Filtering Genesys Cloud EventBridge Telephony Disconnect Codes with C#

What You Will Build

• A C# streaming service that subscribes to Genesys Cloud EventBridge, filters telephony disconnect events using carrier code mapping and timeout classification, normalizes CDR payloads, and synchronizes results with external ACD monitors via webhooks and atomic POST operations.
• This implementation uses the Genesys Cloud Platform SDK and direct HTTP streaming endpoints for event ingestion.
• The tutorial covers C# with .NET 8, System.Net.Http, System.Text.Json, and PureCloudPlatformClientV2 SDK classes.

Prerequisites

• OAuth 2.0 client credentials configured in Genesys Cloud with scopes: event:subscribe, event:stream, routing:webhook:write, telephony:call:read
• Genesys Cloud Platform SDK version 131.0.0 or later (NuGet: GenesysCloudPlatformSDK)
• .NET 8.0 SDK or runtime
• External ACD monitor endpoint accepting JSON payloads over HTTPS
• Network access to api.mypurecloud.com and events.mypurecloud.com

Authentication Setup

Genesys Cloud uses client credentials flow for server-to-server integrations. The SDK handles token acquisition and caching, but explicit configuration ensures predictable refresh behavior.

using PureCloudPlatformClientV2;
using PureCloudPlatformClientV2.Configuration;

var platformClient = PlatformClientFactory.CreatePlatformClient();
var config = new Configuration
{
    ClientId = "YOUR_CLIENT_ID",
    ClientSecret = "YOUR_CLIENT_SECRET",
    BaseUrl = "https://api.mypurecloud.com"
};

platformClient.SetConfiguration(config);
await platformClient.LoginAsync();

The LoginAsync method caches the access token and automatically refreshes before expiration. The event:stream scope is required for WebSocket and HTTP streaming endpoints. The event:subscribe scope is required for creating EventBridge subscriptions. Store credentials in environment variables or a secure secret manager. Never hardcode secrets in source control.

Implementation

Step 1: Validate Filter Schema and Create EventBridge Subscription

EventBridge enforces strict constraints on filter expressions. Maximum expression length is 4096 characters. Maximum conditions per filter is 10. Pattern match limits prevent regex-like operations on streaming data. Validate the filter schema before submission to avoid 400 responses.

using System.Text.Json;
using PureCloudPlatformClientV2;
using PureCloudPlatformClientV2.Api;
using PureCloudPlatformClientV2.Model;

public static class EventBridgeFilterValidator
{
    public static bool ValidateFilterExpression(string expression)
    {
        if (string.IsNullOrWhiteSpace(expression)) return false;
        if (expression.Length > 4096) return false;
        
        var conditionCount = expression.Split(new[] { "&&", "||" }, StringSplitOptions.RemoveEmptyEntries).Length;
        return conditionCount <= 10;
    }
}

public static async Task<Subscription> CreateDisconnectSubscriptionAsync(PlatformClient client, string streamId)
{
    var filterExpression = "type == \"telephony.call.disconnect\" && disconnectCode in [\"DISCONNECT_CODE\", \"NETWORK_ERROR\", \"CARRIER_TIMEOUT\"]";
    
    if (!EventBridgeFilterValidator.ValidateFilterExpression(filterExpression))
    {
        throw new InvalidOperationException("Filter expression exceeds streaming engine constraints.");
    }

    var eventsApi = new EventsApi(client);
    var subscriptionRequest = new SubscriptionCreateRequest
    {
        Name = "Telephony Disconnect Filter",
        StreamId = streamId,
        Filter = new EventFilter
        {
            Expression = filterExpression
        }
    };

    var subscription = await eventsApi.PostEventsSubscriptionAsync(subscriptionRequest);
    return subscription;
}

The PostEventsSubscriptionAsync method calls POST /api/v2/events/subscriptions. The response contains the subscription ID and stream reference. The filter expression uses the EventBridge query language. The in operator supports array matching for disconnect codes. Validation prevents filter failure during high-throughput streaming.

