Resolving NICE CXone Journey Personalization Tokens with Go

What You Will Build

• A Go service that resolves CXone Journey personalization tokens by submitting structured payloads containing journey UUIDs, token path matrices, and fallback directives.
• Uses the CXone /api/v1/personalization/tokens/resolve endpoint with OAuth2 client credentials authentication.
• Implemented in Go with standard library packages, featuring atomic cache lookup, latency tracking, audit logging, REST callback synchronization, and an exposed HTTP resolver endpoint.

Prerequisites

• CXone OAuth2 client credentials (Client ID and Client Secret) with the personalization.tokens.resolve scope.
• Go 1.21 or later.
• No external dependencies. The implementation uses only the standard library (net/http, context, sync, time, log, encoding/json, crypto/sha256, fmt, strings, os).
• A CXone environment with an active Journey containing configured personalization tokens.

Authentication Setup

CXone uses the OAuth2 client credentials flow to issue access tokens. The token endpoint is POST /api/v1/oauth2/token. You must cache the token and refresh it before expiration to avoid 401 Unauthorized errors during high-volume resolve operations.

package main

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

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

type TokenCache struct {
	mu      sync.RWMutex
	token   string
	expires time.Time
}

func (c *TokenCache) Get(ctx context.Context, baseURL, clientID, clientSecret string) (string, error) {
	c.mu.RLock()
	if time.Now().Before(c.expires) {
		token := c.token
		c.mu.RUnlock()
		return token, nil
	}
	c.mu.RUnlock()

	return c.refresh(ctx, baseURL, clientID, clientSecret)
}

func (c *TokenCache) refresh(ctx context.Context, baseURL, clientID, clientSecret string) (string, error) {
	c.mu.Lock()
	defer c.mu.Unlock()

	payload := fmt.Sprintf("grant_type=client_credentials&client_id=%s&client_secret=%s", clientID, clientSecret)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+"/api/v1/oauth2/token", 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")
	req.SetBasicAuth(clientID, clientSecret)

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

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("token fetch returned status %d", resp.StatusCode)
	}

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

	c.token = tr.AccessToken
	c.expires = time.Now().Add(time.Duration(tr.ExpiresIn-60) * time.Second)
	return c.token, nil
}

The cache subtracts 60 seconds from the expiration window to provide a safety margin for network latency and token validation overhead.

Implementation

Step 1: Payload Construction and Schema Validation

CXone rendering engines enforce maximum token depth limits and require strict schema alignment. You must validate the token path matrix before submission to prevent 400 Bad Request responses. The validator checks nesting depth, verifies fallback directives, and ensures journey UUID format compliance.

package main

import (
	"fmt"
	"regexp"
	"strings"
)

type ResolvePayload struct {
	JourneyID string                 `json:"journeyId"`
	ContactID string                 `json:"contactId"`
	Tokens    []string               `json:"tokens"`
	Fallbacks map[string]interface{} `json:"fallbacks,omitempty"`
}

var uuidRegex = regexp.MustCompile(`^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$`)

func ValidateResolvePayload(p ResolvePayload, maxDepth int) error {
	if !uuidRegex.MatchString(p.JourneyID) {
		return fmt.Errorf("invalid journey UUID format: %s", p.JourneyID)
	}
	if len(p.Tokens) == 0 {
		return fmt.Errorf("token matrix cannot be empty")
	}

	for _, token := range p.Tokens {
		if !strings.HasPrefix(token, "{{") || !strings.HasSuffix(token, "}}") {
			return fmt.Errorf("token %q does not follow path matrix syntax", token)
		}
		path := strings.TrimSuffix(strings.TrimPrefix(token, "{{"), "}}")
		depth := strings.Count(path, ".") + 1
		if depth > maxDepth {
			return fmt.Errorf("token %q exceeds maximum depth limit of %d (current: %d)", token, maxDepth, depth)
		}
	}

	return nil
}

The depth calculation counts dot separators and adds one for the root property. CXone typically enforces a depth limit of five to prevent rendering engine stack overflows during complex contact profile traversals.

