of the |
| | | payload data. The value |
| | | is represented either |
| | | as a String with a |
| | | fully qualified IRI, an |
| | | Activity Stream object, |
| | | or an Array of IRIs and |
| | | Objects. If multiple |
| | | values are provided, |
| | | they are to be |
| | | considered mutually |
| | | exclusive alternatives. |
+-----------+-----------------------------+-------------------------+
For example:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"review": {
"objectType": "HttpActionHandler",
"method": "POST",
"url": "http://example.org/foo",
"expects": {
"objectType": "TypedPayload",
"mediaType": "text/json",
}
}
}
}
10. URL Template Objects
Objects with the "UrlTemplate" object type represent [RFC6570] URL
Templates.
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+------------+-------------------------+----------------------------+
| Property | Value | Description |
+------------+-------------------------+----------------------------+
| template | URL Template | The [RFC6570] URL Template |
| parameters | Parameters Object | Defines the URL Template |
| | (Section 11) | parameters |
+------------+-------------------------+----------------------------+
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"review": {
"objectType": "UrlTemplate",
"template": "http://example.org/notes/{noteid}",
"parameters": {
"noteid": {
"type": "nonNegativeInteger",
"totalDigits": 5
}
}
}
}
}
If the given URL template includes any parameter tokens that do not
appear within the "parameters" property, the parameter value type is
assumed to be a UTF-8 encoded xsd:string with no maximum length.
11. Parameters Object
A Parameters Object is used to provide descriptions of the variable
inputs of objects such as HTML Forms (Section 8) and URL Templates
(Section 10). The object is expressed as a JSON dictionary mapping
parameter names to parameter descriptions which take the form of
either an XML Schema type name [W3C.REC-xmlschema-2-20041028], an
absolute IRI, a parameter object (Section 11.1), or in some limited
cases, TypedPayload or UrlTemplate objects.
By default, all parameters are assumed to be required. When a
parameter is described using an object, the object MAY contain a
boolean "required" member. If "required" is false, use of the
parameter is assumed to be optional.
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Using the Parameters Object in UrlTemplate objects:
{
"objectType": "UrlTemplate",
"template": "http://example.org{/foo,bar}"
"parameters": {
"foo": "string",
"bar": {
"type": "string",
"required": false
}
}
}
In this example, both the "foo" and "bar" parameters conform to the
XML Schema type "xsd:string". The "foo" parameter is required while
the "bar" parameter is optional.
Using the Parameters Object in HtmlForm objects:
{
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"foo": {
"displayName": "Foo",
"type": "string"
},
"bar": {
"displayName": "Bar",
"type": "string",
"required": false
}
}
}
11.1. The Parameter Object
Parameter objects provide a rich description of a single parameter in
a manner that is aligned with the commonly used XML Schema type
system [W3C.REC-xmlschema-2-20041028].
+-------------+--------------------------+--------------------------+
| Property | Value | Description |
+-------------+--------------------------+--------------------------+
| displayName | Natural Language Value [ | An Activity Streams 2.0 |
| | I-D.snell-activitystream | Natural Language Value. |
| | s] | |
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| required | boolean | True if the parameter is |
| | | required. Defaults to |
| | | true. |
| repeated | boolean | True if the parameter |
| | | can be repeated zero or |
| | | more times. Defaults to |
| | | false. |
| value | (Any) | Provides a fixed value |
| | | for the parameter. When |
| | | specified, |
| | | implementations MUST use |
| | | the specified value. |
| default | (Any) | Provides a default value |
| | | for the parameter. When |
| | | specified, |
| | | implementations MUST use |
| | | the specified value if |
| | | no other value is not |
| | | supplied. |
| type | XSD [W3C.REC-xmlschema-2 | Identifies the value |
| | -20041028] type name or | type using either an XML |
| | IRI | Schema [W3C.REC-xmlschem |
| | | a-2-20041028] simple |
| | | type name or an absolute |
| | | IRI. If an |
| | | implementation |
| | | encounters a type it |
| | | does not recognize, the |
| | | property MAY be ignored. |
| | | When not specified, the |
| | | value type is assumed to |
| | | be a UTF-8 encoded |
| | | "xsd:string". |
| enumeration | Array of (Any) | Provides a fixed array |
| | | of possible values for |
