com.amplifyframework.apollo.appsync.AppSyncProtocol.kt Maven / Gradle / Ivy
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Allows Apollo to connect to AppSync
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/*
* Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package com.amplifyframework.apollo.appsync
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.ConnectionAck
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.ConnectionError
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.ConnectionInit
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.ConnectionKeepAlive
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionAck
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionComplete
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionData
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionError
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionStart
import com.amplifyframework.apollo.appsync.SubscriptionMessageType.SubscriptionStop
import com.apollographql.apollo.api.ApolloRequest
import com.apollographql.apollo.api.Operation
import com.apollographql.apollo.exception.NullOrMissingField
import com.apollographql.apollo.exception.SubscriptionConnectionException
import com.apollographql.apollo.network.ws.WebSocketConnection
import com.apollographql.apollo.network.ws.WsProtocol
import kotlin.time.Duration.Companion.seconds
import kotlinx.coroutines.CompletableJob
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch
import kotlinx.coroutines.withTimeout
/**
* Implementation of [WsProtocol] that implements the subscription protocol for AppSync.
*
* Pass an instance of the [Factory] class to WebSocketNetworkTransport to use this protocol when subscribing to
* AppSync.
*/
class AppSyncProtocol internal constructor(
private val endpoint: AppSyncEndpoint,
private val authorizer: AppSyncAuthorizer,
webSocketConnection: WebSocketConnection,
listener: Listener,
private val scope: CoroutineScope
) : WsProtocol(webSocketConnection, listener) {
private val connectionAckTimeout = 10.seconds
private val subscriptionAckTimeout = 10.seconds
// Subscriptions for which we are awaiting an acknowledgement from AppSync
private val pendingSubscriptions = mutableMapOf()
override suspend fun connectionInit() {
// See SubscriptionEndpoint.onOpen
sendMessageMapText(mapOf("type" to ConnectionInit.value))
waitForConnectionAck()
}
override fun handleServerMessage(messageMap: Map) {
val message = decodeServerMessage(messageMap)
if (message == null) {
// No type specified
listener.generalError(messageMap)
return
}
// See AmplifyWebsocketListener.processJsonMessage
when (message.type) {
SubscriptionAck -> pendingSubscriptions[message.id]?.complete()
SubscriptionData -> when {
message.id == null -> listener.generalError(message.payload)
message.payload == null -> listener.operationError(message.id, null)
else -> listener.operationResponse(message.id, message.payload)
}
SubscriptionError -> {
if (message.id != null) {
listener.operationError(message.id, message.payload)
} else {
listener.generalError(message.payload)
}
}
SubscriptionComplete -> listener.operationComplete(message.id!!)
ConnectionKeepAlive -> Unit // Connection keep-alive, nothing to do
else -> Unit // other message, nothing to do
}
}
override fun startOperation(request: ApolloRequest) {
scope.launch {
val subscriptionId = request.subscriptionId
// Prepare to wait for the subscription acknowledgement
val subscriptionAck = Job()
pendingSubscriptions[subscriptionId] = subscriptionAck
// Get the request content as a string
val data = request.toJson()
// All authorization types require specifying the host. Append the authorizer-specific headers
val authorization = mapOf(
"host" to endpoint.serverUrl.host
) + authorizer.getWebSocketSubscriptionPayload(endpoint, request)
// See SubscriptionEndpoint.startSubscription
sendMessageMapText(
mapOf(
"id" to subscriptionId,
"type" to SubscriptionStart.value,
"payload" to
mapOf(
"data" to data,
"extensions" to
mapOf(
"authorization" to authorization
)
)
)
)
// Wait for the subscription to be acknowledged. Close with an error if the ack is not received.
try {
withTimeout(subscriptionAckTimeout.inWholeMilliseconds) {
subscriptionAck.join()
}
} catch (e: Exception) {
println("Error waiting for subscription to be acknowledged: $e")
listener.operationError(subscriptionId, null)
} finally {
pendingSubscriptions.remove(subscriptionId)
}
}
}
override fun stopOperation(request: ApolloRequest) {
// See SubscriptionEndpoint.releaseSubscription
sendMessageMapText(
mapOf(
"id" to request.subscriptionId,
"type" to SubscriptionStop.value
)
)
}
private suspend fun waitForConnectionAck() = withTimeout(connectionAckTimeout.inWholeMilliseconds) {
while (true) {
val map = receiveMessageMap()
val type = map["type"] as? String ?: throw NullOrMissingField("No AppSync message type specified: $map")
when (type.messageType) {
ConnectionAck -> return@withTimeout
ConnectionError -> throw SubscriptionConnectionException(map)
else -> continue
}
}
}
private fun decodeServerMessage(message: Map): ServerMessage? {
val type = (message["type"] as? String)?.messageType ?: return null
val id = message["id"] as? String
@Suppress("UNCHECKED_CAST")
val payload = message["payload"] as? Map
return ServerMessage(type, id, payload)
}
/**
* The [WsProtocol.Factory] class for instantiating [AppSyncProtocol] instances. This should be passed to
* the WebSocketNetworkTransport builder to allow the websocket to connect to AppSync.
* @param endpoint The [AppSyncEndpoint] to connect to
* @param authorizer The [AppSyncAuthorizer] that determines the authorization mode to use when connecting to AppSync
*/
class Factory(private val endpoint: AppSyncEndpoint, private val authorizer: AppSyncAuthorizer) :
WsProtocol.Factory {
override val name = "graphql-ws"
override fun create(
webSocketConnection: WebSocketConnection,
listener: Listener,
scope: CoroutineScope
): WsProtocol = AppSyncProtocol(
endpoint = endpoint,
authorizer = authorizer,
webSocketConnection = webSocketConnection,
listener = listener,
scope = scope
)
}
private data class ServerMessage(
val type: SubscriptionMessageType,
val id: String?,
val payload: Map?
)
}