Skip to content

NetworkModelResearch.md

Latest commit

 

History

History
218 lines (185 loc) · 12.3 KB

NetworkModelResearch.md

File metadata and controls

218 lines (185 loc) · 12.3 KB

Network Model Research

This note records the WebKit Network model behavior that WebInspectorCore is comparing against.

WebKit Shape

  • The Network domain is available for itml, page, and service-worker targets in the checked protocol metadata. Many commands and events, including interception and WebSocket events, are narrower and are marked page only.
  • Network.RequestId, Network.FrameId, and Network.LoaderId are protocol string identifiers.
  • The backend creates requestId from ResourceLoaderIdentifier through IdentifiersFactory::requestId, which formats non-zero identifiers through the shared 0.<identifier> inspector id scheme.
  • requestWillBeSent carries requestId, frameId, loaderId, documentURL, request payload, timestamps, initiator, optional redirectResponse, optional resource type, and optional targetId.
  • The optional requestWillBeSent.targetId describes the origin context of the load, such as a target identifier or worker id. It is payload metadata, not the protocol event envelope target.
  • responseReceived, dataReceived, loadingFinished, and loadingFailed continue the same request by requestId.
  • WebInspectorUI stores one Resource per active requestIdentifier in NetworkManager._resourceRequestIdentifierMap.
  • When requestWillBeSent arrives for an existing requestIdentifier, WebInspectorUI treats it as a redirect and updates the same Resource by calling Resource.updateForRedirectResponse.
  • Redirects are stored as WI.Redirect history on the parent Resource. Network table redirect rows are derived entries, not separate protocol request identities.
  • requestServedFromMemoryCache is a one-shot event in WebInspectorUI: it creates a finished cached Resource, fills response/source/size state, and does not keep the requestIdentifier in the active request map.
  • Initial Page.getResourceTree import creates finished Resource objects from frame/resource payloads. These resources may not have a requestIdentifier until a later live network event can associate one.
  • WebSocket events use requestId too, but current WebInspectorUI has a FIXME for iframe and worker WebSockets and attaches WebSocket resources to the main frame path.

Source Evidence

Area WebKit source Relevant fact
Protocol target availability Source/JavaScriptCore/inspector/protocol/Network.json, Source/WebInspectorUI/UserInterface/Protocol/Legacy/iOS/26.4/InspectorBackendCommands.js, Source/WebInspectorUI/UserInterface/Protocol/Legacy/macOS/26.4/InspectorBackendCommands.js Network is registered for itml, page, and service-worker; it activates for itml, service-worker, and web-page. Several commands/events are still page-only.
Protocol identifiers Source/JavaScriptCore/inspector/protocol/Network.json RequestId, FrameId, and LoaderId are separate string types. Continuation events carry requestId; only selected events also carry frame/loader.
Request id generation Source/JavaScriptCore/inspector/IdentifiersFactory.cpp, Source/WebCore/inspector/agents/InspectorNetworkAgent.cpp InspectorNetworkAgent converts ResourceLoaderIdentifier to Network.RequestId with IdentifiersFactory::requestId.
Request start payload Source/JavaScriptCore/inspector/protocol/Network.json, Source/WebCore/inspector/agents/InspectorNetworkAgent.cpp requestWillBeSent contains request metadata, optional redirectResponse, optional resource type, and optional origin targetId.
Redirect handling Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js, Source/WebInspectorUI/UserInterface/Models/Resource.js, Source/WebInspectorUI/UserInterface/Models/Redirect.js An existing requestIdentifier causes Resource.updateForRedirectResponse, which updates current request fields and appends a WI.Redirect.
Redirect rows Source/WebInspectorUI/UserInterface/Views/NetworkTableContentView.js Redirect rows are populated from resource.redirects; their size/timing/type values are derived UI estimates.
Response/data/finish/fail Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js, Source/WebInspectorUI/UserInterface/Models/Resource.js Response events update type, headers, timing, source, and security. Data events increment counters. Finish/fail removes the active request map entry. Finish applies final Network.Metrics when present.
Memory cache event Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js requestServedFromMemoryCache creates and finishes a cached resource and intentionally does not store the id for future loading events.
Initial resource tree Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js Page.getResourceTree import resets frame/resource maps and creates already-finished resources that may lack requestIdentifier.
WebSocket events Source/JavaScriptCore/inspector/protocol/Network.json, Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js, Source/WebInspectorUI/UserInterface/Protocol/NetworkObserver.js WebSocket events use requestId; WebInspectorUI maps them through the same active request map, but frame/worker placement is explicitly incomplete and webSocketFrameError is not implemented in NetworkObserver.
Resource content commands Source/WebInspectorUI/UserInterface/Models/Resource.js, Source/JavaScriptCore/inspector/protocol/Network.json Response body and serialized certificate commands use the parent resource's requestIdentifier on its target's NetworkAgent; redirect history ids are not sent to the backend.

2026-05-16 WebKit Source Reverification

The Network research was rechecked against WebKit source. The request identity conclusion is unchanged: Network.RequestId is the protocol request identity, and redirect rows are derived history. The review narrowed a few edge cases:

  • The optional requestWillBeSent.targetId is origin metadata. The command target remains the protocol event envelope target.
  • WebInspectorUI's live request map is keyed by raw requestIdentifier, but this is inside the active frontend target model. In a multi-target Core, the event envelope target is the collision boundary across targets.
  • requestServedFromMemoryCache is not followed by the usual finish/fail sequence in WebInspectorUI. It creates a finished cached resource directly.
  • WebSocket resources use requestId, but current WebInspectorUI placement is not a complete multi-frame or worker model.
  • Redirect details intentionally contain only basic request/response header and status data. The redirect model comments note that detailed timing, metrics, and security are not populated for redirectResponse.

