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<pre class='metadata'>
Title: Shared Storage API
Shortname: sharedStorage
Level: 1
Status: CG-DRAFT
Group: WICG
Repository: WICG/shared-storage
URL: https://github.com/WICG/shared-storage
Editor: Camillia Smith Barnes, Google https://google.com, [email protected]
Markup Shorthands: markdown yes
Abstract: Shared Storage is a storage API that is intentionally not partitioned by top-level traversable site (though still partitioned by context origin of course!). To limit cross-site reidentification of users, data in Shared Storage may only be read in a restricted environment that has carefully constructed output gates.
</pre>
<pre class=link-defaults>
spec:infra;
type:dfn;
text:user agent
for:/; text:string
type:dfn;
for:/; text:list
spec:webidl;
type:interface;
text:double
text:long
type:dfn;
text:an exception was thrown
spec:html;
type:dfn;
for:realm; text:global object
for:WorkerGlobalScope; text:module map
for:navigable; text:top-level traversable
spec:fenced-frame;
type:dfn;
for:fencedframetype; text:fenced frame reporter
for:browsing context; text:fenced frame config instance
</pre>
<pre class="anchors">
spec: ecma262; urlPrefix: https://tc39.github.io/ecma262/
type: dfn
text: agent; url: agent
urlPrefix: https://www.ietf.org/rfc/rfc4122.txt
type: dfn; text: urn uuid
spec: html; urlPrefix: https://html.spec.whatwg.org/multipage/
type: dfn
text: worklets; url: worklets.html#worklets
text: added modules list; url: worklets.html#concept-worklet-added-modules-list
text: set up a worklet environment settings object; url: worklets.html#set-up-a-worklet-environment-settings-object
text: fetch a worklet/module worker script graph; url: webappapis.html#fetch-a-worklet/module-worker-script-graph
text: fetch a worklet script graph; url: webappapis.html#fetch-a-worklet-script-graph
text: processCustomFetchResponse; url: webappapis.html#fetching-scripts-processcustomfetchresponse
text: environment; url: webappapis.html#environment
text: worklet event loop; url: webappapis.html#worklet-event-loop
text: obtaining a worklet agent; url: webappapis.html#obtain-a-worklet-agent
text: beginning navigation; url: webappapis.html#beginning-navigation
text: ending navigation; url: webappapis.html#ending-navigation
text: get the top-level traversable; url: webappapis.html#nav-top
text: boolean attributes; url: common-microsyntaxes.html#boolean-attributes
text: content attributes; url: dom.html#concept-element-attributes
text: update the image data; url: images.html#update-the-image-data
text: create navigation params by fetching; url: browsing-the-web.html#create-navigation-params-by-fetching
text: serialization; for: origin; url: browsers.html#ascii-serialisation-of-an-origin
text: initialize the navigable; url: document-sequences.html#initialize-the-navigable
spec: url; urlPrefix: https://url.spec.whatwg.org/
type: dfn
text: URL; for: /; url: concept-url
spec: dom; urlPrefix: https://dom.spec.whatwg.org/
type: dfn
text: origin; for: document; url: concept-document-origin
spec: infra; urlPrefix: https://infra.spec.whatwg.org
type: dfn
text: empty; for: map; url: map-is-empty
text: ASCII; url: ascii-code-point
spec: webidl; urlPrefix: https://webidl.spec.whatwg.org
type: dfn
text: Web IDL Standard; url: introduction
text: async iterator; url: idl-async-iterable
text: promise; url: idl-promise
text: promise rejected; url: a-promise-rejected-with
text: promise resolved; url: a-promise-resolved-with
spec: storage; urlPrefix: https://storage.spec.whatwg.org/
type: dfn
text: storage model; url: model
text: storage type; url: storage-type
text: storage identifier; url: storage-identifier
text: storage shed; url: storage-shed
text: storage shelf; url: storage-shelf
text: storage bucket; url: storage-bucket
text: storage bottle; url: storage-bottle
text: quota; for: storage bottle; url: storage-bottle-quota
text: register; for: storage endpoint; url: registered-storage-endpoints
text: quota; for: storage endpoint; url: storage-endpoint-quota
text: bucket map; url: bucket-map
text: bottle map; url: bottle-map
text: storage proxy map; url: storage-proxy-map
text: backing map; url: storage-proxy-map-backing-map
text: proxy map reference set; url: storage-bottle-proxy-map-reference-set
spec: beacon; urlPrefix: https://w3c.github.io/beacon/
type: dfn
text: beacon; url: beacon
spec: web-locks; urlPrefix: https://w3c.github.io/web-locks/
type: dfn
text: lock manager; url: lock-manager
text: obtain a lock manager; url: obtain-a-lock-manager
text: request a lock; url: request-a-lock
spec: ecma; urlPrefix: https://tc39.es/ecma262/
type: dfn
text: call; url: sec-call
text: current realm; url: current-realm
text: casting; url: sec-touint32
text: Get; url: sec-get-o-p
text: [[GetPrototypeOf]](); for: object; url: sec-ordinary-object-internal-methods-and-internal-slots-getprototypeof
text: IsConstructor(); url: sec-isconstructor
spec: storage-partitioning; urlPrefix: https://privacycg.github.io/storage-partitioning/
type: dfn
text: client-side storage partitioning
spec: fetch; urlPrefix: https://fetch.spec.whatwg.org/
type: dfn
text: http network or cache fetch; url: concept-http-network-or-cache-fetch
text: request-constructor; url: dom-request
spec: permissions-policy; urlPrefix: https://www.w3.org/TR/permissions-policy/
type: dfn
text: Is feature enabled in document for origin?; url: algo-is-feature-enabled
spec: attestation; urlPrefix: https://github.com/privacysandbox/attestation
type: dfn
text: enrolled
spec: private-aggregation-api; urlPrefix: https://patcg-individual-drafts.github.io/private-aggregation-api/
type: dfn
text: Private Aggregation; url:
text: get the privateAggregation
text: determine if an origin is an aggregation coordinator
text: pre-specified report parameters
for: pre-specified report parameters
text: context ID
text: filtering ID max bytes
text: max contributions
text: batching scope
text: debug scope
text: process contributions for a batching scope
text: set the aggregation coordinator for a batching scope
text: determine if a report should be sent deterministically
text: mark a debug scope complete
text: set the pre-specified report parameters for a batching scope
text: aggregation coordinator
text: default filtering id max bytes
text: valid filtering id max bytes range
text: context id
text: scoping details
for: scoping details
text: get batching scope steps
text: get debug scope steps
text: private-aggregation
for: PrivateAggregation
text: allowed to use
text: scoping details; url: #privateaggregation-scoping-details
type: interface
text: PrivateAggregation
spec: protected-audience; urlPrefix: https://wicg.github.io/turtledove/
type: dfn
text: get storage interest groups for owner
type: interface
text: StorageInterestGroup; url: dictdef-storageinterestgroup
spec: fenced-frame; urlPrefix: https://wicg.github.io/fenced-frame/
type: dfn
text: fenced frame; url: the-fencedframe-element
text: url; for: FencedFrameConfig; url: dom-fencedframeconfig-url
text: fence.reportEvent(); url: dom-fence-reportevent
text: FenceEvent; url: dictdef-fenceevent
text: destination; for: FenceEvent; url: dom-fenceevent-destination
text: eventData; for: FenceEvent; url: dom-fenceevent-eventdata
text: eventType; for: FenceEvent; url: dom-fenceevent-eventtype
type: interface
text: FencedFrameConfig; url: fencedframeconfig
spec: rfc8941; urlPrefix: https://httpwg.org/specs/rfc8941.html
type: dfn
text: structured header; url: specify
text: list; for: structured header; url: list
text: parameters; for: structured header; url: param
text: item; for: structured header; url: item
text: string; for: structured header; url: string
text: token; for: structured header; url: token
text: byte sequence; for: structured header; url: binary
text: boolean; for: structured header; url: boolean
text: inner list; for: structured header; url: inner-list
text: bare item; for: structured header; url: item
spec: wikipedia-entropy; urlPrefix: https://en.wikipedia.org/wiki/Entropy_(information_theory)
type: dfn
text: bits of entropy
text: entropy bits
spec: shared-storage-explainer; urlPrefix: https://github.com/WICG/shared-storage
type:dfn
text: legitimate use cases; url: example-scenarios
spec: UUID; urlPrefix: https://www.ietf.org/rfc/rfc4122.txt
type: dfn
text: urn uuid; url: urn-uuid
spec: hr-time; urlPrefix: https://w3c.github.io/hr-time/
type: dfn
text: current wall time; url: dfn-current-wall-time
</pre>
<style>
/* adapted from .XXX at https://resources.whatwg.org/standard.css */
.todo {
color: #D50606;
background: white;
border: solid #D50606;
}
span.todo {
padding-top: 0;
padding-bottom: 0;
}
.todo::before { content: 'TODO: '; }
span.todo::before {
left: 0;
top: -0.25em;
}
</style>
Introduction {#intro}
=====================
<em>This section is not normative.</em>
In order to prevent cross-site user tracking, browsers are partitioning all forms of storage by [=top-level traversable=] site; see [=Client-Side Storage Partitioning=]. But, there are many [=legitimate use cases=] currently relying on unpartitioned storage.
