Integrating a Custom ASR Provider with Genesys Cloud Using Spring Boot WebSocket Streams and Transcription Callbacks

What You Will Build

• A Java Spring Boot service that accepts real-time audio streams from Genesys Cloud over WebSocket, processes the audio, and posts transcription results back to the Genesys Cloud Transcription API.
• This implementation uses the Genesys Cloud Transcription API contract for custom external ASR providers.
• The tutorial covers Java 17, Spring Boot 3.2, and standard Jakarta WebSocket libraries.

Prerequisites

• Genesys Cloud OAuth Client configured with Client Credentials grant type
• Required OAuth scope: conversation:transcription:write
• Java 17 or later
• Spring Boot 3.2+
• Maven or Gradle
• External dependencies: spring-boot-starter-web, spring-boot-starter-websocket, jakarta.websocket-api, jackson-databind

Authentication Setup

Genesys Cloud requires every transcription result submission to be authenticated. Your Spring Boot service must obtain a Client Credentials token before posting results to the callback URL. The token must be cached and refreshed before expiration.

The following service handles token acquisition, caching, and automatic refresh logic.

import org.springframework.stereotype.Service;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Instant;
import java.util.Map;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;

@Service
public class OAuthTokenProvider {

    private static final String GENESYS_AUTH_URL = "https://api.mypurecloud.com/oauth/token";
    private static final HttpClient HTTP_CLIENT = HttpClient.newHttpClient();
    private static final ObjectMapper MAPPER = new ObjectMapper();

    private String cachedToken;
    private Instant tokenExpiry;

    public String getAccessToken(String clientId, String clientSecret) throws Exception {
        if (cachedToken != null && Instant.now().isBefore(tokenExpiry.minusSeconds(60))) {
            return cachedToken;
        }

        String body = String.format("grant_type=client_credentials&client_id=%s&client_secret=%s&scope=conversation%%3Atranscription%%3Awrite",
                clientId, clientSecret);

        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(GENESYS_AUTH_URL))
                .header("Content-Type", "application/x-www-form-urlencoded")
                .POST(HttpRequest.BodyPublishers.ofString(body))
                .build();

        HttpResponse<String> response = HTTP_CLIENT.send(request, HttpResponse.BodyHandlers.ofString());

        if (response.statusCode() != 200) {
            throw new RuntimeException("OAuth token request failed with status " + response.statusCode());
        }

        JsonNode json = MAPPER.readTree(response.body());
        this.cachedToken = json.get("access_token").asText();
        this.tokenExpiry = Instant.now().plusSeconds(json.get("expires_in").asInt());

        return cachedToken;
    }
}

The service caches the token and refreshes it automatically when less than sixty seconds remain before expiration. The URL-encoded scope conversation%3Atranscription%3Awrite ensures the token carries the required permission for transcription result submission.

Implementation

Step 1: WebSocket Endpoint Registration and Session Management

Genesys Cloud initiates a WebSocket connection to your external ASR service. You must register a Jakarta WebSocket endpoint and configure Spring Boot to scan for it. The endpoint will receive both text control messages and binary audio frames.

Create a WebSocket configuration class that registers the endpoint and sets appropriate buffer sizes for audio streaming.

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;
import com.fasterxml.jackson.databind.ObjectMapper;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    private final ObjectMapper objectMapper;

    public WebSocketConfig(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(genesisTranscriptionHandler(), "/ws/transcription")
                .setAllowedOrigins("*")
                .withSockJS();
    }

    @Bean
    public GenesisTranscriptionWebSocketHandler genesisTranscriptionHandler() {
        return new GenesisTranscriptionWebSocketHandler(objectMapper);
    }
}

The /ws/transcription path is the endpoint you will configure in the Genesys Cloud admin console under Transcription Services. The setAllowedOrigins("*") directive is required for initial testing but should be restricted to your Genesys Cloud environment domain in production.

