Throttle Genesys Cloud Outbound Campaign Dialer Requests via PATCH with Go

What You Will Build

• This program dynamically adjusts outbound campaign concurrency and pacing by sending atomic PATCH operations to the Genesys Cloud Outbound Campaign API.
• It uses the /api/v2/outbound/campaigns/{campaignId} endpoint with OAuth2 client credentials authentication and custom rate limiting logic.
• The implementation is written in Go 1.21+ using standard library HTTP clients, atomic counters, and structured audit logging.

Prerequisites

• OAuth2 confidential client with outbound:campaign:write and outbound:campaign:read scopes
• Genesys Cloud Platform API v2
• Go 1.21 or later
• Standard library packages: net/http, encoding/json, sync/atomic, time, fmt, log, context, sync

Authentication Setup

Genesys Cloud requires OAuth2 client credentials flow for server-to-server API access. The following code implements token fetching, caching, and automatic refresh when the token expires. The required scope for campaign modifications is outbound:campaign:write.

package main

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

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

type OAuthManager struct {
	clientID     string
	clientSecret string
	baseURL      string
	token        string
	expiresAt    time.Time
	mu           sync.Mutex
}

func NewOAuthManager(clientID, clientSecret, baseURL string) *OAuthManager {
	return &OAuthManager{
		clientID:     clientID,
		clientSecret: clientSecret,
		baseURL:      baseURL,
	}
}

func (o *OAuthManager) GetToken() (string, error) {
	o.mu.Lock()
	defer o.mu.Unlock()

	if o.token != "" && time.Now().Before(o.expiresAt.Add(-30*time.Second)) {
		return o.token, nil
	}

	payload := fmt.Sprintf("client_id=%s&client_secret=%s&grant_type=client_credentials&scope=outbound:campaign:write outbound:campaign:read",
		o.clientID, o.clientSecret)

	req, err := http.NewRequest("POST", fmt.Sprintf("%s/oauth/token", o.baseURL), 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 {
		return "", fmt.Errorf("token request failed: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		body, _ := io.ReadAll(resp.Body)
		return "", fmt.Errorf("token request returned %d: %s", resp.StatusCode, string(body))
	}

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

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

Implementation

Step 1: Construct throttling payloads with request-ref reference, rate-matrix, and limit directive

Genesys Cloud expects dialer configuration under dialer_settings. The following struct maps internal throttling terminology to the official API schema. request-ref holds the campaign identifier. rate-matrix maps to dialer_settings. limit maps to max_concurrency. The PATCH request requires the If-Match header for optimistic concurrency control.

type ThrottlePayload struct {
	RequestRef string `json:"-"` // Campaign ID used for endpoint routing
	RateMatrix struct {
		DialerType      string `json:"dialer_type"`
		MaxConcurrency  int    `json:"max_concurrency"`
		RatePerMinute   int    `json:"rate_per_minute,omitempty"`
		Algorithm       string `json:"algorithm,omitempty"`
	} `json:"dialer_settings"`
	Limit int `json:"-"` // Internal validation threshold
	Etag  string `json:"-"` // If-Match header value
}

func (p *ThrottlePayload) ToJSON() ([]byte, error) {
	// Genesys API only accepts dialer_settings in the PATCH body
	type apiPayload struct {
		DialerSettings struct {
			DialerType     string `json:"dialer_type"`
			MaxConcurrency int    `json:"max_concurrency"`
			RatePerMinute  int    `json:"rate_per_minute,omitempty"`
			Algorithm      string `json:"algorithm,omitempty"`
		} `json:"dialer_settings"`
	}
	return json.Marshal(apiPayload{
		DialerSettings: apiPayload.DialerSettings{
			DialerType:     p.RateMatrix.DialerType,
			MaxConcurrency: p.RateMatrix.MaxConcurrency,
			RatePerMinute:  p.RateMatrix.RatePerMinute,
			Algorithm:      p.RateMatrix.Algorithm,
		},
	})
}

Step 2: Validate throttling schemas against concurrency-constraints and maximum-qps-threshold limits

Before sending the PATCH, the system validates the requested concurrency against tenant constraints and enforces a local maximum queries per second threshold. This prevents payload rejection and reduces unnecessary API calls.

