@@ -18,6 +18,7 @@ import 'instance_e2e.dart';
 import 'load_bundle_e2e.dart';
 import 'query_e2e.dart';
 import 'second_database.dart';
+import 'settings_e2e.dart';
 import 'snapshot_metadata_e2e.dart';
 import 'timestamp_e2e.dart';
 import 'transaction_e2e.dart';
@@ -57,5 +58,8 @@ void main() {
 if (defaultTargetPlatform != TargetPlatform.windows) {
 runSecondDatabaseTests();
 }
+if (kIsWeb) {
+runSettingsTest();
+}
 });
 }

@@ -0,0 +1,45 @@
+// Copyright 2020, the Chromium project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:cloud_firestore/cloud_firestore.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void runSettingsTest() {
+group(
+'$Settings',
+() {
+late FirebaseFirestore firestore;
+
+setUpAll(() async {
+firestore = FirebaseFirestore.instance;
+});
+
+Future<Settings> initializeTest() async {
+Settings firestoreSettings = const Settings(
+persistenceEnabled: false,
+webExperimentalForceLongPolling: true,
+webExperimentalAutoDetectLongPolling: true,
+webExperimentalLongPollingOptions: WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 15),
+),
+);
+
+return firestore.settings = firestoreSettings;
+}
+
+testWidgets('checks if long polling settings were applied', (_) async {
+Settings settings = await initializeTest();
+
+expect(settings.webExperimentalForceLongPolling, true);
+
+expect(settings.webExperimentalAutoDetectLongPolling, true);
+
+expect(
+settings.webExperimentalLongPollingOptions,
+settings.webExperimentalLongPollingOptions,
+);
+});
+},
+);
+}

@@ -33,6 +33,7 @@ export 'package:cloud_firestore_platform_interface/cloud_firestore_platform_inte
 DocumentChangeType,
 PersistenceSettings,
 Settings,
+WebExperimentalLongPollingOptions,
 IndexField,
 Index,
 FieldOverrides,

@@ -315,6 +315,11 @@ class FirebaseFirestore extends FirebasePluginPlatform {
 persistenceEnabled: settings.persistenceEnabled,
 host: settings.host,
 cacheSizeBytes: settings.cacheSizeBytes,
+webExperimentalForceLongPolling: settings.webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling:
+settings.webExperimentalAutoDetectLongPolling,
+webExperimentalLongPollingOptions:
+settings.webExperimentalLongPollingOptions,
 );
 }
 

@@ -16,6 +16,9 @@ class Settings {
 this.host,
 this.sslEnabled,
 this.cacheSizeBytes,
+this.webExperimentalForceLongPolling,
+this.webExperimentalAutoDetectLongPolling,
+this.webExperimentalLongPollingOptions,
 this.ignoreUndefinedProperties = false,
 });
 
@@ -51,13 +54,39 @@ class Settings {
 /// Web only.
 final bool ignoreUndefinedProperties;
 
