Retry Failed Genesys Cloud Webhook Deliveries Using the Integrations API in Java

What You Will Build

• A Java service that programmatically resends failed webhook deliveries using the Genesys Cloud Integrations API.
• The service enforces retry windows, tracks idempotency keys, handles permanent failures via dead-letter routing, and verifies payload signatures.
• The implementation uses Java 17 with the official Genesys Cloud Java SDK.

Prerequisites

• OAuth service account or client credentials with integration:delivery:resend and integration:delivery:view scopes.
• Genesys Cloud Java SDK version 3.0.0 or higher.
• Java 17 runtime.
• Maven or Gradle for dependency management.
• External dependency: com.google.code.gson:gson:2.10.1 for audit log serialization.

Authentication Setup

The Genesys Cloud Java SDK handles OAuth token acquisition and automatic refresh when configured correctly. You must initialize the OAuthClient with your environment, client ID, and client secret. The SDK caches tokens in memory and refreshes them before expiration.

import com.mendix.genesyscloud.auth.OAuthClient;
import com.mendix.genesyscloud.auth.OAuthClientConfiguration;
import com.mendix.genesyscloud.auth.OAuthEnvironment;

public class GenesysAuthenticator {
    private static final String ENVIRONMENT = "mypurecloud.com";
    private static final String CLIENT_ID = System.getenv("GENESYS_CLIENT_ID");
    private static final String CLIENT_SECRET = System.getenv("GENESYS_CLIENT_SECRET");

    public static OAuthClient initializeOAuthClient() throws Exception {
        OAuthClientConfiguration configuration = new OAuthClientConfiguration.Builder()
                .environment(OAuthEnvironment.from(ENVIRONMENT))
                .clientId(CLIENT_ID)
                .clientSecret(CLIENT_SECRET)
                .build();

        return new OAuthClient(configuration);
    }
}

The OAuthClient instance manages the access_token lifecycle. You pass this client directly to the IntegrationsApi constructor. The SDK automatically attaches the Authorization: Bearer <token> header to every request.

Implementation

Step 1: Delivery Validation and Retry Window Enforcement

Before issuing a resend command, you must verify that the delivery falls within the maximum retry window and has not exceeded permanent failure thresholds. Genesys Cloud retains delivery history for 30 days. You query the delivery details, extract the attemptCount, lastAttemptDate, and status, and apply business rules.

import com.mendix.genesyscloud.api.v2.IntegrationsApi;
import com.mendix.genesyscloud.api.v2.model.Delivery;
import com.mendix.genesyscloud.api.v2.model.DeliveryAttempt;
import com.mendix.genesyscloud.auth.OAuthClient;
import com.mendix.genesyscloud.api.client.ApiResponse;

import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.List;

public class DeliveryValidator {
    private final IntegrationsApi integrationsApi;
    private static final long MAX_RETRY_HOURS = 24L;
    private static final int MAX_ATTEMPTS = 5;

    public DeliveryValidator(OAuthClient oauthClient) throws Exception {
        this.integrationsApi = new IntegrationsApi(oauthClient);
    }

    public boolean isRetryable(String integrationId, String deliveryId) throws Exception {
        ApiResponse<Delivery> response = integrationsApi.getIntegrationsIntegrationDeliveriesDelivery(
                integrationId, deliveryId);
        
        if (response.getStatusCode() != 200) {
            throw new RuntimeException("Failed to fetch delivery: " + response.getStatusCode());
        }

        Delivery delivery = response.getBody();
        Instant lastAttempt = delivery.getLastAttemptDate();
        long hoursSinceLastAttempt = ChronoUnit.HOURS.between(lastAttempt, Instant.now());
        
        int totalAttempts = delivery.getAttempts() != null ? delivery.getAttempts().size() : 0;
        
        if (hoursSinceLastAttempt > MAX_RETRY_HOURS) {
            return false;
        }
        
        if (totalAttempts >= MAX_ATTEMPTS) {
            return false;
        }

        List<DeliveryAttempt> attempts = delivery.getAttempts();
        int permanentFailures = (int) attempts.stream()
                .filter(a -> a.getHttpStatusCode() >= 400 && a.getHttpStatusCode() < 500)
                .count();

        return permanentFailures < 2;
    }
}

The validation logic checks three constraints: age of the last attempt, total attempt count, and frequency of permanent HTTP 4xx responses. If any constraint fails, the delivery routes to the dead-letter handler instead of retrying.

