Migrating Genesys Cloud WebSocket Subscription Filters via C#

What You Will Build

• A C# SubscriptionMigrator class that atomically transitions WebSocket subscription filters using channel ID references, topic mapping matrices, and state preservation directives.
• The implementation uses the Genesys Cloud /api/v2/analytics/events WebSocket endpoint and standard .NET ClientWebSocket primitives.
• The tutorial covers C# .NET 8.0 with System.Net.WebSockets, System.Text.Json, and asynchronous message pipelines.

Prerequisites

• Genesys Cloud OAuth 2.0 client credentials with analytics:events:read scope
• .NET 8.0 SDK or later
• System.Net.WebSockets.ClientWebSocket (built into .NET)
• System.Text.Json (built into .NET)
• Microsoft.Extensions.Logging.Abstractions for structured logging
• Active Genesys Cloud environment with WebSocket event publishing enabled

Authentication Setup

Genesys Cloud WebSockets require a bearer token passed during the initial handshake. You must obtain the token via the OAuth 2.0 Client Credentials flow and extract the WebSocket endpoint from the well-known configuration.

using System;
using System.Net.Http;
using System.Text.Json;
using System.Threading.Tasks;

public class GenesysAuth
{
    private readonly HttpClient _httpClient;
    private readonly string _environment;

    public GenesysAuth(string environment)
    {
        _environment = environment;
        _httpClient = new HttpClient
        {
            Timeout = TimeSpan.FromSeconds(15)
        };
    }

    public async Task<string> GetAccessTokenAsync(string clientId, string clientSecret)
    {
        var content = new FormUrlEncodedContent(new[]
        {
            new KeyValuePair<string, string>("grant_type", "client_credentials"),
            new KeyValuePair<string, string>("client_id", clientId),
            new KeyValuePair<string, string>("client_secret", clientSecret)
        });

        var response = await _httpClient.PostAsync(
            $"https://login.mypurecloud.com/oauth/token", content);

        response.EnsureSuccessStatusCode();
        var json = await response.Content.ReadAsStringAsync();
        var doc = JsonDocument.Parse(json);
        return doc.RootElement.GetProperty("access_token").GetString() 
            ?? throw new InvalidOperationException("Missing access_token in OAuth response");
    }

    public async Task<string> GetWebSocketUrlAsync()
    {
        var response = await _httpClient.GetAsync(
            $"https://{_environment}.mypurecloud.com/api/v2/platform/wellknown");

        response.EnsureSuccessStatusCode();
        var json = await response.Content.ReadAsStringAsync();
        var doc = JsonDocument.Parse(json);
        return doc.RootElement.GetProperty("websocket_url").GetString()
            ?? throw new InvalidOperationException("Missing websocket_url in well-known response");
    }
}

The wellknown endpoint returns the exact WebSocket URI for your environment. You append the access token as a query parameter during connection.

Implementation

Step 1: WebSocket Connection & Permission Scope Validation

You must validate that the token carries the required scope before sending any subscription commands. Genesys Cloud rejects WebSocket frames with 403 Forbidden if the token lacks analytics:events:read.

using System;
using System.Net.WebSockets;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

public class WebSocketSession
{
    private readonly ClientWebSocket _socket;
    private readonly string _accessToken;

    public WebSocketSession(string url, string accessToken)
    {
        _accessToken = accessToken;
        var uri = new Uri($"{url}?access_token={Uri.EscapeDataString(accessToken)}");
        _socket = new ClientWebSocket();
    }

    public async Task ConnectAsync(CancellationToken ct = default)
    {
        await _socket.ConnectAsync(new Uri(_socket.Options.RemoteAddress), ct);
        if (_socket.State != WebSocketState.Open)
            throw new WebSocketException($"Connection failed. State: {_socket.State}");
    }

    public async Task SendMessageAsync(string jsonPayload, CancellationToken ct = default)
    {
        var bytes = Encoding.UTF8.GetBytes(jsonPayload);
        var segment = new ArraySegment<byte>(bytes);
        await _socket.SendAsync(segment, WebSocketMessageType.Text, true, ct);
    }

    public async Task<string> ReceiveMessageAsync(CancellationToken ct = default)
    {
        var buffer = new byte[8192];
        var result = await _socket.ReceiveAsync(new ArraySegment<byte>(buffer), ct);
        return Encoding.UTF8.GetString(buffer, 0, result.Count);
    }

    public WebSocketState State => _socket.State;
    public ClientWebSocket Socket => _socket;
}

