Activity Streams (http://activitystrea.ms) J. Snell Internet-Draft IBM Intended status: Standards Track M. Marum Expires: June 19, 2014 SugarCRM December 16, 2013 JSON Activity Streams 2.0 - Action Handlers draft-snell-activitystreams-actions-02 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 June 19, 2014. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. Snell & Marum Expires June 19, 2014 [Page 1] Internet-Draft ActivityStreams December 2013 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Action Handlers . . . . . . . . . . . . . . . . . . . . . . . 2 3. HTTP Action Handler . . . . . . . . . . . . . . . . . . . . . 5 4. Embed Action Handler . . . . . . . . . . . . . . . . . . . . 10 5. Intent Action Handler . . . . . . . . . . . . . . . . . . . . 13 6. Using "service" and "application" objects as action handlers 13 7. HTML Form Objects . . . . . . . . . . . . . . . . . . . . . . 14 8. URL Template Objects . . . . . . . . . . . . . . . . . . . . 15 9. Parameters Object . . . . . . . . . . . . . . . . . . . . . . 16 10. Styles Object . . . . . . . . . . . . . . . . . . . . . . . . 17 11. Security Considerations . . . . . . . . . . . . . . . . . . . 18 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 13. Normative References . . . . . . . . . . . . . . . . . . . . 18 Appendix A. Using Action Handlers From Other Vocabularies . . . 18 A.1. Schema.org Actions Proposal . . . . . . . . . . . . . . . 19 A.2. Google's "Actions in the Inbox" . . . . . . . . . . . . . 19 A.3. Mixing Vocabularies . . . . . . . . . . . . . . . . . . . 20 A.4. Example Drawing From Multiple Vocabularies . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 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 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 Snell & Marum Expires June 19, 2014 [Page 2] Internet-Draft ActivityStreams December 2013 out the verb the action handler has been associated with. For instance, given the following example: { "objectType": "note", ..., "actions": { "share": { "objectType": "HttpActionHandler", "url": "http://example.org/share" }, "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 "HttpActionHandler", 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: +---------+--------------------------+---------+--------------------+ | Propert | Value | Require | Description | | y | | d | | +---------+--------------------------+---------+--------------------+ | confirm | Boolean | No | 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 | No | Contextual | | | | | information | | | | | associated with | | | | | the action | | | | | handler, | | | | | represented as a | Snell & Marum Expires June 19, 2014 [Page 3] Internet-Draft ActivityStreams December 2013 | | | | 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 | Type Value [I-D.snell-ac | No | For action | | | tivitystreams] | | handlers with a | | | | | distinct input | | | | | requirement (e.g. | | | | | HttpActionHandler) | | | | | , the expects | | | | | property provides | | | | | a description of | | | | | the expected | | | | | input. | | returns | Type Value [I-D.snell-ac | No | For action | | | tivitystreams] | | handlers with a | | | | | distinct output, | | | | | the returns | | | | | property provides | | | | | a description of | | | | | the expected | | | | | output. | +---------+--------------------------+---------+--------------------+ This specification defines three specific base types of action handler: o The HTTP Action Handler (Section 3), o The Embed Action Handler (Section 4), and o The Intent Action Handler (Section 5). Snell & Marum Expires June 19, 2014 [Page 4] Internet-Draft ActivityStreams December 2013 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 5). 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": "note", ..., "actions": { "share": [ { "objectType": "HttpActionHandler", "method": "GET", "url": "http://example.org/share-action" }, { "objectType": "EmbedActionHandler", "mediaType": "text/plain", "content": "Hello World!" } ] } } 3. HTTP Action Handler An HTTP Action Handler describes an HTTP request/response flow that is used to carry out an action. It is identified using an objectType value of "HttpActionHandler". Snell & Marum Expires June 19, 2014 [Page 5] Internet-Draft ActivityStreams December 2013 +----------+----------------------------+----------+----------------+ | Property | Value | Required | Description | +----------+----------------------------+----------+----------------+ | url | Link Value | Yes | Specifies the | | | | | HTTP or HTTPS | | | | | URL to which | | | | | the HTTP | | | | | request is | | | | | directed. | | method | HTTP Method String (e.g. | No | The HTTP | | | "GET", "POST", "PUT", etc) | | method to use. | | | | | Defaults to | | | | | "GET" | | target | "DEFAULT" - Consumer | No | Specifies the | | | defined default; "NONE" - | | intended | | | No navigation or UI | | target of the | | | context (e.g. a hidden | | HTTP action. | | | HTTP action that does not | | This | | | result in the creation or | | determines | | | use of a browser window); | | whether the | | | "NEW" - A new navigation | | action results | | | or UI context (e.g. show | | in a new | | | the results of the HTTP | | navigation | | | request in a browser | | context (e.g. | | | window or tab.); "CURRENT" | | new browser | | | - Reuse the existing | | window) or | | | navigation or UI context | | whether the | | | (e.g. show the results of | | action is | | | the HTTP request in an | | "hidden". When | | | existing browser window or | | not specified, | | | tab.); {Other