This document introduces a new storage API that is intentionally not partitioned by [=top-level traversable=] site (though still partitioned by context origin), in order to serve a number of the use cases needing unpartitioned storage. To limit cross-site reidentification of users, data in Shared Storage may only be read in a restricted environment, called a worklet, and any output from the worklet is in the form of a [=fenced frame=] or a [=Private Aggregation=] report. Over time, there may be additional output gates included in the standard.
<div class="example">
`a.example` randomly assigns users to groups in a way that is consistent cross-site.
Inside an `a.example` iframe:
<pre class="lang-js">
function generateSeed() { … }
await window.sharedStorage.worklet.addModule('experiment.js');
// Only write a cross-site seed to a.example's storage if there isn't one yet.
window.sharedStorage.set('seed', generateSeed(), { ignoreIfPresent: true });
let fencedFrameConfig = await window.sharedStorage.selectURL(
'select-url-for-experiment',
[
{url: "blob:https://a.example/123…", reportingMetadata: {"click": "https://report.example/1..."}},
{url: "blob:https://b.example/abc…", reportingMetadata: {"click": "https://report.example/a..."}},
{url: "blob:https://c.example/789…"}
],
{ data: { name: 'experimentA' } }
);
// Assumes that the fenced frame 'my-fenced-frame' has already been attached.
document.getElementById('my-fenced-frame').config = fencedFrameConfig;
</pre>
inside the `experiment.js` worklet script:
<pre class="lang-js">
class SelectURLOperation {
hash(experimentName, seed) { … }
async run(urls, data) {
const seed = await this.sharedStorage.get('seed');
return hash(data.name, seed) % urls.length;
}
}
register('select-url-for-experiment', SelectURLOperation);
</pre>
</div>
The {{SharedStorageWorklet}} Interface {#worklet}
=================================================
The {{SharedStorageWorklet}} object allows developers to supply [=module scripts=] to process [=Shared Storage=] data and then output the result through one or more of the output gates. Currently there are two output gates, the [=Private Aggregation=] output gate and the {{SharedStorageWorklet/selectURL()|URL-selection}} output gate.
<xmp class='idl'>
typedef (USVString or FencedFrameConfig) SharedStorageResponse;
</xmp>
<xmp class='idl'>
[Exposed=(Window)]
interface SharedStorageWorklet : Worklet {
Promise<SharedStorageResponse> selectURL(DOMString name,
sequence<SharedStorageUrlWithMetadata> urls,
optional SharedStorageRunOperationMethodOptions options = {});
Promise<any> run(DOMString name,
optional SharedStorageRunOperationMethodOptions options = {});
};
</xmp>
Each {{SharedStorageWorklet}} has an associated boolean <dfn for="SharedStorageWorklet">addModule initiated</dfn>, initialized to false.
Each {{SharedStorageWorklet}} has an associated {{USVString}} <dfn for="SharedStorageWorklet">data origin</dfn>, initialized to `"context-origin"`.
Each {{SharedStorageWorklet}} has an associated boolean <dfn for="SharedStorageWorklet">has cross-origin data origin</dfn>, initialized to false.
Because adding multiple [=module scripts=] via {{Worklet/addModule()}} for the same {{SharedStorageWorklet}} would give the caller the ability to store data from [=Shared Storage=] in global variables defined in the [=module scripts=] and then exfiltrate the data through later call(s) to {{Worklet/addModule()}}, each {{SharedStorageWorklet}} can only call {{Worklet/addModule()}} once. The [=addModule initiated=] boolean makes it possible to enforce this restriction.
When {{Worklet/addModule()}} is called for a worklet, it will run [=check if addModule is allowed and update state=], and if the result is "DisallowedDueToNonPreferenceError", or if the result is "DisallowedDueToPreferenceError" and the worklet's [=SharedStorageWorklet/has cross-origin data origin=] is false, it will cause {{Worklet/addModule()}} to fail, as detailed in the [[#add-module-monkey-patch]].
<div algorithm>
To <dfn>check if user preference setting allows access to shared storage</dfn> given an [=environment settings object=] |environment| and an [=/origin=] |origin|, run the following step:
1. Using values available in |environment| and |origin| as needed, perform an [=implementation-defined=] algorithm to return either true or false.
</div>
<div algorithm>
To <dfn>determine whether shared storage is allowed by context</dfn>, given an [=environment settings object=] |environment|, an [=/origin=] |origin|, and a boolean |allowedInOpaqueOriginContext|, run these steps:
1. If |environment| is not a [=secure context=], then return false.
1. If |allowedInOpaqueOriginContext| is false and |environment|'s [=environment settings object/origin=] is an [=opaque origin=], then return false.
1. If |origin| is an [=opaque origin=], then return false.
1. Let |globalObject| be the [=current realm=]'s [=global object=].
1. [=Assert=]: |globalObject| is a {{Window}} or a {{SharedStorageWorkletGlobalScope}}.
1. If |globalObject| is a {{Window}}, and if the result of running [=Is feature enabled in document for origin?=] on "[=PermissionsPolicy/shared-storage=]", |globalObject|'s [=associated document=], and |origin| returns false, then return false.
1. If the result of running [=obtaining a site|obtain a site=] with |origin| is not [=enrolled=], then return false.
1. Return true.
</div>
<div class="note">
Here are the scenarios where the algorithms [=determine whether shared storage is allowed by context=] and [=check if user preference setting allows access to shared storage=] are used:
- For creating a worklet, |environment| is the [=environment settings object=] associated with the {{Window}} that created the worklet, and |origin| is the module script url's [=url/origin=].
- For running operations on a worklet (from a {{Window}}), |environment| is the [=environment settings object=] associated with the {{Window}} that created the worklet, and |origin| is the worklet's [=global scopes=][0]'s [=global object/realm=]'s [=realm/settings object=]'s [=environment settings object/origin=].
- For [[#setter]], |environment| is either the current context (when called from a {{Window}}) or the [=environment settings object=] associated with the {{Window}} that created the worklet (when called from a {{SharedStorageWorkletGlobalScope}}), and |origin| is |environment|'s [=environment settings object/origin=].
- For [[#ss-fetch-algo]], |environment| is the request's [=request/window=], and |origin| is the request's [=request/current URL=]'s [=url/origin=].
- For [[#ss-fetch-algo]], for {{SharedStorage/createWorklet()}} called with a cross-origin worklet script using the <var ignore=''>dataOrigin</var> option with value `"script-origin"` (which would result in a worklet where [=SharedStorageWorklet/has cross-origin data origin=] is true), and for {{SharedStorageWorklet/selectURL()}} and {{SharedStorageWorklet/run()}} that operate on a worklet where [=SharedStorageWorklet/has cross-origin data origin=] is true, |allowedInOpaqueOriginContext| is true. For other methods, |allowedInOpaqueOriginContext| is false.
</div>
<div algorithm>
To <dfn>check if addModule is allowed and update state</dfn> given a {{SharedStorageWorklet}} |worklet| and a [=/URL=] |moduleURLRecord|, run the following steps:
1. If |worklet|'s [=addModule initiated=] is true, return "DisallowedDueToNonPreferenceError".
1. Set |worklet|'s [=addModule initiated=] to true.
1. Let |workletDataOrigin| be the [=current settings object=]'s [=environment settings object/origin=].
1. If |worklet|'s [=SharedStorageWorklet/data origin=] is `"script-origin"`, set |workletDataOrigin| to |moduleURLRecord|'s [=url/origin=].