Step 2: Atomic Cache Lookup and API Execution with Retry Logic

You must implement an atomic cache lookup to prevent redundant API calls during rapid resolve iterations. The resolver computes a cryptographic hash of the payload, checks the cache, and proceeds to the CXone endpoint only on a miss. The HTTP client implements exponential backoff for 429 Too Many Requests responses.

package main

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"time"
)

type ResolveResult struct {
	ResolvedTokens map[string]interface{} `json:"resolvedTokens"`
	SuccessRate    float64                `json:"successRate"`
	LatencyMs      float64                `json:"latencyMs"`
}

type ResolveCache struct {
	mu    sync.RWMutex
	store map[string]*cachedEntry
}

type cachedEntry struct {
	result    ResolveResult
	expiresAt time.Time
}

func (c *ResolveCache) GetOrSet(ctx context.Context, key string, ttl time.Duration, fn func() (ResolveResult, error)) (ResolveResult, error) {
	c.mu.RLock()
	entry, exists := c.store[key]
	c.mu.RUnlock()

	if exists && time.Now().Before(entry.expiresAt) {
		return entry.result, nil
	}

	result, err := fn()
	if err != nil {
		return ResolveResult{}, err
	}

	c.mu.Lock()
	c.store[key] = &cachedEntry{result: result, expiresAt: time.Now().Add(ttl)}
	c.mu.Unlock()

	return result, nil
}

func payloadHash(p ResolvePayload) string {
	b, _ := json.Marshal(p)
	h := sha256.Sum256(b)
	return hex.EncodeToString(h[:])
}

func callCXoneResolve(ctx context.Context, baseURL, token string, p ResolvePayload) (ResolveResult, error) {
	body, _ := json.Marshal(p)
	client := &http.Client{Timeout: 15 * time.Second}

	var lastErr error
	for attempt := 0; attempt < 3; attempt++ {
		req, err := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+"/api/v1/personalization/tokens/resolve", bytes.NewReader(body))
		if err != nil {
			return ResolveResult{}, fmt.Errorf("request creation failed: %w", err)
		}
		req.Header.Set("Authorization", "Bearer "+token)
		req.Header.Set("Content-Type", "application/json")
		req.Header.Set("Accept", "application/json")

		start := time.Now()
		resp, err := client.Do(req)
		if err != nil {
			lastErr = fmt.Errorf("network error: %w", err)
			time.Sleep(time.Duration(attempt+1) * 2 * time.Second)
			continue
		}
		defer resp.Body.Close()

		if resp.StatusCode == http.StatusTooManyRequests {
			retryAfter := 2 * time.Duration(attempt+1) * time.Second
			time.Sleep(retryAfter)
			continue
		}
		if resp.StatusCode != http.StatusOK {
			return ResolveResult{}, fmt.Errorf("API returned status %d", resp.StatusCode)
		}

		var rr ResolveResult
		if err := json.NewDecoder(resp.Body).Decode(&rr); err != nil {
			return ResolveResult{}, fmt.Errorf("decode error: %w", err)
		}
		rr.LatencyMs = float64(time.Since(start).Microseconds()) / 1000.0
		return rr, nil
	}

	return ResolveResult{}, fmt.Errorf("resolve failed after retries: %w", lastErr)
}

The retry loop respects CXone rate limit headers implicitly by backing off exponentially. The latency metric captures only the network round trip, excluding cache lookup time.

Step 3: Audit Logging, CMS Callback Synchronization, and Metrics Tracking

Production resolvers must emit structured audit logs for governance and synchronize resolved events with external content management systems. You will implement a logging pipeline and an asynchronous callback dispatcher that fires after successful resolution.

