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Add fallback request
1 parent 984c318 commit 387ea6b

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‎docs/reference-tables/ea-settings.md‎

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Original file line numberDiff line numberDiff line change
@@ -61,6 +61,7 @@
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| TLS_PASSPHRASE | string | | Password to be used to generate an encryption key | | |
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| TLS_PRIVATE_KEY | string | undefined | Base64 Private Key of TSL/SSL certificate | - Value must be a valid base64 string | |
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| TLS_PUBLIC_KEY | string | undefined | Base64 Public Key of TSL/SSL certificate | - Value must be a valid base64 string | |
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| TRANSPORT_FALLBACK_ENABLED | boolean | false | Flag to enable endpoint fallback transports when configured | | |
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| WARMUP_SUBSCRIPTION_TTL | number | 300000 | TTL for batch warmer subscriptions | - Value must be an integer<br> - Value must be above the minimum<br> - Value must be below the maximum | 0 | 3600000 |
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| WS_CONNECTION_OPEN_TIMEOUT | number | 10000 | The maximum amount of time in milliseconds to wait for the websocket connection to open (including custom open handler) | - Value must be an integer<br> - Value must be above the minimum<br> - Value must be below the maximum | 500 | 30000 |
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| WS_HEARTBEAT_INTERVAL_MS | number | 10000 | The number of ms between each hearbeat message that EA sends to server, only works if heartbeat handler is provided | - Value must be an integer<br> - Value must be above the minimum<br> - Value must be below the maximum | 5000 | 300000 |

‎src/adapter/basic.ts‎

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@@ -15,6 +15,7 @@ import {
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highestRateLimitTiers,
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} from '../rate-limiting'
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import { RateLimiterFactory, RateLimitingStrategy } from '../rate-limiting/factory'
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import { Transport } from '../transports'
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import {
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AdapterRequest,
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AdapterResponse,
@@ -449,6 +450,21 @@ export class Adapter<
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const endpoint = this.endpointsMap[req.requestContext.endpointName]
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const transport = endpoint.transportRoutes.get(req.requestContext.transportName)
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// TODO: Handle fallback transport
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const fallbackTransportName = endpoint.getFallbackTransportNameForRequest(
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req.requestContext.transportName,
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this.config.settings,
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)
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this.createFallbackRequest(req, fallbackTransportName)
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return this.handleSingleTransportRequest(req, replySent, transport)
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}
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private async handleSingleTransportRequest(
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req: AdapterRequest<EmptyInputParameters>,
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replySent: Promise<unknown>,
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transport: Transport<EndpointGenerics>,
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): Promise<Readonly<AdapterResponse>> {
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// First try to find the response in our cache, keep it ready
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const cachedResponse = await this.findResponseInCache(req)
454470

@@ -544,4 +560,19 @@ export class Adapter<
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statusCode: 504,
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})
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}
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private createFallbackRequest(req: AdapterRequest<EmptyInputParameters>, transportName?: string) {
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if (!transportName) {
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return
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}
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return {
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...req,
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requestContext: {
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...req.requestContext,
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transportName,
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cacheKey: `${req.requestContext.cacheKey}-fallback`,
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},
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} as AdapterRequest<EmptyInputParameters>
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}
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}

‎src/adapter/endpoint.ts‎

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@@ -46,6 +46,7 @@ export class AdapterEndpoint<T extends EndpointGenerics> implements AdapterEndpo
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settings: T['Settings'],
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) => string
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defaultTransport?: string
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fallbackTransport?: string
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constructor(params: AdapterEndpointParams<T>) {
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this.name = params.name
@@ -55,6 +56,7 @@ export class AdapterEndpoint<T extends EndpointGenerics> implements AdapterEndpo
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this.transportRoutes = params.transportRoutes
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this.customRouter = params.customRouter
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this.defaultTransport = params.defaultTransport
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this.fallbackTransport = params.fallbackTransport?.toLowerCase()
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} else {
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this.transportRoutes = new TransportRoutes<T>().register(
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DEFAULT_TRANSPORT_NAME,
@@ -186,6 +188,34 @@ export class AdapterEndpoint<T extends EndpointGenerics> implements AdapterEndpo
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return transportName
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}
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getFallbackTransportNameForRequest(primaryTransportName: string, settings: T['Settings']) {
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if (!settings.TRANSPORT_FALLBACK_ENABLED || !this.fallbackTransport) {
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logger.trace('TRANSPORT_FALLBACK_ENABLED is false or fallbackTransport is not set')
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return
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}
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const fallbackTransportName = this.fallbackTransport.toLowerCase()
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if (!this.transportRoutes.get(fallbackTransportName)) {
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throw new AdapterError({
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statusCode: 400,
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message: `No fallback transport found for key "${fallbackTransportName}", must be one of ${JSON.stringify(
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this.transportRoutes.routeNames(),
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)}`,
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})
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}
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if (fallbackTransportName === primaryTransportName.toLowerCase()) {
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throw new AdapterError({
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statusCode: 400,
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message: `Fallback transport "${fallbackTransportName}" cannot be the same as primary transport.`,
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})
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}
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logger.debug(`Request can fall back to transport "${fallbackTransportName}"`)
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return fallbackTransportName
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}
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/**
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* Default routing strategy. Will try and use the transport override if present
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* or transport input parameter in the request body.