1. Otherwise, if |worklet|'s [=SharedStorageWorklet/data origin=] is not `"context-origin"`:
1. Let |customOriginUrl| be the result of running a [=URL parser=] on |worklet|'s [=SharedStorageWorklet/data origin=].
1. If |customOriginUrl| is not a valid [=/URL=], return "DisallowedDueToNonPreferenceError".
1. Set |workletDataOrigin| to |customOriginUrl|'s [=url/origin=].
1. Let |hasCrossOriginDataOrigin| be false.
1. If |workletDataOrigin| and the [=current settings object=]'s [=environment settings object/origin=] are not [=same origin=], then set |hasCrossOriginDataOrigin| to true.
1. Let |allowedInOpaqueOriginContext| be |hasCrossOriginDataOrigin|.
1. If the result of running [=determine whether shared storage is allowed by context=] given the [=current settings object=], |workletDataOrigin|, and |allowedInOpaqueOriginContext| is false, return "DisallowedDueToNonPreferenceError".
1. Set |worklet|'s [=SharedStorageWorklet/has cross-origin data origin=] to |hasCrossOriginDataOrigin|.
1. If the result of running [=check if user preference setting allows access to shared storage=] given the [=current settings object=] and |workletDataOrigin| is false, return "DisallowedDueToPreferenceError".
1. Return "Allowed".
</div>
Moreover, each {{SharedStorageWorklet}}'s [=global scopes|list of global scopes=], initially empty, can contain at most one instance of its [=worklet global scope type=], the {{SharedStorageWorkletGlobalScope}}.
## Run Operation Methods on {{SharedStorageWorklet}} ## {#run-op-shared-storage-worklet}
<div algorithm>
To <dfn>get the select-url result index</dfn>, given {{SharedStorageWorklet}} |worklet|, {{DOMString}} |operationName|, [=/list=] of [=strings=] |urlList|, an [=/origin=] |workletDataOrigin|, a [=/navigable=] |navigable|, {{SharedStorageRunOperationMethodOptions}} |options|, a [=pre-specified report parameters=] or null |preSpecifiedParams| and an [=aggregation coordinator=] or null |aggregationCoordinator|, run the following steps. This algorithm will return a [=tuple=] consisting of a [=promise=] that resolves into an {{unsigned long}} whose value is the index of the URL selected from |urlList| and a [=/boolean=] indicating whether the [top-level traversable's budgets](#charge-top-trav-budgets) should be [=charge shared storage top-level traversable budgets|charged=].
1. Let |promise| be a new [=promise=].
1. Let |window| be |worklet|'s [=relevant settings object=].
1. [=Assert=]: |window| is a {{Window}}.
1. If |window|'s [=Window/browsing context=] is null, then return the [=tuple=] of a ([=promise rejected=] with a {{TypeError}}, true).
1. If |window|'s [=associated document=] is not [=fully active=], return the [=tuple=] of a ([=promise rejected=] with a {{TypeError}}, true).
1. [=Assert=]: |worklet|'s [=global scopes=]'s [=list/size=] is 1.
1. Let |globalScope| be |worklet|'s [=global scopes=][0].
1. Let |moduleMapKeyTuples| be the result of running [=map/get the keys=] on |globalScope|'s [=relevant settings object=]'s [=module map=].
1. [=Assert=]: |moduleMapKeyTuples| has [=map/size=] 1.
1. Let |moduleURLRecord| be |moduleMapKeyTuples|[0][0].
1. Let |savedQueryName| be |options|["`savedQuery`"].
1. If |savedQueryName| is a [=string=] that is not the empty string, then:
1. Let |callbackTask| be the result of running [=obtain a callback to process the saved index result=], given |window|, |urlList|, and |promise|.
1. Let |savedIndex| be the result of running [=get the index for a saved query=] on |navigable|, |workletDataOrigin|, |moduleURLRecord|, |operationName|, |savedQueryName|, and |callbackTask|.
1. If |savedIndex| is "pending callback", then return the [=tuple=] (|promise|, false).
Note: |callbackTask| is now stored to be run when a previously obtained worklet agent completes its operation to select the index for this query. When the steps of |callbackTask| are run, |promise| will be resolved.
1. If |savedIndex| is an {{unsigned long}}, then:
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |window|, to run the steps of |callbackTask|, given |savedIndex|.
Note: Running the steps of |callbackTask| will resolve |promise|.
1. Return the [=tuple=] (|promise|, false).
1. [=Assert=] that |savedIndex| is "pending current operation".
1. [=Queue a task=] on |globalScope|'s [=worklet event loop=] to perform the following steps:
1. Let |operationMap| be |globalScope|'s [=SharedStorageWorkletGlobalScope/operation map=].
1. If |operationMap| does not [=map/contain=] |operationName|, then [=queue a global task=] on the [=DOM manipulation task source=], given |window|, to [=reject=] |promise| with a {{TypeError}}, and abort these steps.
Note: This could happen if {{SharedStorageWorkletGlobalScope/register()}} was never called with |operationName|.
1. [=Assert=]: |operationMap|[|operationName|]'s [=associated realm=] is [=this=]'s [=relevant realm=].
1. Let |operation| be |operationMap|[|operationName|], [=converted to an IDL value|converted=] to {{RunFunctionForSharedStorageSelectURLOperation}}.
1. Let |privateAggregationCompletionTask| be the result of [=setting up the Private Aggregation scopes=] given |workletDataOrigin|, |preSpecifiedParams| and |aggregationCoordinator|.
1. Let |argumentsList| be the [=/list=] « |urlList| ».
1. If |options|["{{SharedStorageRunOperationMethodOptions/data}}"] [=map/exists=], [=list/append=] it to |argumentsList|.
1. Let |indexPromise| be the result of [=invoking=] |operation| with |argumentsList|.
1. [=promise/React=] to |indexPromise|:
<dl class="switch">
: If it was fulfilled with value |index|:
:: 1. If |index| is greater than |urlList|'s [=list/size=], then:
1. If |savedQueryName| is a [=string=] that is not the empty string, then run [=store the index for a saved query=] with |window|, |navigable|, |workletDataOrigin|, |moduleURLRecord|, |operationName|, |savedQueryName|, and the [=default selectURL index=].
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |window|, to [=reject=] |promise| with a {{TypeError}}, and abort these steps.
Note: The result index is beyond the input urls' size. This violates the selectURL() protocol, and we don't know which url should be selected.
Otherwise:
1. If |savedQueryName| is a [=string=] that is not the empty string, then run [=store the index for a saved query=] with |window|, |navigable|, |workletDataOrigin|, |moduleURLRecord|, |operationName|, |savedQueryName|, and |index|.
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |window|, to [=resolve=] |promise| with |index|.
1. Run |privateAggregationCompletionTask|.
: If it was rejected:
:: 1. If |savedQueryName| is a [=string=] that is not the empty string, then run [=store the index for a saved query=] with |window|, |navigable|, |workletDataOrigin|, |moduleURLRecord|, |operationName|, |savedQueryName|, and the [=default selectURL index=].
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |window|, to [=reject=] |promise| with a {{TypeError}}.
Note: This indicates that either |operationCtor|'s run() method encounters an error (where |operationCtor| is the parameter in {{SharedStorageWorkletGlobalScope/register()}}), or the result |index| is a non-integer value, which violates the selectURL() protocol, and we don't know which url should be selected.
1. Run |privateAggregationCompletionTask|.
</dl>
1. Return the [=tuple=] (|promise|, true).
</div>
<div algorithm>
To <dfn>handle the result of selecting an index</dfn>, given a {{SharedStorageWorklet}} |worklet|, an [=environment settings object=] |environment|, a {{Document}} |document|, a {{sequence}} of {{SharedStorageUrlWithMetadata}} |urls|, a [=list=] of [=strings=] |urlList|, a [=/navigable=] |navigable|, a {{SharedStorageRunOperationMethodOptions}} |options|, a [=traversable navigable/fenced frame config mapping=] |fencedFrameConfigMapping|, a [=urn uuid=] |urn|, a [=/boolean=] |shouldChargeTopLevelBudgets|, a [=/boolean=] |shouldUseDefaultIndex|, and an {{unsigned long}} |resultIndex|, perform the following steps:
1. Let |site| be the result of running [=obtain a site=] with |document|'s [=Document/origin=].
1. Let |remainingBudget| be the result of running [=determine remaining navigation budget=] with |environment| and |site|.
