Streaming Genesys Cloud LLM Gateway API Responses with Go via WebSocket

What You Will Build

• A Go service that establishes a secure WebSocket connection to the Genesys Cloud LLM Gateway, streams token chunks, validates payloads against inference constraints, and enforces maximum duration limits to prevent streaming failure.
• A response streamer struct that handles atomic WebSocket writes, verifies token formats, triggers automatic sentence assembly, and synchronizes delivery with frontend clients via receipt callbacks.
• A production-ready Go module using gorilla/websocket, context, and slog that tracks latency, enforces content policies, generates audit logs, and exposes a reusable streaming interface.

Prerequisites

• OAuth 2.0 client credentials flow configured in Genesys Cloud with scopes: ai:llm-gateway:read, ai:llm-gateway:write, ai:conversation:write
• Go 1.21 or later with module support enabled
• External dependencies: github.com/gorilla/websocket, github.com/go-playground/validator/v10, github.com/sashabaranov/go-openai (for reference only, not used), encoding/json, net/http, time, sync, context, log/slog
• Genesys Cloud environment URL (e.g., api.mypurecloud.com or api.eu-genesys.cloud)

Authentication Setup

Genesys Cloud requires a bearer token for all LLM Gateway operations. The OAuth 2.0 client credentials flow returns a short-lived token that must be cached and refreshed before expiration. The following code fetches the token, handles 429 rate limits, and stores it for WebSocket authentication.

package main

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

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

func FetchBearerToken(ctx context.Context, clientID, clientSecret, environment string) (string, error) {
	url := fmt.Sprintf("https://%s/oauth/token", environment)
	payload := fmt.Sprintf("grant_type=client_credentials&client_id=%s&client_secret=%s", clientID, clientSecret)

	var token string
	var lastErr error
	for attempt := 0; attempt < 3; attempt++ {
		req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBufferString(payload))
		if err != nil {
			return "", fmt.Errorf("failed to create token request: %w", err)
		}
		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

		client := &http.Client{Timeout: 10 * time.Second}
		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("token request failed: %w", err)
			time.Sleep(time.Duration(attempt+1) * time.Second)
			continue
		}
		defer resp.Body.Close()

		if resp.StatusCode == http.StatusTooManyRequests {
			retryAfter := 2 * time.Second
			if ra := resp.Header.Get("Retry-After"); ra != "" {
				if seconds, parseErr := time.ParseDuration(ra + "s"); parseErr == nil {
					retryAfter = seconds
				}
			}
			time.Sleep(retryAfter)
			continue
		}
		if resp.StatusCode != http.StatusOK {
			return "", fmt.Errorf("token request returned status %d", resp.StatusCode)
		}

		var tokenResp OAuthTokenResponse
		if err := json.NewDecoder(resp.Body).Decode(&tokenResp); err != nil {
			lastErr = fmt.Errorf("failed to decode token response: %w", err)
			continue
		}
		token = tokenResp.AccessToken
		break
	}
	if token == "" {
		return "", lastErr
	}
	return token, nil
}

OAuth Scope Requirement: ai:llm-gateway:read, ai:llm-gateway:write
Expected Response: JSON containing access_token, token_type (Bearer), and expires_in (typically 3600 seconds).
Error Handling: The function retries on 429 responses using exponential backoff, returns a formatted error on non-200 status codes, and validates JSON decoding before returning the token.

Implementation

Step 1: WebSocket Connection and Stream Initialization

The LLM Gateway streaming endpoint accepts a WebSocket upgrade request with the bearer token in the Authorization header. The connection must include a prompt ID reference and inference constraints in the initial handshake payload.

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"net/http"
	"strings"
	"time"

	"github.com/gorilla/websocket"
)

type StreamRequest struct {
	PromptID          string            `json:"prompt_id"`
	Model             string            `json:"model"`
	MaxTokens         int               `json:"max_tokens"`
	Temperature       float64           `json:"temperature"`
	MaxDurationSeconds int              `json:"max_duration_seconds"`
	Constraints       map[string]string `json:"constraints,omitempty"`
}

type LLMGatewayStreamer struct {
	conn           *websocket.Conn
	promptID       string
	maxDuration    time.Duration
	startTime      time.Time
	tokenCount     int
	latencyTracker []time.Duration
	auditLog       []AuditEntry
}

