Implementing Custom Push Notification Gateways for Mobile Agent Application Alerts

How-To-Articles
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Implementing Custom Push Notification Gateways for Mobile Agent Application Alerts

What This Guide Covers

This guide details the architectural implementation of a custom middleware service to intercept Genesys Cloud CX inbound events and relay them as native push notifications to mobile agents via Apple Push Notification service (APNs) and Firebase Cloud Messaging (FCM). The end result is a sub-second alert system that bypasses the standard mobile app polling latency, ensuring agents receive call, chat, or callback notifications immediately, even when the application is in the background or terminated.

Prerequisites, Roles & Licensing

Licensing

  • Genesys Cloud CX: Standard CX license for agents. No specific “Mobile Push” add-on is required as this leverages the standard Event Streams API.
  • Mobile App: Agents must use the official Genesys Cloud Mobile App (iOS/Android) or a custom-built app utilizing the Genesys Cloud WebRTC SDK. Note that the official mobile app does not expose a direct API key for custom push payloads; this guide assumes a hybrid approach where you build a lightweight wrapper or utilize the WebRTC SDK in a custom container to handle the deep link and media negotiation.

Permissions & Roles

  • Admin Role: admin:api:read and admin:api:write are required to configure Event Streams.
  • API User: A dedicated service account with the following OAuth scopes:
    • event:stream:read
    • routing:conversation:read
    • user:read
    • routing:queue:read
  • Mobile Backend: Access to APNs Key (.p8) and FCM Server Key.

External Dependencies

  • Middleware Runtime: Node.js, Python, or Go instance to handle WebSocket persistence and HTTP POST requests to APNs/FCM.
  • Database: Redis or DynamoDB for mapping Genesys Cloud User IDs to Device Tokens (APNs/FCM).
  • SSL Certificates: Valid TLS certificates for the middleware endpoint if exposing it directly, though AWS API Gateway or Azure Functions is recommended for serverless deployment.

The Implementation Deep-Dive

1. Establishing the Event Stream Subscription

The foundation of this architecture is the Genesys Cloud Event Streams API. Unlike Webhooks, which are HTTP-based and can suffer from retry storms and ordering issues under high load, Event Streams uses WebSocket protocols to maintain a persistent, ordered connection. This is critical for mobile push notifications because you must distinguish between a call being assigned to an agent and a call being abandoned or transferred away from that same agent within milliseconds.

Configuring the Stream

You must create an Event Stream subscription in the Genesys Cloud Admin console or via the API. The subscription must target specific event types to minimize payload size and processing overhead.

API Call: Create Event Stream Subscription

POST /api/v2/analytics/eventstreams/subscriptions
Authorization: Bearer <ACCESS_TOKEN>
Content-Type: application/json

JSON Payload:

{
  "name": "MobilePushGateway_Subscription",
  "description": "Captures inbound routing events for mobile push relay",
  "streamType": "WEBSOCKET",
  "events": [
    "routing.queue.member.added",
    "routing.conversation.created",
    "routing.conversation.updated",
    "routing.conversation.deleted"
  ],
  "filters": [
    {
      "type": "conversation",
      "field": "mediaType",
      "operator": "EQ",
      "value": "voice"
    },
    {
      "type": "conversation",
      "field": "mediaType",
      "operator": "EQ",
      "value": "chat"
    }
  ]
}

The Trap: Unfiltered Streams

The most common misconfiguration is subscribing to all events without filtering by media type or interaction state. Genesys Cloud generates thousands of internal state-change events per conversation (e.g., routing.interaction.updated, routing.interaction.mediaUpdated). If your middleware processes every single event, you will hit the WebSocket message rate limits (typically 100 messages per second per connection) and introduce significant CPU overhead.

Architectural Reasoning:
Filter at the subscription level using the filters array in the payload. Do not filter in your middleware code. If you filter in code, you are still consuming the bandwidth and connection slots for events you discard. By filtering in the Genesys Cloud API, you reduce the network payload to only the events that trigger a push notification logic branch.

2. Designing the Middleware Translation Layer

Your middleware acts as the bridge between Genesys Cloud’s JSON event structure and the binary/JSON structures required by APNs and FCM. This service must maintain a stateful registry of active device tokens.

Token Mapping Strategy

Genesys Cloud does not natively store APNs/FCM device tokens for security and privacy reasons. You must build a mapping table.

Data Structure:
Store a hash map in Redis:
Key: gen_user_id_<uuid>
Value: { "apn_token": "hex_string", "fcm_token": "long_string", "platform": "ios|android" }

This mapping is populated when the agent logs into the mobile app. Your mobile app must call your middleware’s /register-token endpoint upon successful Genesys Cloud authentication.