Step 2: Stream Events and Execute Disconnect Classification Pipeline

Streaming uses the HTTP Accept: application/json;stream=true header. The SDK returns an observable stream, but direct HttpClient usage provides precise control over connection lifecycle and retry logic. The classification pipeline maps carrier codes, verifies timeout conditions, and prevents false drop detection.

using System.Collections.Concurrent;
using System.Diagnostics;
using System.Text.Json;
using PureCloudPlatformClientV2;

public record DisconnectEvent(string EventType, string DisconnectCode, string Direction, 
                               int DurationMs, string CarrierCode, DateTime Timestamp);

public class DisconnectClassifier
{
    private static readonly Dictionary<string, string> CarrierCodeMap = new()
    {
        { "DISCONNECT_CODE", "CARRIER_TERMINATED" },
        { "NETWORK_ERROR", "NETWORK_PATH_FAILURE" },
        { "CARRIER_TIMEOUT", "CARRIER_RESPONSE_TIMEOUT" }
    };

    public static (bool IsTimeout, string ClassifiedReason) Classify(DisconnectEvent evt)
    {
        var mappedReason = CarrierCodeMap.GetValueOrDefault(evt.DisconnectCode, "UNKNOWN");
        
        var isTimeout = evt.DisconnectCode == "CARRIER_TIMEOUT" || 
                        (evt.DisconnectCode == "NETWORK_ERROR" && evt.DurationMs < 30000);
        
        return (isTimeout, mappedReason);
    }
}

public static async Task StreamDisconnectEventsAsync(PlatformClient client, string streamId, 
                                                      ConcurrentBag<DisconnectEvent> eventBuffer)
{
    var streamUrl = $"https://events.mypurecloud.com/api/v2/events/streams/{streamId}";
    using var httpClient = new HttpClient();
    httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {client.Configuration.TokenManager.CurrentAccessToken}");
    httpClient.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json;stream=true"));

    var response = await httpClient.GetAsync(streamUrl, HttpCompletionOption.ResponseHeadersRead);
    response.EnsureSuccessStatusCode();

    using var stream = await response.Content.ReadAsStreamAsync();
    using var reader = new StreamReader(stream);

    while (!reader.EndOfStream)
    {
        var line = await reader.ReadLineAsync();
        if (string.IsNullOrWhiteSpace(line)) continue;

        try
        {
            var evt = JsonSerializer.Deserialize<DisconnectEvent>(line, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
            if (evt != null && evt.EventType == "telephony.call.disconnect")
            {
                var (isTimeout, reason) = DisconnectClassifier.Classify(evt);
                evt = evt with { DisconnectCode = reason };
                eventBuffer.Add(evt);
            }
        }
        catch (JsonException ex)
        {
            Console.WriteLine($"Malformed event payload: {ex.Message}");
        }
    }
}

The streaming endpoint returns newline-delimited JSON. The StreamReader reads sequentially to prevent memory exhaustion. The classifier applies carrier code mapping and timeout verification. Duration thresholds prevent false drop detection during Genesys Cloud scaling events. The pipeline writes validated events to a thread-safe buffer.

Step 3: Normalize CDR Payloads and Trigger Aggregation Windows

CDR normalization requires atomic POST operations. Batching prevents API throttling and ensures format verification before transmission. An aggregation window triggers after a time threshold or event count limit.

using System.Text.Json;
using System.Text.Json.Serialization;

public record NormalizedCdr(string CallId, string DisconnectReason, string Direction, 
                            int DurationMs, string Carrier, long Timestamp);

public class CdrAggregationWindow
{
    private readonly ConcurrentBag<DisconnectEvent> _buffer;
    private readonly int _maxBatchSize;
    private readonly TimeSpan _windowDuration;
    private readonly HttpClient _httpClient;
    private readonly string _targetEndpoint;
    private DateTime _lastFlush;
    private int _batchCount;

    public CdrAggregationWindow(ConcurrentBag<DisconnectEvent> buffer, int maxBatchSize, 
                                TimeSpan windowDuration, HttpClient httpClient, string targetEndpoint)
    {
        _buffer = buffer;
        _maxBatchSize = maxBatchSize;
        _windowDuration = windowDuration;
        _httpClient = httpClient;
        _targetEndpoint = targetEndpoint;
        _lastFlush = DateTime.UtcNow;
    }

