Playing Genesys Cloud Voice API Media Files via WebSocket with Java

What You Will Build

You will build a Java utility that validates media files against voice constraints, constructs atomic play directives with file references and media matrices, streams them over the Genesys Cloud Voice API WebSocket, and tracks playback latency and success metrics. The code uses the Genesys Cloud REST API for validation and the Voice API WebSocket for real-time playback control. The implementation covers Java with the official Genesys Cloud SDK and java.net.http.WebSocket.

Prerequisites

• OAuth 2.0 Client Credentials flow with scopes: media:read, voice:control, webhooks:write
• Genesys Cloud Java SDK versions: api-auth, api-media, api-voice (v12.0.0+)
• Java 17 runtime or later
• External dependencies: com.fasterxml.jackson.core:jackson-databind:2.15.2, com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.15.2
• Environment variables: GENESYS_CLIENT_ID, GENESYS_CLIENT_SECRET, GENESYS_REGION, GENESYS_MEDIA_ID, WEBHOOK_URL

Authentication Setup

The Genesys Cloud API requires a bearer token obtained via the OAuth 2.0 Client Credentials flow. The SDK handles token acquisition and refresh logic. You must cache the token and handle expiration before initiating WebSocket connections or REST calls.

import com.mypurecloud.api.client.ApiClient;
import com.mypurecloud.api.client.auth.OAuthClient;
import com.mypurecloud.api.client.auth.OAuthToken;
import java.util.concurrent.TimeUnit;

public class GenesysAuth {
    private static final String CLIENT_ID = System.getenv("GENESYS_CLIENT_ID");
    private static final String CLIENT_SECRET = System.getenv("GENESYS_CLIENT_SECRET");
    private static final String REGION = System.getenv("GENESYS_REGION");

    public static ApiClient createAuthenticatedClient() throws Exception {
        ApiClient client = new ApiClient();
        client.setBasePath("https://api." + REGION + ".genesyscloud.com");
        
        OAuthClient oauthClient = new OAuthClient(client);
        String[] scopes = {"media:read", "voice:control", "webhooks:write"};
        OAuthToken token = oauthClient.requestClientCredentialsToken(CLIENT_ID, CLIENT_SECRET, scopes);
        
        client.setAccessToken(token.getAccessToken());
        
        // Implement token refresh logic
        long expiresIn = token.getExpiresIn();
        if (expiresIn > 0) {
            // In production, schedule a refresh task using ScheduledExecutorService
            // to request a new token 60 seconds before expiration.
        }
        return client;
    }
}

The requestClientCredentialsToken method returns an OAuthToken containing the access token and expiration window. The SDK automatically attaches the Authorization: Bearer <token> header to subsequent REST requests. Store the token securely and never log it in plaintext.

Implementation

Step 1: Validate Media File Existence and Constraints

Before sending a play directive, you must verify the media file exists and complies with voice channel constraints. The Voice API enforces a maximum duration of 300 seconds per play action and requires volume normalization between 0.0 and 1.0. You will query the Media API to retrieve file metadata and validate it against these constraints.

import com.mypurecloud.api.client.ApiClient;
import com.mypurecloud.api.media.api.MediaApi;
import com.mypurecloud.api.model.MediaFile;
import java.time.Duration;

public class MediaValidator {
    private static final Duration MAX_DURATION = Duration.ofSeconds(300);
    private static final double MIN_VOLUME = 0.0;
    private static final double MAX_VOLUME = 1.0;

    public static void validateMediaFile(ApiClient client, String mediaId, double requestedVolume) throws Exception {
        MediaApi mediaApi = new MediaApi(client);
        MediaFile media = mediaApi.getMediaFile(mediaId);
        
        if (media == null || media.getId() == null) {
            throw new IllegalArgumentException("Media file does not exist or returned null.");
        }

        Long durationSeconds = media.getDuration();
        if (durationSeconds == null || durationSeconds > MAX_DURATION.getSeconds()) {
            throw new IllegalArgumentException("Media duration exceeds maximum voice constraint of 300 seconds.");
        }

        if (requestedVolume < MIN_VOLUME || requestedVolume > MAX_VOLUME) {
            throw new IllegalArgumentException("Volume must be normalized between 0.0 and 1.0.");
        }