| | | the parameter. When |
| | | specified, |
| | | implementations MUST use |
| | | one of the specified |
| | | values. |
| minLength | Non-Negative Integer | Specifies the minimum |
| | | "unit of length" for the |
| | | value. The "unit of |
| | | length" depends entirely |
| | | on the value type as |
| | | specified by the "type" |
| | | property. For instance, |
| | | For xsd:string, the |
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| | | length is determined by |
| | | the number of |
| | | characters; for |
| | | xsd:hexBinary, the |
| | | length is determined by |
| | | the number of encoded |
| | | 8-bit octets. |
| maxLength | Non-Negative Integer | Specifies the maximum |
| | | "unit of length" for the |
| | | value. The "unit of |
| | | length" depends entirely |
| | | on the value type as |
| | | specified by the "type" |
| | | property. For instance, |
| | | For xsd:string, the |
| | | length is determined by |
| | | the number of |
| | | characters; for |
| | | xsd:hexBinary, the |
| | | length is determined by |
| | | the number of encoded |
| | | 8-bit octets. |
| maxInclusiv | (Any) | A value that is |
| e | | considered to be the |
| | | inclusive upper bound of |
| | | a range of possible |
| | | values. This would |
| | | typically be used only |
| | | with numeric parameters. |
| maxExclusiv | (Any) | A value that is |
| e | | considered to be the |
| | | exclusive upper bound of |
| | | a range of possible |
| | | values. This would |
| | | typically be used only |
| | | with numeric parameters. |
| minInclusiv | (Any) | A value that is |
| e | | considered to be the |
| | | inclusive lower bound of |
| | | a range of possible |
| | | values. This would |
| | | typically be used only |
| | | with numeric parameters. |
| minExclusiv | (Any) | A value that is |
| e | | considered to be the |
| | | exclusive lower bound of |
| | | a range of possible |
| | | values. This would |
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| | | typically be used only |
| | | with numeric parameters. |
| step | Non-negative Number | Specifies the legal |
| | | numeric interval between |
| | | acceptable values for |
| | | the parameter. The step |
| | | value MUST be a number |
| | | and MUST conform to the |
| | | specified type. For |
| | | instance, if type is |
| | | "unsignedInt", then |
| | | step=2 would indicate |
| | | legal values of 0, 2, 4, |
| | | 6, and so on. The step |
| | | property MAY be ignored |
| | | if it's value does not |
| | | correspond to the |
| | | expected type. |
| totalDigits | Non-negative integer | Specifies the maximum |
| | | number of digits |
| | | (integer and fractional) |
| | | that can be included in |
| | | numeric values. The |
| | | totalDigits property |
| | | MUST be ignored if the |
| | | value type identified by |
| | | the type property is not |
| | | a numeric type. |
| fractionDig | Non-negative integer | Specifies the maximum |
| its | | number of fractional |
| | | digits that can be |
| | | included in numeric |
| | | values. The |
| | | fractionDigits property |
| | | MUST be ignored if the |
| | | value type identified by |
| | | the type property is not |
| | | a numeric type. |
| pattern | String or Array of | One or more Regular |
| | Strings | Expressions that |
| | | describe the acceptable |
| | | structure of the value. |
| | | Typically used when the |
| | | value is a string. |
| | | Multiple patterns are |
| | | mutually exclusive |
| | | options. That is, the |
| | | parameter value is |
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| | | expected to conform to |
| | | at least one of the |
| | | given patterns. |
| placeholder | Natural Language Value [ | An optional Natural |
| | I-D.snell-activitystream | Language Value providing |
| | s] | a text hint that |
| | | describes the expected |
| | | value of the parameter. |
+-------------+--------------------------+--------------------------+
Using the Parameter Object in HtmlForm objects:
{
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"foo": "string",
"bar": {
"displayName": "Bar",
"required": false,
"repeated": false,
"type": "unsignedInt",
"default": 3,
"minInclusive": 1,
"maxInclusive": 5
}
}
}
11.2. Using UrlTemplate and TypedPayload objects as parameter
descriptions
In certain cases, when the value of a parameter is expected to be
either a URI or IRI, the UrlTemplate objectType (Section 10) MAY be
used as the parameter description. In such cases, the "required",
"repeated", "default" and "placeholder" properties from the Parameter
objectType (Section 11.1) can be used as additional properties within
the UrlTemplate object.