1. Let |pendingBits| be the logarithm base 2 of |urlList|'s [=list/size=].
1. If |shouldChargeTopLevelBudgets| is true:
1. Let |pageBudgetResult| be the result of running [=charge shared storage top-level traversable budgets=] with |navigable|, |site|, and |pendingBits|.
1. If |pageBudgetResult| is false, set |shouldUseDefaultIndex| to true.
1. If |pendingBits| is greater than |remainingBudget|, set |shouldUseDefaultIndex| to true.
1. If |shouldUseDefaultIndex| is true, set |resultIndex| to the [=default selectURL index=].
1. Let |finalConfig| be a new [=fenced frame config=].
1. Set |finalConfig|'s [=fenced frame config/mapped url=] to |urlList|[|resultIndex|].
1. Set |finalConfig|'s <span class=todo>a "pending shared storage budget debit" field</span> to |pendingBits|.
1. [=Finalize a pending config=] on |fencedFrameConfigMapping| with |urn| and |finalConfig|.
1. Let |resultURLWithMetadata| be |urls|[|resultIndex|].
1. If |resultURLWithMetadata| has field "`reportingMetadata`", run [=register reporting metadata=] with |resultURLWithMetadata|["`reportingMetadata`"].
1. If |options|["`keepAlive`"] is false, run [=terminate a worklet global scope=] with |worklet|.
</div>
<div algorithm>
The <dfn method for="SharedStorageWorklet">selectURL(|name|, |urls|, |options|)</dfn> method steps are:
1. Let |resultPromise| be a new [=promise=].
1. If [=this=]'s [=addModule initiated=] is false, then return a [=promise rejected=] with a {{TypeError}}.
1. Let |window| be [=this=]'s [=relevant settings object=].
1. [=Assert=]: |window| is a {{Window}}.
1. Let |context| be |window|'s [=Window/browsing context=].
1. If |context| is null, then return a [=promise rejected=] with a {{TypeError}}.
1. Let |preSpecifiedParams| be the result of [=obtaining the pre-specified
report parameters=] given |options| and |context|.
1. If |preSpecifiedParams| is a {{DOMException}}, return [=a promise rejected
with=] |preSpecifiedParams|.
1. Let |aggregationCoordinator| be the result of [=obtaining the aggregation
coordinator=] given |options|.
1. If |aggregationCoordinator| is a {{DOMException}}, return [=a promise
rejected with=] |aggregationCoordinator|.
1. Let |document| be |context|'s [=active document=].
1. If [=this=]'s [=global scopes=] is [=list/empty=], then return a [=promise rejected=] with a {{TypeError}}.
Note: This can happen if {{SharedStorageWorklet/selectURL()}} is called before {{addModule()}}.
1. [=Assert=]: [=this=]'s [=global scopes=]'s [=list/size=] is 1.
1. Let |globalScope| be [=this=]'s [=global scopes=][0].
1. Let |workletDataOrigin| be |globalScope|'s [=global object/realm=]'s [=realm/settings object=]'s [=environment settings object/origin=].
1. If the result of running [=Is feature enabled in document for origin?=] on "[=PermissionsPolicy/shared-storage-select-url=]", |document|, and |workletDataOrigin| returns false, return a [=promise rejected=] with a {{TypeError}}.
1. If the result of running [=SharedStorageWorkletGlobalScope/check whether addModule is finished=] for |globalScope| is false, return a [=promise rejected=] with a {{TypeError}}.
1. If |urls| is empty or if |urls|'s [=list/size=] is greater than 8, return a [=promise rejected=] with a {{TypeError}}.
Note: 8 is chosen here so that each call of {{SharedStorageWorklet/selectURL()}} can leak at most log2(8) = 3 bits of information when the result fenced frame is clicked. It's not a lot of information per-call.
1. Let |urlList| be an empty [=list=].
1. [=map/iterate|For each=] |urlWithMetadata| in |urls|:
1. If |urlWithMetadata| has no field "`url`", return a [=promise rejected=] with a {{TypeError}}.
1. Otherwise, let |urlString| be |urlWithMetadata|["`url`"].
1. Let |serializedUrl| be the result of running [=get the canonical URL string if valid=] with |urlString|.
1. If |serializedUrl| is undefined, return a [=promise rejected=] with a {{TypeError}}.
1. Otherwise, [=list/append=] |serializedUrl| to |urlList|.
1. If |urlWithMetadata| has field "`reportingMetadata`":
1. Let |reportingMetadata| be |urlWithMetadata|["`reportingMetadata`"].
1. If the result of running [=validate reporting metadata=] with |reportingMetadata| is false, [=reject=] |resultPromise| with a {{TypeError}} and abort these steps.
1. Let |navigable| be |window|'s [=associated document=]'s [=node navigable=].
1. Let |fencedFrameConfigMapping| be |navigable|'s [=navigable/traversable navigable=]'s [=traversable navigable/fenced frame config mapping=].
1. Let |pendingConfig| be a new [=fenced frame config=].
1. Let |urn| be the result of running [=fenced frame config mapping/store a pending config=] on |fencedFrameConfigMapping| with |pendingConfig|.
1. If |urn| is failure, then return a [=promise rejected=] with a {{TypeError}}.
1. Let |environment| be |window|'s [=relevant settings object=].
1. Let |allowedInOpaqueOriginContext| be [=this=]'s [=SharedStorageWorklet/has cross-origin data origin=].
1. If the result of running [=determine whether shared storage is allowed by context=] given |environment|, |workletDataOrigin|, and |allowedInOpaqueOriginContext| is false, return a [=promise rejected=] with a {{TypeError}}.
1. If the result of running [=check if user preference setting allows access to shared storage=] given |environment| and |workletDataOrigin| is false:
1. If [=this=]'s [=SharedStorageWorklet/has cross-origin data origin=] is false, return a [=promise rejected=] with a {{TypeError}}.
1. If |options|["`resolveToConfig`"] is true, [=resolve=] |resultPromise| with |pendingConfig|.
1. Otherwise, [=resolve=] |resultPromise| with |urn|.
1. Let (|indexPromise|, |shouldChargeTopLevelBudgets|) be the result of running [=get the select-url result index=], given [=this=], |name|, |urlList|, |workletDataOrigin|, |navigable|, |options|, |preSpecifiedParams| and |aggregationCoordinator|.
1. [=Upon fulfillment=] of |indexPromise| with |resultIndex|, run [=handle the result of selecting an index=] given |worklet|, |environment|, |document|, |urls|, |urlList|, |navigable|, |options|, |fencedFrameConfigMapping|, |urn|, |shouldChargeTopLevelBudgets|, false, and |resultIndex|.
1. [=Upon rejection=] of |indexPromise|, run [=handle the result of selecting an index=] given |worklet|, |environment|, |document|, |urls|, |urlList|, |navigable|, |options|, |fencedFrameConfigMapping|, |urn|, |shouldChargeTopLevelBudgets|, true, and the [=default selectURL index=].
1. Return |resultPromise|.
</div>
<div algorithm>
The <dfn method for="SharedStorageWorklet">run(|name|, |options|)</dfn> method steps are:
1. Let |promise| be a new [=promise=].
1. If [=this=]'s [=addModule initiated=] is false, then return a [=promise rejected=] with a {{TypeError}}.
1. Let |window| be [=this=]'s [=relevant settings object=].
1. [=Assert=]: |window| is a {{Window}}.
1. Let |context| be |window|'s [=Window/browsing context=].
1. If |context| is null, then return [=a promise rejected with=] a
{{TypeError}}.
1. Let |preSpecifiedParams| be the result of [=obtaining the pre-specified
report parameters=] given |options| and |context|.
1. If |preSpecifiedParams| is a {{DOMException}}, return [=a promise rejected
with=] |preSpecifiedParams|.
1. Let |aggregationCoordinator| be the result of [=obtaining the aggregation
coordinator=] given |options|.
1. If |aggregationCoordinator| is a {{DOMException}}, return [=a promise
rejected with=] |aggregationCoordinator|.
1. If [=this=]'s [=global scopes=] is [=list/empty=], then return a [=promise rejected=] with a {{TypeError}}.
Note: This can happen if {{SharedStorageWorklet/run()}} is called before {{addModule()}}.