        String format = media.getContentType();
        if (!"audio/wav".equals(format) && !"audio/mpeg".equals(format)) {
            throw new IllegalArgumentException("Unsupported codec format. Voice API requires audio/wav or audio/mpeg.");
        }
    }
}

Expected Response: A MediaFile object containing id, name, duration, contentType, and size.
Error Handling: A 404 Not Found indicates the media ID is invalid. A 403 Forbidden indicates missing media:read scope. Catch com.mypurecloud.api.client.ApiException and inspect getCode() for HTTP status.

Step 2: Construct and Validate Play Payloads

The Voice API WebSocket accepts atomic JSON messages. You must construct a play directive that includes a file reference, media matrix configuration, stream directive parameters, codec conversion calculations, and jitter buffer evaluation. The payload must conform to the Voice API schema to prevent playback failure.

import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.Map;
import java.util.UUID;

public class PlayPayloadBuilder {
    private static final ObjectMapper MAPPER = new ObjectMapper();

    public static String buildPlayDirective(String mediaId, double volume, String codec, String jitterBuffer) {
        Map<String, Object> payload = Map.of(
            "action", "play",
            "sequenceId", UUID.randomUUID().toString(),
            "target", Map.of("type", "file", "id", mediaId),
            "volume", volume,
            "maxDuration", 295,
            "streamDirective", Map.of(
                "codec", codec,
                "bitrateCalculation", calculateBitrate(codec),
                "jitterBuffer", jitterBuffer
            ),
            "mediaMatrix", Map.of(
                "formatVerification", true,
                "autoNextTrack", true,
                "loopEnabled", false
            )
        );
        return MAPPER.writeValueAsString(payload);
    }

    private static int calculateBitrate(String codec) {
        // Codec conversion calculation for voice channel optimization
        switch (codec.toLowerCase()) {
            case "opus": return 64; // 64 kbps optimized for voice
            case "pcmu": return 64; // G.711u fixed 64 kbps
            case "pcma": return 64; // G.711a fixed 64 kbps
            default: return 64;
        }
    }
}

Expected Response: A valid JSON string conforming to the Voice API control schema.
Error Handling: Invalid JSON structure causes the WebSocket server to return a {"action": "error", "message": "Invalid payload"} response. Always validate payload syntax before transmission.

Step 3: Establish WebSocket Connection and Stream Control

The Voice API uses a persistent WebSocket connection for real-time control. You will connect to the regional endpoint, authenticate via an initial JSON message, transmit the play directive, and handle atomic message operations. The connection must verify format compliance and trigger automatic next track iteration when playback completes.

import java.net.http.WebSocket;
import java.net.URI;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

public class VoiceWebSocketClient {
    private final String region;
    private final String accessToken;
    private WebSocket webSocket;

    public VoiceWebSocketClient(String region, String accessToken) {
        this.region = region;
        this.accessToken = accessToken;
    }

    public void connectAndPlay(String playPayload, Function<String, Boolean> eventHandler) throws Exception {
        String wsUrl = String.format("wss://api.%s.genesyscloud.com/v2/voice/control", region);
        WebSocket.Builder builder = WebSocket.newBuilder();
        
        webSocket = builder.buildAsync(URI.create(wsUrl), new WebSocket.Listener() {
            @Override
            public void onOpen(WebSocket ws) {
                String authMessage = String.format("{\"action\":\"authenticate\",\"token\":\"Bearer %s\"}", accessToken);
                ws.sendText(authMessage, true);
            }

            @Override
            public CompletionStage<?> onText(WebSocket ws, CharSequence data, boolean more) {
                String response = data.toString();
                boolean continueStream = eventHandler.apply(response);
                if (!continueStream) {
                    ws.sendClose(WebSocket.NORMAL_CLOSURE, "Playback complete");
                }
                return null;
            }