    public async Task ProcessBatchAsync()
    {
        var now = DateTime.UtcNow;
        if (now - _lastFlush < _windowDuration && _batchCount < _maxBatchSize) return;

        var batch = new List<DisconnectEvent>();
        while (_buffer.TryTake(out var evt) && batch.Count < _maxBatchSize)
        {
            batch.Add(evt);
        }

        if (batch.Count == 0) return;

        var normalized = batch.Select(e => new NormalizedCdr
        {
            CallId = e.Timestamp.ToString("o"),
            DisconnectReason = e.DisconnectCode,
            Direction = e.Direction,
            DurationMs = e.DurationMs,
            Carrier = e.CarrierCode,
            Timestamp = e.Timestamp.Ticks
        }).ToList();

        var payload = JsonSerializer.Serialize(normalized, new JsonSerializerOptions { WriteIndented = false });
        
        var content = new StringContent(payload, System.Text.Encoding.UTF8, "application/json");
        var response = await _httpClient.PostAsync(_targetEndpoint, content);
        
        if (!response.IsSuccessStatusCode)
        {
            var errorBody = await response.Content.ReadAsStringAsync();
            throw new HttpRequestException($"CDR POST failed: {(int)response.StatusCode} - {errorBody}");
        }

        _lastFlush = now;
        _batchCount += batch.Count;
    }
}

The aggregation window checks time and count thresholds. The ConcurrentBag.TryTake method drains events atomically. Format verification occurs during serialization. The atomic POST ensures the external ACD monitor receives complete batches. The window resets after successful transmission.

Step 4: Synchronize with External ACD Monitors and Track Metrics

Webhook creation aligns Genesys Cloud filtering with external systems. Metric tracking records latency and classification success rates. Audit logs capture governance data.

using PureCloudPlatformClientV2.Api;
using PureCloudPlatformClientV2.Model;
using System.Diagnostics;

public class FilterMetricsTracker
{
    private long _totalEvents;
    private long _successfulClassifications;
    private readonly Stopwatch _latencyTimer;
    private readonly List<string> _auditLogs;

    public FilterMetricsTracker()
    {
        _latencyTimer = new Stopwatch();
        _auditLogs = new List<string>();
    }

    public void RecordEvent(bool success, TimeSpan processingTime)
    {
        _totalEvents++;
        if (success) _successfulClassifications++;
        _latencyTimer.Stop();
        
        var auditEntry = new
        {
            timestamp = DateTime.UtcNow.ToString("o"),
            totalEvents = _totalEvents,
            successRate = _totalEvents > 0 ? _successfulClassifications * 100.0 / _totalEvents : 0,
            avgLatencyMs = _latencyTimer.Elapsed.TotalMilliseconds / _totalEvents,
            processingTimeMs = processingTime.TotalMilliseconds
        };

        _auditLogs.Add(System.Text.Json.JsonSerializer.Serialize(auditEntry));
        _latencyTimer.Restart();
    }

    public string GetAuditLog() => string.Join("\n", _auditLogs);
}

public static async Task SetupAcidWebhookAsync(PlatformClient client, string subscriptionId, string webhookUrl)
{
    var webhooksApi = new RoutingWebhooksApi(client);
    var webhookRequest = new WebhookCreateRequest
    {
        Name = "ACD Monitor Sync",
        Description = "Synchronizes filtered disconnect events with external ACD",
        Enabled = true,
        RequestUrl = webhookUrl,
        EventTypes = new List<string> { "telephony.call.disconnect" },
        Filter = new EventFilter
        {
            Expression = $"subscriptionId == \"{subscriptionId}\""
        }
    };

    var createdWebhook = await webhooksApi.PostRoutingWebhooksAsync(webhookRequest);
    Console.WriteLine($"Webhook created: {createdWebhook.Id}");
}

The PostRoutingWebhooksAsync method calls POST /api/v2/routing/webhooks. The webhook filter references the subscription ID to ensure alignment. The metrics tracker records latency and success rates. Audit logs serialize to JSON for governance compliance. The Stopwatch class provides precise timing.