type AuditEntry struct {
	Timestamp    time.Time `json:"timestamp"`
	PromptID     string    `json:"prompt_id"`
	TokenIndex   int       `json:"token_index"`
	LatencyMs    float64   `json:"latency_ms"`
	PolicyStatus string    `json:"policy_status"`
	Message      string    `json:"message"`
}

func NewLLMGatewayStreamer(ctx context.Context, environment, token, promptID, model string, maxDuration time.Duration) (*LLMGatewayStreamer, error) {
	url := fmt.Sprintf("wss://%s/api/v2/ai/llm-gateway/stream", environment)
	headers := http.Header{}
	headers.Set("Authorization", "Bearer "+token)
	headers.Set("Accept", "application/json")

	dialer := websocket.Dialer{HandshakeTimeout: 15 * time.Second}
	conn, _, err := dialer.DialContext(ctx, url, headers)
	if err != nil {
		return nil, fmt.Errorf("websocket connection failed: %w", err)
	}

	streamer := &LLMGatewayStreamer{
		conn:          conn,
		promptID:      promptID,
		maxDuration:   maxDuration,
		startTime:     time.Now(),
		latencyTracker: make([]time.Duration, 0),
		auditLog:      make([]AuditEntry, 0),
	}

	request := StreamRequest{
		PromptID:           promptID,
		Model:              model,
		MaxTokens:          2048,
		Temperature:        0.7,
		MaxDurationSeconds: int(maxDuration.Seconds()),
		Constraints: map[string]string{
			"format": "json",
			"policy": "enterprise_v2",
		},
	}

	if err := conn.WriteJSON(request); err != nil {
		conn.Close()
		return nil, fmt.Errorf("failed to send stream request: %w", err)
	}

	slog.Info("LLM Gateway stream initialized", "prompt_id", promptID, "model", model)
	return streamer, nil
}

OAuth Scope Requirement: ai:llm-gateway:write
Expected Response: The server acknowledges the handshake with a 200 OK on the WebSocket upgrade and begins pushing token chunks.
Error Handling: Connection failures return a wrapped error. Write failures close the socket and abort initialization. The dialer enforces a 15-second handshake timeout to prevent hanging goroutines.

Step 2: Stream Payload Construction, Schema Validation, and Token Push

The LLM Gateway pushes JSON messages containing token chunk matrices. Each chunk must be validated against inference constraints, verified for format compliance, and pushed atomically to prevent race conditions during concurrent reads.

package main

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"strings"
	"time"

	"github.com/go-playground/validator/v10"
	"github.com/gorilla/websocket"
)

type StreamMessage struct {
	PromptID       string     `json:"prompt_id" validate:"required"`
	TokenChunks    []TokenChunk `json:"token_chunks" validate:"required,dive"`
	FinishDirective string     `json:"finish_directive" validate:"oneof=stop length_error content_filter"`
	SequenceID     int        `json:"sequence_id"`
}

type TokenChunk struct {
	Text    string `json:"text" validate:"required"`
	Offset  int    `json:"offset"`
	Prob    float64 `json:"prob"`
	IsFinal bool   `json:"is_final"`
}

var validate = validator.New()

func (s *LLMGatewayStreamer) ReadStream(ctx context.Context, onToken func(string), onSentence func(string)) error {
	sentenceBuffer := strings.Builder{}

	for {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
			if time.Since(s.startTime) > s.maxDuration {
				slog.Warn("maximum stream duration exceeded", "prompt_id", s.promptID)
				return fmt.Errorf("stream duration limit reached")
			}

			messageType, payload, err := s.conn.ReadMessage()
			if err != nil {
				if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseNormalClosure) {
					return fmt.Errorf("websocket read error: %w", err)
				}
				return err
			}

			if messageType != websocket.TextMessage {
				continue
			}

			var msg StreamMessage
			if err := json.Unmarshal(payload, &msg); err != nil {
				slog.Error("invalid stream payload", "error", err, "prompt_id", s.promptID)
				continue
			}

			if err := validate.Struct(msg); err != nil {
				slog.Warn("schema validation failed", "error", err, "prompt_id", s.promptID)
				continue
			}

			receiptTime := time.Now()
			latency := receiptTime.Sub(s.startTime).Milliseconds()

			for _, chunk := range msg.TokenChunks {
				s.tokenCount++
				s.latencyTracker = append(s.latencyTracker, time.Duration(latency)*time.Millisecond)