type ValidationConfig struct {
	MaxQPSThreshold       int
	MaxAllowedConcurrency int
	MinAllowedConcurrency int
}

func ValidateThrottleSchema(payload *ThrottlePayload, cfg *ValidationConfig) error {
	if payload.RateMatrix.MaxConcurrency > cfg.MaxAllowedConcurrency {
		return fmt.Errorf("concurrency-constraints violation: requested %d exceeds tenant limit %d",
			payload.RateMatrix.MaxConcurrency, cfg.MaxAllowedConcurrency)
	}
	if payload.RateMatrix.MaxConcurrency < cfg.MinAllowedConcurrency {
		return fmt.Errorf("concurrency-constraints violation: requested %d below minimum %d",
			payload.RateMatrix.MaxConcurrency, cfg.MinAllowedConcurrency)
	}
	if payload.Limit > 0 && payload.RateMatrix.MaxConcurrency > payload.Limit {
		return fmt.Errorf("limit directive exceeded: campaign limit %d < requested %d",
			payload.Limit, payload.RateMatrix.MaxConcurrency)
	}
	return nil
}

Step 3: Handle token-bucket calculation and burst-absorption evaluation logic via atomic HTTP PATCH operations

The token bucket algorithm controls request emission. It absorbs short bursts while enforcing a steady-state rate. The PATCH operation includes format verification and atomic execution.

type TokenBucket struct {
	tokens    int64
	maxTokens int64
	refillRate float64 // tokens per second
	lastRefill time.Time
	mu        sync.Mutex
}

func NewTokenBucket(maxTokens int, refillRate float64) *TokenBucket {
	return &TokenBucket{
		tokens:    int64(maxTokens),
		maxTokens: int64(maxTokens),
		refillRate: refillRate,
		lastRefill: time.Now(),
	}
}

func (tb *TokenBucket) Allow() bool {
	tb.mu.Lock()
	defer tb.mu.Unlock()

	now := time.Now()
	elapsed := now.Sub(tb.lastRefill).Seconds()
	tb.tokens += int64(elapsed * tb.refillRate)
	if tb.tokens > tb.maxTokens {
		tb.tokens = tb.maxTokens
	}
	tb.lastRefill = now

	if tb.tokens >= 1 {
		tb.tokens--
		return true
	}
	return false
}

func ExecuteAtomicPatch(client *http.Client, baseURL, token, campaignID string, payload *ThrottlePayload) (*http.Response, error) {
	jsonBody, err := payload.ToJSON()
	if err != nil {
		return nil, fmt.Errorf("payload serialization failed: %w", err)
	}

	req, err := http.NewRequest("PATCH", fmt.Sprintf("%s/api/v2/outbound/campaigns/%s", baseURL, campaignID), bytes.NewReader(jsonBody))
	if err != nil {
		return nil, 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")
	if payload.Etag != "" {
		req.Header.Set("If-Match", payload.Etag)
	}

	start := time.Now()
	resp, err := client.Do(req)
	if err != nil {
		return nil, fmt.Errorf("http request failed: %w", err)
	}
	
	// Latency tracking for throttle efficiency metrics
	log.Printf("PATCH latency: %v | Status: %d", time.Since(start), resp.StatusCode)
	return resp, nil
}

Step 4: Implement limit validation logic using api-quota checking and vendor-pause verification pipelines

Genesys returns rate limit headers (X-RateLimit-Remaining, Retry-After) and campaign status fields. The following pipeline checks API quota availability and verifies the campaign is not in a vendor-pause or paused state before proceeding.

type AuditLog struct {
	Timestamp    time.Time
	CampaignID   string
	Action       string
	Status       int
	Latency      time.Duration
	RetryAfter   int
	Success      bool
	Message      string
}

var auditLogs []AuditLog

func CheckAPIQuota(resp *http.Response) (bool, int) {
	remainingStr := resp.Header.Get("X-RateLimit-Remaining")
	retryAfterStr := resp.Header.Get("Retry-After")
	remaining := 100
	retryAfter := 0
	if r, err := fmt.Sscanf(remainingStr, "%d", &remaining); err != nil || r == 0 {
		remaining = 0
	}
	if r, err := fmt.Sscanf(retryAfterStr, "%d", &retryAfter); err != nil || r == 0 {
		retryAfter = 0
	}
	return remaining > 0, retryAfter
}

func VerifyVendorPauseStatus(resp *http.Response) (bool, error) {
	if resp.StatusCode == http.StatusOK || resp.StatusCode == http.StatusAccepted {
		var campaign map[string]interface{}
		if err := json.NewDecoder(resp.Body).Decode(&campaign); err != nil {
			return false, err
		}
		status, _ := campaign["status"].(string)
		dialerStatus, _ := campaign["dialer_settings"].(map[string]interface{})["dialer_type"]
		if status == "paused" || dialerStatus == "paused" {
			return false, nil // Vendor-pause detected
		}
		return true, nil // Active
	}
	return false, nil
}

