feat: Add support for conditional event source capabilities.

packages/sdk/react-native/__tests__/ReactNativeLDClient.test.ts

@@ -42,6 +42,7 @@ jest.mock('../src/platform', () => ({
  requests: {
  createEventSource: jest.fn(),
  fetch: jest.fn(),
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -70,6 +71,7 @@ it('uses correct default diagnostic url', () => {
  requests: {
  createEventSource: jest.fn(),
  fetch: mockedFetch,
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -97,6 +99,7 @@ it('uses correct default analytics event url', async () => {
  requests: {
  createEventSource: createMockEventSource,
  fetch: mockedFetch,
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -128,6 +131,7 @@ it('uses correct default polling url', async () => {
  requests: {
  createEventSource: jest.fn(),
  fetch: mockedFetch,
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -158,6 +162,7 @@ it('uses correct default streaming url', (done) => {
  requests: {
  createEventSource: mockedCreateEventSource,
  fetch: jest.fn(),
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -197,6 +202,7 @@ it('includes authorization header for polling', async () => {
  requests: {
  createEventSource: jest.fn(),
  fetch: mockedFetch,
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),
@@ -231,6 +237,7 @@ it('includes authorization header for streaming', (done) => {
  requests: {
  createEventSource: mockedCreateEventSource,
  fetch: jest.fn(),
+ getEventSourceCapabilities: jest.fn(),
  },
  encoding: new PlatformEncoding(),
  storage: new PlatformStorage(logger),

packages/sdk/react-native/src/platform/PlatformRequests.ts

@@ -1,6 +1,7 @@
 import type {
  EventName,
  EventSource,
+ EventSourceCapabilities,
  EventSourceInitDict,
  LDLogger,
  Options,
@@ -21,6 +22,14 @@ export default class PlatformRequests implements Requests {
  });
  }
 
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: false,
+ headers: true,
+ customMethod: true,
+ };
+ }
+
  fetch(url: string, options?: Options): Promise<Response> {
  // @ts-ignore
  return fetch(url, options);

packages/sdk/server-node/src/platform/NodeRequests.ts

@@ -7,6 +7,7 @@ import { HttpsProxyAgentOptions } from 'https-proxy-agent';
 import { EventSource as LDEventSource } from 'launchdarkly-eventsource';
 
 import {
+ EventSourceCapabilities,
  LDLogger,
  LDProxyOptions,
  LDTLSOptions,
@@ -158,6 +159,14 @@ export default class NodeRequests implements platform.Requests {
  return new LDEventSource(url, expandedOptions);
  }
 
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: true,
+ headers: true,
+ customMethod: true,
+ };
+ }
+
  usingProxy(): boolean {
  return this.hasProxy;
  }

packages/shared/akamai-edgeworker-sdk/src/platform/requests.ts

@@ -2,6 +2,7 @@
 import { Headers, NullEventSource } from '@launchdarkly/js-server-sdk-common';
 import type {
  EventSource,
+ EventSourceCapabilities,
  EventSourceInitDict,
  Options,
  Requests,
@@ -41,4 +42,12 @@ export default class EdgeRequests implements Requests {
  createEventSource(url: string, eventSourceInitDict: EventSourceInitDict): EventSource {
  return new NullEventSource(url, eventSourceInitDict);
  }
+
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: false,
+ headers: false,
+ customMethod: false,
+ };
+ }
 }

packages/shared/common/src/api/platform/Requests.ts

@@ -78,11 +78,38 @@ export interface Options {
  timeout?: number;
 }
 
+export interface EventSourceCapabilities {
+ /**
+ * If true the event source supports read timeouts. A read timeout for an
+ * event source represents the maximum time between receiving any data.
+ * If you receive 1 byte, and then a period of time greater than the read
+ * time out elapses, and you do not receive a second byte, then that would
+ * cause the event source to timeout.
+ *
+ * It is not a timeout for the read of the entire body, which should be
+ * indefinite.
+ */
+ readTimeout: boolean;
+
+ /**
+ * If true the event source supports customized verbs POST/REPORT instead of
+ * only the default GET.
+ */
+ customMethod: boolean;
+
+ /**
+ * If true the event source supports setting HTTP headers.
+ */
+ headers: boolean;
+}
+
 export interface Requests {
  fetch(url: string, options?: Options): Promise<Response>;
 
  createEventSource(url: string, eventSourceInitDict: EventSourceInitDict): EventSource;
 