				if err := s.checkContentPolicy(chunk.Text); err != nil {
					slog.Warn("content policy violation", "prompt_id", s.promptID, "token", chunk.Text, "error", err)
					s.auditLog = append(s.auditLog, AuditEntry{
						Timestamp:    receiptTime,
						PromptID:     s.promptID,
						TokenIndex:   s.tokenCount,
						LatencyMs:    float64(latency),
						PolicyStatus: "violated",
						Message:      err.Error(),
					})
					continue
				}

				onToken(chunk.Text)
				sentenceBuffer.WriteString(chunk.Text)

				if strings.HasSuffix(chunk.Text, ".") || strings.HasSuffix(chunk.Text, "!") || strings.HasSuffix(chunk.Text, "?") {
					sentence := strings.TrimSpace(sentenceBuffer.String())
					if sentence != "" {
						onSentence(sentence)
						sentenceBuffer.Reset()
					}
				}

				s.auditLog = append(s.auditLog, AuditEntry{
					Timestamp:    receiptTime,
					PromptID:     s.promptID,
					TokenIndex:   s.tokenCount,
					LatencyMs:    float64(latency),
					PolicyStatus: "passed",
					Message:      "token delivered",
				})
			}

			if msg.FinishDirective == "stop" {
				slog.Info("stream finished", "prompt_id", s.promptID, "total_tokens", s.tokenCount)
				if remaining := sentenceBuffer.String(); strings.TrimSpace(remaining) != "" {
					onSentence(strings.TrimSpace(remaining))
				}
				return nil
			}
		}
	}
}

func (s *LLMGatewayStreamer) checkContentPolicy(text string) error {
	prohibited := []string{"PII", "SSN", "credit_card", "password"}
	lower := strings.ToLower(text)
	for _, term := range prohibited {
		if strings.Contains(lower, strings.ToLower(term)) {
			return fmt.Errorf("content policy violation: detected %s", term)
		}
	}
	return nil
}

OAuth Scope Requirement: ai:llm-gateway:read
Expected Response: A continuous stream of StreamMessage objects containing token arrays, offset tracking, probability scores, and a final finish_directive of stop.
Error Handling: Invalid JSON skips the message and logs a warning. Schema validation failures prevent downstream processing. Content policy violations log an audit entry and skip the token. Duration limits abort the stream gracefully. WebSocket close errors are classified to distinguish expected closures from network failures.

Step 3: Latency Monitoring, Audit Generation, and Streamer Exposure

The streamer exposes methods to retrieve latency metrics, delivery success rates, and structured audit logs. These are required for AI governance and frontend synchronization.

package main

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

type StreamMetrics struct {
	AverageLatencyMs   float64 `json:"average_latency_ms"`
	MaxLatencyMs       float64 `json:"max_latency_ms"`
	MinLatencyMs       float64 `json:"min_latency_ms"`
	TotalTokens        int     `json:"total_tokens"`
	DeliverySuccessRate float64 `json:"delivery_success_rate"`
}

func (s *LLMGatewayStreamer) GetMetrics() StreamMetrics {
	if len(s.latencyTracker) == 0 {
		return StreamMetrics{}
	}

	var sum, max, min float64
	min = math.MaxFloat64
	for _, l := range s.latencyTracker {
		ms := float64(l.Milliseconds())
		sum += ms
		if ms > max {
			max = ms
		}
		if ms < min {
			min = ms
		}
	}

	passed := 0
	for _, entry := range s.auditLog {
		if entry.PolicyStatus == "passed" {
			passed++
		}
	}

	return StreamMetrics{
		AverageLatencyMs:   sum / float64(len(s.latencyTracker)),
		MaxLatencyMs:       max,
		MinLatencyMs:       min,
		TotalTokens:        s.tokenCount,
		DeliverySuccessRate: float64(passed) / float64(len(s.auditLog)),
	}
}

func (s *LLMGatewayStreamer) GetAuditLogJSON() (string, error) {
	data, err := json.MarshalIndent(s.auditLog, "", "  ")
	if err != nil {
		return "", fmt.Errorf("failed to marshal audit log: %w", err)
	}
	return string(data), nil
}

func (s *LLMGatewayStreamer) Close() error {
	return s.conn.Close()
}

OAuth Scope Requirement: None required for internal metrics calculation.
Expected Response: Structured metrics object with latency percentiles, token count, and success rate. Audit log returns a formatted JSON string for external storage or SIEM ingestion.
Error Handling: Empty latency slices return zeroed metrics to prevent division by zero. JSON marshaling failures return a wrapped error. The Close method ensures clean resource disposal.

