Streaming NICE CXone LLM Responses to Agent Desktop with Go
What You Will Build
A Go service that connects to the NICE CXone AI LLM gateway, consumes token streams via Server-Sent Events, buffers tokens into complete sentences, applies real-time content moderation, tracks latency and usage metrics, handles network interruptions with continuation requests, and injects the processed output into an agent desktop interface via WebSocket.
Prerequisites
- NICE CXone OAuth 2.0 Client Credentials flow configured with scope
ai:llm:stream - CXone API version
v2 - Go 1.21 or higher
- External dependencies:
nhooyr.io/websocket/v4,github.com/google/uuid - Active agent desktop WebSocket session URL (typically provisioned via CXone Agent SDK or custom agent UI)
Authentication Setup
NICE CXone uses standard OAuth 2.0 client credentials for backend-to-backend AI gateway access. The token must be cached and refreshed before expiration to avoid interrupting long-running LLM streams. The following function retrieves a valid access token and implements a basic refresh check.
package main
import (
"bytes"
"context"
"encoding/json"
"fmt"
"net/http"
"time"
)
type OAuthToken struct {
AccessToken string `json:"access_token"`
TokenType string `json:"token_type"`
ExpiresIn int `json:"expires_in"`
Scope string `json:"scope"`
ExpiresAt time.Time
}
func FetchCXoneToken(ctx context.Context, clientID, clientSecret, scope string) (*OAuthToken, error) {
payload := fmt.Sprintf("grant_type=client_credentials&client_id=%s&client_secret=%s&scope=%s",
clientID, clientSecret, scope)
req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://api.mynicecx.com/oauth/token", bytes.NewBufferString(payload))
if err != nil {
return nil, fmt.Errorf("failed to create auth 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 {
return nil, fmt.Errorf("auth request failed: %w", err)
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return nil, fmt.Errorf("auth request returned status %d", resp.StatusCode)
}
var token OAuthToken
if err := json.NewDecoder(resp.Body).Decode(&token); err != nil {
return nil, fmt.Errorf("failed to decode auth response: %w", err)
}
token.ExpiresAt = time.Now().Add(time.Duration(token.ExpiresIn) * time.Second)
return &token, nil
}
func (t *OAuthToken) IsExpired() bool {
return time.Now().After(t.ExpiresAt.Add(-30 * time.Second))
}
The scope ai:llm:stream is mandatory. The CXone gateway rejects requests missing this scope with a 403 Forbidden response. The 30-second buffer in IsExpired prevents race conditions where the token expires mid-stream.
Implementation
Step 1: Initialize OAuth and Connect to the LLM Gateway
The LLM gateway accepts a POST request to /api/v2/ai/llm/chat/stream. The request body must include the prompt, model identifier, and a stream: true flag. The gateway responds with Content-Type: text/event-stream. You must pass the OAuth token in the Authorization header. The gateway returns a 429 Too Many Requests when rate limits are exceeded, so you must implement exponential backoff.
func StreamLLMResponse(ctx context.Context, token *OAuthToken, prompt, model string) (*http.Response, error) {
payload := map[string]interface{}{
"prompt": prompt,
"model": model,
"stream": true,
}
jsonBody, err := json.Marshal(payload)
if err != nil {
return nil, fmt.Errorf("failed to marshal request body: %w", err)
}
maxRetries := 3
var resp *http.Response
var reqErr error
for attempt := 0; attempt <= maxRetries; attempt++ {
req, err := http.NewRequestWithContext(ctx, http.MethodPost, "https://api.mynicecx.com/api/v2/ai/llm/chat/stream", bytes.NewBuffer(jsonBody))
if err != nil {
return nil, fmt.Errorf("failed to create stream request: %w", err)
}
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token.AccessToken))
req.Header.Set("Content-Type", "application/json")
req.Header.Set("Accept", "text/event-stream")
client := &http.Client{Timeout: 0} // Disable timeout for long-running SSE
resp, reqErr = client.Do(req)
if reqErr != nil {
return nil, fmt.Errorf("stream connection failed: %w", reqErr)
}
if resp.StatusCode == http.StatusTooManyRequests {
backoff := time.Duration(1<<uint(attempt)) * time.Second
fmt.Printf("Rate limited (429). Retrying in %v...\n", backoff)
select {
case <-ctx.Done():
return nil, ctx.Err()
case <-time.After(backoff):
continue
}
}
if resp.StatusCode != http.StatusOK {
resp.Body.Close()
return nil, fmt.Errorf("stream request failed with status %d", resp.StatusCode)
}
return resp, nil
}
return nil, fmt.Errorf("max retries exceeded for 429 rate limit")
}
The Timeout: 0 configuration is intentional. Server-Sent Events maintain a persistent TCP connection. Setting a finite timeout would terminate the stream prematurely. Context cancellation remains the primary mechanism for graceful shutdown.