+/// Forces the SDK’s underlying network transport (WebChannel) to use long-polling.
+///
+/// Each response from the backend will be closed immediately after the backend sends data
+/// (by default responses are kept open in case the backend has more data to send).
+/// This avoids incompatibility issues with certain proxies, antivirus software, etc.
+/// that incorrectly buffer traffic indefinitely.
+/// Use of this option will cause some performance degradation though.
+final bool? webExperimentalForceLongPolling;
+
+///	Configures the SDK's underlying transport (WebChannel) to automatically detect if long-polling should be used.
+///
+///This is very similar to [webExperimentalForceLongPolling], but only uses long-polling if required.
+final bool? webExperimentalAutoDetectLongPolling;
+
+/// Options that configure the SDK’s underlying network transport (WebChannel) when long-polling is used.
+///
+/// These options are only used if experimentalForceLongPolling is true
+/// or if [webExperimentalAutoDetectLongPolling] is true and the auto-detection determined that long-polling was needed.
+/// Otherwise, these options have no effect.
+final WebExperimentalLongPollingOptions? webExperimentalLongPollingOptions;
+
 /// Returns the settings as a [Map]
 Map<String, dynamic> get asMap {
 return {
 'persistenceEnabled': persistenceEnabled,
 'host': host,
 'sslEnabled': sslEnabled,
 'cacheSizeBytes': cacheSizeBytes,
+'webExperimentalForceLongPolling': webExperimentalForceLongPolling,
+'webExperimentalAutoDetectLongPolling':
+webExperimentalAutoDetectLongPolling,
+'webExperimentalLongPollingOptions':
+webExperimentalLongPollingOptions?.asMap,
 if (kIsWeb) 'ignoreUndefinedProperties': ignoreUndefinedProperties,
 };
 }
@@ -67,7 +96,10 @@ class Settings {
 String? host,
 bool? sslEnabled,
 int? cacheSizeBytes,
+bool? webExperimentalForceLongPolling,
+bool? webExperimentalAutoDetectLongPolling,
 bool? ignoreUndefinedProperties,
+WebExperimentalLongPollingOptions? webExperimentalLongPollingOptions,
 }) {
 assert(
 cacheSizeBytes == null ||
@@ -81,6 +113,13 @@ class Settings {
 host: host ?? this.host,
 sslEnabled: sslEnabled ?? this.sslEnabled,
 cacheSizeBytes: cacheSizeBytes ?? this.cacheSizeBytes,
+webExperimentalForceLongPolling: webExperimentalForceLongPolling ??
+this.webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling:
+webExperimentalAutoDetectLongPolling ??
+this.webExperimentalAutoDetectLongPolling,
+webExperimentalLongPollingOptions: webExperimentalLongPollingOptions ??
+this.webExperimentalLongPollingOptions,
 ignoreUndefinedProperties:
 ignoreUndefinedProperties ?? this.ignoreUndefinedProperties,
 );
@@ -94,6 +133,12 @@ class Settings {
 other.host == host &&
 other.sslEnabled == sslEnabled &&
 other.cacheSizeBytes == cacheSizeBytes &&
+other.webExperimentalForceLongPolling ==
+webExperimentalForceLongPolling &&
+other.webExperimentalAutoDetectLongPolling ==
+webExperimentalAutoDetectLongPolling &&
+other.webExperimentalLongPollingOptions ==
+webExperimentalLongPollingOptions &&
 other.ignoreUndefinedProperties == ignoreUndefinedProperties;
 
 @override
@@ -103,9 +148,46 @@ class Settings {
 host,
 sslEnabled,
 cacheSizeBytes,
+webExperimentalForceLongPolling,
+webExperimentalAutoDetectLongPolling,
+webExperimentalLongPollingOptions,
 ignoreUndefinedProperties,
 );
 
 @override
 String toString() => 'Settings($asMap)';
 }
+
+/// Options that configure the SDK’s underlying network transport (WebChannel) when long-polling is used.
+@immutable
+class WebExperimentalLongPollingOptions {
+/// The desired maximum timeout interval, in seconds, to complete a long-polling GET response
+///
+/// Valid values are between 5 and 30, inclusive.
+/// By default, when long-polling is used the "hanging GET" request sent by the client times out after 30 seconds.
+/// To request a different timeout from the server, set this setting with the desired timeout.
+/// Changing the default timeout may be useful, for example,
+/// if the buffering proxy that necessitated enabling long-polling in the first place has a shorter timeout for hanging GET requests,
+/// in which case setting the long-polling timeout to a shorter value,
+/// such as 25 seconds, may fix prematurely-closed hanging GET requests.
+final Duration? timeoutDuration;
+
+const WebExperimentalLongPollingOptions({
+this.timeoutDuration,
+});
+
+Map<String, dynamic> get asMap {
+return {
+'timeoutDuration': timeoutDuration?.inSeconds,
+};
+}
+
+@override
+bool operator ==(Object other) =>
+other is WebExperimentalLongPollingOptions &&
+other.runtimeType == runtimeType &&
+other.timeoutDuration == timeoutDuration;
+
+@override
+int get hashCode => Object.hash(runtimeType, timeoutDuration);
+}