Complete Working Example

using System;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Net.Http;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using PureCloudPlatformClientV2;
using PureCloudPlatformClientV2.Api;
using PureCloudPlatformClientV2.Model;
using PureCloudPlatformClientV2.Configuration;

public record DisconnectEvent(string EventType, string DisconnectCode, string Direction, 
                              int DurationMs, string CarrierCode, DateTime Timestamp);

public record NormalizedCdr(string CallId, string DisconnectReason, string Direction, 
                            int DurationMs, string Carrier, long Timestamp);

public static class EventBridgeFilterValidator
{
    public static bool ValidateFilterExpression(string expression)
    {
        if (string.IsNullOrWhiteSpace(expression)) return false;
        if (expression.Length > 4096) return false;
        var conditionCount = expression.Split(new[] { "&&", "||" }, StringSplitOptions.RemoveEmptyEntries).Length;
        return conditionCount <= 10;
    }
}

public class DisconnectClassifier
{
    private static readonly Dictionary<string, string> CarrierCodeMap = new()
    {
        { "DISCONNECT_CODE", "CARRIER_TERMINATED" },
        { "NETWORK_ERROR", "NETWORK_PATH_FAILURE" },
        { "CARRIER_TIMEOUT", "CARRIER_RESPONSE_TIMEOUT" }
    };

    public static (bool IsTimeout, string ClassifiedReason) Classify(DisconnectEvent evt)
    {
        var mappedReason = CarrierCodeMap.GetValueOrDefault(evt.DisconnectCode, "UNKNOWN");
        var isTimeout = evt.DisconnectCode == "CARRIER_TIMEOUT" || 
                        (evt.DisconnectCode == "NETWORK_ERROR" && evt.DurationMs < 30000);
        return (isTimeout, mappedReason);
    }
}

public class CdrAggregationWindow
{
    private readonly ConcurrentBag<DisconnectEvent> _buffer;
    private readonly int _maxBatchSize;
    private readonly TimeSpan _windowDuration;
    private readonly HttpClient _httpClient;
    private readonly string _targetEndpoint;
    private DateTime _lastFlush;
    private int _batchCount;

    public CdrAggregationWindow(ConcurrentBag<DisconnectEvent> buffer, int maxBatchSize, 
                                TimeSpan windowDuration, HttpClient httpClient, string targetEndpoint)
    {
        _buffer = buffer;
        _maxBatchSize = maxBatchSize;
        _windowDuration = windowDuration;
        _httpClient = httpClient;
        _targetEndpoint = targetEndpoint;
        _lastFlush = DateTime.UtcNow;
    }

    public async Task ProcessBatchAsync()
    {
        var now = DateTime.UtcNow;
        if (now - _lastFlush < _windowDuration && _batchCount < _maxBatchSize) return;

        var batch = new List<DisconnectEvent>();
        while (_buffer.TryTake(out var evt) && batch.Count < _maxBatchSize)
        {
            batch.Add(evt);
        }

        if (batch.Count == 0) return;

        var normalized = batch.Select(e => new NormalizedCdr
        {
            CallId = e.Timestamp.ToString("o"),
            DisconnectReason = e.DisconnectCode,
            Direction = e.Direction,
            DurationMs = e.DurationMs,
            Carrier = e.CarrierCode,
            Timestamp = e.Timestamp.Ticks
        }).ToList();

        var payload = JsonSerializer.Serialize(normalized, new JsonSerializerOptions { WriteIndented = false });
        var content = new StringContent(payload, Encoding.UTF8, "application/json");
        var response = await _httpClient.PostAsync(_targetEndpoint, content);

        if (!response.IsSuccessStatusCode)
        {
            var errorBody = await response.Content.ReadAsStringAsync();
            throw new HttpRequestException($"CDR POST failed: {(int)response.StatusCode} - {errorBody}");
        }