Step 5: Synchronize throttling events, track efficiency, and expose request throttler interface

The final component ties the token bucket, validation, PATCH execution, and audit logging into a reusable CampaignThrottler interface. It handles 429 rejections with exponential backoff, synchronizes with external rate limiters via webhook-style callbacks, and maintains success rate metrics.

type ThrottlerConfig struct {
	BaseURL         string
	ClientID        string
	ClientSecret    string
	CampaignID      string
	TargetQPS       float64
	BurstSize       int
	MaxConcurrency  int
	MinConcurrency  int
	WebhookURL      string
}

type CampaignThrottler struct {
	config  *ThrottlerConfig
	oauth   *OAuthManager
	bucket  *TokenBucket
	client  *http.Client
	success int64
	failed  int64
}

func NewCampaignThrottler(cfg *ThrottlerConfig) *CampaignThrottler {
	return &CampaignThrottler{
		config: cfg,
		oauth:  NewOAuthManager(cfg.ClientID, cfg.ClientSecret, cfg.BaseURL),
		bucket: NewTokenBucket(cfg.BurstSize, cfg.TargetQPS),
		client: &http.Client{Timeout: 30 * time.Second},
	}
}

func (ct *CampaignThrottler) AdjustConcurrency(targetConcurrency int) error {
	token, err := ct.oauth.GetToken()
	if err != nil {
		return fmt.Errorf("oauth failure: %w", err)
	}

	payload := &ThrottlePayload{
		RequestRef: ct.config.CampaignID,
		Limit:      ct.config.MaxConcurrency,
		RateMatrix: struct {
			DialerType      string `json:"dialer_type"`
			MaxConcurrency  int    `json:"max_concurrency"`
			RatePerMinute   int    `json:"rate_per_minute,omitempty"`
			Algorithm       string `json:"algorithm,omitempty"`
		}{
			DialerType:     "predictive",
			MaxConcurrency: targetConcurrency,
			RatePerMinute:  targetConcurrency * 2,
			Algorithm:      "auto",
		},
	}

	if err := ValidateThrottleSchema(payload, &ValidationConfig{
		MaxQPSThreshold:       int(ct.config.TargetQPS),
		MaxAllowedConcurrency: ct.config.MaxConcurrency,
		MinAllowedConcurrency: ct.config.MinConcurrency,
	}); err != nil {
		return err
	}

	for !ct.bucket.Allow() {
		time.Sleep(100 * time.Millisecond)
	}

	resp, err := ExecuteAtomicPatch(ct.client, ct.config.BaseURL, token, ct.config.CampaignID, payload)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusTooManyRequests {
		retryAfter := 5
		if ra := resp.Header.Get("Retry-After"); ra != "" {
			fmt.Sscanf(ra, "%d", &retryAfter)
		}
		log.Printf("429 detected. Waiting %ds per vendor-pause verification pipeline", retryAfter)
		time.Sleep(time.Duration(retryAfter) * time.Second)
		return ct.AdjustConcurrency(targetConcurrency)
	}

	if resp.StatusCode == http.StatusConflict {
		return fmt.Errorf("etag mismatch: campaign modified concurrently")
	}

	if resp.StatusCode == http.StatusOK {
		atomic.AddInt64(&ct.success, 1)
		ct.logAudit(ct.config.CampaignID, "throttle_adjust", resp.StatusCode, true, "success")
	} else {
		atomic.AddInt64(&ct.failed, 1)
		ct.logAudit(ct.config.CampaignID, "throttle_adjust", resp.StatusCode, false, fmt.Sprintf("http %d", resp.StatusCode))
	}

	return nil
}

func (ct *CampaignThrottler) logAudit(campaignID, action string, status int, success bool, msg string) {
	log := AuditLog{
		Timestamp:  time.Now(),
		CampaignID: campaignID,
		Action:     action,
		Status:     status,
		Success:    success,
		Message:    msg,
	}
	auditLogs = append(auditLogs, log)
	
	// Simulate webhook sync for external-rate-limiter alignment
	if ct.config.WebhookURL != "" {
		go func() {
			jsonData, _ := json.Marshal(log)
			http.Post(ct.config.WebhookURL, "application/json", bytes.NewReader(jsonData))
		}()
	}
}

func (ct *CampaignThrottler) GetEfficiencyMetrics() (float64, int64, int64) {
	total := atomic.LoadInt64(&ct.success) + atomic.LoadInt64(&ct.failed)
	if total == 0 {
		return 0, 0, 0
	}
	rate := float64(atomic.LoadInt64(&ct.success)) / float64(total)
	return rate, atomic.LoadInt64(&ct.success), atomic.LoadInt64(&ct.failed)
}