package main

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

type AuditLog struct {
	Timestamp    time.Time `json:"timestamp"`
	JourneyID    string    `json:"journeyId"`
	ContactID    string    `json:"contactId"`
	TokenCount   int       `json:"tokenCount"`
	SuccessRate  float64   `json:"successRate"`
	LatencyMs    float64   `json:"latencyMs"`
	CacheHit     bool      `json:"cacheHit"`
	ExternalSync bool      `json:"externalSync"`
}

type Resolver struct {
	TokenCache     *TokenCache
	ResolveCache   *ResolveCache
	BaseURL        string
	ClientID       string
	ClientSecret   string
	CMSWebhookURL  string
	MaxDepth       int
	CacheTTL       time.Duration
}

func (r *Resolver) Resolve(ctx context.Context, p ResolvePayload) (ResolveResult, error) {
	if err := ValidateResolvePayload(p, r.MaxDepth); err != nil {
		return ResolveResult{}, fmt.Errorf("validation failed: %w", err)
	}

	cacheKey := payloadHash(p)
	token, err := r.TokenCache.Get(ctx, r.BaseURL, r.ClientID, r.ClientSecret)
	if err != nil {
		return ResolveResult{}, fmt.Errorf("authentication failed: %w", err)
	}

	var cacheHit bool
	result, err := r.ResolveCache.GetOrSet(ctx, cacheKey, r.CacheTTL, func() (ResolveResult, error) {
		return callCXoneResolve(ctx, r.BaseURL, token, p)
	})
	if err != nil {
		return ResolveResult{}, err
	}
	cacheHit = (err == nil && result.LatencyMs == 0)

	audit := AuditLog{
		Timestamp:    time.Now().UTC(),
		JourneyID:    p.JourneyID,
		ContactID:    p.ContactID,
		TokenCount:   len(p.Tokens),
		SuccessRate:  result.SuccessRate,
		LatencyMs:    result.LatencyMs,
		CacheHit:     cacheHit,
		ExternalSync: r.CMSWebhookURL != "",
	}
	log.Printf("AUDIT: %s", mustMarshalJSON(audit))

	if r.CMSWebhookURL != "" {
		go r.triggerCMSWebhook(ctx, audit)
	}

	return result, nil
}

func (r *Resolver) triggerCMSWebhook(ctx context.Context, audit AuditLog) {
	payload, _ := json.Marshal(audit)
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, r.CMSWebhookURL, bytes.NewReader(payload))
	if err != nil {
		return
	}
	req.Header.Set("Content-Type", "application/json")
	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("CMS webhook failed: %v", err)
		return
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		log.Printf("CMS webhook returned status %d", resp.StatusCode)
	}
}

func mustMarshalJSON(v interface{}) string {
	b, _ := json.Marshal(v)
	return string(b)
}

The webhook dispatcher runs in a separate goroutine to prevent blocking the resolve pipeline. Audit logs capture cache hit status, latency, and synchronization flags for downstream analytics.

Step 4: HTTP Server Exposure for Automated Journey Management

You will expose a REST endpoint that accepts resolve requests, tracks aggregate metrics, and returns structured responses. The server maintains a thread-safe metrics counter and exposes health checks.

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"sync/atomic"
)

type Metrics struct {
	TotalRequests  atomic.Int64
	SuccessfulResolves atomic.Int64
	FailedResolves   atomic.Int64
}

func (r *Resolver) HandleResolve(w http.ResponseWriter, req *http.Request) {
	r.Metrics.TotalRequests.Add(1)

	var p ResolvePayload
	if err := json.NewDecoder(req.Body).Decode(&p); err != nil {
		http.Error(w, "invalid payload", http.StatusBadRequest)
		return
	}

	result, err := r.Resolve(req.Context(), p)
	if err != nil {
		r.Metrics.FailedResolves.Add(1)
		log.Printf("RESOLVE ERROR: %v", err)
		http.Error(w, fmt.Sprintf("resolve failed: %v", err), http.StatusInternalServerError)
		return
	}

	r.Metrics.SuccessfulResolves.Add(1)
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(result)
}

func (r *Resolver) HandleMetrics(w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]int64{
		"total_requests":     r.Metrics.TotalRequests.Load(),
		"successful_resolves": r.Metrics.SuccessfulResolves.Load(),
		"failed_resolves":    r.Metrics.FailedResolves.Load(),
	})
}

The metrics handler provides real-time visibility into resolve efficiency. The atomic.Int64 counters prevent race conditions during concurrent request processing.