For example:
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{
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"foo": "http://example.org/FooProperty",
"bar": {
"objectType": "UrlTemplate",
"template": "http://example.org{/baz}",
"displayName": "Bar",
"required": false,
"repeated": false
}
}
}
Likewise, when the value of a parameter is expected to be an instance
of a specific MIME media type, the TypedPayload objectType
(Section 9) can be used.
{
"objectType": "HtmlForm",
"mediaType": "multipart/form-data",
"parameters": {
"file": {
"objectType": "TypedPayload",
"mediaType": "image/*",
"repeated": true
}
}
}
12. Authentication Object
An Authentication Object is used by Action Handlers that require
specific authentication options to be supported in order to carry out
the Action. The object is expresed as a JSON dictionary mapping
authentication schema labels to JSON dictionaries that provide a
specific description of properties and requirements specific to the
scheme.
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Example Authentication details:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note",
"actions": {
"view": {
"objectType": "ViewActionHandler",
"method": "GET",
"url": "http://example.org/notes/1",
"target": "_new",
"auth": {
"basic": {
"realm": "http://example.org"
},
"oauth": {
"scopes": [
"some.oauth.scope",
"another.oauth.scope"
]
}
}
}
}
}
This specification does not define the authentication schemes or
their associated properties. Unrecognized authentication schemes MAY
be ignored. However, if an implementation fails to recognize any of
the authentication schemes specified by an Action Handler, it might
not be possible to successfully carry out the Action.
13. Styles Object
A Styles Object is used by EmbedActionHandlers to provide CSS style
hints for the container within which embedded content is to be
displayed. The object is expressed as either a single JSON
dictionary object mapping CSS property names to appropriate CSS
values, or an array of JSON dictionary objects. An optional "media"
member can be included within the dictionary providing a CSS Media
Query.
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Example style hints:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "EmbedActionHandler",
"content": "Some plain text content",
"mediaType": "text/plain",
"style": {
"height": "100px",
"width": "100px",
"box-shadow": "10px 10px 5px #888888"
}
}
}
}
Multiple style hints for specific media query targets:
{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"view": {
"objectType": "EmbedActionHandler",
"content": "Some plain text content",
"mediaType": "text/plain",
"style": [
{
"media": "print",
"height": "100px",
"width": "100px",
"box-shadow": "10px 10px 5px #888888"
},
{
"media": "screen and (orientation: landscape)",
"height": "100px",
"width": "100px",
"box-shadow": "10px 10px 5px #888888"
}
]
}
}
}
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14. Security Considerations
TBD
15. IANA Considerations
TBD
16. Normative References
[I-D.snell-activitystreams]
Snell, J., "JSON Activity Streams 2.0", draft-snell-
activitystreams-07 (work in progress), April 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, December
2011.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570, March 2012.
[W3C.CR-html5-20140429]
Berjon, R., Faulkner, S., Leithead, T., Navara, E.,
O'Connor, E., and S. Pfeiffer, "HTML5", World Wide
Web Consortium CR CR-html5-20140429, April 2014,
<http://www.w3.org/TR/2014/CR-html5-20140429>.
[W3C.REC-json-ld-20140116]
Sporny, M., Kellogg, G., and M. Lanthaler, "JSON-LD 1.0",
World Wide Web Consortium Recommendation REC-json-
ld-20140116, January 2014,
<http://www.w3.org/TR/2014/REC-json-ld-20140116>.
[W3C.REC-xmlschema-2-20041028]
Biron, P. and A. Malhotra, "XML Schema Part 2: Datatypes
Second Edition", World Wide Web Consortium Recommendation
REC-xmlschema-2-20041028, October 2004,
<http://www.w3.org/TR/2004/REC-xmlschema-2-20041028>.
[W3C.WD-CSP11-20140211]
Barth, A., Veditz, D., and M. West, "Content Security
Policy 1.1", World Wide Web Consortium WD WD-
CSP11-20140211, February 2014,
<http://www.w3.org/TR/2014/WD-CSP11-20140211>.
