FDC3 for Web Browsers Discussion group 29th Aug 2024

[kriswest]

Group overview

Group convened to discuss how to enable FDC3 use in a web browser, without the use of a browser extension (such as fdc3-desktop-agent or a container).

Issue: #896
Mailing list discussion: https://groups.google.com/a/finos.org/g/fdc3/c/jCvlLjokBLs

In a recent email on the FDC3 mailing list, @kriswest wrote:

... I also want to add that there is clearly significant interest in the community in enabling FDC3 use on the web. There is a strong use case in that it would enable better onboarding journeys with less drop-off (where you use an app on the web with others before adopting a desktop container or similar).

and:

But there are also additional challenges such as how to make the API available reliably without importing a proprietary module from a particular vendor into every app, how to deal with more than one implementation of API/Desktop Agent in the browser at once, how to do this reliably and securely within the browser sandbox etc.. Work needs to be done in the Standard to solve these issues and to make web browser use possible in a future FDC3 Standard version - which I believe is possible (and likely to involve using a vendor-agnostic FDC3 NPM module to detect and connect to API implementation(s)). However, we're going to need to do that work to enable the aforementioned API implementations to be compliant and if we fail to hold the line now on compliance with the current version of the FDC3 Standard, that may never happen.

Shared doc with current draft: https://tick42-my.sharepoint.com/:w:/g/personal/finsemble_datastore_interop_io/EZ0dfTCdRlJCnIF3C_1Oit0BF3fsXyvlMbisXp722DC9Kg?e=H2y7fn

Relevant issue tags

Current open issues that relate to the above concepts with the label:

Meeting Date

Thursday 29th August 2024 - 9am (US eastern timezone EDT) / 2pm (London, BST)

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Agenda

• Convene & roll call, review meeting notices (5mins)
• Review action items from previous meeting (5mins)
  • FDC3 for Web Browsers Discussion group 18th July 2024 #1267
• Summary of recent updates and clarifications to proposed protocols:
  • Corrections:
    • Missing context element in OpenRequest payload: 14952ae
    • Corrected title in FindIntentsByContextsResponse (affects generated type names): 14952ae
    • Corrected title in PrivateChannelOnUnsubscribeEvent: 5c592c9
    • Corrected PrivateChannelAddEventListener definition: 5deeb5d
    • Spelling Error: FindIntentsByContextsResponse #1308: 204e736
    • Make channelId nullable in broadcastEvent (for use with fdc3.open): a42798c
    • Question: How does DesktopAgentProxy remove event listener? #1315: Added missing eventListenerUnsubscribeRequest/Response: f9fddc1
    • GetAgentParams Not Optional #1319: 23020b1
  • Changes and Additions:
    • IntentMetadata.displayName made optional as displayName is deprecated in Intent Standard: Make IntentMetadata.displayName optional as its deprecated #1280
    • Tear down (added WCP6Goodbye message to indicate app disconnect): Question: Disposal/Teardown patterns in FDC3 #1263
    • Switch to URL for app identity: Simplify Web Connection Protocol #1301 / a628009
    • Added missing messages and docs for Intent Results: 70ea90f
    • Set window.fdc3 by default: GetAgent setWindowFDC3 parameter #1274
    • API: Inconsistent Use of Promises #1294 & Make Listener.unsubscribe() async for consistency #1300: Async listener and private channel events #1305
  • Clarifications:
    • AddContextListenerResponsePayload does not (need to) contain channelId: Question: AddContextListenerResponsePayload does not contain channelId #1296
    • Clarification of intent result delivery exchanges: RaiseIntentResultResponse #1303 (comment)
    • Why do we need to handle UIs for Intent Resolution and Channel Selection in getAgent? Question: resolvers / channel selectors UI #1307
    • Using broadcastEvent to deliver context passed on fdc3.open: broadcastEvent on no channel #1310
    • Delivering auto-broadcast context on join/addContextListener: Adding Channel State For JoinUserChannel / AddContextListener #1311
    • We do not support metadata properties for message routing as the DA is intended to route messages itself: Question: IntentEvent has no targetApp property #1313
    • Targetting WCP1Hello messages: window.origin Requirement #1316
• Discuss further changes to be made:
  • Add heartbeat messages: App Liveness Check #1320
    • 0dbdf24
  • IFrame positioning: IFramePositioning #1302
    • 6bb5699
• Question: Disposal/Teardown patterns in FDC3 #1263 and application to Support for Multiple Application Scopes (Agents) within a single window process #1250
• Next steps (completing and raising the proposal, mono-repo refactor, draft module publishing)
• AOB & Adjourn