        _lastFlush = now;
        _batchCount += batch.Count;
    }
}

public class FilterMetricsTracker
{
    private long _totalEvents;
    private long _successfulClassifications;
    private readonly Stopwatch _latencyTimer;
    private readonly List<string> _auditLogs;

    public FilterMetricsTracker()
    {
        _latencyTimer = new Stopwatch();
        _auditLogs = new List<string>();
        _latencyTimer.Start();
    }

    public void RecordEvent(bool success, TimeSpan processingTime)
    {
        _totalEvents++;
        if (success) _successfulClassifications++;
        _latencyTimer.Stop();

        var auditEntry = new
        {
            timestamp = DateTime.UtcNow.ToString("o"),
            totalEvents = _totalEvents,
            successRate = _totalEvents > 0 ? _successfulClassifications * 100.0 / _totalEvents : 0,
            avgLatencyMs = _latencyTimer.Elapsed.TotalMilliseconds / _totalEvents,
            processingTimeMs = processingTime.TotalMilliseconds
        };

        _auditLogs.Add(JsonSerializer.Serialize(auditEntry));
        _latencyTimer.Restart();
    }

    public string GetAuditLog() => string.Join("\n", _auditLogs);
}

public class Program
{
    public static async Task Main(string[] args)
    {
        var clientId = Environment.GetEnvironmentVariable("GENESYS_CLIENT_ID") ?? "YOUR_CLIENT_ID";
        var clientSecret = Environment.GetEnvironmentVariable("GENESYS_CLIENT_SECRET") ?? "YOUR_CLIENT_SECRET";
        var streamId = "telephony";
        var acdEndpoint = "https://acdsync.example.com/api/v1/cdr-ingest";
        var webhookUrl = "https://acdsync.example.com/api/v1/webhook";

        var platformClient = PlatformClientFactory.CreatePlatformClient();
        platformClient.SetConfiguration(new Configuration
        {
            ClientId = clientId,
            ClientSecret = clientSecret,
            BaseUrl = "https://api.mypurecloud.com"
        });

        await platformClient.LoginAsync();

        var eventsApi = new EventsApi(platformClient);
        var filterExpression = "type == \"telephony.call.disconnect\" && disconnectCode in [\"DISCONNECT_CODE\", \"NETWORK_ERROR\", \"CARRIER_TIMEOUT\"]";

        if (!EventBridgeFilterValidator.ValidateFilterExpression(filterExpression))
        {
            Console.WriteLine("Filter validation failed. Exiting.");
            return;
        }

        var subscriptionRequest = new SubscriptionCreateRequest
        {
            Name = "Telephony Disconnect Filter",
            StreamId = streamId,
            Filter = new EventFilter { Expression = filterExpression }
        };

        var subscription = await eventsApi.PostEventsSubscriptionAsync(subscriptionRequest);
        Console.WriteLine($"Subscription created: {subscription.Id}");

        await SetupAcidWebhookAsync(platformClient, subscription.Id, webhookUrl);

        var buffer = new ConcurrentBag<DisconnectEvent>();
        var metrics = new FilterMetricsTracker();
        var httpClient = new HttpClient { Timeout = TimeSpan.FromSeconds(30) };
        var aggregator = new CdrAggregationWindow(buffer, 50, TimeSpan.FromSeconds(5), httpClient, acdEndpoint);

        var streamTask = StreamDisconnectEventsAsync(platformClient, streamId, buffer, metrics);
        var aggregationTask = RunAggregationLoopAsync(aggregator, metrics);

        await Task.WhenAll(streamTask, aggregationTask);
    }

    private static async Task StreamDisconnectEventsAsync(PlatformClient client, string streamId, 
                                                           ConcurrentBag<DisconnectEvent> buffer, FilterMetricsTracker metrics)
    {
        var streamUrl = $"https://events.mypurecloud.com/api/v2/events/streams/{streamId}";
        using var httpClient = new HttpClient();
        httpClient.DefaultRequestHeaders.Add("Authorization", $"Bearer {client.Configuration.TokenManager.CurrentAccessToken}");
        httpClient.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json;stream=true"));

        var response = await httpClient.GetAsync(streamUrl, HttpCompletionOption.ResponseHeadersRead);
        response.EnsureSuccessStatusCode();

        using var stream = await response.Content.ReadAsStreamAsync();
        using var reader = new StreamReader(stream);
        var stopwatch = new Stopwatch();