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Appendix A. Using Action Handlers From Other Vocabularies
The Activity Streams 2.0 Actions mechanism is specifically designed
to allow Action Handlers from multiple vocabularies.
A.1. Schema.org Actions Proposal
Based on http://www.w3.org/wiki/images/b/b9/Actionsinschema.org.pdf:
{
"objectType": "video",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"watch": [
{
"objectType": "http://schema.org/WebPageHandler",
"url": "http://movies.example.com/player?id=123"
},
{
"objectType": "http://schema.org/AndroidHandler",
"url": "http://movies.example.com/player?id=123",
"package": "com.movies"
}
]
}
}
A.2. Google's "Actions in the Inbox"
Based on https://developers.google.com/gmail/actions/reference/
review-action:
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{
"objectType": "note",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"review": {
"objectType": "http://schema.org/ReviewAction",
"review": {
"objectType": "http://schema.org/Review",
"itemReviewed": {
"objectType": "http://schema.org/FoodEstablishment",
"name": "Joe's Diner"
},
"reviewRating": {
"objectType": "http://schema.org/Rating",
"bestRating": "5",
"worstRating": "1"
}
},
"handler": {
"objectType": "http://schema.org/HttpActionHandler",
"url": "http://reviews.com/review?id=123",
"requiredProperty": {
"objectType": "http://schema.org/Property",
"name": "review.reviewRating.ratingValue"
},
"method": "http://schema.org/HttpRequestMethod/POST"
}
}
}
}
A.3. Mixing Vocabularies
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{
"objectType": "video",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"watch": [
{
"objectType": "ViewActionHandler",
"url": "http://movies.example.com/player?id=123",
"target": "_new"
},
{
"objectType": "http://schema.org/AndroidHandler",
"url": "http://movies.example.com/player?id=123",
"package": "com.movies"
}
]
}
}
A.4. Example Drawing From Multiple Vocabularies
{
"objectType": "video",
"displayName": "A Movie!",
"displayName": "A simple note object",
"content": "This is a simple note.",
"actions": {
"watch": [
{
"objectType": "EmbedActionHandler",
"displayName": "HD",
"mediaType": "video/mpeg",
"url": "http://cdn.example.org?id=123amp;fmt=HD",
},
{
"objectType": "EmbedActionHandler",
"displayName": "SD",
"mediaType": "video/mpeg",
"url": "http://cdn.example.org?id=123&fmt=SD",
},
{
"objectType": "application",
"displayName": "Watch on Netflix",
"url": "http://netflix.com..."
}
],
"like": {
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"objectType": "EmbedActionHandler",
"mediaType": "text/html",
"url": "http://www.facebook.com/plugins/like.php...",
"style": {
"width": "150px",
"height": "50px"
}
},
"share": [
{
"objectType": "ViewActionHandler",
"displayName": "Twitter",
"url": "https://twitter.com/share?url=...",
"target": "dialog"
},
{
"objectType": "ViewActionHandler",
"displayName": "Facebook",
"url": "https://www.facebook.com/sharer/sharer.php?u=...",
"target": "dialog"
}
],
"save": [
{
"objectType": "service",
"id": "http://getpocket.com",
"displayName": "Pocket",
"context": {
"url": "http://example.org/movie?id=123",
"title": "A Movie!",
"tags": "foo, bar, baz"
}
},
{
"objectType": "service",
"id": "http://instapaper.com",
"displayName": "Instapaper",
"context": {
"url": "http://example.org/movie?id=123",
"title": "A Movie!",
"selection": "An action movie!"
}
}
],
"review": {
"objectType": "HttpActionHandler",
"displayName": "Rate this movie!",
"url": "http://review.example.org/movie?id=123",
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"method": "POST",
"expects": {
"objectType": "HtmlForm",
"mediaType": "application/x-www-form-urlencoded",
"parameters": {
"rating": {
"maxInclusive": 5,
"minInclusive": 0,
"fractionDigits": 2,
"totalDigits": 3
"type": "float",
"displayName": "Rating"
},
"comments": {
"displayName": "Comments",
"type": "string",
"required": false
}
}
}
}
}
}
Authors' Addresses
James M Snell
IBM
Email: jasnell@gmail.com
Matthew Marum
SugarCRM
Email: mgmarum@gmail.com
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