Minutes

• Recent Changes to the proposal

  • @kriswest ran through all recent changes to the proposal and provided an overview.
  • A number of items were discussed or clarified for participants, and a few additional actions agreed including:
    • App identity procedures, including identityURL, actualUrl - pseudo-code needed for comparison procedure
    • Correction of a typo in broadcastEvent schema

• Add heartbeat messages: App Liveness Check #1320

  • @kriswest provided an overview of discussions about app liveness checks, how DAs can know that an app has gone away
  • Created WCP6Goodbye message in proposal for apps to indicate closing
    • there were recent objections from the Chrome security team to the onClose event on a MessagePort (provides information on when garbage collection is occurring, which can be used to time certain attacks) which is preventing them from implementing it - unfortunate as that event would have been ideal to catch apps closing
    • POC code should attempt to call this whenever it detects an app is closing
      • Discussed using onbeforeunload - this is not correct as thats a cancellable event and other handlers might cancel close
        • onunload fits better, but is deprecated and unreliable - although we are aware of/planning for unreliability with the heartbeat messages..
        • pagelifecycle API provides other options - further notes have been added to the issue (used pagehide where persisted == false: App Liveness Check #1320 (comment)
  • Created heartbeatEvent and heartbeatResponseRequest in proposal
    • Direction is reversed vs. most other interactions (which start with a request from an app to a DA, or are events from the DA without responses
    • There was consensus that we should rename heartbeatResponseRequest to heartbestAcknowledgment
    • The heartbeat messages can be used on a repeating schedule to check if apps are liv
    • They can also be used for adHoc checks - for example are all app instances being shown in the intent resolver alive? Check and remove those that are not.
    • There maybe issues with apps that enter a frozen state (chrome memorySaveer mode) as they may not be able to to respond to heartbeat messages until a resume event. Again see the pagelifecycle API and notes on the issue App Liveness Check #1320 (comment)
      • heartbeats should be added to the proposal, but not a requirement on usage until this issue has been further explored in implementations

• Question: Disposal/Teardown patterns in FDC3 #1263

  • There was not time to discuss this issue, but discussion at the last SWG meeting was referenced: Standard WG Meeting - August 22nd, 2024 #1317
  • The subagent proposal is unlikely to be ready for FDC3 2.2 and will be added to the scope for 2.3 - it will need to include a teardown pattern/api call for subagents.

• Next steps

  • @kriswest to send an email to meeting participants when the first draft of the documentation is available for review. Once reviewed the proposal will be advertised to the FDC3 community ready to check that there is consensus that it should become part of FDC3 in 2.2. This should occur before the next SWG meeting.

Action Items

• @kriswest Complete WCP and DACP documentation, Desktop Agent specs in proposal and include all clarifications
  • To include
    • Describe identity arguments (identityURL, actual URL, URL from appDirectory) and pseudo-code for comparison procedure (all elements from appD URL need to be present in identityURL, origin must match actual URL.
• @kriswest Rename heartbeatResponseRequest to heartbestAcknowledgment
• @robmoffat Implement app closing messages (WCP6Goodbye) in the getAgent() code, to be called on pagehide when the event has persisted == false and an example of using the heartbeat messages (needs support for automated responses in getAgent() implementation - DA implementations can then use the heartbeat as they see fit

Rolled over and/or still in progress:

• @robmoffat @kriswest to to review @Roaders work on generating type predicates automatically using TSMorph
• @robmoffat to look at cleaning up resources for windows and iframes that have gone away under the main proposal.
• @Davidhanson90 to look into tear-down patterns for subagents.
• @robmoffat to update the POC to work on URLs for identity - if not specified the current window.location.href should be used by default, and window.location.href should always have a matching origin to the specified URL.
• @kriswest to ensure that a README and screencast video is provided on maintaining schemas and code generation.

Untracked attendees

Full name	Affiliation	GitHub username

[Lecss]

Alex Dumitru / Citi

[Davidhanson90]

David Hanson / Morgan Stanley 🚀

[robmoffat]

Rob Moffat / FINOS

[openfin-johans]

Johan Sandersson / Here (formerly OpenFin) 🎁

[Roaders]

Giles Roadnight / Morgan Stanley

[hughtroeger]

Hugh Troeger / FactSet

[kriswest]

Kris West / interop.io 🚀