Step 2: Parsing Start Messages and Processing Audio Frames

Genesys Cloud sends a JSON start message immediately after the WebSocket handshake. This message contains the callback URL, conversation identifiers, media format, and sample rate. Your handler must extract these values and store them in the WebSocket session for later use during result submission.

The handler must also manage binary audio frames. In a production ASR integration, you would pipe these bytes to your speech recognition engine. This example demonstrates the frame lifecycle, buffer management, and session metadata extraction.

import org.springframework.web.socket.BinaryMessage;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.BinaryWebSocketHandler;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class GenesisTranscriptionWebSocketHandler extends BinaryWebSocketHandler {

    private static final Logger log = LoggerFactory.getLogger(GenesisTranscriptionWebSocketHandler.class);
    private final ObjectMapper objectMapper;

    public GenesisTranscriptionWebSocketHandler(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        log.info("Genesys Cloud WebSocket connection established: {}", session.getId());
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        JsonNode payload = objectMapper.readTree(message.getPayload());
        String messageType = payload.path("type").asText();

        if ("start".equals(messageType)) {
            String callbackUrl = payload.path("callbackUrl").asText();
            String conversationId = payload.path("conversationId").asText();
            String participantId = payload.path("participantId").asText();
            String mediaType = payload.path("mediaType").asText();
            int sampleRate = payload.path("sampleRate").asInt();

            session.getAttributes().put("callbackUrl", callbackUrl);
            session.getAttributes().put("conversationId", conversationId);
            session.getAttributes().put("participantId", participantId);
            session.getAttributes().put("mediaType", mediaType);
            session.getAttributes().put("sampleRate", sampleRate);

            log.info("Transcription session initialized: conv={}, part={}, media={}, sampleRate={}",
                    conversationId, participantId, mediaType, sampleRate);
        } else if ("stop".equals(messageType)) {
            log.info("Genesys Cloud requested transcription stop for session {}", session.getId());
            session.close();
        }
    }

    @Override
    protected void handleBinaryMessage(WebSocketSession session, BinaryMessage message) throws Exception {
        byte[] audioData = message.getPayload().array();
        String conversationId = (String) session.getAttributes().get("conversationId");
        String participantId = (String) session.getAttributes().get("participantId");
        String callbackUrl = (String) session.getAttributes().get("callbackUrl");

        if (callbackUrl == null) {
            log.warn("Received audio before start message. Dropping frame.");
            return;
        }

        // Simulate ASR processing. In production, pipe audioData to your recognition engine.
        processAudioChunk(audioData, conversationId, participantId, callbackUrl, session);
    }

    private void processAudioChunk(byte[] audioData, String conversationId, String participantId,
                                   String callbackUrl, WebSocketSession session) {
        // Placeholder for actual ASR engine invocation
        log.debug("Processing {} bytes of audio for conv={}", audioData.length, conversationId);
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) {
        log.error("WebSocket transport error for session {}: {}", session.getId(), exception.getMessage(), exception);
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, org.springframework.web.socket.CloseStatus status) {
        log.info("Genesys Cloud WebSocket connection closed: {} - {}", session.getId(), status);
    }
}

The start message attributes are stored in the WebSocketSession attributes map. This allows the binary handler to access the callback URL without maintaining external state. The stop message triggers session cleanup.

Step 3: HTTP Callback to Genesys Cloud Transcription API

After processing audio, your service must POST the transcription result to the callback URL extracted from the start message. Genesys Cloud expects a specific JSON schema, proper authentication headers, and strict content-type declaration. The following service handles result formatting, HTTP submission, and retry logic for rate limits and transient errors.

import org.springframework.stereotype.Service;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