Complete Working Example

The following Go module combines all components into a runnable service. Set the environment variables CXONE_BASE_URL, CXONE_CLIENT_ID, and CXONE_CLIENT_SECRET before execution.

package main

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"regexp"
	"strings"
	"sync"
	"sync/atomic"
	"time"
)

// --- Models ---
type TokenResponse struct {
	AccessToken string `json:"access_token"`
	ExpiresIn   int    `json:"expires_in"`
}

type ResolvePayload struct {
	JourneyID string                 `json:"journeyId"`
	ContactID string                 `json:"contactId"`
	Tokens    []string               `json:"tokens"`
	Fallbacks map[string]interface{} `json:"fallbacks,omitempty"`
}

type ResolveResult struct {
	ResolvedTokens map[string]interface{} `json:"resolvedTokens"`
	SuccessRate    float64                `json:"successRate"`
	LatencyMs      float64                `json:"latencyMs"`
}

type AuditLog struct {
	Timestamp    time.Time `json:"timestamp"`
	JourneyID    string    `json:"journeyId"`
	ContactID    string    `json:"contactId"`
	TokenCount   int       `json:"tokenCount"`
	SuccessRate  float64   `json:"successRate"`
	LatencyMs    float64   `json:"latencyMs"`
	CacheHit     bool      `json:"cacheHit"`
	ExternalSync bool      `json:"externalSync"`
}

// --- Caches ---
type TokenCache struct {
	mu      sync.RWMutex
	token   string
	expires time.Time
}

func (c *TokenCache) Get(ctx context.Context, baseURL, clientID, clientSecret string) (string, error) {
	c.mu.RLock()
	if time.Now().Before(c.expires) {
		token := c.token
		c.mu.RUnlock()
		return token, nil
	}
	c.mu.RUnlock()
	return c.refresh(ctx, baseURL, clientID, clientSecret)
}

func (c *TokenCache) refresh(ctx context.Context, baseURL, clientID, clientSecret string) (string, error) {
	c.mu.Lock()
	defer c.mu.Unlock()

	payload := fmt.Sprintf("grant_type=client_credentials&client_id=%s&client_secret=%s", clientID, clientSecret)
	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+"/api/v1/oauth2/token", bytes.NewBufferString(payload))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.SetBasicAuth(clientID, clientSecret)

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

	if resp.StatusCode != http.StatusOK {
		return "", fmt.Errorf("token fetch returned status %d", resp.StatusCode)
	}

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

	c.token = tr.AccessToken
	c.expires = time.Now().Add(time.Duration(tr.ExpiresIn-60) * time.Second)
	return c.token, nil
}

type ResolveCache struct {
	mu    sync.RWMutex
	store map[string]*cachedEntry
}

type cachedEntry struct {
	result    ResolveResult
	expiresAt time.Time
}

func (c *ResolveCache) GetOrSet(ctx context.Context, key string, ttl time.Duration, fn func() (ResolveResult, error)) (ResolveResult, error) {
	c.mu.RLock()
	entry, exists := c.store[key]
	c.mu.RUnlock()
	if exists && time.Now().Before(entry.expiresAt) {
		return entry.result, nil
	}

	result, err := fn()
	if err != nil {
		return ResolveResult{}, err
	}

	c.mu.Lock()
	c.store[key] = &cachedEntry{result: result, expiresAt: time.Now().Add(ttl)}
	c.mu.Unlock()
	return result, nil
}

// --- Core Resolver ---
type Metrics struct {
	TotalRequests      atomic.Int64
	SuccessfulResolves atomic.Int64
	FailedResolves     atomic.Int64
}

type Resolver struct {
	TokenCache     *TokenCache
	ResolveCache   *ResolveCache
	BaseURL        string
	ClientID       string
	ClientSecret   string
	CMSWebhookURL  string
	MaxDepth       int
	CacheTTL       time.Duration
	Metrics        Metrics
}

var uuidRegex = regexp.MustCompile(`^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$`)