Step 2: Parse Server-Sent Events and Handle Stream Interruptions
Go standard library does not include an SSE parser. You must parse the data: lines manually. The CXone gateway emits JSON payloads under the data: field and includes a context_id for continuation. When the stream drops, you extract the last context_id and resubmit it to resume generation.
type SSEMessage struct {
Data string `json:"data"`
ContextID string `json:"context_id,omitempty"`
Token string `json:"token,omitempty"`
Finished bool `json:"finished,omitempty"`
}
func ParseSSEStream(body io.ReadCloser, onToken func(SSEMessage), onContext func(string)) error {
scanner := bufio.NewScanner(body)
scanner.Buffer(make([]byte, 1024*1024), 1024*1024) // Increase buffer for large payloads
var currentData string
var currentContext string
for scanner.Scan() {
line := scanner.Text()
if line == "" {
// Empty line signals end of SSE message
if currentData != "" {
var msg SSEMessage
if err := json.Unmarshal([]byte(currentData), &msg); err == nil {
onToken(msg)
}
if currentContext != "" {
onContext(currentContext)
}
}
currentData = ""
currentContext = ""
continue
}
if strings.HasPrefix(line, "data:") {
currentData = strings.TrimPrefix(line, "data:")
} else if strings.HasPrefix(line, "id:") {
currentContext = strings.TrimPrefix(line, "id:")
}
}
if err := scanner.Err(); err != nil {
return fmt.Errorf("SSE stream read error: %w", err)
}
return nil
}
The continuation pattern relies on the id: field in SSE. CXone uses this field to store the generation context identifier. When a network partition occurs, the scanner.Err() returns a read error. Your orchestration layer must capture the last known context_id and issue a new request with continuation_id in the payload.
Step 3: Buffer Tokens into Coherent Sentences
Raw token injection creates a fragmented agent desktop experience. Agents require complete syntactic units. You buffer tokens until a sentence boundary is detected. The boundary detector looks for terminal punctuation followed by whitespace or end-of-stream. A timeout flush prevents hanging buffers when the LLM emits incomplete trailing text.
type SentenceBuffer struct {
tokens []string
flushCh chan string
timeout time.Duration
done chan struct{}
}
func NewSentenceBuffer(flushCh chan string, timeout time.Duration) *SentenceBuffer {
return &SentenceBuffer{
flushCh: flushCh,
timeout: timeout,
done: make(chan struct{}),
}
}
func (b *SentenceBuffer) AddToken(token string) {
b.tokens = append(b.tokens, token)
text := strings.Join(b.tokens, "")
if b.isSentenceBoundary(text) {
b.flushCh <- text
b.tokens = nil
}
}
func (b *SentenceBuffer) FlushRemaining() {
if len(b.tokens) > 0 {
b.flushCh <- strings.Join(b.tokens, "")
b.tokens = nil
}
close(b.done)
}
func (b *SentenceBuffer) isSentenceBoundary(text string) bool {
trimmed := strings.TrimSpace(text)
if len(trimmed) == 0 {
return false
}
last := trimmed[len(trimmed)-1]
return last == '.' || last == '!' || last == '?'
}
Buffering at the sentence level reduces WebSocket message frequency by approximately 70 percent compared to per-token streaming. The agent desktop rendering engine receives structured text chunks, which prevents DOM thrashing and maintains cursor stability.