Step 2: Atomic Resend Execution with Idempotency and 429 Handling

The resend operation uses an atomic HTTP POST. You must track processed delivery identifiers to prevent duplicate retry requests. The implementation below includes exponential backoff for 429 Too Many Requests responses and idempotency verification.

import com.mendix.genesyscloud.api.client.ApiResponse;
import com.mendix.genesyscloud.api.v2.model.ResendDeliveryResponse;

import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

public class WebhookRetryExecutor {
    private final IntegrationsApi integrationsApi;
    private final Set<String> processedDeliveryRefs = ConcurrentHashMap.newKeySet();
    private static final int MAX_RESEND_RETRIES = 3;
    private static final long INITIAL_BACKOFF_MS = 1000L;

    public WebhookRetryExecutor(IntegrationsApi integrationsApi) {
        this.integrationsApi = integrationsApi;
    }

    public ResendDeliveryResponse executeResend(String integrationId, String deliveryId) throws Exception {
        if (processedDeliveryRefs.contains(deliveryId)) {
            throw new IllegalStateException("Delivery reference already processed: " + deliveryId);
        }

        processedDeliveryRefs.add(deliveryId);
        int retryCount = 0;
        long currentBackoff = INITIAL_BACKOFF_MS;

        while (retryCount < MAX_RESEND_RETRIES) {
            try {
                ApiResponse<ResendDeliveryResponse> response = integrationsApi.postIntegrationsIntegrationDeliveriesDeliveryResend(
                        integrationId, deliveryId, null);

                if (response.getStatusCode() == 200 || response.getStatusCode() == 202) {
                    return response.getBody();
                } else if (response.getStatusCode() == 429) {
                    Thread.sleep(currentBackoff);
                    currentBackoff *= 2;
                    retryCount++;
                } else {
                    throw new RuntimeException("Resend failed with status: " + response.getStatusCode());
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw e;
            }
        }

        throw new RuntimeException("Exhausted resend retries due to rate limiting");
    }
}

The postIntegrationsIntegrationDeliveriesDeliveryResend method maps to POST /api/v2/integrations/integrations/{integrationId}/deliveries/{deliveryId}/resend. The request body is intentionally null because the API triggers a server-side replay of the original payload. The idempotency set prevents parallel execution threads from issuing duplicate resend commands for the same deliveryId.

Step 3: Permanent Error Detection and Dead Letter Routing

When a delivery exceeds retry limits or consistently returns permanent HTTP 4xx errors, the system must halt retry attempts and route the payload to a dead-letter queue. The following component captures failed deliveries, preserves the original request context, and persists them for manual inspection.

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import java.io.FileWriter;
import java.io.IOException;
import java.time.Instant;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;

public class DeadLetterManager {
    private final List<Map<String, Object>> deadLetterQueue = new CopyOnWriteArrayList<>();
    private final Gson gson = new GsonBuilder().setPrettyPrinting().create();

    public void routeToDeadLetter(String deliveryId, String integrationId, int httpStatusCode, String responseBody) {
        Map<String, Object> deadLetterRecord = Map.of(
                "deliveryId", deliveryId,
                "integrationId", integrationId,
                "httpStatusCode", httpStatusCode,
                "responseBody", responseBody,
                "timestamp", Instant.now().toString(),
                "status", "PERMANENT_FAILURE"
        );

        deadLetterQueue.add(deadLetterRecord);
        persistDeadLetter(deadLetterRecord);
    }

    private void persistDeadLetter(Map<String, Object> record) {
        try (FileWriter writer = new FileWriter("dead_letters/" + record.get("deliveryId") + ".json", true)) {
            writer.write(gson.toJson(record));
            writer.write(System.lineSeparator());
        } catch (IOException e) {
            System.err.println("Failed to persist dead letter: " + e.getMessage());
        }
    }
}

The dead-letter manager isolates failed deliveries from the retry pipeline. It records the HTTP status, response body, and timestamp. In production, you replace the file writer with an Amazon SQS queue, Azure Service Bus, or Kafka topic.

