Transferring Genesys Cloud Interaction Media Streams via WebSocket API with Go

What You Will Build

• A production-grade Go media transferor that authenticates, connects to the Genesys Cloud WebSocket, validates gateway constraints, constructs atomic transfer payloads with media matrices, handles codec negotiation, tracks latency, and generates audit logs.
• This implementation uses the Genesys Cloud WebSocket API (wss://api.mypurecloud.com/api/v2/websocket) combined with OAuth2 client credentials.
• The code is written in Go 1.21+ using standard libraries alongside nhooyr.io/websocket, github.com/myPureCloud/platform-client-v2-go, and go.uber.org/zap.

Prerequisites

• OAuth2 Client Credentials flow with a Genesys Cloud API key
• Required scopes: interaction:transfer, websocket:use, interaction:view
• Go 1.21 or later
• External dependencies:
  • github.com/myPureCloud/platform-client-v2-go
  • nhooyr.io/websocket
  • go.uber.org/zap
  • github.com/google/uuid

Authentication Setup

Genesys Cloud requires a valid OAuth2 bearer token for WebSocket handshake authentication. The following code fetches the token, caches it, and implements automatic refresh logic before expiration.

package auth

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"sync"
	"time"
)

type OAuthConfig struct {
	Environment string
	ClientID    string
	ClientSecret string
}

type TokenResponse struct {
	AccessToken string `json:"access_token"`
	ExpiresIn   int    `json:"expires_in"`
	TokenType   string `json:"token_type"`
}

type TokenManager struct {
	mu          sync.Mutex
	config      OAuthConfig
	token       TokenResponse
	expiresAt   time.Time
	httpClient  *http.Client
}

func NewTokenManager(cfg OAuthConfig) *TokenManager {
	return &TokenManager{
		config:     cfg,
		httpClient: &http.Client{Timeout: 10 * time.Second},
	}
}

func (tm *TokenManager) GetToken(ctx context.Context) (string, error) {
	tm.mu.Lock()
	defer tm.mu.Unlock()

	if time.Until(tm.expiresAt) > 5*time.Minute {
		return tm.token.AccessToken, nil
	}

	token, err := tm.fetchToken(ctx)
	if err != nil {
		return "", fmt.Errorf("oauth token fetch failed: %w", err)
	}

	tm.token = token
	tm.expiresAt = time.Now().Add(time.Duration(token.ExpiresIn) * time.Second)
	return token.AccessToken, nil
}

func (tm *TokenManager) fetchToken(ctx context.Context) (TokenResponse, error) {
	endpoint := fmt.Sprintf("https://api.%s.mypurecloud.com/oauth/token", tm.config.Environment)
	
	payload := map[string]string{
		"grant_type":    "client_credentials",
		"client_id":     tm.config.ClientID,
		"client_secret": tm.config.ClientSecret,
		"scope":         "interaction:transfer websocket:use interaction:view",
	}

	data, err := json.Marshal(payload)
	if err != nil {
		return TokenResponse{}, fmt.Errorf("marshal oauth payload: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, endpoint, nil)
	if err != nil {
		return TokenResponse{}, fmt.Errorf("create oauth request: %w", err)
	}

	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.SetBasicAuth(tm.config.ClientID, tm.config.ClientSecret)

	resp, err := tm.httpClient.Do(req)
	if err != nil {
		return TokenResponse{}, fmt.Errorf("execute oauth request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return TokenResponse{}, fmt.Errorf("oauth request failed with status %d", resp.StatusCode)
	}

	var tokenResp TokenResponse
	if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
		return TokenResponse{}, fmt.Errorf("decode oauth response: %w", err)
	}

	return tokenResp, nil
}

Implementation

Step 1: WebSocket Connection and Session Validation

The Genesys Cloud WebSocket requires a secure connection with a bearer token in the Authorization header. Session continuity is verified through ping/pong monitoring and TLS state validation before any transfer operation executes.

package transferor

import (
	"context"
	"crypto/tls"
	"fmt"
	"net/http"
	"time"

	"github.com/myPureCloud/platform-client-v2-go/auth"
	"github.com/nhooyr.io/websocket"
	"go.uber.org/zap"
)

type WebSocketSession struct {
	conn      *websocket.Conn
	tlsState  *tls.ConnectionState
	alive     bool
	logger    *zap.Logger
	tokenMgr  *auth.TokenManager
}

func NewWebSocketSession(ctx context.Context, env string, tokenMgr *auth.TokenManager, logger *zap.Logger) (*WebSocketSession, error) {
	token, err := tokenMgr.GetToken(ctx)
	if err != nil {
		return nil, fmt.Errorf("retrieve oauth token: %w", err)
	}

	u := fmt.Sprintf("wss://api.%s.mypurecloud.com/api/v2/websocket", env)
	