+ getEventSourceCapabilities(): EventSourceCapabilities;
+
  /**
  * Returns true if a proxy is configured.
  */

packages/shared/mocks/src/platform.ts

@@ -49,6 +49,7 @@ export const createBasicPlatform = () => ({
  requests: {
  fetch: jest.fn(),
  createEventSource: jest.fn(),
+ getEventSourceCapabilities: jest.fn(),
  },
  storage: {
  get: jest.fn(),

packages/shared/sdk-client/__tests__/flag-manager/FlagPersistence.test.ts

@@ -329,6 +329,7 @@ function makeMockPlatform(storage: Storage, crypto: Crypto): Platform {
  requests: {
  fetch: jest.fn(),
  createEventSource: jest.fn(),
+ getEventSourceCapabilities: jest.fn(),
  },
  };
 }

packages/shared/sdk-client/__tests__/polling/PollingProcessot.test.ts → packages/shared/sdk-client/__tests__/polling/PollingProcessor.test.ts

@@ -2,6 +2,7 @@ import { waitFor } from '@testing-library/dom';
 
 import {
  EventSource,
+ EventSourceCapabilities,
  EventSourceInitDict,
  Info,
  PlatformData,
@@ -45,6 +46,13 @@ function makeRequests(): Requests {
  createEventSource(_url: string, _eventSourceInitDict: EventSourceInitDict): EventSource {
  throw new Error('Function not implemented.');
  },
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: false,
+ headers: false,
+ customMethod: false,
+ };
+ },
  };
 }
 
@@ -169,6 +177,13 @@ it('stops polling when stopped', (done) => {
  createEventSource(_url: string, _eventSourceInitDict: EventSourceInitDict): EventSource {
  throw new Error('Function not implemented.');
  },
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: false,
+ headers: false,
+ customMethod: false,
+ };
+ },
  };
  const dataCallback = jest.fn();
  const errorCallback = jest.fn();

packages/shared/sdk-server-edge/src/platform/requests.ts

@@ -1,6 +1,7 @@
 import { NullEventSource } from '@launchdarkly/js-server-sdk-common';
 import type {
  EventSource,
+ EventSourceCapabilities,
  EventSourceInitDict,
  Options,
  Requests,
@@ -16,4 +17,12 @@ export default class EdgeRequests implements Requests {
  createEventSource(url: string, eventSourceInitDict: EventSourceInitDict): EventSource {
  return new NullEventSource(url, eventSourceInitDict);
  }
+
+ getEventSourceCapabilities(): EventSourceCapabilities {
+ return {
+ readTimeout: false,
+ headers: false,
+ customMethod: false,
+ };
+ }
 }

packages/shared/sdk-server/__tests__/data_sources/Requestor.test.ts

@@ -75,6 +75,9 @@ describe('given a requestor', () => {
  createEventSource(_url: string, _eventSourceInitDict: EventSourceInitDict): EventSource {
  throw new Error('Function not implemented.');
  },
+ getEventSourceCapabilities() {
+ throw new Error('Function not implemented.');
+ },
  };
 
  requestor = new Requestor(

packages/shared/sdk-server/__tests__/events/EventProcessor.test.ts

@@ -111,6 +111,9 @@ function makePlatform(requestState: RequestState) {
  createEventSource(_url: string, _eventSourceInitDict: EventSourceInitDict): EventSource {
  throw new Error('Function not implemented.');
  },
+ getEventSourceCapabilities() {
+ throw new Error('Function not implemented.');
+ },
  };
  return {
  info,