Server feature list changed and resource updated notifications #441
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kpavlov
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kpavlov
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Dec 3, 2025
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Thank you, @tiginamaria very good PR
I have few comments about logging, but it can be addressed in a separate PR
| object : FeatureListener { | ||
| override fun onFeatureUpdated(featureKey: FeatureKey) { | ||
| val notification = notificationProvider(featureKey) | ||
| logger.info { "Emitting notification: ${notification.method.value}" } |
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| logger.info { "Emitting notification: ${notification.method.value}" } | |
| logger.debug { "Emitting notification: ${notification.method.value}" } |
| logger.info { "Starting notification job from timestamp $fromTimestamp for sessionId: ${session.sessionId} " } | ||
| job = scope.launch { | ||
| events.takeWhile { it !is EndEvent }.collect { event -> | ||
| when (event) { |
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let's extract handleEvent method
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| sessionNotificationJobs.getAndUpdate { | ||
| if (it.containsKey(session.sessionId)) { | ||
| logger.info { "Session already subscribed: ${session.sessionId}" } |
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| logger.info { "Session already subscribed: ${session.sessionId}" } | |
| logger.debug { "Session already subscribed: ${session.sessionId}" } |
| // Create a timestamp before emit to ensure notifications are processed in order | ||
| val timestamp = getCurrentTimestamp() | ||
| if (closingService.value) { | ||
| logger.warn { "Skipping emitting notification as service is closing: $notification" } |
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This is a normal condition.
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| logger.warn { "Skipping emitting notification as service is closing: $notification" } | |
| logger.debug { "Skipping emitting notification as service is closing: $notification" } |
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| // Launching emit lazily to put it to the jobs queue before the completion | ||
| val job = notificationScope.launch(start = CoroutineStart.LAZY) { | ||
| logger.info { "Actually emitting notification $timestamp: $notification" } |
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| logger.info { "Actually emitting notification $timestamp: $notification" } | |
| logger.debug { "Actually emitting notification $timestamp: $notification" } |
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| val timestamp = getCurrentTimestamp() | ||
| if (closingService.value) { | ||
| logger.warn { "Skipping subscription notification as service is closing: ${session.sessionId}" } |
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| logger.warn { "Skipping subscription notification as service is closing: ${session.sessionId}" } | |
| logger.debug { "Skipping subscription notification as service is closing: ${session.sessionId}" } |
| val job = notificationScope.launch(start = CoroutineStart.LAZY) { | ||
| logger.info { "Actually emitting notification $timestamp: $notification" } | ||
| notificationEvents.emit(SendEvent(timestamp, notification)) | ||
| logger.info { "Notification emitted $timestamp: $notification" } |
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| logger.info { "Notification emitted $timestamp: $notification" } | |
| logger.debug { "Notification emitted $timestamp: $notification" } |
Fix logging levels Extract send event handling
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Motivation and Context
Implemented thread-safe notification service following eventual consistency principle.
Fixes #249
Contracts:
The flow of the notification is explained in the diagram:
Documentation references:
https://modelcontextprotocol.io/specification/2025-06-18/server/prompts#list-changed-notification
https://modelcontextprotocol.io/specification/2025-06-18/server/tools#list-changed-notification
https://modelcontextprotocol.io/specification/2025-06-18/server/resources#list-changed-notification
https://modelcontextprotocol.io/specification/2025-06-18/server/resources#subscriptions
Questions:
How Has This Been Tested?
Multiple tests with various notification scenarios were added
Breaking Changes
Types of changes
Checklist
Additional context