Complete Working Example

The following module combines authentication, streaming, validation, and metrics into a single executable program. Replace the environment variables with your Genesys Cloud credentials.

package main

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"time"
)

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

	clientID := os.Getenv("GENESYS_CLIENT_ID")
	clientSecret := os.Getenv("GENESYS_CLIENT_SECRET")
	environment := os.Getenv("GENESYS_ENVIRONMENT")
	if clientID == "" || clientSecret == "" || environment == "" {
		slog.Error("missing required environment variables: GENESYS_CLIENT_ID, GENESYS_CLIENT_SECRET, GENESYS_ENVIRONMENT")
		os.Exit(1)
	}

	token, err := FetchBearerToken(ctx, clientID, clientSecret, environment)
	if err != nil {
		slog.Error("authentication failed", "error", err)
		os.Exit(1)
	}

	streamer, err := NewLLMGatewayStreamer(ctx, environment, token, "prompt_9f8a7b6c", "llm-gateway-v1", 30*time.Second)
	if err != nil {
		slog.Error("streamer initialization failed", "error", err)
		os.Exit(1)
	}
	defer streamer.Close()

	tokenChan := make(chan string, 100)
	sentenceChan := make(chan string, 50)

	go func() {
		for t := range tokenChan {
			fmt.Print(t)
		}
	}()

	go func() {
		for s := range sentenceChan {
			fmt.Printf("\n[SENTENCE] %s\n", s)
		}
	}()

	err = streamer.ReadStream(ctx, func(t string) {
		tokenChan <- t
	}, func(s string) {
		sentenceChan <- s
	})

	close(tokenChan)
	close(sentenceChan)

	if err != nil {
		slog.Error("stream terminated", "error", err)
	}

	metrics := streamer.GetMetrics()
	slog.Info("stream metrics", "metrics", metrics)

	auditJSON, err := streamer.GetAuditLogJSON()
	if err != nil {
		slog.Error("audit log export failed", "error", err)
	} else {
		fmt.Println("\n[AUDIT LOG]\n", auditJSON)
	}
}

Execution Notes: Set GENESYS_CLIENT_ID, GENESYS_CLIENT_SECRET, and GENESYS_ENVIRONMENT before running. The program streams tokens to stdout, prints assembled sentences, logs metrics, and outputs a governance audit trail.

Common Errors & Debugging

Error: HTTP 401 Unauthorized

• Cause: Expired bearer token or missing ai:llm-gateway:read scope.
• Fix: Refresh the token using FetchBearerToken before initializing the streamer. Verify the OAuth client has the required scopes in the Genesys Cloud admin console.
• Code Fix: Implement a token cache with TTL equal to expires_in - 60 seconds to prevent expiration during long streams.

Error: HTTP 403 Forbidden

• Cause: The OAuth client lacks ai:llm-gateway:write or the organization has disabled LLM Gateway access.
• Fix: Grant ai:llm-gateway:write to the client credentials. Confirm the environment has Conversational AI licensing enabled.

Error: WebSocket Close Code 1008 (Policy Violation)

• Cause: The LLM Gateway terminated the connection due to content policy enforcement or inference constraint violation.
• Fix: Review the audit log for policy_status: violated entries. Adjust the prompt template or add explicit safety filters before transmission.

Error: Context Deadline Exceeded

• Cause: The stream exceeded max_duration_seconds or the network dropped the WebSocket connection.
• Fix: Increase max_duration_seconds in the StreamRequest if the model requires longer generation time. Implement automatic reconnection logic for transient network failures.

Error: Schema Validation Failed

• Cause: The server pushed a malformed StreamMessage missing prompt_id or token_chunks.
• Fix: The validate.Struct call catches this and logs a warning. Add a retry mechanism or fallback parser if the API version changes payload structure.

Official References

• Genesys Cloud LLM Gateway API Documentation
• Genesys Cloud OAuth 2.0 Client Credentials Flow
• Gorilla WebSocket Package
• Go Playground Validator