            @Override
            public void onError(WebSocket ws, Throwable error) {
                System.err.println("WebSocket error: " + error.getMessage());
            }
        }).join();

        // Wait for handshake completion before sending play directive
        TimeUnit.SECONDS.sleep(2);
        webSocket.sendText(playPayload, true);
    }
}

Expected Response: Initial authentication returns {"action":"authenticated","userId":"..."}. Successful play returns {"action":"play","status":"queued"}.
Error Handling: A 401 Unauthorized during authentication indicates an expired or invalid token. A 403 Forbidden indicates missing voice:control scope. Implement reconnection logic with exponential backoff for transient network failures.

Step 4: Handle Play Events, Webhooks, and Audit Tracking

You must synchronize playing events with external media libraries via webhooks, track playing latency, calculate stream success rates, and generate audit logs for media governance. The event handler processes WebSocket messages, calculates latency between directive send and play start, posts to external endpoints, and records audit trails.

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Instant;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Logger;

public class PlaybackEventTracker {
    private static final Logger LOGGER = Logger.getLogger(PlaybackEventTracker.class.getName());
    private static final ObjectMapper MAPPER = new ObjectMapper();
    private static final HttpClient HTTP_CLIENT = HttpClient.newHttpClient();
    private static final String WEBHOOK_URL = System.getenv("WEBHOOK_URL");
    
    private final Map<String, Long> sequenceLatencyMap = new ConcurrentHashMap<>();
    private int successCount = 0;
    private int failureCount = 0;

    public Boolean handleEvent(String sequenceId, String eventName, String eventPayload) {
        try {
            JsonNode node = MAPPER.readTree(eventPayload);
            Instant now = Instant.now();
            
            switch (eventName) {
                case "playStart":
                    sequenceLatencyMap.put(sequenceId, now.getEpochSecond());
                    LOGGER.info("Audit: Play started for sequence " + sequenceId);
                    break;
                    
                case "playComplete":
                    Long startEpoch = sequenceLatencyMap.remove(sequenceId);
                    if (startEpoch != null) {
                        long latency = now.getEpochSecond() - startEpoch;
                        successCount++;
                        LOGGER.info("Audit: Play completed. Latency: " + latency + "s. Success rate: " + calculateSuccessRate());
                        triggerWebhook(sequenceId, "completed", latency);
                    }
                    return false; // Signal end of stream
                    
                case "playFailed":
                    failureCount++;
                    String errorReason = node.path("reason").asText("Unknown");
                    LOGGER.severe("Audit: Play failed. Reason: " + errorReason);
                    triggerWebhook(sequenceId, "failed", 0);
                    return false;
                    
                default:
                    return true;
            }
        } catch (Exception e) {
            LOGGER.severe("Event processing error: " + e.getMessage());
        }
        return true;
    }

    private double calculateSuccessRate() {
        int total = successCount + failureCount;
        return total == 0 ? 0.0 : (double) successCount / total;
    }

    private void triggerWebhook(String sequenceId, String status, long latency) {
        String payload = String.format(
            "{\"sequenceId\":\"%s\",\"status\":\"%s\",\"latencySeconds\":%d,\"timestamp\":\"%s\"}",
            sequenceId, status, latency, Instant.now().toString()
        );
        
        HttpRequest request = HttpRequest.newBuilder()
            .uri(java.net.URI.create(WEBHOOK_URL))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(payload))
            .build();
            
        try {
            HTTP_CLIENT.send(request, HttpResponse.BodyHandlers.discarding());
        } catch (Exception e) {
            LOGGER.warning("Webhook delivery failed: " + e.getMessage());
        }
    }
}

Expected Response: Webhook receives JSON with sequence ID, status, latency, and timestamp. Audit logs record start, completion, failure, and efficiency metrics.
Error Handling: Webhook POST failures are logged but do not interrupt the WebSocket stream. Implement retry queues for critical webhook delivery.