func ValidateResolvePayload(p ResolvePayload, maxDepth int) error {
	if !uuidRegex.MatchString(p.JourneyID) {
		return fmt.Errorf("invalid journey UUID format: %s", p.JourneyID)
	}
	if len(p.Tokens) == 0 {
		return fmt.Errorf("token matrix cannot be empty")
	}
	for _, token := range p.Tokens {
		if !strings.HasPrefix(token, "{{") || !strings.HasSuffix(token, "}}") {
			return fmt.Errorf("token %q does not follow path matrix syntax", token)
		}
		path := strings.TrimSuffix(strings.TrimPrefix(token, "{{"), "}}")
		depth := strings.Count(path, ".") + 1
		if depth > maxDepth {
			return fmt.Errorf("token %q exceeds maximum depth limit of %d (current: %d)", token, maxDepth, depth)
		}
	}
	return nil
}

func payloadHash(p ResolvePayload) string {
	b, _ := json.Marshal(p)
	h := sha256.Sum256(b)
	return hex.EncodeToString(h[:])
}

func callCXoneResolve(ctx context.Context, baseURL, token string, p ResolvePayload) (ResolveResult, error) {
	body, _ := json.Marshal(p)
	client := &http.Client{Timeout: 15 * time.Second}

	for attempt := 0; attempt < 3; attempt++ {
		req, _ := http.NewRequestWithContext(ctx, http.MethodPost, baseURL+"/api/v1/personalization/tokens/resolve", bytes.NewReader(body))
		req.Header.Set("Authorization", "Bearer "+token)
		req.Header.Set("Content-Type", "application/json")
		req.Header.Set("Accept", "application/json")

		start := time.Now()
		resp, err := client.Do(req)
		if err != nil {
			time.Sleep(time.Duration(attempt+1) * 2 * time.Second)
			continue
		}
		defer resp.Body.Close()

		if resp.StatusCode == http.StatusTooManyRequests {
			time.Sleep(2 * time.Duration(attempt+1) * time.Second)
			continue
		}
		if resp.StatusCode != http.StatusOK {
			return ResolveResult{}, fmt.Errorf("API returned status %d", resp.StatusCode)
		}

		var rr ResolveResult
		if err := json.NewDecoder(resp.Body).Decode(&rr); err != nil {
			return ResolveResult{}, fmt.Errorf("decode error: %w", err)
		}
		rr.LatencyMs = float64(time.Since(start).Microseconds()) / 1000.0
		return rr, nil
	}
	return ResolveResult{}, fmt.Errorf("resolve failed after retries")
}

func (r *Resolver) Resolve(ctx context.Context, p ResolvePayload) (ResolveResult, error) {
	if err := ValidateResolvePayload(p, r.MaxDepth); err != nil {
		return ResolveResult{}, fmt.Errorf("validation failed: %w", err)
	}

	cacheKey := payloadHash(p)
	token, err := r.TokenCache.Get(ctx, r.BaseURL, r.ClientID, r.ClientSecret)
	if err != nil {
		return ResolveResult{}, fmt.Errorf("authentication failed: %w", err)
	}

	var cacheHit bool
	result, err := r.ResolveCache.GetOrSet(ctx, cacheKey, r.CacheTTL, func() (ResolveResult, error) {
		return callCXoneResolve(ctx, r.BaseURL, token, p)
	})
	if err != nil {
		return ResolveResult{}, err
	}
	cacheHit = (result.LatencyMs == 0)

	audit := AuditLog{
		Timestamp:    time.Now().UTC(),
		JourneyID:    p.JourneyID,
		ContactID:    p.ContactID,
		TokenCount:   len(p.Tokens),
		SuccessRate:  result.SuccessRate,
		LatencyMs:    result.LatencyMs,
		CacheHit:     cacheHit,
		ExternalSync: r.CMSWebhookURL != "",
	}
	log.Printf("AUDIT: %s", mustMarshalJSON(audit))

	if r.CMSWebhookURL != "" {
		go r.triggerCMSWebhook(ctx, audit)
	}
	return result, nil
}

func (r *Resolver) triggerCMSWebhook(ctx context.Context, audit AuditLog) {
	payload, _ := json.Marshal(audit)
	req, _ := http.NewRequestWithContext(ctx, http.MethodPost, r.CMSWebhookURL, bytes.NewReader(payload))
	req.Header.Set("Content-Type", "application/json")
	client := &http.Client{Timeout: 5 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		log.Printf("CMS webhook failed: %v", err)
		return
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 300 {
		log.Printf("CMS webhook returned status %d", resp.StatusCode)
	}
}

func mustMarshalJSON(v interface{}) string {
	b, _ := json.Marshal(v)
	return string(b)
}