Handling the “Added to Queue” Event

When a call is assigned to a mobile agent, Genesys Cloud emits a routing.queue.member.added event. This is the trigger for the push notification.

Sample Event Payload (Genesys Cloud):

{
  "eventType": "routing.queue.member.added",
  "timestamp": "2023-10-27T10:00:00.000Z",
  "data": {
    "queueId": "12345678-1234-1234-1234-123456789012",
    "memberId": "87654321-4321-4321-4321-210987654321",
    "memberType": "user",
    "conversationId": "conv-abc-123",
    "mediaType": "voice"
  }
}

Middleware Logic:

  1. Extract memberId (User ID).
  2. Look up device tokens in Redis.
  3. If multiple devices exist (e.g., iPhone and iPad), send pushes to all.
  4. Construct the Push Payload.

Constructing the Push Payload

The payload must contain enough information for the mobile app to initiate the WebRTC session without requiring the user to click through multiple screens.

APNs Payload Structure:

{
  "aps": {
    "alert": {
      "title": "Inbound Call",
      "body": "From: +15550199888 | Queue: Sales Support",
      "sound": "default"
    },
    "content-available": 1,
    "category": "INCOMING_CALL",
    "custom": {
      "genesys_conversation_id": "conv-abc-123",
      "genesys_user_id": "87654321-4321-4321-4321-210987654321",
      "media_type": "voice",
      "timestamp": "2023-10-27T10:00:00.000Z"
    }
  }
}

The Trap: Missing content-available
On iOS, if you omit "content-available": 1, the app will only wake up when the user taps the notification. This is unacceptable for voice calls. This key forces the app to wake up in the background, allowing your code to execute the WebRTC join logic immediately. On Android, ensure the notification channel is configured with IMPORTANCE_HIGH to bypass Do Not Disturb modes if permitted by company policy.

Architectural Reasoning:
Include the genesys_conversation_id in the custom payload. When the app wakes up, it must use this ID to fetch the current conversation state via the Genesys Cloud REST API (GET /api/v2/routing/conversations/{conversationId}). Do not assume the state is still “ringing.” The agent might have missed it, or it might have been transferred. Fetching the live state prevents race conditions where the app tries to join a conversation that has already ended.

3. Implementing Idempotency and Race Condition Handling

Mobile push notifications are not guaranteed delivery mechanisms. APNs and FCM may retry failed deliveries. Your middleware must handle duplicate events gracefully.

The Double-Ring Problem

Scenario:

  1. Genesys Cloud sends routing.queue.member.added.
  2. Middleware sends Push Notification A.
  3. APNs fails to deliver and retries Push Notification B 2 seconds later.
  4. The agent’s phone rings twice.

Solution: Deduplication Window
In your middleware, maintain a short-lived cache (e.g., 5 seconds) of sent push IDs.

// Pseudo-code for Node.js middleware
const sentPushCache = new Map(); // Key: conversationId, Value: timestamp

async function handlePushEvent(event) {
  const convId = event.data.conversationId;
  const now = Date.now();
  
  if (sentPushCache.has(convId)) {
    const lastSent = sentPushCache.get(convId);
    if (now - lastSent < 5000) {
      console.log("Duplicate push suppressed for", convId);
      return;
    }
  }

  sentPushCache.set(convId, now);
  await sendToApnsAndFcm(event);
}

The Trap: Ignoring Conversation State Changes

If the agent does not answer, the conversation state changes to routing.conversation.deleted (abandoned) or routing.queue.member.removed (transferred). If your middleware does not listen for these subsequent events, the agent’s phone might continue to ring indefinitely if the mobile app does not handle the timeout locally.

Architectural Reasoning:
Your middleware must also subscribe to routing.conversation.deleted and routing.queue.member.removed. When these events occur for a conversation ID that was previously pushed, you must send a “Cancel Ring” push notification.

Cancel Push Payload (APNs):

{
  "aps": {
    "alert": {
      "title": "Call Cancelled",
      "body": "The call has been transferred or abandoned."
    },
    "content-available": 1,
    "category": "CALL_CANCEL",
    "custom": {
      "genesys_conversation_id": "conv-abc-123",
      "action": "cancel_ring"
    }
  }
}

The mobile app must implement logic to dismiss the local ringing UI if a CALL_CANCEL push is received before the user answers.