@@ -14,14 +14,25 @@ void main() {
 persistenceEnabled: true,
 host: 'foo bar',
 sslEnabled: true,
+webExperimentalForceLongPolling: false,
+webExperimentalAutoDetectLongPolling: false,
 cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
+webExperimentalLongPollingOptions: WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 4),
+),
 ),
 equals(
 const Settings(
 persistenceEnabled: true,
 host: 'foo bar',
 sslEnabled: true,
+webExperimentalForceLongPolling: false,
+webExperimentalAutoDetectLongPolling: false,
 cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
+webExperimentalLongPollingOptions:
+WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 4),
+),
 ),
 ),
 );
@@ -49,6 +60,11 @@ void main() {
 persistenceEnabled: true,
 host: 'foo bar',
 sslEnabled: true,
+webExperimentalAutoDetectLongPolling: false,
+webExperimentalForceLongPolling: false,
+webExperimentalLongPollingOptions: WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 4),
+),
 cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
 );
 
@@ -60,21 +76,35 @@ void main() {
 'persistenceEnabled': null,
 'host': null,
 'sslEnabled': null,
-'cacheSizeBytes': null
+'cacheSizeBytes': null,
+'webExperimentalForceLongPolling': null,
+'webExperimentalAutoDetectLongPolling': null,
+'webExperimentalLongPollingOptions': null,
 });
 
 expect(
 const Settings(
-persistenceEnabled: true,
-host: 'foo bar',
-sslEnabled: true,
-cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
-).asMap,
+persistenceEnabled: true,
+host: 'foo bar',
+sslEnabled: true,
+cacheSizeBytes: Settings.CACHE_SIZE_UNLIMITED,
+webExperimentalAutoDetectLongPolling: true,
+webExperimentalForceLongPolling: true,
+webExperimentalLongPollingOptions:
+WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 4),
+)).asMap,
 <String, dynamic>{
 'persistenceEnabled': true,
 'host': 'foo bar',
 'sslEnabled': true,
 'cacheSizeBytes': Settings.CACHE_SIZE_UNLIMITED,
+'webExperimentalForceLongPolling': true,
+'webExperimentalAutoDetectLongPolling': true,
+'webExperimentalLongPollingOptions':
+const WebExperimentalLongPollingOptions(
+timeoutDuration: Duration(seconds: 4),
+).asMap
 });
 });
 

@@ -719,6 +719,9 @@ abstract class FirestoreSettings {
 JSString? host,
 JSBoolean? ssl,
 JSBoolean? ignoreUndefinedProperties,
+JSBoolean? experimentalForceLongPolling,
+JSBoolean? experimentalAutoDetectLongPolling,
+JSAny? experimentalLongPollingOptions,
 JSObject localCache,
 });
 }
@@ -748,6 +751,35 @@ extension FirestoreSettingsExtension on FirestoreSettings {
 external set localCache(JSObject u);
 }
 
+/// Options that configure the SDK’s underlying network transport (WebChannel) when long-polling is used
+/// These options are only used if experimentalForceLongPolling is true
+/// or if experimentalAutoDetectLongPolling is true and the auto-detection determined that long-polling was needed.
+/// Otherwise, these options have no effect.
+@anonymous
+@JS()
+@staticInterop
+abstract class ExperimentalLongPollingOptions {
+external factory ExperimentalLongPollingOptions({
+JSNumber? timeoutSeconds,
+});
+}
+
+extension ExperimentalLongPollingOptionsExtension
+on ExperimentalLongPollingOptions {
+/// The desired maximum timeout interval, in seconds, to complete a long-polling GET response
+/// Valid values are between 5 and 30, inclusive.
+/// Floating point values are allowed and will be rounded to the nearest millisecond
+/// By default, when long-polling is used the "hanging GET" request sent by the client times out after 30 seconds.
+/// To request a different timeout from the server, set this setting with the desired timeout.
+/// Changing the default timeout may be useful, for example,
+/// if the buffering proxy that necessitated enabling long-polling in the first place has a shorter timeout for hanging GET requests,
+/// in which case setting the long-polling timeout to a shorter value,
+/// such as 25 seconds, may fix prematurely-closed hanging GET requests.
+external JSNumber? get timeoutSeconds;
+
+external set timeoutSeconds(JSNumber? v);
+}
+
 /// Union type from all supported SDK cache layer.
 ///
 /// [MemoryLocalCache] and [MemoryCacheSettings] are the two only cache types supported by the SDK. Custom implementation is not supported.

@@ -21,6 +21,6 @@
 <key>CFBundleVersion</key>
 <string>1.0</string>
 <key>MinimumOSVersion</key>
-<string>11.0</string>
+<string>12.0</string>
 </dict>
 </plist>