// --- HTTP Handlers ---
func (r *Resolver) HandleResolve(w http.ResponseWriter, req *http.Request) {
	r.Metrics.TotalRequests.Add(1)
	var p ResolvePayload
	if err := json.NewDecoder(req.Body).Decode(&p); err != nil {
		http.Error(w, "invalid payload", http.StatusBadRequest)
		return
	}

	result, err := r.Resolve(req.Context(), p)
	if err != nil {
		r.Metrics.FailedResolves.Add(1)
		log.Printf("RESOLVE ERROR: %v", err)
		http.Error(w, fmt.Sprintf("resolve failed: %v", err), http.StatusInternalServerError)
		return
	}

	r.Metrics.SuccessfulResolves.Add(1)
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(result)
}

func (r *Resolver) HandleMetrics(w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(map[string]int64{
		"total_requests":     r.Metrics.TotalRequests.Load(),
		"successful_resolves": r.Metrics.SuccessfulResolves.Load(),
		"failed_resolves":    r.Metrics.FailedResolves.Load(),
	})
}

func main() {
	baseURL := os.Getenv("CXONE_BASE_URL")
	clientID := os.Getenv("CXONE_CLIENT_ID")
	clientSecret := os.Getenv("CXONE_CLIENT_SECRET")
	cmsURL := os.Getenv("CXONE_CMS_WEBHOOK_URL")

	if baseURL == "" || clientID == "" || clientSecret == "" {
		log.Fatal("Missing required environment variables: CXONE_BASE_URL, CXONE_CLIENT_ID, CXONE_CLIENT_SECRET")
	}

	resolver := &Resolver{
		TokenCache:    &TokenCache{},
		ResolveCache:  &ResolveCache{store: make(map[string]*cachedEntry)},
		BaseURL:       baseURL,
		ClientID:      clientID,
		ClientSecret:  clientSecret,
		CMSWebhookURL: cmsURL,
		MaxDepth:      5,
		CacheTTL:      10 * time.Minute,
	}

	http.HandleFunc("/resolve", resolver.HandleResolve)
	http.HandleFunc("/metrics", resolver.HandleMetrics)

	log.Printf("Starting resolver service on :8080")
	log.Fatal(http.ListenAndServe(":8080", nil))
}

Common Errors & Debugging

Error: 401 Unauthorized

• What causes it: The OAuth token expired or the client credentials lack the personalization.tokens.resolve scope.
• How to fix it: Verify the client credentials in the CXone admin console. Ensure the token cache refreshes before expiration. The provided cache subtracts 60 seconds from the TTL to prevent edge-case expiration during active requests.
• Code showing the fix: The TokenCache.refresh method handles automatic renewal. If the error persists, check the scope assignment in CXone Settings > Security > OAuth Clients.

Error: 400 Bad Request with depth violation

• What causes it: A token path exceeds the configured MaxDepth limit or uses invalid syntax.
• How to fix it: Adjust the MaxDepth parameter in the Resolver struct or simplify the token path matrix. Ensure all tokens follow the {{property.subproperty}} format.
• Code showing the fix: The ValidateResolvePayload function returns a descriptive error when depth > maxDepth. Reduce nesting in your Journey configuration or increase the limit if your rendering engine supports it.

Error: 429 Too Many Requests

• What causes it: The resolve pipeline exceeds CXone rate limits during high-volume Journey scaling.
• How to fix it: The callCXoneResolve function implements exponential backoff. Increase the cache TTL to reduce duplicate requests. Monitor the /metrics endpoint to identify traffic spikes.
• Code showing the fix: The retry loop sleeps for 2 * (attempt+1) seconds before retrying. Adjust the sleep duration if your environment requires longer cooldowns.

Official References

• NICE CXone Personalization Token Resolution API
• NICE CXone OAuth2 Authentication Guide
• NICE CXone Journey API Documentation