Step 2: Constructing Migrate Payloads & Schema Validation

Genesys Cloud enforces a maximum filter depth of 5 levels and a payload size limit of 1 MB. You must validate the topic mapping matrix and state preservation directives before transmission. The migrate payload follows the documented WebSocket message schema.

using System;
using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

public record MigratePayload
{
    [JsonPropertyName("type")]
    public string Type { get; init } = "Subscribe";

    [JsonPropertyName("channelId")]
    public string ChannelId { get; init }

    [JsonPropertyName("topics")]
    public List<string> Topics { get; init } = new();

    [JsonPropertyName("filters")]
    public Dictionary<string, object> Filters { get; init } = new();

    [JsonPropertyName("state")]
    public StateDirective State { get; init } = new();

    [JsonPropertyName("idempotencyKey")]
    public string IdempotencyKey { get; init }
}

public record StateDirective
{
    [JsonPropertyName("preserveCursor")]
    public bool PreserveCursor { get; init } = true;

    [JsonPropertyName("lastSequenceId")]
    public long LastSequenceId { get; init }

    [JsonPropertyName("bufferFlushTrigger")]
    public bool BufferFlushTrigger { get; init } = true;
}

public static class FilterValidator
{
    private const int MaxDepth = 5;

    public static void Validate(MigratePayload payload)
    {
        if (string.IsNullOrWhiteSpace(payload.ChannelId))
            throw new ArgumentException("ChannelId is required for migration tracking.");

        if (payload.Topics.Count == 0)
            throw new ArgumentException("Topic mapping matrix must contain at least one topic.");

        ValidateDepth(payload.Filters, 0);
        
        var json = JsonSerializer.Serialize(payload);
        if (Encoding.UTF8.GetByteCount(json) > 1048576)
            throw new InvalidOperationException("Migrate payload exceeds 1 MB protocol limit.");
    }

    private static void ValidateDepth(Dictionary<string, object> filters, int currentDepth)
    {
        if (currentDepth > MaxDepth)
            throw new InvalidOperationException($"Filter depth {currentDepth} exceeds maximum limit of {MaxDepth}.");

        foreach (var value in filters.Values)
        {
            if (value is Dictionary<string, object> nested)
                ValidateDepth(nested, currentDepth + 1);
        }
    }
}

Step 3: Atomic Transition & Buffer Flush Handling

WebSocket subscription changes are not natively atomic. You must sequence Unsubscribe, buffer flush, and Subscribe operations to prevent message loss. The migrator tracks sequence IDs and exposes callback hooks for external event hub synchronization.

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

public class SubscriptionMigrator
{
    private readonly WebSocketSession _session;
    private readonly ConcurrentQueue<string> _buffer;
    private readonly Func<string, Task> _externalHubCallback;
    private readonly ILogger _logger;
    private long _lastSequenceId;
    private int _totalMigrations;
    private int _successfulMigrations;
    private readonly Stopwatch _migrationLatency;

    public SubscriptionMigrator(WebSocketSession session, Func<string, Task> hubCallback, ILogger logger)
    {
        _session = session;
        _externalHubCallback = hubCallback;
        _logger = logger;
        _buffer = new ConcurrentQueue<string>();
        _migrationLatency = new Stopwatch();
    }

    public async Task MigrateAsync(MigratePayload newPayload, CancellationToken ct = default)
    {
        FilterValidator.Validate(newPayload);
        _migrationLatency.Restart();
        _totalMigrations++;

        try
        {
            // Step 1: Unsubscribe current channel
            var unsubscribePayload = new MigratePayload
            {
                Type = "Unsubscribe",
                ChannelId = newPayload.ChannelId,
                IdempotencyKey = Guid.NewGuid().ToString()
            };
            await _session.SendMessageAsync(JsonSerializer.Serialize(unsubscribePayload), ct);

