feat: Add subscriptions support to ktor server #1774

thevietto · 2023-05-10T13:07:36Z

📝 Description

Out of the box subscriptions support to the ktor-server

I added an implementation for both legacy subscriptions-transport-ws and graphql-ws protocols. Latter is the default.

basic configuration example:

    install(GraphQL) {
        schema {
            subscriptions = listOf(
                ExampleSubscriptionService()
            )
        }
    }
    install(Routing) {
        graphQLSubscriptionsRoute()
    }

Docs updated
Example app updated

🔗 Related Issues

#1587
#1756

...lin-ktor-server/src/main/kotlin/com/expediagroup/graphql/server/ktor/GraphQLConfiguration.kt

...in/kotlin/com/expediagroup/graphql/server/ktor/subscriptions/KtorGraphQLSubscriptionHooks.kt

allebdev · 2023-05-11T09:05:44Z

...in/kotlin/com/expediagroup/graphql/server/ktor/subscriptions/KtorGraphQLSubscriptionHooks.kt

+/**
+ * Default implementation of Apollo Subscription Lifecycle Events (No-op).
+ */
+open class DefaultKtorGraphQLLegacySubscriptionHooks : KtorGraphQLSubscriptionHooks


Probably, it doesn't make sense to make the default implementation open

I hate library classes that closes themselves from being extended (e.g if just need to add 1 line, not copying all of the code). Even though the default impl is empty, it may be convenient to declare MyImpl extends DefaultImpl

since those hooks are generic and applicable to both graphql-ws and subscriptions-transport-ws lets drop the Legacy from the name. We can probably update KDoc to be more generic as well - yes you can use similar hooks in apollo-server but again those are pretty generic lifecycle events.

Suggested change

open class DefaultKtorGraphQLLegacySubscriptionHooks : KtorGraphQLSubscriptionHooks

open class DefaultKtorGraphQLSubscriptionHooks : KtorGraphQLSubscriptionHooks

allebdev · 2023-05-11T09:32:35Z

...ediagroup/graphql/server/ktor/subscriptions/graphqlws/KtorGraphQLWebSocketProtocolHandler.kt

+    private val pongMessage = objectMapper.writeValueAsString(SubscriptionOperationMessage(MessageTypes.GQL_PONG))
+
+    override suspend fun handle(session: WebSocketServerSession) {
+        logger.debug("New client connected")


log message without context (and there are more below in the class)

unfortunately Ktor doesn't provide any ID or something contextual for the WebSocketSession. So if there is a new client connected, it doesn't seem obvious what to log (except you generate an artificial ID and log it, but I decided not to do that)

what you will get in the log though, is the coroutine trace, which is good enough I think

...ediagroup/graphql/server/ktor/subscriptions/graphqlws/KtorGraphQLWebSocketProtocolHandler.kt

dariuszkuc

nice work! lets drop the Apollo subscriptions-transport-ws protocol as it is unmaintained since 2018 so there is no point in adding support for it

dariuszkuc · 2023-05-17T16:57:42Z

...s/graphql-kotlin-ktor-server/src/main/kotlin/com/expediagroup/graphql/server/ktor/GraphQL.kt

@@ -160,6 +166,15 @@ class GraphQL(config: GraphQLConfiguration) {
        )
    )

+    val subscriptionsHandler: KtorGraphQLSubscriptionHandler = KtorGraphQLWebSocketProtocolHandler(


can we make it lazily created? not everyone needs subscriptions so this object may never be used

Suggested change

val subscriptionsHandler: KtorGraphQLSubscriptionHandler = KtorGraphQLWebSocketProtocolHandler(

val subscriptionsHandler: KtorGraphQLSubscriptionHandler by lazy {

KtorGraphQLWebSocketProtocolHandler(...)