	httpHeader := http.Header{}
	httpHeader.Set("Authorization", "Bearer "+token)
	httpHeader.Set("Accept", "application/json")

	conn, resp, err := websocket.Dial(ctx, u, &websocket.DialOptions{
		HTTPClient: &http.Client{Timeout: 15 * time.Second},
		HTTPHeader: httpHeader,
	})
	if err != nil {
		if resp != nil && resp.StatusCode == http.StatusUnauthorized {
			return nil, fmt.Errorf("websocket handshake failed: 401 Unauthorized. Verify scopes and token validity")
		}
		return nil, fmt.Errorf("websocket dial failed: %w", err)
	}

	tlsState := conn.CloseHandler().(*tls.ConnectionState)
	if tlsState == nil || tlsState.Version < tls.VersionTLS12 {
		conn.Close(websocket.StatusInternalError, "insecure tls version")
		return nil, fmt.Errorf("encryption parameter verification failed: tls version below 1.2")
	}

	return &WebSocketSession{
		conn:     conn,
		tlsState: tlsState,
		alive:    true,
		logger:   logger,
		tokenMgr: tokenMgr,
	}, nil
}

func (ws *WebSocketSession) ValidateSession(ctx context.Context) error {
	if !ws.alive {
		return fmt.Errorf("session continuity check failed: websocket connection closed")
	}

	deadline := time.Now().Add(3 * time.Second)
	if err := ws.conn.SetReadDeadline(deadline); err != nil {
		return fmt.Errorf("set read deadline: %w", err)
	}

	if err := ws.conn.Ping(ctx); err != nil {
		ws.alive = false
		return fmt.Errorf("session continuity check failed: ping timeout or connection reset")
	}

	return nil
}

Step 2: Constraint Validation and Payload Construction

Genesys Cloud interaction gateways enforce bandwidth limits and media type compatibility. This step validates the transfer request against maximum bandwidth constraints, constructs a media type matrix, and formats the destination URI directive before serialization.

package transferor

import (
	"encoding/json"
	"fmt"
	"time"
)

type MediaMatrix struct {
	Audio struct {
		Codec string `json:"codec"`
		BandwidthKbps int `json:"bandwidth_kbps"`
		BitDepth int `json:"bit_depth"`
	} `json:"audio"`
	Video struct {
		Codec string `json:"codec"`
		Resolution string `json:"resolution"`
		FPS int `json:"fps"`
	} `json:"video,omitempty"`
}

type TransferPayload struct {
	Type string `json:"type"`
	ID   string `json:"id"`
	InteractionID string `json:"interaction_id"`
	DestinationURI string `json:"destination_uri"`
	MediaMatrix MediaMatrix `json:"media_matrix"`
	Timestamp time.Time `json:"timestamp"`
	Triggers struct {
		CodecNegotiation bool `json:"codec_negotiation"`
		FormatVerification bool `json:"format_verification"`
	} `json:"triggers"`
}

type GatewayConstraint struct {
	MaxBandwidthKbps int
	SupportedCodecs []string
	MaxFPS int
}

func ValidateConstraints(matrix MediaMatrix, constraint GatewayConstraint) error {
	if matrix.Audio.BandwidthKbps > constraint.MaxBandwidthKbps {
		return fmt.Errorf("bandwidth limit exceeded: requested %d kbps exceeds gateway maximum %d kbps", 
			matrix.Audio.BandwidthKbps, constraint.MaxBandwidthKbps)
	}

	codecValid := false
	for _, c := range constraint.SupportedCodecs {
		if c == matrix.Audio.Codec {
			codecValid = true
			break
		}
	}
	if !codecValid {
		return fmt.Errorf("codec negotiation trigger required: %s is not in gateway supported list", matrix.Audio.Codec)
	}

	if matrix.Video.FPS > constraint.MaxFPS {
		return fmt.Errorf("video fps exceeds gateway constraint: %d > %d", matrix.Video.FPS, constraint.MaxFPS)
	}

	return nil
}

func BuildTransferPayload(interactionID, destinationURI string, matrix MediaMatrix) (TransferPayload, error) {
	payload := TransferPayload{
		Type: "interaction.transfer",
		ID: generateUUID(),
		InteractionID: interactionID,
		DestinationURI: destinationURI,
		MediaMatrix: matrix,
		Timestamp: time.Now().UTC(),
		Triggers: struct {
			CodecNegotiation bool `json:"codec_negotiation"`
			FormatVerification bool `json:"format_verification"`
		}{
			CodecNegotiation: true,
			FormatVerification: true,
		},
	}

	if payload.InteractionID == "" {
		return TransferPayload{}, fmt.Errorf("interaction id reference cannot be empty")
	}
	if payload.DestinationURI == "" {
		return TransferPayload{}, fmt.Errorf("destination uri directive cannot be empty")
	}

	return payload, nil
}

func generateUUID() string {
	return fmt.Sprintf("%d", time.Now().UnixNano())
}

Step 3: Atomic Send, Codec Negotiation, and Metrics Tracking

The transfer execution uses an atomic send pattern with exponential backoff for 429 rate limits. The system tracks latency, verifies codec negotiation responses, and syncs with external media servers via callback handlers.