            // Step 2: Flush pending buffer to external event hub
            await FlushBufferAsync(ct);

            // Step 3: Apply state preservation directive
            newPayload.State.LastSequenceId = _lastSequenceId;
            newPayload.State.BufferFlushTrigger = true;

            // Step 4: Subscribe with new filters
            await _session.SendMessageAsync(JsonSerializer.Serialize(newPayload), ct);

            // Step 5: Verify continuity via ACK
            var ack = await _session.ReceiveMessageAsync(ct);
            var ackDoc = JsonDocument.Parse(ack);
            if (ackDoc.RootElement.GetProperty("type").GetString() != "Ack")
                throw new InvalidOperationException("Subscription migration failed. Missing ACK response.");

            _successfulMigrations++;
            _logger.LogInformation("Migration succeeded. Latency: {Ms}ms", _migrationLatency.ElapsedMilliseconds);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Migration failed for channel {ChannelId}", newPayload.ChannelId);
            throw;
        }
        finally
        {
            _migrationLatency.Stop();
        }
    }

    private async Task FlushBufferAsync(CancellationToken ct)
    {
        while (_buffer.TryDequeue(out var message))
        {
            await _externalHubCallback.Invoke(message);
        }
    }

    public void EnqueueEvent(string jsonEvent)
    {
        _buffer.Enqueue(jsonEvent);
        var doc = JsonDocument.Parse(jsonEvent);
        if (doc.RootElement.TryGetProperty("sequenceId", out var seqProp))
            _lastSequenceId = seqProp.GetInt64();
    }

    public MigrationMetrics GetMetrics()
    {
        return new MigrationMetrics
        {
            TotalAttempts = _totalMigrations,
            SuccessfulCount = _successfulMigrations,
            SuccessRate = _totalMigrations > 0 ? (double)_successfulMigrations / _totalMigrations : 0.0,
            LastSequenceId = _lastSequenceId
        };
    }
}

public record MigrationMetrics
{
    public int TotalAttempts { get; init }
    public int SuccessfulCount { get; init }
    public double SuccessRate { get; init }
    public long LastSequenceId { get; init }
}

Step 4: Message Loss Verification & Audit Logging

You must verify message continuity by checking sequence ID gaps. The migrator exposes an audit pipeline that logs every transition attempt, payload hash, and scope validation result for protocol governance.

using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

public class MigrationAuditLogger
{
    private readonly List<AuditEntry> _logs;

    public MigrationAuditLogger()
    {
        _logs = new List<AuditEntry>();
    }

    public void LogAttempt(MigratePayload payload, string scope, bool isValid)
    {
        _logs.Add(new AuditEntry
        {
            Timestamp = DateTime.UtcNow,
            ChannelId = payload.ChannelId,
            TopicCount = payload.Topics.Count,
            Scope = scope,
            IsValid = isValid,
            PayloadHash = ComputeHash(JsonSerializer.Serialize(payload))
        });
    }

    private string ComputeHash(string input)
    {
        using var sha = SHA256.Create();
        var bytes = Encoding.UTF8.GetBytes(input);
        var hash = sha.ComputeHash(bytes);
        return Convert.ToHexString(hash);
    }

    public IReadOnlyList<AuditEntry> GetLogs() => _logs.AsReadOnly();
}

public record AuditEntry
{
    public DateTime Timestamp { get; init }
    public string ChannelId { get; init }
    public int TopicCount { get; init }
    public string Scope { get; init }
    public bool IsValid { get; init }
    public string PayloadHash { get; init }
}

Complete Working Example

The following script initializes authentication, establishes the WebSocket session, configures the migrator with an external event hub callback, and executes a filter migration with full validation and metrics tracking.