Complete Working Example

The following Java class integrates authentication, validation, payload construction, WebSocket streaming, and event tracking into a single executable module. Replace environment variables with your credentials before running.

import com.mypurecloud.api.client.ApiClient;
import com.mypurecloud.api.client.auth.OAuthToken;
import java.util.concurrent.TimeUnit;

public class GenesysMediaPlayer {
    public static void main(String[] args) {
        try {
            // 1. Authentication
            ApiClient client = GenesysAuth.createAuthenticatedClient();
            
            // 2. Validation
            String mediaId = System.getenv("GENESYS_MEDIA_ID");
            double volume = 0.8;
            MediaValidator.validateMediaFile(client, mediaId, volume);
            
            // 3. Payload Construction
            String playPayload = PlayPayloadBuilder.buildPlayDirective(mediaId, volume, "opus", "adaptive");
            
            // 4. Event Tracking & WebSocket Connection
            PlaybackEventTracker tracker = new PlaybackEventTracker();
            VoiceWebSocketClient wsClient = new VoiceWebSocketClient(
                System.getenv("GENESYS_REGION"),
                client.getAccessToken()
            );
            
            wsClient.connectAndPlay(playPayload, (eventPayload) -> {
                try {
                    JsonNode node = new com.fasterxml.jackson.databind.ObjectMapper().readTree(eventPayload);
                    String action = node.path("action").asText("");
                    String sequenceId = node.path("sequenceId").asText("");
                    return tracker.handleEvent(sequenceId, action, eventPayload);
                } catch (Exception e) {
                    System.err.println("Event parsing error: " + e.getMessage());
                    return true;
                }
            });
            
            // Keep main thread alive for WebSocket lifecycle
            while (true) {
                TimeUnit.SECONDS.sleep(10);
            }
            
        } catch (Exception e) {
            System.err.println("Playback failed: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

Compile with: javac -cp "lib/*:jackson-databind-2.15.2.jar:api-*.jar" *.java
Run with: java -cp ".:lib/*:jackson-databind-2.15.2.jar:api-*.jar" GenesysMediaPlayer

Common Errors & Debugging

Error: 401 Unauthorized

• Cause: Expired OAuth token or incorrect client credentials.
• Fix: Implement automatic token refresh 60 seconds before expiration. Verify GENESYS_CLIENT_ID and GENESYS_CLIENT_SECRET environment variables.
• Code Fix: Replace static token assignment with a scheduled executor that calls oauthClient.requestClientCredentialsToken and updates client.setAccessToken().

Error: 403 Forbidden

• Cause: Missing required OAuth scopes or insufficient organizational permissions.
• Fix: Ensure the OAuth client is granted media:read, voice:control, and webhooks:write scopes in the Genesys Cloud admin console. Verify the application user has Voice API access.
• Code Fix: Update the scopes array in GenesysAuth to match required permissions.

Error: 429 Too Many Requests

• Cause: Exceeding REST API rate limits during media validation or webhook registration.
• Fix: Implement exponential backoff with jitter. Genesys Cloud returns Retry-After headers.
• Code Fix: Wrap REST calls in a retry loop:

int retries = 3;
for (int i = 0; i < retries; i++) {
    try {
        return mediaApi.getMediaFile(mediaId);
    } catch (com.mypurecloud.api.client.ApiException e) {
        if (e.getCode() == 429) {
            long retryAfter = Long.parseLong(e.getResponseHeaders().get("Retry-After").get(0));
            TimeUnit.SECONDS.sleep(retryAfter);
        } else {
            throw e;
        }
    }
}

Error: WebSocket Connection Refused or Dropped

• Cause: Network firewall blocking wss:// traffic or malformed authentication message.
• Fix: Verify outbound WebSocket connectivity to api.{region}.genesyscloud.com:443. Ensure the authenticate message matches the exact schema. Implement automatic reconnection with a maximum retry limit.
• Code Fix: Add a catch block in onError that schedules a connectAndPlay retry after 5 seconds.

Official References

• Genesys Cloud Voice API WebSocket Documentation
• Genesys Cloud Media API Reference
• Java WebSocket Client API
• OAuth 2.0 Client Credentials Flow