Step 4: Payload Signature Verification and Audit Logging

Before processing any retry or dead-letter event, you must verify the HMAC-SHA256 signature of the incoming webhook payload. The following utility validates the signature against a shared secret. The audit logger records every retry action, success rate, and latency measurement for governance compliance.

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.time.Instant;
import java.util.Base64;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;

public class WebhookSecurityAndAudit {
    private final String sharedSecret;
    private final AtomicInteger successfulRetries = new AtomicInteger(0);
    private final AtomicLong totalRetryLatencyMs = new AtomicLong(0);

    public WebhookSecurityAndAudit(String sharedSecret) {
        this.sharedSecret = sharedSecret;
    }

    public boolean verifySignature(String payload, String signatureHeader) {
        try {
            Mac mac = Mac.getInstance("HmacSHA256");
            SecretKeySpec keySpec = new SecretKeySpec(sharedSecret.getBytes(StandardCharsets.UTF_8), "HmacSHA256");
            mac.init(keySpec);
            byte[] rawHmac = mac.doFinal(payload.getBytes(StandardCharsets.UTF_8));
            String computedSignature = Base64.getEncoder().encodeToString(rawHmac);
            return computedSignature.equals(signatureHeader);
        } catch (Exception e) {
            return false;
        }
    }

    public void recordRetryMetrics(String deliveryId, boolean success, long latencyMs) {
        if (success) {
            successfulRetries.incrementAndGet();
        }
        totalRetryLatencyMs.addAndGet(latencyMs);

        String auditEntry = String.format(
                "{\"event\":\"webhook_retry\",\"deliveryId\":\"%s\",\"success\":%s,\"latencyMs\":%d,\"timestamp\":\"%s\",\"successRate\":%.2f}",
                deliveryId, success, latencyMs, Instant.now().toString(),
                calculateSuccessRate()
        );
        System.out.println(auditEntry);
    }

    public double calculateSuccessRate() {
        int total = successfulRetries.get();
        // Simplified rate calculation for demonstration
        return total > 0 ? (double) total / (total + 1) : 0.0;
    }
}

The audit logger emits structured JSON lines containing delivery identifiers, success flags, latency measurements, and calculated success rates. You pipe this output to Elasticsearch, Splunk, or Datadog for real-time monitoring.

Complete Working Example

The following class orchestrates authentication, validation, execution, dead-letter routing, and audit logging into a single reusable service. Replace the environment variables with your Genesys Cloud credentials.

import com.mendix.genesyscloud.api.v2.IntegrationsApi;
import com.mendix.genesyscloud.api.v2.model.ResendDeliveryResponse;
import com.mendix.genesyscloud.auth.OAuthClient;
import com.mendix.genesyscloud.auth.OAuthClientConfiguration;
import com.mendix.genesyscloud.auth.OAuthEnvironment;

import java.time.Instant;
import java.util.concurrent.TimeUnit;

public class GenesysWebhookRetryer {
    private final IntegrationsApi integrationsApi;
    private final DeliveryValidator validator;
    private final WebhookRetryExecutor executor;
    private final DeadLetterManager deadLetterManager;
    private final WebhookSecurityAndAudit auditLogger;

    public GenesysWebhookRetryer(String environment, String clientId, String clientSecret, String hmacSecret) throws Exception {
        OAuthClientConfiguration config = new OAuthClientConfiguration.Builder()
                .environment(OAuthEnvironment.from(environment))
                .clientId(clientId)
                .clientSecret(clientSecret)
                .build();
        OAuthClient oauthClient = new OAuthClient(config);
        this.integrationsApi = new IntegrationsApi(oauthClient);
        this.validator = new DeliveryValidator(oauthClient);
        this.executor = new WebhookRetryExecutor(integrationsApi);
        this.deadLetterManager = new DeadLetterManager();
        this.auditLogger = new WebhookSecurityAndAudit(hmacSecret);
    }

    public void processRetry(String integrationId, String deliveryId, String rawPayload, String signatureHeader) throws Exception {
        if (!auditLogger.verifySignature(rawPayload, signatureHeader)) {
            throw new SecurityException("Invalid HMAC signature for delivery: " + deliveryId);
        }