package transferor

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"time"

	"github.com/nhooyr.io/websocket"
	"go.uber.org/zap"
)

type TransferMetrics struct {
	LatencyMs float64 `json:"latency_ms"`
	Retries   int     `json:"retries"`
	Status    string  `json:"status"`
}

type ExternalCallback struct {
	URL     string
	Method  string
	Payload []byte
}

type MediaTransferor struct {
	session    *WebSocketSession
	logger     *zap.Logger
	maxRetries int
}

func NewMediaTransferor(session *WebSocketSession, logger *zap.Logger) *MediaTransferor {
	return &MediaTransferor{
		session:    session,
		logger:     logger,
		maxRetries: 3,
	}
}

func (mt *MediaTransferor) ExecuteTransfer(ctx context.Context, payload TransferPayload) (*TransferMetrics, error) {
	startTime := time.Now()
	metrics := &TransferMetrics{}

	jsonData, err := json.Marshal(payload)
	if err != nil {
		return metrics, fmt.Errorf("marshal transfer payload: %w", err)
	}

	for attempt := 0; attempt <= mt.maxRetries; attempt++ {
		metrics.Retries = attempt
		
		err := mt.session.conn.Write(ctx, websocket.MessageText, jsonData)
		if err != nil {
			if websocket.CloseStatus(err) == 1008 || isRateLimitError(err) {
				mt.logger.Warn("websocket send failed, retrying", zap.Int("attempt", attempt))
				time.Sleep(time.Duration(attempt+1) * time.Second)
				continue
			}
			return metrics, fmt.Errorf("atomic send operation failed: %w", err)
		}

		metrics.LatencyMs = time.Since(startTime).Seconds() * 1000
		metrics.Status = "sent"
		
		mt.logger.Info("transfer payload delivered", 
			zap.String("interaction_id", payload.InteractionID),
			zap.Float64("latency_ms", metrics.LatencyMs))

		return metrics, mt.waitForCodecNegotiation(ctx, payload.ID)
	}

	return metrics, fmt.Errorf("max retries exceeded for atomic send operation")
}

func (mt *MediaTransferor) waitForCodecNegotiation(ctx context.Context, messageID string) error {
	deadline := time.Now().Add(10 * time.Second)
	ctx, cancel := context.WithDeadline(ctx, deadline)
	defer cancel()

	for {
		msgType, payload, err := mt.session.conn.Read(ctx)
		if err != nil {
			return fmt.Errorf("read websocket response: %w", err)
		}

		if msgType != websocket.MessageText {
			continue
		}

		var response map[string]interface{}
		if err := json.Unmarshal(payload, &response); err != nil {
			continue
		}

		if id, ok := response["id"].(string); ok && id == messageID {
			if status, ok := response["status"].(string); ok {
				if status == "codec_negotiated" || status == "transfer_initiated" {
					return nil
				}
				return fmt.Errorf("transfer rejected by gateway: %s", status)
			}
		}
	}
}

func isRateLimitError(err error) bool {
	// WebSocket does not return HTTP 429 directly, but Genesys Cloud may close with specific status codes
	// or return error messages containing rate limit indicators
	return websocket.CloseStatus(err) == 1008
}

func (mt *MediaTransferor) SyncExternalServer(ctx context.Context, callback ExternalCallback) error {
	req, err := http.NewRequestWithContext(ctx, callback.Method, callback.URL, bytes.NewReader(callback.Payload))
	if err != nil {
		return fmt.Errorf("create callback request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")

	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("execute callback: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		return fmt.Errorf("external server callback failed with status %d", resp.StatusCode)
	}

	return nil
}

Complete Working Example

The following module integrates authentication, WebSocket session management, constraint validation, atomic transfer execution, metrics tracking, and structured audit logging into a single runnable application.

package main

import (
	"context"
	"fmt"
	"os"
	"time"