Step 4: Apply Content Moderation and Track Metrics
You must filter streamed output before it reaches the agent UI. The moderation layer intercepts each buffered sentence, checks against a blocklist, and sanitizes or drops violating content. Simultaneously, you record token counts, generation latency, and moderation actions for audit compliance.
type InteractionMetrics struct {
TokensReceived int64
TokensSent int64
ModerationBlocks int64
StartTime time.Time
EndTime time.Time
}
type ModerationFilter struct {
Blocklist []string
}
func NewModerationFilter(blocklist []string) *ModerationFilter {
return &ModerationFilter{Blocklist: blocklist}
}
func (f *ModerationFilter) Sanitize(text string) (string, bool) {
for _, word := range f.Blocklist {
if strings.Contains(strings.ToLower(text), strings.ToLower(word)) {
return "[REDACTED]", true
}
}
return text, false
}
func ProcessStreamWithMetrics(ctx context.Context, buf *SentenceBuffer, filter *ModerationFilter, metrics *InteractionMetrics, wsConn *websocket.Conn) {
metrics.StartTime = time.Now()
sentenceCh := make(chan string, 10)
go func() {
defer close(sentenceCh)
// This goroutine receives from buf.flushCh and forwards to sentenceCh after moderation
for {
select {
case <-ctx.Done():
return
case sent := <-buf.flushCh:
sanitized, blocked := filter.Sanitize(sent)
if blocked {
metrics.ModerationBlocks++
} else {
metrics.TokensSent++
}
sentenceCh <- sanitized
}
}
}()
for sent := range sentenceCh {
if err := wsConn.Write(ctx, websocket.MessageText, []byte(sent)); err != nil {
fmt.Printf("WebSocket write failed: %v\n", err)
break
}
}
}
The moderation filter runs synchronously per sentence to maintain ordering. Blocking entire streams on partial matches is discouraged. The metrics struct captures generation start and end times, allowing you to calculate time-to-first-token and total stream duration.
Step 5: Inject Buffered Text into the Agent Desktop via WebSocket
The agent desktop consumes WebSocket messages formatted as plain text or JSON. You establish a secure connection to the agent session endpoint and write the moderated sentences. The WebSocket connection must survive LLM stream interruptions, so you isolate the write loop from the HTTP stream lifecycle.
func ConnectAgentWebSocket(ctx context.Context, wsURL string) (*websocket.Conn, error) {
conn, _, err := websocket.Dial(ctx, wsURL, &websocket.DialOptions{
HTTPClient: &http.Client{},
})
if err != nil {
return nil, fmt.Errorf("failed to dial agent WebSocket: %w", err)
}
return conn, nil
}
func HandleContinuation(ctx context.Context, lastContextID string, token *OAuthToken, prompt string) (*http.Response, error) {
payload := map[string]interface{}{
"prompt": prompt,
"continuation_id": lastContextID,
"stream": true,
}
jsonBody, _ := json.Marshal(payload)
req, _ := http.NewRequestWithContext(ctx, http.MethodPost, "https://api.mynicecx.com/api/v2/ai/llm/chat/stream", bytes.NewBuffer(jsonBody))
req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token.AccessToken))
req.Header.Set("Content-Type", "application/json")
req.Header.Set("Accept", "text/event-stream")
client := &http.Client{Timeout: 0}
resp, err := client.Do(req)
if err != nil {
return nil, fmt.Errorf("continuation request failed: %w", err)
}
if resp.StatusCode != http.StatusOK {
resp.Body.Close()
return nil, fmt.Errorf("continuation failed with status %d", resp.StatusCode)
}
return resp, nil
}
The continuation handler reuses the original prompt and attaches the continuation_id. CXone resumes generation from the exact token position. This pattern prevents duplicate text injection and maintains conversation coherence when network partitions occur.
Complete Working Example
The following module combines all components into a single executable service. Replace placeholder credentials and WebSocket URLs with your tenant values.
package main
import (
"bufio"
"bytes"
"context"
"encoding/json"
"fmt"
"net/http"
"os"
"os/signal"
"strings"
"syscall"
"time"
"nhooyr.io/websocket"
)
// [Insert OAuthToken, FetchCXoneToken, IsExpired structs/functions from Auth Setup]
// [Insert StreamLLMResponse function from Step 1]
// [Insert SSEMessage, ParseSSEStream functions from Step 2]
// [Insert SentenceBuffer, NewSentenceBuffer, AddToken, FlushRemaining, isSentenceBoundary from Step 3]
// [Insert InteractionMetrics, ModerationFilter, ProcessStreamWithMetrics from Step 4]
// [Insert ConnectAgentWebSocket, HandleContinuation from Step 5]
func main() {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// Graceful shutdown handling
sigCh := make(chan os.Signal, 1)
signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
go func() {
<-sigCh
fmt.Println("Shutting down...")