@Service
public class TranscriptionCallbackService {

    private static final Logger log = LoggerFactory.getLogger(TranscriptionCallbackService.class);
    private static final HttpClient HTTP_CLIENT = HttpClient.newBuilder()
            .connectTimeout(java.time.Duration.ofSeconds(10))
            .build();
    private final ObjectMapper objectMapper;
    private final OAuthTokenProvider tokenProvider;

    public TranscriptionCallbackService(ObjectMapper objectMapper, OAuthTokenProvider tokenProvider) {
        this.objectMapper = objectMapper;
        this.tokenProvider = tokenProvider;
    }

    public void submitResult(String callbackUrl, String conversationId, String participantId,
                             String text, double confidence, String language, String clientId, String clientSecret) {
        String jsonPayload = objectMapper.createObjectNode()
                .put("conversationId", conversationId)
                .put("participantId", participantId)
                .put("text", text)
                .put("confidence", confidence)
                .put("language", language)
                .put("status", "completed")
                .put("transcriptionId", java.util.UUID.randomUUID().toString())
                .toString();

        String token;
        try {
            token = tokenProvider.getAccessToken(clientId, clientSecret);
        } catch (Exception e) {
            log.error("Failed to acquire OAuth token for callback submission", e);
            return;
        }

        HttpRequest.Builder requestBuilder = HttpRequest.newBuilder()
                .uri(URI.create(callbackUrl))
                .header("Authorization", "Bearer " + token)
                .header("Content-Type", "application/json")
                .header("Accept", "application/json");

        int maxRetries = 3;
        int attempt = 0;
        long baseDelayMs = 500;

        while (attempt < maxRetries) {
            try {
                HttpRequest request = requestBuilder.POST(HttpRequest.BodyPublishers.ofString(jsonPayload)).build();
                HttpResponse<String> response = HTTP_CLIENT.send(request, HttpResponse.BodyHandlers.ofString());
                int statusCode = response.statusCode();

                if (statusCode == 200 || statusCode == 201 || statusCode == 202) {
                    log.info("Transcription result submitted successfully for conv={} status={}", conversationId, statusCode);
                    return;
                } else if (statusCode == 401 || statusCode == 403) {
                    log.error("Authentication or authorization failed for callback. Status: {}. Payload: {}", statusCode, jsonPayload);
                    return;
                } else if (statusCode == 429) {
                    long retryAfter = parseRetryAfter(response.headers());
                    long delay = Math.max(baseDelayMs * Math.pow(2, attempt), retryAfter);
                    log.warn("Rate limited (429). Retrying in {} ms. Attempt {}/{}", delay, attempt + 1, maxRetries);
                    Thread.sleep(delay);
                    attempt++;
                } else if (statusCode >= 500) {
                    long delay = baseDelayMs * Math.pow(2, attempt);
                    log.warn("Server error ({}). Retrying in {} ms. Attempt {}/{}", statusCode, delay, attempt + 1, maxRetries);
                    Thread.sleep(delay);
                    attempt++;
                } else {
                    log.error("Unexpected response status {} for callback. Body: {}", statusCode, response.body());
                    return;
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                log.error("Retry loop interrupted", e);
                return;
            } catch (Exception e) {
                log.error("HTTP callback failed: {}", e.getMessage(), e);
                return;
            }
        }
        log.error("Max retries exceeded for transcription callback submission");
    }

    private long parseRetryAfter(java.net.http.HttpHeaders headers) {
        try {
            return Long.parseLong(headers.firstValue("Retry-After").orElse("1000"));
        } catch (Exception e) {
            return 1000;
        }
    }
}

The retry loop handles 429 Too Many Requests by parsing the Retry-After header and applying exponential backoff. Authentication failures (401, 403) terminate immediately because retrying will not resolve scope or credential mismatches. Server errors (5xx) trigger retries to accommodate transient Genesys Cloud platform load.

Step 4: Wiring the WebSocket Handler to the Callback Service

To complete the integration, the WebSocket handler must invoke the callback service after processing audio. In a production ASR engine, you would trigger the callback when a final transcription segment is ready. The following method demonstrates how to bridge the binary handler to the callback service.