Derived Concepts

The source evidence implies these separate concepts:

  • ProtocolTarget: protocol routing endpoint that receives Network events and owns Network commands.
  • TargetCapabilities: per-target Network domain and command availability. A target kind alone is not enough; WebInspectorUI enables Network only after target.hasDomain("Network").
  • NetworkRequest: the live request/resource identity for a Network.RequestId within one protocol event target.
  • OriginatingTargetID: optional payload metadata from requestWillBeSent. It can place a Resource under a worker or other target, but it is not the same as the event envelope target.
  • NetworkFrameID: protocol frame id used to place page resources in the frame tree. It is not DOM node identity.
  • NetworkLoaderID: loader lifetime identifier used to group main resource and subresource activity for frame/provisional load state.
  • NetworkRedirectHop: derived history attached to one NetworkRequest. It may have its own UI row and detail view, but it does not become a backend request id.
  • InitialResourceTreeResource: resource imported from Page.getResourceTree. It can be finished and visible without a live requestIdentifier.
  • MemoryCacheResource: one-shot cached resource created from requestServedFromMemoryCache.

Derived Model Invariants

  • Primary request identity is ProtocolTarget.ID + Network.RequestId.
  • redirectIndex is a derived UI/history discriminator only. It is not sent to WebKit as a request id.
  • requestWillBeSent for an existing active request id with redirectResponse appends redirect history and replaces the current request payload on the same request.
  • responseReceived is authoritative for response headers, MIME type, response source, timing, security, and final resource type.
  • loadingFinished is authoritative for source map URL and final Network.Metrics. Exact byte sizes from metrics supersede estimated data counters when available.
  • loadingFailed and loadingFinished close the active request map entry.
  • requestServedFromMemoryCache creates a completed cached request directly; it does not require a matching loadingFinished.
  • Initial resource tree import is a page/frame snapshot, not a live request event replay.
  • WebSocket handshake, frame, and close events share requestId with Network, but WebInspectorUI's current placement is a known incomplete area.

Event Flow

Network.requestWillBeSent
  ├─ no active request:
  │   └─ create NetworkRequest(eventTargetID + requestID)
  ├─ active request + redirectResponse:
  │   ├─ append NetworkRedirectHop(requestID + redirectIndex)
  │   └─ replace current request URL/method/headers/referrer/integrity
  └─ active request without redirectResponse:
      └─ ambiguous duplicate; not a new primary identity

Network.responseReceived
  └─ update current response, type, timing, source, and security

Network.dataReceived
  └─ add decoded and encoded byte counters when available

Network.loadingFinished
  ├─ apply final Network.Metrics when present
  ├─ record sourceMapURL when present
  ├─ mark finished
  └─ close active request entry

Network.loadingFailed
  ├─ mark failed/canceled
  └─ close active request entry

Network.requestServedFromMemoryCache
  └─ create finished cached request directly

Network.webSocket*
  └─ use requestID for handshake/resource/frame history, with upstream
     frame/worker placement limitations

Identity Diagram

Protocol event target: page-1
RequestId: 0.42

NetworkRequest.ID
  └─ page-1 + 0.42

Redirect hop rows
  ├─ page-1 + 0.42 + redirectIndex 0
  └─ page-1 + 0.42 + redirectIndex 1

Protocol commands
  └─ target page-1, requestId 0.42

redirectIndex never goes back to WebKit as a protocol request identity. It is a WebInspector UI/HAR/history identifier only.

Contradicted Interpretations

targetID + requestID + redirectIndex == primary request identity
or
requestWillBeSent.targetId == protocol event envelope target
or
redirect response == separate Resource
or
requestServedFromMemoryCache requires a later loadingFinished
or
initial Page resource tree import is a replay of live Network events

Relationship to DOM and Targets

  • Network frameId belongs to the Page/Network frame tree. It is not a DOM node id and does not identify iframe owner elements.
  • DOM selection can hand a target/node identity to CSS, but Network request identity is independent of DOM node identity.
  • Network target routing follows protocol target capabilities. Optional targetId in a request payload is placement/origin metadata, not a replacement for the event target.
  • Service worker resources can be attached to a target without a page frame. Page resources can be attached to frames. Orphaned resource handling exists when a payload references a target that is not yet available.

Source References

  • Source/JavaScriptCore/inspector/protocol/Network.json
  • Source/JavaScriptCore/inspector/IdentifiersFactory.cpp
  • Source/WebCore/inspector/agents/InspectorNetworkAgent.cpp
  • Source/WebInspectorUI/UserInterface/Protocol/NetworkObserver.js
  • Source/WebInspectorUI/UserInterface/Controllers/NetworkManager.js
  • Source/WebInspectorUI/UserInterface/Models/Resource.js
  • Source/WebInspectorUI/UserInterface/Models/Redirect.js
  • Source/WebInspectorUI/UserInterface/Views/NetworkTableContentView.js
  • Source/WebInspectorUI/UserInterface/Protocol/Legacy/iOS/26.4/InspectorBackendCommands.js
  • Source/WebInspectorUI/UserInterface/Protocol/Legacy/macOS/26.4/InspectorBackendCommands.js