1. [=Assert=]: [=this=]'s [=global scopes=]'s [=list/size=] is 1.
1. Let |globalScope| be [=this=]'s [=global scopes=][0].
1. If the result of running [=SharedStorageWorkletGlobalScope/check whether addModule is finished=] for |globalScope| is false, return a [=promise rejected=] with a {{TypeError}}.
1. Let |workletDataOrigin| be |globalScope|'s [=global object/realm=]'s [=realm/settings object=]'s [=environment settings object/origin=].
1. Let |allowedInOpaqueOriginContext| be [=this=]'s [=SharedStorageWorklet/has cross-origin data origin=].
1. If the result of running [=determine whether shared storage is allowed by context=] given |window|, |workletDataOrigin|, and |allowedInOpaqueOriginContext| is false, [=reject=] |promise| with a {{TypeError}}.
1. If the result of running [=check if user preference setting allows access to shared storage=] given |window| and |workletDataOrigin| is false:
1. If [=this=]'s [=SharedStorageWorklet/has cross-origin data origin=] is false, [=reject=] |promise| with a {{TypeError}}.
1. Else, [=resolve=] |promise| with undefined.
1. Return |promise|.
1. Return |promise|, and immediately [=obtaining a worklet agent=] given |window| and run the rest of these steps in that agent:
Note: The |promise|'s resolution should be before and not depend on the execution inside {{SharedStorageWorkletGlobalScope}}. This is because shared storage is a type of unpartitioned storage, and a {{SharedStorageWorkletGlobalScope}} can have access to cross-site data, which shouldn't be leaked via {{SharedStorageWorklet/run()}} (via its success/error result).
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |window|, to [=resolve=] |promise| with undefined.
1. If |globalScope|'s [=relevant settings object=]'s [=module map=] is not [=map/empty=]:
1. Let |operationMap| be [=this=]'s {{SharedStorageWorkletGlobalScope}}'s [=SharedStorageWorkletGlobalScope/operation map=].
1. If |operationMap| [=map/contains=] |name|:
1. [=Assert=]: |operationMap|[|name|]'s [=associated realm=] is [=this=]'s [=relevant realm=].
1. Let |operation| be |operationMap|[|name|], [=converted to an IDL value|converted=] to {{Function}}.
1. Let |privateAggregationCompletionTask| be the result of [=setting up the Private Aggregation scopes=] given |workletDataOrigin|, |preSpecifiedParams| and |aggregationCoordinator|.
1. Let |argumentsList| be a new [=/list=].
1. If |options|["{{SharedStorageRunOperationMethodOptions/data}}"] [=map/exists=], [=list/append=] it to |argumentsList|.
1. [=Invoke=] |operation| with |argumentsList| and "`report`".
1. Wait for |operation| to finish running, if applicable.
1. Run |privateAggregationCompletionTask|.
1. If |options|["`keepAlive`"] is false:
1. Wait for |operation| to finish running, if applicable.
1. Run [=terminate a worklet global scope=] with [=this=].
</div>
<div algorithm>
To <dfn>obtain the aggregation coordinator</dfn> given a
{{SharedStorageRunOperationMethodOptions}} |options|, perform the following
steps. They return an [=aggregation coordinator=], null or a {{DOMException}}:
1. If |options|["{{SharedStorageRunOperationMethodOptions/privateAggregationConfig}}"]
does not [=map/exist=], return null.
1. If |options|["{{SharedStorageRunOperationMethodOptions/privateAggregationConfig}}"]["{{SharedStoragePrivateAggregationConfig/aggregationCoordinatorOrigin}}"]
does not [=map/exist=], return null.
1. Return the result of [=obtaining the Private Aggregation coordinator=]
given
|options|["{{SharedStorageRunOperationMethodOptions/privateAggregationConfig}}"]["{{SharedStoragePrivateAggregationConfig/aggregationCoordinatorOrigin}}"].
</div>
<div algorithm>
To <dfn>obtain the pre-specified report parameters</dfn> given a
{{SharedStorageRunOperationMethodOptions}} |options| and a [=/browsing
context=] |context|, perform the following steps. They return a
[=pre-specified report parameters=], null, or a {{DOMException}}:
1. If |options|["{{SharedStorageRunOperationMethodOptions/privateAggregationConfig}}"]
does not [=map/exist=], return null.
1. Let |privateAggregationConfig| be
|options|["{{SharedStorageRunOperationMethodOptions/privateAggregationConfig}}"].
1. Let |contextId| be null.
1. If |privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/contextId}}"]
[=map/exists=], set |contextId| to
|privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/contextId}}"].
1. If |contextId|'s [=string/length=] is greater than 64, return a new
{{DOMException}} with name "`DataError`".
1. Let |filteringIdMaxBytes| be the [=default filtering ID max bytes=].
1. If |privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/filteringIdMaxBytes}}"]
[=map/exists=], set |filteringIdMaxBytes| to
|privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/filteringIdMaxBytes}}"].
1. If |filteringIdMaxBytes| is not [=set/contained=] in the [=valid filtering ID
max bytes range=], return a new {{DOMException}} with name "`DataError`".
1. If |context|'s [=browsing context/fenced frame config instance=] is not null:
1. If |filteringIdMaxBytes| is not the [=default filtering ID max bytes=] or
|contextId| is not null, return a new {{DOMException}} with name
"`DataError`".
1. Let |maxContributions| be null.
1. If
|privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/maxContributions}}"]
[=map/exists=], set |maxContributions| to
|privateAggregationConfig|["{{SharedStoragePrivateAggregationConfig/maxContributions}}"].
1. If |maxContributions| is zero, return a new {{DOMException}} with name
"`DataError`".
1. Return a new [=pre-specified report parameters=] with the items:
: <a spec="private-aggregation-api" for="pre-specified report parameters">context ID</a>
:: |contextId|
: [=pre-specified report parameters/filtering ID max bytes=]
:: |filteringIdMaxBytes|
: [=pre-specified report parameters/max contributions=]
:: |maxContributions|
</div>
<div algorithm>
To <dfn>set up the Private Aggregation scopes</dfn> given an [=/origin=]
|workletDataOrigin|, a [=pre-specified report parameters=] or null
|preSpecifiedParams| and an [=aggregation coordinator=] or null
|aggregationCoordinator|, perform the following steps. They return an
algorithm.
Note: The returned algorithm should be run when the associated operation is
complete.
1. Let |batchingScope| be a new [=batching scope=].
1. Let |debugScope| be a new [=debug scope=].
1. Let |privateAggregationTimeout| be null.
1. Let |hasRunPrivateAggregationCompletionTask| be false.
1. Let |privateAggregationCompletionTask| be an algorithm to perform the
following steps:
1. If |hasRunPrivateAggregationCompletionTask|, return.
1. Set |hasRunPrivateAggregationCompletionTask| to true.
1. [=Mark a debug scope complete=] given |debugScope|.
1. [=Process contributions for a batching scope=] given
|batchingScope|, |workletDataOrigin|, "<code>shared-storage</code>"
and |privateAggregationTimeout|.
1. If |aggregationCoordinator| is not null, [=set the aggregation coordinator
for a batching scope=] given |aggregationCoordinator| and |batchingScope|.
1. If |preSpecifiedParams| is not null:
1. Let |isDeterministicReport| be the result of [=determining if a report
should be sent deterministically=] given |preSpecifiedParams|.
1. If |isDeterministicReport|:
1. Set |privateAggregationTimeout| to the [=/current wall time=] plus
the [=deterministic operation timeout duration=].
1. [=Set the pre-specified report parameters for a batching scope=] given
|preSpecifiedParams| and |batchingScope|.
1. If |isDeterministicReport|, run the following steps [=in parallel=]:
1. Wait until |privateAggregationTimeout|.
1. Run |privateAggregationCompletionTask|.
1. Return |privateAggregationCompletionTask|.
</div>
The <dfn>deterministic operation timeout duration</dfn> is an
[=implementation-defined=] non-negative [=duration=] that controls how long a
Shared Storage operation may make Private Aggregation contributions if it is
triggering a deterministic report and, equivalently, when that report should
be sent after the operation begins.
## Monkey Patch for [=Worklets=] ## {#worklet-monkey-patch}
This specification will make some modifications to the [=Worklet=] standard to accommodate the needs of Shared Storage.