        Instant start = Instant.now();
        boolean isRetryable = validator.isRetryable(integrationId, deliveryId);

        if (!isRetryable) {
            deadLetterManager.routeToDeadLetter(deliveryId, integrationId, 410, "Exceeded retry window or permanent failure threshold");
            long latency = TimeUnit.MILLISECONDS.convert(Instant.now().getEpochSecond() - start.getEpochSecond(), TimeUnit.SECONDS);
            auditLogger.recordRetryMetrics(deliveryId, false, latency);
            return;
        }

        try {
            ResendDeliveryResponse response = executor.executeResend(integrationId, deliveryId);
            long latency = TimeUnit.MILLISECONDS.convert(Instant.now().getEpochSecond() - start.getEpochSecond(), TimeUnit.SECONDS);
            auditLogger.recordRetryMetrics(deliveryId, true, latency);
            System.out.println("Successfully rescheduled delivery: " + deliveryId + " | Resend ID: " + response.getResendId());
        } catch (Exception e) {
            long latency = TimeUnit.MILLISECONDS.convert(Instant.now().getEpochSecond() - start.getEpochSecond(), TimeUnit.SECONDS);
            auditLogger.recordRetryMetrics(deliveryId, false, latency);
            deadLetterManager.routeToDeadLetter(deliveryId, integrationId, 500, e.getMessage());
            throw e;
        }
    }

    public static void main(String[] args) throws Exception {
        String env = System.getenv("GENESYS_ENVIRONMENT");
        String clientId = System.getenv("GENESYS_CLIENT_ID");
        String clientSecret = System.getenv("GENESYS_CLIENT_SECRET");
        String hmacSecret = System.getenv("WEBHOOK_HMAC_SECRET");

        GenesysWebhookRetryer retryer = new GenesysWebhookRetryer(env, clientId, clientSecret, hmacSecret);
        
        // Simulate processing a failed delivery
        retryer.processRetry("a1b2c3d4-e5f6-7890-g1h2-i3j4k5l6m7n8", "d9e8f7g6-h5i4-j3k2-l1m0-n9o8p7q6r5s4", "{}", "validSignatureString");
    }
}

Common Errors & Debugging

Error: 401 Unauthorized

• Cause: The OAuth token has expired, the client credentials are incorrect, or the service account lacks the integration:delivery:resend scope.
• Fix: Verify environment variables. Ensure the OAuth client is configured with the correct client_id and client_secret. Confirm the service account has the required scopes in the Genesys Cloud admin console.
• Code: The OAuthClient automatically refreshes tokens. If you receive 401 repeatedly, force a token refresh by recreating the OAuthClient instance or checking network connectivity to https://api.<environment>/oauth/token.

Error: 403 Forbidden

• Cause: The service account does not have the integration:delivery:resend or integration:delivery:view scopes assigned.
• Fix: Navigate to Admin > Security > OAuth clients. Select your client. Add integration:delivery:resend and integration:delivery:view to the authorized scopes. Save and restart the application.

Error: 404 Not Found

• Cause: The integrationId or deliveryId does not exist, or the delivery has been purged from the 30-day retention window.
• Fix: Validate identifiers against the Genesys Cloud admin UI or query the /api/v2/integrations/integrations/{integrationId}/deliveries endpoint. Implement fallback logic to skip purged deliveries.

Error: 429 Too Many Requests

• Cause: The Genesys Cloud platform rate limit has been exceeded. The default limit for integration delivery operations is 50 requests per minute per client ID.
• Fix: The WebhookRetryExecutor implements exponential backoff. Increase INITIAL_BACKOFF_MS or reduce parallel retry threads. Implement a token bucket algorithm for stricter rate control.

Error: 409 Conflict

• Cause: A resend operation is already in progress for the specified delivery identifier.
• Fix: The idempotency set in WebhookRetryExecutor prevents duplicate calls. If you encounter 409, log the conflict and skip the delivery. The platform guarantees eventual consistency.

Official References

• Integrations API - Resend Delivery Documentation
• Genesys Cloud Java SDK Reference
• OAuth 2.0 Client Credentials Flow
• Webhook Signature Verification Guide