4. Handling Agent Presence and Capacity

Sending a push notification to an agent who is already on a call or set to “Offline” is a waste of resources and a poor user experience.

Filtering by Presence

Before sending a push, query the Genesys Cloud Presence API.

API Call: Get User Presence

GET /api/v2/users/{userId}/presence
Authorization: Bearer <ACCESS_TOKEN>

Response Check:

{
  "currentPresence": {
    "presenceDefinitionId": "123",
    "presenceStatus": {
      "id": "offline",
      "name": "Offline"
    }
  }
}

Logic:

  • If presenceStatus.id is offline, away, or onACall, suppress the push.
  • If presenceStatus.id is available, proceed.

The Trap: Presence Latency
Presence updates in Genesys Cloud are near-real-time but not instantaneous. There is a potential 2-3 second lag. If an agent just clicked “Available,” your middleware might still see “Offline” and suppress the push, causing a missed call.

Architectural Reasoning:
To mitigate this, rely on the routing.queue.member.added event as the source of truth. If Genesys Cloud has assigned the call to the agent, the platform has already verified that the agent has capacity. You can skip the explicit Presence API check if you trust the routing engine’s decision. However, if you want to avoid sending pushes to agents who are manually set to “Offline” but still in a queue (misconfiguration), you can use the Presence check as a soft filter, but log suppressed calls for audit.

Validation, Edge Cases & Troubleshooting

Edge Case 1: WebSocket Reconnection Storms

The Failure Condition
During a Genesys Cloud platform maintenance window or network blip, your middleware loses its WebSocket connection. Upon reconnection, the middleware attempts to re-establish multiple connections if the application logic is not idempotent.

The Root Cause
The Event Streams API does not provide a “catch-up” mechanism for missed events over WebSocket. If you drop the connection, you miss events. If you reconnect too aggressively, you may hit rate limits on the WebSocket endpoint.

The Solution
Implement exponential backoff for WebSocket reconnections. Start with a 1-second delay, doubling up to 30 seconds. Additionally, use the lastEventId header if available in your SDK implementation to request resume points, though Genesys Cloud WebSockets generally do not support resume from a specific ID in the same way Kafka does. You must accept that brief gaps in connectivity result in missed pushes. To mitigate, ensure your mobile app polls the Genesys Cloud “Unassigned Conversations” API every 10 seconds as a fallback for any calls missed by the push gateway.

Edge Case 2: Token Rotation and Invalid Tokens

The Failure Condition
APNs and FCM periodically invalidate device tokens. If your middleware sends a push to an invalid token, you receive an error response. If you do not handle this, your error logs will fill up, and you may inadvertently ban your middleware IP if you spam invalid tokens.

The Root Cause
Mobile operating systems rotate tokens for security or when the app is reinstalled. Your Redis cache becomes stale.

The Solution
Implement a “Token Health Check” loop. When APNs or FCM returns a 410 Gone or 401 Unauthorized error for a specific token, immediately remove that token from your Redis cache.

APNs Error Handling (Node.js Example):

apnProvider.send(notification, token)
  .then(result => {
    if (result.sent.length === 0 && result.failed.length > 0) {
      const failure = result.failed[0];
      if (failure.statusCode === 410) {
        // Token invalid, remove from cache
        redis.del(`gen_user_id_${failure.device}`);
        console.log("Removed invalid token for", failure.device);
      }
    }
  });

The Trap: Not Handling FCM UNREGISTERED
FCM returns a UNREGISTERED error code if the token is no longer valid. You must map this error code to a cache removal action just like APNs. Failure to do so results in a growing list of dead tokens in your database, increasing latency and cost.

Edge Case 3: Cross-Platform Notification Conflicts

The Failure Condition
An agent has both an iOS device and an Android device registered. Both ring simultaneously. The agent answers on iOS. The Android phone continues to ring.

The Root Cause
Genesys Cloud routes the call to the user, not the device. Your middleware pushes to all registered devices for that user.

The Solution
This requires coordination between the mobile apps. When the agent answers on iOS, the iOS app must notify the middleware via a webhook (POST /api/v1/agent/answered/{conversationId}). The middleware then immediately sends a CALL_CANCEL push to all other devices associated with that user.

Architectural Reasoning:
This is a complex distributed system problem. A simpler alternative is to rely on the Genesys Cloud routing engine. If the agent answers, the conversation state changes to connected. Your middleware listens for routing.conversation.updated with status connected. Upon detecting this, it broadcasts a CALL_CANCEL to all other devices. This removes the need for the mobile app to call back to your middleware, reducing dependency coupling.

Official References