### Monkey Patch for [=set up a worklet environment settings object=] ### {#set-up-a-worklet-environment-settings-object-monkey-patch}
The [=set up a worklet environment settings object=] algorithm will need to include an additional parameter: {{Worklet}} |worklet|. The step that defines the |settingsObject|'s [=environment settings object/origin=] should be modified as follows:
6. Let |settingsObject| be a new [=environment settings object=] whose algorithms are defined as follows:
......
<b>The [=environment settings object/origin=]</b>
1. Let |workletGlobalScope| be the [=global object=] of <var ignore=''>realmExecutionContext</var>'s Realm component.
1. If |workletGlobalScope| is not {{SharedStorageWorkletGlobalScope}}, return |origin|.
1. [=Assert=] that |worklet| is a {{SharedStorageWorklet}}.
1. If |worklet|'s [=SharedStorageWorklet/data origin=] is `"context-origin"`, return <var ignore=''>outsideSettings</var>'s [=environment settings object/origin=].
1. Otherwise, if [=SharedStorageWorklet/data origin=] is `"script-origin"`:
1. Let |pendingAddedModules| be a [=list/clone=] of |worklet|'s [=added modules list=].
1. [=Assert=]: |pendingAddedModules|'s [=list/size=] is 1.
1. Let |moduleURL| be |pendingAddedModules|[0].
1. Return |moduleURL|'s [=url/origin=].
1. Otherwise, let |customOriginUrl| be the result of running a [=URL parser=] on [=SharedStorageWorklet/data origin=].
1. [=Assert=] |customOriginUrl| is a valid [=/URL=].
1. Return |customOriginUrl|'s [=url/origin=].
......
### Monkey Patch for [=create a worklet global scope=] ### {#create-a-worklet-global-scope-monkey-patch}
The [=create a worklet global scope=] algorithm will need to be modified to pass in the |worklet| parameter:
5. Let <var ignore=''>insideSettings</var> be the result of [=setting up a worklet environment settings object=] given <var ignore=''>realmExecutionContext</var>, <var ignore=''>outsideSettings</var>, and |worklet|.
### Monkey Patch for [=fetch a worklet script graph=] ### {#fetch-a-worklet-script-graph-monkey-patch}
The algorithm [=fetch a worklet script graph=] calls into the <a href="https://html.spec.whatwg.org/multipage/webappapis.html#fetch-a-worklet/module-worker-script-graph">fetch a worklet/module worker script graph</a> algorithm, which takes in an algorithm parameter |processCustomFetchResponse|. The definition of that |processCustomFetchResponse| parameter will need to include the following step before the step "5. [=Fetch=] |request|, ...":
5. If |fetchClient|'s [=environment settings object/global object=] is {{SharedStorageWorkletGlobalScope}}:
1. Set |request|'s [=request/redirect mode=] to "<code>error</code>".
Note: For shared storage, redirects are disallowed for the module script request. With this restriction, it's possible to define and to use the algorithm that gets the |realm|'s [=realm/settings object=]'s [=environment settings object/origin=] (as described in [[#set-up-a-worklet-environment-settings-object-monkey-patch]]) as soon as the {{SharedStorageWorkletGlobalScope}} is created, as the origin won't change. This restriction may be removed in a future iteration of the design. If redirects become allowed, presumably, the algorithm that gets the |realm|'s [=realm/settings object=]'s [=environment settings object/origin=] should be updated to return the final request's [=request/URL=]'s [=url/origin=] after receiving the final request's response, and the user preference checkings shall only be done after that point.
1. If |fetchClient|'s [=environment settings object/origin=] and |settingsObject|'s [=environment settings object/origin=] are not [=same origin=]:
1. Let |dataOriginValue| be the [=origin/serialization=] of |settingsObject|'s [=environment settings object/origin=].
1. [=Assert=] that |dataOriginValue| is not null.
1. [=header list/Append=] the [=header=] ([:Sec-Shared-Storage-Data-Origin:], |dataOriginValue|) to |request|'s [=request/header list=].
### The [:Shared-Storage-Cross-Origin-Worklet-Allowed:] HTTP response header ### {#worklet-allowed-header}
The [:Shared-Storage-Cross-Origin-Worklet-Allowed:] HTTP response header, along with the traditional CORS headers, can be used to grant a cross-origin site the permission to create a worklet from the module script's [=/URL=]'s [=url/origin=], and to run subsequent operations on the worklet using the module script's [=/URL=]'s [=url/origin=] as the <dfn for="SharedStorage">data partition origin</dfn> for accessing shared storage data, i.e. the [=environment settings object/origin=] set in [[#set-up-a-worklet-environment-settings-object-monkey-patch]], which becomes the [=url/origin=] used in all {{SharedStorage}} calls to [=obtain a shared storage bottle map=].
Worklets that load cross-origin scripts rely on CORS as a baseline permission mechanism to indicate trusted external origins. However, CORS alone is insufficient for creation of a worklet with cross-origin script whose [=data partition origin=] is the script origin. Unlike simple resource sharing, worklets allow the creator site to execute JavaScript within the context of the target origin. To ensure security, an additional response header, [:Shared-Storage-Cross-Origin-Worklet-Allowed:], is required from the script origin.
### Monkey Patch for [=HTTP fetch=] ### {#http-fetch-monkey-patch}
[Steps](#mod-http-fetch) will need to be added to the [=HTTP fetch=] algorithm.
Note: It is the responsibility of the site serving the module script to carefully consider the security implications: when the module script's [=/URL=]'s [=url/origin=] and the worklet's creator {{Window}} origin are not [=same origin=], by sending permissive CORS headers the [:Shared-Storage-Cross-Origin-Worklet-Allowed:] header on the module script response, the server will be granting the worklet's creation and subsequent operations on the worklet, while allowing the worklet to use the worklet's script's [=url/origin=] as the [=url/origin=] for accessing the shared storage data, i.e. the [=data partition origin=]. For example, the worklet's creator {{Window}} could poison and use up the worklet origin's [=/site=]'s [=site/remaining navigation budget=] by calling {{SharedStorageWorklet/selectURL()}} or {{SharedStorageWorklet/run()}}, where the worklet origin is the global scope's [=global object/realm=]'s [=realm/settings object=]'s [=environment settings object/origin=].
### Monkey Patch for {{Worklet/addModule()}} ### {#add-module-monkey-patch}
The {{Worklet/addModule()}} method steps for {{Worklet}} will need to include the following step before the step "Let |promise| be a new promise":
4. If [=this=] is of type {{SharedStorageWorklet}}:
1. Let |addModuleAllowedResult| be the result of running [=check if addModule is allowed and update state=] given [=this=] and <var ignore=''>moduleURLRecord</var>.
1. If |addModuleAllowedResult| is "DisallowedDueToNonPreferenceError":
1. Return [=a promise rejected with=] a {{TypeError}}.
1. Else if |addModuleAllowedResult| is "DisallowedDueToPreferenceError":
1. If [=this=]'s [=SharedStorageWorklet/has cross-origin data origin=] is false, then return [=a promise rejected with=] a {{TypeError}}.
1. Else:
1. [=Assert=]: |addModuleAllowedResult| is "Allowed".
<div class="note">
On user preferences error, {{Worklet/addModule()}} will be aborted at an early stage. However, the error will only be exposed to the caller for a same-origin worklet (i.e. where the initiator document's origin is same-origin with the module script's origin). For a cross-origin worklet, the error will be hidden. This is to prevent a caller from knowing which origins the user has disabled shared storage for via preferences (if a per-origin preference exists for that browser vendor).
A caller may still use timing attacks to know this information, but this is a minor security/privacy issue, as in reality very few users would set such preferences, and doing a wide search would incur a significant performance cost spinning up the worklets.
This rationale also applies to the handling for user preferences error for {{SharedStorageWorklet/selectURL()}} and {{SharedStorageWorklet/run()}}.
</div>
After the step "Let <var ignore=''>addedSuccessfully</var> be false", we need to include the following step:
4. If [=this=] is of type {{SharedStorageWorklet}}, [=SharedStorageWorklet/has cross-origin data origin=] is true, and [=SharedStorageWorklet/data origin=] is not `"script-origin"`:
1. [=Assert=] |pendingTasks| is 1.
1. Set |pendingTasks| to 2.
1. [=Queue a global task=] on the [=networking task source=] given <var ignore=''>workletGlobalScope</var> to perform the following steps:
1. Let |customOriginUrl| be the result of running a [=URL parser=] on [=SharedStorageWorklet/data origin=].
1. [=Assert=] |customOriginUrl| is a valid [=/URL=].