	"github.com/myPureCloud/platform-client-v2-go/auth"
	"github.com/myPureCloud/platform-client-v2-go/transferor"
	"go.uber.org/zap"
)

func main() {
	ctx := context.Background()

	logger, err := zap.NewProduction()
	if err != nil {
		fmt.Printf("initialize logger: %v\n", err)
		os.Exit(1)
	}
	defer logger.Sync()

	tokenMgr := auth.NewTokenManager(auth.OAuthConfig{
		Environment: "us",
		ClientID:    os.Getenv("GENESYS_CLIENT_ID"),
		ClientSecret: os.Getenv("GENESYS_CLIENT_SECRET"),
	})

	session, err := transferor.NewWebSocketSession(ctx, "us", tokenMgr, logger)
	if err != nil {
		logger.Fatal("websocket connection failed", zap.Error(err))
	}
	defer session.Close()

	if err := session.ValidateSession(ctx); err != nil {
		logger.Fatal("session validation failed", zap.Error(err))
	}

	transferor := transferor.NewMediaTransferor(session, logger)

	matrix := transferor.MediaMatrix{
		Audio: struct {
			Codec string `json:"codec"`
			BandwidthKbps int `json:"bandwidth_kbps"`
			BitDepth int `json:"bit_depth"`
		}{
			Codec: "opus",
			BandwidthKbps: 64,
			BitDepth: 16,
		},
	}

	constraint := transferor.GatewayConstraint{
		MaxBandwidthKbps: 128,
		SupportedCodecs: []string{"opus", "g722", "pcmu"},
		MaxFPS: 30,
	}

	if err := transferor.ValidateConstraints(matrix, constraint); err != nil {
		logger.Fatal("gateway constraint validation failed", zap.Error(err))
	}

	payload, err := transferor.BuildTransferPayload(
		"interaction-12345-abcde",
		"genesys://user/agent-id-98765",
		matrix,
	)
	if err != nil {
		logger.Fatal("payload construction failed", zap.Error(err))
	}

	metrics, err := transferor.ExecuteTransfer(ctx, payload)
	if err != nil {
		logger.Error("transfer execution failed", zap.Error(err))
		os.Exit(1)
	}

	logger.Info("transfer completed successfully",
		zap.Float64("latency_ms", metrics.LatencyMs),
		zap.Int("retries", metrics.Retries),
		zap.String("status", metrics.Status))

	callback := transferor.ExternalCallback{
		URL:     os.Getenv("MEDIA_SERVER_WEBHOOK"),
		Method:  "POST",
		Payload: []byte(fmt.Sprintf(`{"interaction_id":"%s","status":"transferred","latency_ms":%.2f}`, payload.InteractionID, metrics.LatencyMs)),
	}

	if err := transferor.SyncExternalServer(ctx, callback); err != nil {
		logger.Warn("external callback failed, non-fatal", zap.Error(err))
	}
}

func (s *WebSocketSession) Close() {
	s.conn.Close(websocket.StatusNormalClosure, "session terminated")
	s.alive = false
}

Common Errors & Debugging

Error: 401 Unauthorized on WebSocket Handshake

• What causes it: Expired OAuth token, missing websocket:use scope, or incorrect environment URL.
• How to fix it: Verify the token manager refreshes tokens five minutes before expiration. Ensure the Authorization header uses the exact format Bearer <token>. Confirm the OAuth client has interaction:transfer and websocket:use scopes attached.
• Code showing the fix: The TokenManager.GetToken method already implements a five-minute safety buffer. Add explicit scope logging during initialization to verify scope attachment.

Error: 429 Rate Limit Cascade or WebSocket Close 1008

• What causes it: Exceeding Genesys Cloud WebSocket message throughput limits or triggering gateway protection during rapid transfer iterations.
• How to fix it: Implement exponential backoff with jitter. The ExecuteTransfer method retries up to three times with linear backoff. Add jitter by modifying the sleep duration to time.Duration(attempt+1)*time.Second + time.Duration(rand.Intn(500))*time.Millisecond.
• Code showing the fix: The retry loop in ExecuteTransfer already handles 1008 close codes. Wrap the send operation in a circuit breaker pattern for production scaling.

Error: Codec Negotiation Timeout

• What causes it: Destination endpoint does not support the requested media matrix, or the interaction gateway cannot route the specified codec.
• How to fix it: Populate the Triggers.CodecNegotiation field to true to allow Genesys Cloud to fall back to compatible codecs. Verify the SupportedCodecs list in GatewayConstraint matches actual endpoint capabilities.
• Code showing the fix: The waitForCodecNegotiation method reads responses until it receives a matching id. Extend the deadline or implement a fallback matrix switch if the response contains status: "codec_unsupported".

Error: Interaction ID Reference Invalid

• What causes it: Providing a UUID that does not exist in the active interaction registry, or attempting to transfer a terminated session.
• How to fix it: Validate the interaction ID against the Genesys Cloud REST API before WebSocket transmission. Use GET /api/v2/interactions/{interactionId} to confirm state equals active or queued.
• Code showing the fix: Add a pre-flight REST check in BuildTransferPayload that returns an error if the interaction state is completed or abandoned.

Official References

• Genesys Cloud WebSocket API Documentation
• Interaction Transfer REST Endpoint
• Go Platform Client SDK v2
• OAuth2 Client Credentials Flow
• WebSocket Message Schema Reference