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.socket.WebSocketSession;

// Inside GenesisTranscriptionWebSocketHandler
@Autowired
private TranscriptionCallbackService callbackService;

@Autowired
private OAuthTokenProvider tokenProvider;

private void processAudioChunk(byte[] audioData, String conversationId, String participantId,
                               String callbackUrl, WebSocketSession session) {
    // Simulate ASR processing completion
    String simulatedTranscript = "Hello, how can I assist you today?";
    double simulatedConfidence = 0.94;
    String language = "en-US";

    // Retrieve credentials from environment or configuration
    String clientId = System.getenv("GENESYS_CLIENT_ID");
    String clientSecret = System.getenv("GENESYS_CLIENT_SECRET");

    if (clientId == null || clientSecret == null) {
        log.error("OAuth credentials not configured. Abandoning callback.");
        return;
    }

    callbackService.submitResult(callbackUrl, conversationId, participantId,
            simulatedTranscript, simulatedConfidence, language, clientId, clientSecret);
}

This wiring demonstrates the complete data flow: Genesys Cloud streams audio via WebSocket, the handler extracts metadata, processes the audio, and posts the result to the Genesys Cloud Transcription API callback endpoint.

Complete Working Example

The following Maven configuration and application entry point provide a runnable foundation. Combine the classes from the previous sections into a standard Spring Boot project structure.

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.0</version>
    </parent>
    <groupId>com.example</groupId>
    <artifactId>genesys-transcription-asr</artifactId>
    <version>1.0.0</version>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>
        <dependency>
            <groupId>jakarta.websocket</groupId>
            <artifactId>jakarta.websocket-api</artifactId>
            <version>2.1.0</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Application.java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Set the following environment variables before execution:

export GENESYS_CLIENT_ID="your-client-id"
export GENESYS_CLIENT_SECRET="your-client-secret"
export GENESYS_ENVIRONMENT="mypurecloud.com"

Run the application with mvn spring-boot:run. The WebSocket endpoint will be available at wss://your-domain.com/ws/transcription. Configure this URL in the Genesys Cloud admin console under Transcription Services.

Common Errors & Debugging

Error: 401 Unauthorized on Callback Submission

• Cause: The OAuth token expired, was malformed, or lacks the conversation:transcription:write scope.
• Fix: Verify the client credentials match a Genesys Cloud OAuth client. Confirm the scope is granted in the Admin console under Security > OAuth 2.0 Clients. Check that the OAuthTokenProvider refreshes the token before expiration.
• Code Fix: Ensure the grant_type=client_credentials request includes the exact scope string. Add logging to print the raw token response during initial setup.

Error: 403 Forbidden on Callback Submission

• Cause: The OAuth client does not have the required scope, or the callback URL belongs to a different Genesys Cloud subdomain than the token issuer.
• Fix: Validate that the callbackUrl extracted from the WebSocket start message matches the environment used to generate the token. Cross-environment token usage is not permitted.
• Code Fix: Add a domain validation check in TranscriptionCallbackService to ensure the token issuer matches the callback URL host.

Error: 429 Too Many Requests

• Cause: Your service submits transcription results faster than Genesys Cloud accepts them, or you exceeded the per-participant rate limit.
• Fix: Implement exponential backoff with jitter. Parse the Retry-After header precisely. Reduce result submission frequency by batching partial results.
• Code Fix: The provided submitResult method already implements Retry-After parsing and exponential backoff. Increase baseDelayMs if cascading rate limits occur.

Error: WebSocket Handshake Failure or Immediate Closure

• Cause: Mismatched WebSocket protocol expectations, missing Sec-WebSocket-Protocol header, or TLS certificate validation failure on the Genesys Cloud side.
• Fix: Ensure your endpoint accepts standard WebSocket upgrades without custom subprotocols unless explicitly required. Verify your server presents a valid public TLS certificate. Genesys Cloud rejects self-signed certificates in production.
• Code Fix: Remove withSockJS() from WebSocketConfig if you require native WebSocket behavior. SockJS falls back to HTTP long-polling, which Genesys Cloud does not support for transcription audio streams.

Official References

• Genesys Cloud Transcription API Documentation
• Custom Transcription Provider Integration Guide
• Genesys Cloud OAuth 2.0 Client Credentials Flow
• Spring Boot WebSocket Configuration
• Jakarta WebSocket API Specification