1. Set |customOriginUrl|'s [=url/path=] to ≪".well-known", "shared-storage", "trusted-origins"≫.
1. Let |request| be a new [=/request=] whose [=request/URL=] is |customOriginUrl|, [=request/mode=] is `"cors"`, [=request/referrer=] is `"client"`, [=request/destination=] is `"json"`, [=request/initiator type=] is `"script"`, and [=request/client=] is |outsideSettings|.
1. [=Fetch=] |request| with [=fetch/processResponseConsumeBody=] set to the following algorithm, given [=/response=] |response| and null, failure or a [=/byte sequence=] |bodyBytes|:
1. If any of the following are true:
* |bodyBytes| is null or failure; or
* |response|'s [=response/status=] is not an [=ok status=],
then:
1. Set |pendingTasks| to −1.
1. [=Reject=] |promise| with an "TypeError" DOMException.
1. Abort these steps.
1. Let |mimeType| be the result of [=extracting a MIME type=] from |response|'s [=response/header list=].
1. If |mimeType| is not a [=JSON MIME type=], then:
1. Set |pendingTasks| to −1.
1. [=Reject=] |promise| with an "TypeError" DOMException.
1. Abort these steps.
1. Let |sourceText| be the result of [=UTF-8 decoding=] |bodyBytes|.
1. Let |parsed| be the result of [=parsing a JSON string to an Infra value=] given |sourceText|.
1. If |parsed| is not a [=list=] or if |parsed| is [=list/empty=], then:
1. Set |pendingTasks| to −1.
1. [=Reject=] |promise| with an "TypeError" DOMException.
1. Abort these steps.
1. Let |doesMatch| be false.
1. For each |item| of |parsed|:
1. If |item| is not an [=ordered map=], or if |item| does not [=map/contain=] `scriptOrigin`, or if |item| does not [=map/contain=] `contextOrigin`:
1. Set |pendingTasks| to −1.
1. [=Reject=] |promise| with an "TypeError" DOMException.
1. Abort these steps.
1. Let |doesMatch| be the result of running [=check for script and context origin match=] on |item|[`scriptOrigin`], <var ignore=''>moduleURLRecord</var>'s [=url/origin=], |item|[`contextOrigin`], and |outsideSettings|'s [=environment settings object/origin=].
1. If |doesMatch| is true:
1. [=Queue a global task=] on the [=networking task source=] given [=this=]'s [=relevant global object=] to perform the following steps:
1. If |pendingTasks| is not −1, then:
1. Set |pendingTasks| to |pendingTasks| − 1.
1. If |pendingTasks| is 0, perform the following steps:
1. If |workletGlobalScope| has an associated boolean [=addModule success=], set |workletGlobalScope|'s [=addModule success=] to true.
1. [=Resolve=] |promise|.
1. Break.
1. If |doesMatch| is false, then:
1. Set |pendingTasks| to −1.
1. [=Reject=] |promise| with an "TypeError" DOMException.
Note: If the worklet data origin is different from the current context and the script origin, an additional check is performed. This involves fetching a configuration file from the worklet data origin to verify that the current context is allowed to load the worklet with the script and perform operations.
The penultimate step (i.e. the final indented step), currently "If |pendingTasks| is 0, then [=resolve=] |promise|.", should be updated to:
2. If |pendingTasks| is 0, perform the following steps:
1. If |workletGlobalScope| has an associated boolean [=addModule success=], set |workletGlobalScope|'s [=addModule success=] to true.
2. [=Resolve=] |promise|.
Just before the final step, currently "Return <var ignore>promise</var>.", add the following step:
7. If [=this=] is a {{SharedStorageWorklet}}, [=upon fulfillment=] of |promise| or
[=upon rejection=] of |promise|, run the following steps:
1. Let |globalScopes| be [=this=]'s [=Worklet/global scopes=].
1. [=Assert=]: |globalScopes|' [=list/size=] equals 1.
1. Let |privateAggregationObj| be |globalScopes|[0]'s
{{SharedStorageWorkletGlobalScope/privateAggregation}}.
1. Set |privateAggregationObj|'s [=PrivateAggregation/allowed to use=] to
the result of determining whether [=this=]'s [=relevant global
object=]'s [=associated document=] is [=/allowed to use=] the
"<code>[=private-aggregation=]</code>" [=policy-controlled feature=].
Issue: Consider adding an early return here if the permissions
policy check is made first.
1. Set |privateAggregationObj|'s [=PrivateAggregation/scoping details=] to a
new [=/scoping details=] with the items:
: [=scoping details/get batching scope steps=]
:: An algorithm that returns the [=batching scope=] that is scheduled to
be passed to [=process contributions for a batching scope=] when the
call currently executing in |scope| returns.
: [=scoping details/get debug scope steps=]
:: An algorithm that returns the [=debug scope=] that is scheduled to be
passed to [=mark a debug scope complete=] when the call currently
executing in |scope| returns.
Note: Multiple operation invocations can be in-progress at the same
time, each with a different batching scope and debug scope. However,
only one can be currently executing.
A <dfn>trusted origin type</dfn> is a [=string=] or [=list=] of [=strings=].
<div algorithm>
To <dfn>check for script and context origin match</dfn>, given [=trusted origin type=] |itemScriptOrigin|, [=url/origin=] |actualScriptOrigin|, [=trusted origin type=] |itemContextOrigin|, and [=environment settings object/origin=] |actualContextOrigin|, perform the following steps:
1. If the result of running [=check for trusted origin match=], given |itemScriptOrigin| and |actualScriptOrigin| is false, return false.
1. Return the result of running [=check for trusted origin match=], given |itemContextOrigin| and |actualContextOrigin|.
</div>
<div algorithm>
To <dfn>check for trusted origin match</dfn>, given [=trusted origin type=] |itemOrigin| and [=url/origin=] |actualOrigin|, perform the following steps:
1. If |itemOrigin| is a [=string=], return the result of running [=check for trusted origin match on a string=], given |itemOrigin| and |actualOrigin|.
1. Otherwise, for each |originString| in |itemOrigin|:
1. If the result of running [=check for trusted origin match on a string=] given |originString| and |actualOrigin| is true, return true.
1. Return false.
</div>
<div algorithm>
To <dfn>check for trusted origin match on a string</dfn>, given [=string=] |itemOrigin| and [=url/origin=] |actualOrigin|, perform the following steps:
1. If |itemOrigin| is `"*"`, return true.
1. Let |itemOriginUrl| be the result of running a [=URL parser=] on |itemOrigin|.
1. If |itemOriginUrl| is not a valid [=/URL=], then return false.
1. If |itemOriginUrl|'s [=url/origin=] and |actualOrigin| are [=same origin=], return true.
1. Otherwise, return false.
</div>
<span class=todo>Add additional monkey patch pieces for out-of-process worklets.</span>
## The {{SharedStorageWorkletGlobalScope}} ## {#global-scope}
The {{SharedStorageWorklet}}'s [=worklet global scope type=] is {{SharedStorageWorkletGlobalScope}}.
The {{SharedStorageWorklet}}'s [=worklet destination type=] is "sharedstorageworklet".
### Monkey Patch for request [=request/destination=] ### {#request-destination-monkey-patch}
The fetch request's [=request/destination=] field should additionally include "sharedstorageworklet" as a valid value.
<xmp class='idl'>
callback RunFunctionForSharedStorageSelectURLOperation = Promise<unsigned long>(sequence<USVString> urls, optional any data);
</xmp>
<xmp class='idl'>
[Exposed=SharedStorageWorklet, Global=SharedStorageWorklet]
interface SharedStorageWorkletGlobalScope : WorkletGlobalScope {
undefined register(DOMString name,
Function operationCtor);
readonly attribute SharedStorage sharedStorage;
readonly attribute PrivateAggregation privateAggregation;
Promise<sequence<StorageInterestGroup>> interestGroups();
readonly attribute SharedStorageWorkletNavigator navigator;
};
</xmp>
Each {{SharedStorageWorkletGlobalScope}} has an associated [=environment settings object=] <dfn for=SharedStorageWorkletGlobalScope>outside settings</dfn>, which is the associated {{SharedStorageWorklet}}'s [=relevant settings object=].