        while (!reader.EndOfStream)
        {
            stopwatch.Restart();
            var line = await reader.ReadLineAsync();
            if (string.IsNullOrWhiteSpace(line)) continue;

            try
            {
                var evt = JsonSerializer.Deserialize<DisconnectEvent>(line, new JsonSerializerOptions { PropertyNameCaseInsensitive = true });
                if (evt != null && evt.EventType == "telephony.call.disconnect")
                {
                    var (isTimeout, reason) = DisconnectClassifier.Classify(evt);
                    evt = evt with { DisconnectCode = reason };
                    buffer.Add(evt);
                    stopwatch.Stop();
                    metrics.RecordEvent(true, stopwatch.Elapsed);
                }
            }
            catch (JsonException ex)
            {
                stopwatch.Stop();
                metrics.RecordEvent(false, stopwatch.Elapsed);
                Console.WriteLine($"Malformed event payload: {ex.Message}");
            }
        }
    }

    private static async Task RunAggregationLoopAsync(CdrAggregationWindow aggregator, FilterMetricsTracker metrics)
    {
        while (true)
        {
            try
            {
                await aggregator.ProcessBatchAsync();
                await Task.Delay(TimeSpan.FromSeconds(1));
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Aggregation error: {ex.Message}");
                await Task.Delay(TimeSpan.FromSeconds(5));
            }
        }
    }

    private static async Task SetupAcidWebhookAsync(PlatformClient client, string subscriptionId, string webhookUrl)
    {
        var webhooksApi = new RoutingWebhooksApi(client);
        var webhookRequest = new WebhookCreateRequest
        {
            Name = "ACD Monitor Sync",
            Description = "Synchronizes filtered disconnect events with external ACD",
            Enabled = true,
            RequestUrl = webhookUrl,
            EventTypes = new List<string> { "telephony.call.disconnect" },
            Filter = new EventFilter { Expression = $"subscriptionId == \"{subscriptionId}\"" }
        };

        var createdWebhook = await webhooksApi.PostRoutingWebhooksAsync(webhookRequest);
        Console.WriteLine($"Webhook created: {createdWebhook.Id}");
    }
}

Common Errors & Debugging

Error: 400 Bad Request - Invalid Filter Expression

• Cause: Filter expression exceeds 4096 characters or contains unsupported operators. EventBridge rejects regex patterns and nested function calls.
• Fix: Validate expression length and condition count before submission. Use only supported operators: ==, !=, in, contains, &&, ||.
• Code Fix: The EventBridgeFilterValidator.ValidateFilterExpression method enforces limits. Replace complex logic with explicit array matching.

Error: 429 Too Many Requests - Streaming Throttle

• Cause: Excessive subscription creation or rapid POST operations to external endpoints. Genesys Cloud applies rate limits per tenant.
• Fix: Implement exponential backoff. Cache tokens. Batch CDR transmissions.
• Code Fix: The CdrAggregationWindow enforces time and count thresholds. Add retry logic with Task.Delay(TimeSpan.FromSeconds(Math.Pow(2, retryCount))) for 429 responses.

Error: 502 Bad Gateway - Stream Connection Drop

• Cause: Network instability or Genesys Cloud scaling events interrupt the HTTP stream.
• Fix: Detect connection closure. Reauthenticate and reconnect. Preserve buffer state.
• Code Fix: Wrap the streaming loop in a while (true) block. Catch HttpRequestException. Call platformClient.LoginAsync() to refresh tokens before reconnecting.

Error: 401 Unauthorized - Token Expired During Stream

• Cause: Access token expires mid-session. The streaming endpoint does not automatically refresh.
• Fix: Monitor token expiration. Reinitialize headers when refresh occurs.
• Code Fix: Subscribe to client.Configuration.TokenManager.TokenRefreshed event. Update HttpClient.DefaultRequestHeaders.Authorization when the event fires.

Official References

• EventBridge API Documentation
• Subscription Management
• Streaming Events Endpoint
• Routing Webhooks API
• C# Platform SDK Reference
• OAuth 2.0 Client Credentials Flow