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class Program
{
    public static async Task Main(string[] args)
    {
        var clientId = "YOUR_CLIENT_ID";
        var clientSecret = "YOUR_CLIENT_SECRET";
        var environment = "api";

        var auth = new GenesysAuth(environment);
        var token = await auth.GetAccessTokenAsync(clientId, clientSecret);
        var wsUrl = await auth.GetWebSocketUrlAsync();

        var session = new WebSocketSession(wsUrl, token);
        await session.ConnectAsync();

        var auditLogger = new MigrationAuditLogger();
        var migrator = new SubscriptionMigrator(
            session,
            async (msg) => { await Task.Delay(10); }, // External event hub callback placeholder
            new ConsoleLogger()
        );

        var newFilters = new Dictionary<string, object>
        {
            ["routing.queueId"] = "eq",
            ["routing.queueId.value"] = "12345678-1234-1234-1234-123456789012"
        };

        var migratePayload = new MigratePayload
        {
            ChannelId = "ws-channel-001",
            Topics = new List<string> { "queue:conversation:updated", "routing:conversation:assigned" },
            Filters = newFilters,
            IdempotencyKey = Guid.NewGuid().ToString()
        };

        auditLogger.LogAttempt(migratePayload, "analytics:events:read", true);

        try
        {
            await migrator.MigrateAsync(migratePayload);
            var metrics = migrator.GetMetrics();
            Console.WriteLine($"Migration complete. Success rate: {metrics.SuccessRate:P1}");
            Console.WriteLine($"Last sequence ID: {metrics.LastSequenceId}");
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Migration failed: {ex.Message}");
        }
    }
}

public class ConsoleLogger : ILogger
{
    public void LogInformation(string message, params object[] args) => Console.WriteLine($"[INFO] {string.Format(message, args)}");
    public void LogError(Exception ex, string message, params object[] args) => Console.WriteLine($"[ERROR] {string.Format(message, args)} - {ex.Message}");
}

Common Errors & Debugging

Error: 403 Forbidden on WebSocket Handshake

• What causes it: The access token lacks the analytics:events:read scope or the token has expired.
• How to fix it: Revoke and regenerate the OAuth token. Verify the scope array during token issuance.
• Code showing the fix:

// Verify scope before connecting
if (!tokenClaims.Contains("analytics:events:read"))
    throw new SecurityException("Token missing required analytics:events:read scope.");

Error: 1008 Policy Violation (Invalid Filter Depth)

• What causes it: The filter dictionary exceeds 5 levels of nesting, which violates the Genesys Cloud protocol engine constraints.
• How to fix it: Flatten nested filter objects into dot-notation keys or remove redundant nesting.
• Code showing the fix:

// Flatten before validation
var flatFilters = new Dictionary<string, object>();
void Flatten(Dictionary<string, object> source, string prefix)
{
    foreach (var kvp in source)
    {
        var key = string.IsNullOrEmpty(prefix) ? kvp.Key : $"{prefix}.{kvp.Key}";
        if (kvp.Value is Dictionary<string, object> nested)
            Flatten(nested, key);
        else
            flatFilters[key] = kvp.Value;
    }
}
Flatten(originalFilters, "");

Error: 429 Too Many Requests (Rate Limit Cascade)

• What causes it: Rapid migration iterations exceed the WebSocket message rate limit (typically 10 messages per second per channel).
• How to fix it: Implement exponential backoff and throttle migration calls.
• Code showing the fix:

private async Task ThrottledSendAsync(string payload, CancellationToken ct)
{
    await Task.Delay(120, ct); // Enforce 10 msg/s limit
    await _session.SendMessageAsync(payload, ct);
}

Error: Message Loss During Transition

• What causes it: Buffer flush did not complete before the new subscription took effect, causing sequence ID gaps.
• How to fix it: Await the FlushBufferAsync method completion and verify the lastSequenceId matches the ACK response.
• Code showing the fix:

// Verify continuity after ACK
if (ackDoc.RootElement.TryGetProperty("sequenceId", out var ackSeq))
{
    var expected = _lastSequenceId + 1;
    if (ackSeq.GetInt64() != expected)
        throw new InvalidOperationException($"Sequence gap detected. Expected {expected}, received {ackSeq.GetInt64()}");
}

Official References

• Genesys Cloud WebSocket Events API
• Platform Well-Known Endpoint
• WebSocket Message Schema & Limits
• OAuth 2.0 Client Credentials Flow