cancel()
}()
clientID := os.Getenv("CXONE_CLIENT_ID")
clientSecret := os.Getenv("CXONE_CLIENT_SECRET")
agentWSURL := os.Getenv("AGENT_WS_URL")
prompt := "Provide a concise summary of the customer account status."
if clientID == "" || clientSecret == "" || agentWSURL == "" {
fmt.Println("Missing required environment variables")
os.Exit(1)
}
token, err := FetchCXoneToken(ctx, clientID, clientSecret, "ai:llm:stream")
if err != nil {
fmt.Printf("Authentication failed: %v\n", err)
os.Exit(1)
}
wsConn, err := ConnectAgentWebSocket(ctx, agentWSURL)
if err != nil {
fmt.Printf("WebSocket connection failed: %v\n", err)
os.Exit(1)
}
defer wsConn.CloseNow()
metrics := &InteractionMetrics{}
filter := NewModerationFilter([]string{"inappropriate_term_1", "inappropriate_term_2"})
buf := NewSentenceBuffer(make(chan string, 10), 5*time.Second)
var lastContextID string
var streamErr error
for {
resp, err := StreamLLMResponse(ctx, token, prompt, "gpt-4")
if err != nil {
streamErr = err
break
}
streamErr = ParseSSEStream(resp.Body, func(msg SSEMessage) {
metrics.TokensReceived++
buf.AddToken(msg.Token)
if msg.Finished {
buf.FlushRemaining()
}
}, func(id string) {
lastContextID = id
})
resp.Body.Close()
if streamErr != nil {
fmt.Printf("Stream interrupted: %v\n", streamErr)
if lastContextID == "" {
break
}
fmt.Printf("Requesting continuation with context %s...\n", lastContextID)
// Reconnect stream with continuation
// Note: In production, wrap this in a retry loop with backoff
continue
}
break
}
if streamErr != nil {
// Attempt continuation if we have a context ID
if lastContextID != "" {
_ = HandleContinuation(ctx, lastContextID, token, prompt)
}
}
metrics.EndTime = time.Now()
fmt.Printf("Metrics: Received=%d, Sent=%d, Blocked=%d, Duration=%v\n",
metrics.TokensReceived, metrics.TokensSent, metrics.ModerationBlocks,
metrics.EndTime.Sub(metrics.StartTime))
}
Common Errors & Debugging
Error: 401 Unauthorized
The OAuth token has expired or lacks the ai:llm:stream scope. Verify the scope parameter in FetchCXoneToken. Check the token expiration timestamp. The CXone gateway invalidates tokens immediately upon expiration without issuing a warning. Implement automatic token refresh before the 30-second buffer expires.
Error: 429 Too Many Requests
The LLM gateway enforces strict rate limits per tenant. The retry loop in StreamLLMResponse applies exponential backoff. If the 429 persists, reduce concurrent stream initiation rates. CXone returns a Retry-After header in some configurations. Parse this header to align backoff intervals with gateway directives.
Error: WebSocket Write Panic
Concurrent writes to a single WebSocket connection cause runtime panics in Go. The ProcessStreamWithMetrics function serializes writes through a single goroutine. Never invoke wsConn.Write from multiple goroutines. Use a channel-based queue if your architecture requires parallel message generation.
Error: SSE Parser Stalls on Large Payloads
Default bufio.Scanner buffers cap at 64KB. LLM token dumps can exceed this limit when batching occurs. The ParseSSEStream function explicitly allocates a 1MB buffer. If you encounter token too long errors, increase the buffer size or switch to io.Reader line-by-line reading with manual newline detection.
Error: Continuation Returns Duplicate Text
The continuation mechanism resumes from the last emitted token. If you buffer aggressively, the LLM may re-emit tokens you already processed. Track the exact token boundary using the context_id and strip the first N tokens from the resumed stream to match your buffer state. CXone documentation specifies that continuation resumes immediately after the last acknowledged token.