token value} | | defaults to | | | - Any other TOKEN value. | | "DEFAULT", | | | Interpretation and support | | meaning that | | | of such extension tokens | | the consuming | | | is dependent on the | | application is | | | consuming application. | | free to | | | Unknown or unsupported | | determine an | | | values MUST be ignored. | | appropriate | | | | | target | | | | | context. | +----------+----------------------------+----------+----------------+ For example: Snell & Marum Expires June 19, 2014 [Page 6] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "view": { "objectType": "HttpActionHandler", "url": "http://example.org/foo", "method": "GET" } } } As a shortcut, HttpActionHandlers that use the "GET" method and a "DEFAULT" target can be specified using a JSON string containing the absolute URL. For instance: { "objectType": "note", ..., "actions": { "view": "http://example.org/foo" } } 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 8) 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: Snell & Marum Expires June 19, 2014 [Page 7] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "review": { "objectType": "HttpActionHandler", "url": { "objectType": "UrlTemplate", "method": "POST", "template": "http://example.org/note/123{?rating}", "parameters": { "rating": { "id": "http://schema.org/ratingValue", "displayName": "Rating", "bestRating": 5, "worstRating": 1 } } }, "method": "GET", "target": "NEW" } } } If the intended HTTP request uses the GET method and DEFAULT target, the UrlTemplate object itself can be used directly as the action handler. Snell & Marum Expires June 19, 2014 [Page 8] Internet-Draft ActivityStreams December 2013 "GET" HttpActionHandler shortcut using a URL Template: { "objectType": "note", ..., "actions": { "review": { "objectType": "UrlTemplate", "template": "http://example.org/note/123{?rating}", "parameters": { "rating": { "id": "http://schema.org/ratingValue", "displayName": "Rating", "bestRating": 5, "worstRating": 1 } } } } } 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 "Type Value" represented either as a simple JSON string containing a fully qualified IRI or as an Activity Stream object. This specification defines a new HtmlForm (Section 7) objectType to be used whenever the input of the HTTP request is an HTML Form POST. For example, the following describes an HTML Form post with a single "foo" parameter submitted using the "application/x-www-form- urlencoded" format: Snell & Marum Expires June 19, 2014 [Page 9] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "share": { "objectType": "HttpActionHandler", "method": "POST", "url": "http://example.org/foo", "expects": { "objectType": "HtmlForm", "mediaType": "application/x-www-form-urlencoded", "parameters": { "foo": { "id": "http://example.org/foo", "type": "http://www.w3.org/2001/XMLSchema#string", "displayName": "Foo Property" } } } } } } 4. 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". Snell & Marum Expires June 19, 2014 [Page 10] Internet-Draft ActivityStreams December 2013 +-----------+------------+--------------+---------------------------+ | Property | Value | Required | Description | +-----------+------------+--------------+---------------------------+ | url | Link Value | Yes if | The URL from which to | | | | "content" is | retrieve the content for | | | | not | this embed. | | | | specified. | | | content | String | Yes if "url" | The character based | | | | is not | "static" content to be | | | | specified. | embeded. The "mediaType" | | | | | parameter specifies the | | | | | MIME media type of the | | | | | content. | | mediaType | MIME Media | No (but | The MIME Media Type of | | | Type | strongly | the embedded content. | | | | recommended) | | | style | Styles | No | Visual CSS styling hints | | | Object | | to apply to the element | | | (Section | | containing the embedded | | | 10) | | content. | | preview | Link Value | No | A reference to a | | | | | "preview" representation | | | | | of the embedded content. | | | | | Typically, this would a | | | | | URL to a thumbnail or | | | | | screenshot image of the | | | | | content. | | target | "DEFAULT"; | No | | | | "INLINE"; | | | | | {Other | | | | | token | | | | | value} | | | +-----------+------------+--------------+---------------------------+ In the following example, the "view" action is associated with an "EmbedActionHandler" containing a static fragment of HTML markup: Snell & Marum Expires June 19, 2014 [Page 11] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "view": { "objectType": "EmbedActionHandler", "content": "
This is some bit of embedded HTML
", "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" } } } Alternatively, the embedded content can be referenced by URL: { "objectType": "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: Snell & Marum Expires June 19, 2014 [Page 12] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "view": { "objectType": "EmbedActionHandler", "url": "http://example.org/foo.mpg", "mediaType": "video/mpeg" } } } 5. 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", ..., "actions": { "share": { "objectType": "IntentActionHandler", "displayName": "Share This", "context": { "foo": "ABC", "bar": 123 } } } } 6. 