}

dariuszkuc · 2023-05-17T16:59:01Z

...hql-kotlin-ktor-server/src/main/kotlin/com/expediagroup/graphql/server/ktor/GraphQLRoutes.kt

-import io.ktor.server.routing.application
-import io.ktor.server.routing.get
-import io.ktor.server.routing.post
+import io.ktor.http.*


please don't use wildcard imports, use single import per line -> this comment applies to all other files as well

dariuszkuc · 2023-05-17T17:00:10Z

...kotlin-ktor-server/src/main/kotlin/com/expediagroup/graphql/server/ktor/KtorGraphQLServer.kt

@@ -18,6 +18,7 @@ package com.expediagroup.graphql.server.ktor

 import com.expediagroup.graphql.server.execution.GraphQLRequestHandler
 import com.expediagroup.graphql.server.execution.GraphQLServer
+import com.expediagroup.graphql.server.ktor.subscriptions.KtorGraphQLSubscriptionHandler


guessing this will fail linting as it is not used in the file

Suggested change

import com.expediagroup.graphql.server.ktor.subscriptions.KtorGraphQLSubscriptionHandler

dariuszkuc · 2023-05-17T17:06:49Z

...in/kotlin/com/expediagroup/graphql/server/ktor/subscriptions/KtorGraphQLSubscriptionHooks.kt

+/**
+ * Default implementation of Apollo Subscription Lifecycle Events (No-op).
+ */
+open class DefaultKtorGraphQLLegacySubscriptionHooks : KtorGraphQLSubscriptionHooks


since those hooks are generic and applicable to both graphql-ws and subscriptions-transport-ws lets drop the Legacy from the name. We can probably update KDoc to be more generic as well - yes you can use similar hooks in apollo-server but again those are pretty generic lifecycle events.

Suggested change

open class DefaultKtorGraphQLLegacySubscriptionHooks : KtorGraphQLSubscriptionHooks

open class DefaultKtorGraphQLSubscriptionHooks : KtorGraphQLSubscriptionHooks

thevietto · 2023-05-18T12:57:30Z

thanks @dariuszkuc
all fixed, could you re-review?

dariuszkuc · 2023-05-18T14:55:25Z

website/docs/server/ktor-server/ktor-subscriptions.md

+}
+```
+
+### `subscriptions-transport-ws` (legacy)


this was just dropped so lets update the docs to reflect it

right, updated 👍

dariuszkuc

Changes look fine to me. @samuelAndalon any thoughts on this PR?

website/docs/server/ktor-server/ktor-subscriptions.md

Co-authored-by: Dariusz Kuc <9501705+dariuszkuc@users.noreply.github.com>

feat: Add subscriptions support to ktor server

8cdb1fb

allebdev reviewed May 11, 2023

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chore: typo fix

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thevietto requested a review from allebdev May 11, 2023 09:55

dariuszkuc requested changes May 17, 2023

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thevietto added 8 commits May 18, 2023 16:21

chore: remove Legacy word and update KDoc

ef75365

chore: remove legacy subscriptions impl

a1f3d7b

chore: remove wildcard import

29f0f2d

feat: add subscriptionsEndpoint to graphiQLRoute

84b7e5a

chore: remove unused import

442882d

chore: update GQL plugin test

4e31b28

chore: remove wildcard imports

79507a9

chore: update jacoco coverage config for ktor module

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thevietto requested a review from dariuszkuc May 18, 2023 12:57

chore: make subscriptionsHandler lazy

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chore: update ktor-server GQL subscriptions docs

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thevietto requested a review from dariuszkuc May 18, 2023 18:41

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thevietto and others added 2 commits May 19, 2023 19:28

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samuelAndalon merged commit 98e900e into ExpediaGroup:master May 19, 2023

dariuszkuc mentioned this pull request Jun 1, 2023

Update ktor sample for subscriptions #1587

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feat: Add subscriptions support to ktor server #1774

feat: Add subscriptions support to ktor server #1774

thevietto commented May 10, 2023

allebdev May 11, 2023

thevietto May 11, 2023 •

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	open class DefaultKtorGraphQLLegacySubscriptionHooks : KtorGraphQLSubscriptionHooks
	open class DefaultKtorGraphQLSubscriptionHooks : KtorGraphQLSubscriptionHooks

-    val subscriptionsHandler: KtorGraphQLSubscriptionHandler = KtorGraphQLWebSocketProtocolHandler(
+    val subscriptionsHandler: KtorGraphQLSubscriptionHandler by lazy {
+      KtorGraphQLWebSocketProtocolHandler(...)
+    }

feat: Add subscriptions support to ktor server #1774

feat: Add subscriptions support to ktor server #1774

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thevietto commented May 10, 2023

📝 Description

Out of the box subscriptions support to the ktor-server

🔗 Related Issues

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thevietto May 11, 2023 • edited Loading

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thevietto commented May 18, 2023

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thevietto May 11, 2023 •

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