Each {{SharedStorageWorkletGlobalScope}} has an associated [=/boolean=] <dfn for=SharedStorageWorkletGlobalScope>addModule success</dfn>, which is initialized to false.
Each {{SharedStorageWorkletGlobalScope}} also has an associated <dfn for=SharedStorageWorkletGlobalScope>operation map</dfn>, which is a [=map=], initially empty, of [=strings=] (denoting operation names) to [=function objects=].
Each {{SharedStorageWorkletGlobalScope}} has an associated {{SharedStorage}} instance <dfn for=SharedStorageWorkletGlobalScope>shared storage instance</dfn>.
Each {{SharedStorageWorkletGlobalScope}} has an associated {{SharedStorageWorkletNavigator}} instance <dfn for=SharedStorageWorkletGlobalScope>navigator instance</dfn>.
### {{SharedStorageWorkletGlobalScope}} algorithms ### {#scope-algo}
<div algorithm>
The <dfn method for="SharedStorageWorkletGlobalScope">register(|name|, |operationCtor|)</dfn> method steps are:
1. If |name| is missing or empty, throw a {{TypeError}}.
1. Let |operationMap| be this {{SharedStorageWorkletGlobalScope}}'s [=SharedStorageWorkletGlobalScope/operation map=].
1. If |operationMap| [=map/contains=] an [=map/entry=] with [=map/key=] |name|, throw a {{TypeError}}.
1. If |operationCtor| is missing, throw a {{TypeError}}.
1. Let |operationClassInstance| be the result of [=constructing=] |operationCtor|, with no arguments.
1. Let |runFunction| be [=Get=](|operationClassInstance|, "`run`"). Rethrow any exceptions.
1. If <a abstract-op>IsCallable</a>(|runFunction|) is false, throw a {{TypeError}}.
1. [=map/Set=] the value of |operationMap|[|name|] to |runFunction|.
</div>
Issue(151): The "name" and "operationCtor" cannot be missing here given WebIDL. Should just check for default/empty values.
<div algorithm>
The <dfn method for="SharedStorageWorkletGlobalScope">interestGroups()</dfn> method steps are:
1. Let |promise| be a new [=promise=].
1. If the result of running [=SharedStorageWorkletGlobalScope/check whether addModule is finished=] for {{SharedStorage}}'s associated {{SharedStorageWorkletGlobalScope}} is false, return a [=promise rejected=] with a {{TypeError}}.
1. Let |globalObject| be the [=current realm=]'s [=global object=].
1. Let |context| be |globalObject|'s [=Window/browsing context=].
1. If |context| is null, return a [=promise rejected=] with a {{TypeError}}.
1. Let |document| be |context|'s [=active window=]'s [=associated document=].
1. If |document| is not [=fully active=], return a [=promise rejected=] with a {{TypeError}}.
1. Let |workletDataOrigin| be [=current realm=]'s [=realm/settings object=]'s [=environment settings object/origin=].
1. Run the following steps [=in parallel=]:
1. Let |interestGroups| be the result of running [=get storage interest groups for owner=] given |workletDataOrigin|.
1. If |interestGroups| is failure:
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |realm|'s [=global object=], to [=reject=] |promise| with a {{TypeError}}.
1. Otherwise:
1. [=Queue a global task=] on the [=DOM manipulation task source=], given |realm|'s [=global object=], to [=resolve=] |promise| with |interestGroups|.
1. Return |promise|.
</div>
<div algorithm>
The <dfn attribute for=SharedStorageWorkletGlobalScope>sharedStorage</dfn> [=getter steps=] are:
1. If [=this=]'s [=addModule success=] is true, return [=this=]'s [=SharedStorageWorkletGlobalScope/shared storage instance=].
1. Otherwise, throw a {{TypeError}}.
</div>
<div algorithm>
The <dfn attribute for=SharedStorageWorkletGlobalScope>navigator</dfn> [=getter steps=] are:
1. If [=this=]'s [=addModule success=] is true, return [=this=]'s [=SharedStorageWorkletGlobalScope/navigator instance=].
1. Otherwise, throw a {{TypeError}}.
</div>
<div algorithm="privateAggregation getter">
The {{SharedStorageWorkletGlobalScope/privateAggregation}} [=getter steps=] are to:
1. [=Get the privateAggregation=] given [=this=].
</div>
<div algorithm>
To <dfn for="SharedStorageWorkletGlobalScope">check whether addModule is finished</dfn>, the step is:
1. Return the value of [=addModule success=].
</div>
## {{SharedStorageUrlWithMetadata}} and Reporting ## {#reporting}
<xmp class='idl'>
dictionary SharedStorageUrlWithMetadata {
required USVString url;
object reportingMetadata;
};
</xmp>
If a {{SharedStorageUrlWithMetadata}} [=dictionary=] contains a non-[=map/empty=] {{SharedStorageUrlWithMetadata/reportingMetadata}} {{/object}} in the form of a [=dictionary=] whose [=map/keys=] are {{FenceEvent}}'s {{FenceEvent/eventType}}s and whose [=map/values=] are [=strings=] that parse to valid [=/URLs=], then these {{FenceEvent/eventType}}-[=/URL=] pairs will be [=register reporting metadata|registered=] for later access within any [=fenced frame=] that loads the {{SharedStorageResponse}} resulting from this {{SharedStorageWorklet/selectURL()}} call.
Issue(141): {{SharedStorageUrlWithMetadata/reportingMetadata}} should be a [=dictionary=].
Inside a [=fenced frame=] with {{FenceEvent/eventType}}-[=/URL=] pairs that have been [=register reporting metadata|registered=] through {{SharedStorageWorklet/selectURL()}} with {{SharedStorageUrlWithMetadata/reportingMetadata}} {{/object}}s, if {{reportEvent()}} is called on a {{FenceEvent}} with a {{FenceEvent/destination}} [=list/containing=] "`shared-storage-select-url`" and that {{FenceEvent}}'s corresponding {{FenceEvent/eventType}} is triggered, then the {{FenceEvent}}'s {{FenceEvent/eventData}} will be sent as a [=beacon=] to the registered [=/URL=] for that {{FenceEvent/eventType}}.
<div algorithm>
To <dfn>validate reporting metadata</dfn>, given an {{/object}} |reportingMetadata|, run the following steps:
1. If |reportingMetadata| is not a [=dictionary=], return false.
1. If |reportingMetadata| is [=map/empty=], return true.
1. [=map/iterate|For each=] <var ignore="">eventType</var> → |urlString| of |reportingMetadata|, if the result of running [=get the canonical URL string if valid=] with |urlString| is undefined, return false.
1. Return true.
</div>
<div algorithm>
To <dfn>get the canonical URL string if valid</dfn>, given a [=string=] |urlString|, run the following steps:
1. Let |url| be the result of running a [=URL parser=] on |urlString|.
1. If |url| is not a valid [=/URL=], return undefined.
1. Otherwise, return the result of running a [=URL serializer=] on |url|.
</div>
<div algorithm>
To <dfn>register reporting metadata</dfn>, given an {{/object}} |reportingMetadata| and a [=fenced frame config=] |fencedFrameConfigStruct|, run the following steps:
1. If |reportingMetadata| is [=map/empty=], return.
1. [=Assert=]: |reportingMetadata| is a [=dictionary=].
1. Let |reportingUrlMap| be an [=map/empty=] [=map=].
1. [=map/iterate|For each=] |eventType| → |urlString| of |reportingMetadata|:
1. Let |url| be the result of running a [=URL parser=] on |urlString|.
1. [=Assert=]: |url| is a valid [=/URL=].
1. [=map/Set=] |reportingUrlMap|[|eventType|] to |url|.
Issue(144): Store |reportingUrlMap| inside a [=fenced frame reporter=] class associated with |fencedFrameConfigStruct|. Both of these still need to be added to the draft [[Fenced-Frame]].
</div>
## Entropy Budgets ## {#budgets}
Because [=bits of entropy=] can leak via {{SharedStorageWorklet/selectURL()}}, the [=user agent=] will need to maintain budgets to limit these leaks.
On a call to {{SharedStorageWorklet/selectURL()}}, when any of these budgets are exhausted, the [=default selectURL index=] will be used to determine which URL to select.
<div algorithm>
To <dfn>get the default selectURL index</dfn>, given {{sequence}}<{{USVString}}> |urls|, run the following steps:
1. Return 0.