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. Snell & Marum Expires June 19, 2014 [Page 13] Internet-Draft ActivityStreams December 2013 For example: { "objectType": "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/..." } } } 7. HTML Form Objects +----------+-----------+----------+---------------------------------+ | Property | Value | Required | Description | +----------+-----------+----------+---------------------------------+ | mediaTyp | MIME | No | Defaults to "application/x-www- | | e | Media | | form-urlencoded" | | | Type | | | | paramete | Parameter | No | Defines the HTML form | | rs | s Object | | parameters. | | | (Section | | | | | 9) | | | +----------+-----------+----------+---------------------------------+ For example: Snell & Marum Expires June 19, 2014 [Page 14] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "review": { "objectType": "HttpActionHandler", "method": "POST", "url": "http://example.org/foo", "expects": { "objectType": "HtmlForm", "mediaType": "application/x-www-form-urlencoded", "parameters": { "foo": { "displayName": "Foo", "id": "http://example.org/FooProperty", "type": "http://www.w3.org/2001/XMLSchema#string", "required": True }, "bar": { "displayName": "Bar", "id": "http://example.org/BarProperty", "type": "http://www.w3.org/2001/XMLSchema#", "required": True, "value": "Provided Value" } } } } } } 8. URL Template Objects Objects with the "UrlTemplate" object type represent [RFC6570] URL Templates. +------------+-------------------+----------+-----------------------+ | Property | Value | Required | Description | +------------+-------------------+----------+-----------------------+ | template | URL Template | Yes | The [RFC6570] URL | | | | | Template | | parameters | Parameters Object | No | Defines the URL | | | (Section 9) | | Template parameters | +------------+-------------------+----------+-----------------------+ Snell & Marum Expires June 19, 2014 [Page 15] Internet-Draft ActivityStreams December 2013 { "objectType": "note", ..., "actions": { "review": { "objectType": "UrlTemplate", "template": "http://example.org/foo/123{?rating}", "parameters": { "rating": { "displayName": "Rating", "id": "http://example.org/RatingProperty", "required": True } } } } } 9. Parameters Object A Parameters Object is used to provide descriptions of the variable inputs of objects such as HTML Forms (Section 7) and URL Templates (Section 8). The object is expressed as a JSON dictionary mapping parameter names to Type Values [I-D.snell-activitystreams] describing the parameters. By default, all parameters defined within the object are assumed to be required. When a parameter is described using an Object, the object MAY contained a boolean "required" member. If "required" is false, use of the parameter is assumed to be optional. Using the Parameters Object in UrlTemplate objects: { "objectType": "UrlTemplate", "template": "http://example.org{/foo,bar}" "parameters": { "foo": "http://example.org/FooProperty", "bar": { "id": "http://example.org/BarProperty", "displayName": "Bar", "required": False } } } Using the Parameters Object in HtmlForm objects: Snell & Marum Expires June 19, 2014 [Page 16] Internet-Draft ActivityStreams December 2013 { "objectType": "HtmlForm", "mediaType": "application/x-www-form-urlencoded", "parameters": { "foo": "http://example.org/FooProperty", "bar": { "id": "http://example.org/BarProperty", "displayName": "Bar", "required": False } } } 10. 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. Example style hints: { "objectType": "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: Snell & Marum Expires June 19, 2014 [Page 17] Internet-Draft ActivityStreams December 2013 { "objectType": "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" } ] } } } 11. Security Considerations TBD 12. IANA Considerations TBD 13. Normative References [I-D.snell-activitystreams] Snell, J., "JSON Activity Streams 2.0", draft-snell- activitystreams-05 (work in progress), November 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M., and D. Orchard, "URI Template", RFC 6570, March 2012. Appendix A. Using Action Handlers From Other Vocabularies Snell & Marum Expires June 19, 2014 [Page 18] Internet-Draft ActivityStreams December 2013 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", ..., "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: Snell & Marum Expires June 19, 2014 [Page 19] Internet-Draft ActivityStreams December 2013 { "objectType": "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 Snell & Marum Expires June 19, 2014 [Page 20] Internet-Draft ActivityStreams December 2013 { "objectType": "video", ..., "actions": { "watch": [ { "objectType": "HttpActionHandler", "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!", ..., "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": { "objectType": "EmbedActionHandler", "mediaType": "text/html", Snell & Marum Expires June 19, 2014 [Page 21] Internet-Draft ActivityStreams December 2013 "url": "http://www.facebook.com/plugins/like.php...", "style": { "width": "150px", "height": "50px" } }, "share": [ { "objectType": "HttpActionHandler", "displayName": "Twitter", "url": "https://twitter.com/share?url=...", "target": "DIALOG" }, { "objectType": "HttpActionHandler", "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", "method": "POST", "expects": { Snell & Marum Expires June 19, 2014 [Page 22] Internet-Draft ActivityStreams December 2013 "objectType": "HtmlForm", "mediaType": "application/x-www-form-urlencoded", "parameters": { "rating": { "id": "http://schema.org/ratingValue", "bestRating": 5, "worstRating": 0, "displayName": "Rating", "required": true }, "comments": { "id": "http://schema.org/commentText", "displayName": "Comments", "required": "false" } } } } } } Authors' Addresses James M Snell IBM Email: jasnell@gmail.com Matthew Marum SugarCRM Email: mgmarum@gmail.com Snell & Marum Expires June 19, 2014 [Page 23]