‎src/adapter/types.ts‎

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@@ -183,6 +183,9 @@ type MultiTransportAdapterEndpointParams<T extends EndpointGenerics> = {
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/** If no value is returned from the custom router or the default (transport param), which transport to use */
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defaultTransport?: string
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/** Backup transport to use when the primary transport is unable to return data */
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fallbackTransport?: string
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}
187190

188191
/**

‎src/config/index.ts‎

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@@ -276,6 +276,11 @@ export const BaseSettingsDefinition = {
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default: 200,
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validate: validator.integer({ min: 10, max: 1000 }),
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},
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TRANSPORT_FALLBACK_ENABLED: {
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description: 'Flag to enable endpoint fallback transports when configured',
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type: 'boolean',
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default: false,
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},
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DEFAULT_CACHE_KEY: {
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description: 'Default key to be used when one cannot be determined from request parameters',
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type: 'string',

‎test/transports/routing.test.ts‎

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Original file line numberDiff line numberDiff line change
@@ -680,6 +680,75 @@ test.serial('transports with same name throws error', async (t) => {
680680
)
681681
})
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test.serial('fallback transport is ignored when disabled', (t) => {
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const endpoint = new AdapterEndpoint<BaseEndpointTypes>({
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inputParameters,
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name: 'price',
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transportRoutes: transports,
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fallbackTransport: 'invalid',
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})
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const config = new AdapterConfig(settings)
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config.initialize()
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t.is(endpoint.getFallbackTransportNameForRequest('batch', config.settings), undefined)
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})
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test.serial('fallback transport is normalized when enabled', (t) => {
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const endpoint = new AdapterEndpoint<BaseEndpointTypes>({
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inputParameters,
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name: 'price',
700+
transportRoutes: transports,
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fallbackTransport: 'WEBSOCKET',
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})
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const config = new AdapterConfig(settings, {
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envDefaultOverrides: {
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TRANSPORT_FALLBACK_ENABLED: true,
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},
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})
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config.initialize()
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t.is(endpoint.getFallbackTransportNameForRequest('batch', config.settings), 'websocket')
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})
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713+
test.serial('fallback transport must be registered when enabled', (t) => {
714+
const endpoint = new AdapterEndpoint<BaseEndpointTypes>({
715+
inputParameters,
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name: 'price',
717+
transportRoutes: transports,
718+
fallbackTransport: 'invalid',
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})
720+
const config = new AdapterConfig(settings, {
721+
envDefaultOverrides: {
722+
TRANSPORT_FALLBACK_ENABLED: true,
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},
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})
725+
config.initialize()
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727+
t.throws(() => endpoint.getFallbackTransportNameForRequest('batch', config.settings), {
728+
message:
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'No fallback transport found for key "invalid", must be one of ["websocket","batch","sse"]',
730+
})
731+
})
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733+
test.serial('fallback transport cannot match primary transport', (t) => {
734+
const endpoint = new AdapterEndpoint<BaseEndpointTypes>({
735+
inputParameters,
736+
name: 'price',
737+
transportRoutes: transports,
738+
fallbackTransport: 'batch',
739+
})
740+
const config = new AdapterConfig(settings, {
741+
envDefaultOverrides: {
742+
TRANSPORT_FALLBACK_ENABLED: true,
743+
},
744+
})
745+
config.initialize()
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747+
t.throws(() => endpoint.getFallbackTransportNameForRequest('batch', config.settings), {
748+
message: 'Fallback transport "batch" cannot be the same as primary transport.',
749+
})
750+
})
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test.serial('transport override routes to correct Transport', async (t) => {
684753
axiosMock
685754
.onPost(`${restUrl}/price`, {

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