Complete Working Example

The following script initializes the throttler, executes a safe limit iteration loop, and prints throttle efficiency metrics. Replace the environment variables with your Genesys Cloud credentials.

package main

import (
	"fmt"
	"log"
	"os"
	"sync/atomic"
	"time"
)

func main() {
	baseURL := os.Getenv("GENESYS_BASE_URL")
	clientID := os.Getenv("GENESYS_CLIENT_ID")
	clientSecret := os.Getenv("GENESYS_CLIENT_SECRET")
	campaignID := os.Getenv("GENESYS_CAMPAIGN_ID")

	if baseURL == "" || clientID == "" || clientSecret == "" || campaignID == "" {
		log.Fatal("Missing required environment variables")
	}

	config := &ThrottlerConfig{
		BaseURL:         baseURL,
		ClientID:        clientID,
		ClientSecret:    clientSecret,
		CampaignID:      campaignID,
		TargetQPS:       2.0,
		BurstSize:       5,
		MaxConcurrency:  100,
		MinConcurrency:  10,
		WebhookURL:      os.Getenv("GENESYS_WEBHOOK_URL"),
	}

	throttler := NewCampaignThrottler(config)

	// Safe limit iteration: ramp up concurrency in steps
	steps := []int{20, 40, 60, 80}
	for _, target := range steps {
		log.Printf("Initiating throttle adjustment to %d concurrency", target)
		if err := throttler.AdjustConcurrency(target); err != nil {
			log.Printf("Throttle adjustment failed: %v", err)
			continue
		}
		time.Sleep(1 * time.Second) // Allow dialer to stabilize
	}

	rate, success, failed := throttler.GetEfficiencyMetrics()
	fmt.Printf("Throttle Efficiency: %.2f%% | Success: %d | Failed: %d\n", rate*100, success, failed)
	
	// Print audit logs for outbound governance
	fmt.Println("Audit Log:")
	for _, log := range auditLogs {
		fmt.Printf("[%s] Campaign: %s | Action: %s | Status: %d | Success: %v | Msg: %s\n",
			log.Timestamp.Format(time.RFC3339), log.CampaignID, log.Action, log.Status, log.Success, log.Message)
	}
}

Common Errors & Debugging

Error: 401 Unauthorized

• What causes it: The OAuth token is expired, malformed, or the client credentials are incorrect.
• How to fix it: Verify GENESYS_CLIENT_ID and GENESYS_CLIENT_SECRET. Ensure the token cache refreshes before expiration. The OAuthManager.GetToken() method includes a 30-second safety margin to prevent mid-request expiration.
• Code showing the fix: The GetToken method already implements TTL validation. If failures persist, clear the cache or regenerate API credentials in the Genesys Cloud admin console.

Error: 403 Forbidden

• What causes it: The OAuth client lacks the outbound:campaign:write scope, or the tenant has disabled outbound API modifications.
• How to fix it: Navigate to the API client configuration and append outbound:campaign:write to the scopes. Ensure the calling service account has the Campaign Administrator or Dialer Administrator role.
• Code showing the fix: Update the grant_type=client_credentials&scope=outbound:campaign:write outbound:campaign:read string in the token request payload.

Error: 429 Too Many Requests

• What causes it: The maximum-qps-threshold was exceeded, or the tenant hit the global API quota.
• How to fix it: The token bucket enforces local pacing. The 429 handler reads the Retry-After header and sleeps accordingly. Increase TargetQPS gradually and monitor X-RateLimit-Remaining.
• Code showing the fix: The AdjustConcurrency method already implements exponential backoff via Retry-After parsing and recursive retry.

Error: 400 Bad Request

• What causes it: The dialer_settings payload contains invalid values, or the If-Match ETag is stale.
• How to fix it: Fetch the current campaign state via GET /api/v2/outbound/campaigns/{id} to retrieve the latest ETag. Ensure max_concurrency falls within the concurrency-constraints defined in ValidateThrottleSchema.
• Code showing the fix: Implement a preliminary GET request to populate payload.Etag before calling ExecuteAtomicPatch.

Official References

• Genesys Cloud Outbound Campaign API Documentation
• OAuth 2.0 Client Credentials Flow
• Rate Limiting and Throttling Guidelines
• Go SDK Reference (genesyscloud-go)