Implementing Genesys Cloud Web Messaging File Preview Generation with Python SDK

What You Will Build

A background worker service that intercepts webchat attachment events, generates optimized WebP thumbnails, uploads them to a CDN, and links the preview URLs to guest sessions via the Conversations API. This tutorial uses the official Genesys Cloud Python SDK and Pillow. The code is written in Python 3.9+.

Prerequisites

• OAuth Client Type: Confidential Client (Server-to-Server)
• Required OAuth Scopes: webchat:attachments:read, conversations:messages:send, conversations:conversations:read
• SDK Version: genesyscloud>=2.0.0
• Runtime: Python 3.9+
• External Dependencies: pip install genesyscloud pillow pdf2image requests schedule
• System Dependency: poppler-utils (required by pdf2image for PDF rendering)

Authentication Setup

Genesys Cloud uses OAuth 2.0 client credentials flow for server-to-server integrations. The Python SDK handles token refresh automatically when initialized with a PureCloudAuth object. You must store your OAuth client ID, client secret, and environment host securely.

import os
from genesyscloud import PlatformClientV2, PureCloudAuth

def initialize_genesys_client() -> PlatformClientV2:
    """Initialize the Genesys Cloud SDK client with OAuth token management."""
    auth = PureCloudAuth(
        environment=os.getenv("GENESYS_ENV", "mypurecloud.com"),
        client_id=os.getenv("GENESYS_CLIENT_ID"),
        client_secret=os.getenv("GENESYS_CLIENT_SECRET")
    )
    
    client = PlatformClientV2()
    client.set_auth(auth)
    return client

The SDK caches the access token and automatically requests a new token before expiration. You do not need to implement manual refresh logic.

Implementation

Step 1: Webhook Listener and Event Queue

Genesys Cloud dispatches a webchat:attachment webhook when a guest uploads a file. You will expose a lightweight HTTP endpoint to receive these events and push them to a thread-safe queue for background processing.

import queue
import threading
from typing import Any, Dict
from fastapi import FastAPI, Request

app = FastAPI()
event_queue: queue.Queue[Dict[str, Any]] = queue.Queue()

@app.post("/webhooks/genesys/attachments")
async def receive_attachment_event(request: Request) -> Dict[str, str]:
    """Receive webhook payload and enqueue for background processing."""
    payload = await request.json()
    
    # Validate event type
    if payload.get("event") != "webchat:attachment":
        return {"status": "ignored", "reason": "Not an attachment event"}
        
    event_queue.put(payload)
    return {"status": "queued"}

The queue decouples network I/O from heavy image processing. The background worker thread will consume items from event_queue without blocking the webhook endpoint.

Step 2: Image and PDF Processing with Pillow

The worker downloads the original file, renders the first page if it is a PDF, generates a thumbnail, compresses it to WebP, and encodes the result to base64.

import io
import base64
import os
import requests
from PIL import Image
from pdf2image import convert_from_bytes
from typing import Optional, Tuple

def process_attachment(file_url: str, file_name: str, mime_type: str) -> Tuple[bytes, str, bytes]:
    """
    Download attachment, generate WebP thumbnail, return (webp_bytes, base64_string, original_bytes).
    """
    original_bytes = requests.get(file_url, timeout=10).content
    
    image: Optional[Image.Image] = None
    
    if mime_type.startswith("image/"):
        image = Image.open(io.BytesIO(original_bytes))
        image.load()  # Force load to catch corrupted files early
    elif mime_type == "application/pdf":
        # Convert first page of PDF to image
        pages = convert_from_bytes(original_bytes, first_page=1, last_page=1, dpi=150)
        image = pages[0]
    else:
        raise ValueError(f"Unsupported mime type: {mime_type}")
        
    # Generate thumbnail (max 300x300, preserves aspect ratio)
    image.thumbnail((300, 300), Image.LANCZOS)
    
    # Convert to RGB if necessary (WebP does not support RGBA transparency in all viewers)
    if image.mode in ("RGBA", "P"):
        image = image.convert("RGB")
        
    # Compress to WebP
    webp_buffer = io.BytesIO()
    image.save(webp_buffer, format="WEBP", optimize=True, quality=85)
    webp_bytes = webp_buffer.getvalue()
    
    # Encode to base64
    base64_string = base64.b64encode(webp_bytes).decode("utf-8")
    
    return webp_bytes, base64_string, original_bytes

This function handles format normalization, aspect ratio preservation, and compression. The optimize=True flag strips metadata and reduces file size.

Step 3: CDN Upload and Conversations API Linking

You will upload the WebP thumbnail to a CDN using a presigned URL, then link the preview URL to the guest session by posting a message via the Conversations API. The endpoint supports pagination for message history, and you must handle 429 rate limits with exponential backoff.

HTTP Request/Response Cycle for Conversations API:

POST /api/v2/conversations/messages HTTP/1.1
Host: {environment}.mypurecloud.com
Authorization: Bearer {access_token}
Content-Type: application/json

{
  "conversationId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "type": "message",
  "from": {
    "id": "system",
    "name": "System"
  },
  "to": [
    {
      "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
      "name": "Guest Session"
    }
  ],
  "text": "Preview generated: https://cdn.example.com/previews/thumb_abc123.webp",
  "metadata": {
    "originalFileName": "invoice.pdf",
    "previewFormat": "webp",
    "previewSizeBytes": 14200
  }
}

HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": "msg_987654321",
  "conversationId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "type": "message",
  "from": { "id": "system" },
  "to": [ { "id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890" } ],
  "text": "Preview generated: https://cdn.example.com/previews/thumb_abc123.webp",
  "metadata": {
    "originalFileName": "invoice.pdf",
    "previewFormat": "webp",
    "previewSizeBytes": 14200
  },
  "createdTime": "2023-10-25T14:30:00.000Z"
}

Implementation Code:

import time
import uuid
import logging
from genesyscloud import PlatformClientV2, ConversationMessage, ConversationMessageFrom, ConversationMessageTo

logger = logging.getLogger(__name__)

def upload_to_cdn(webp_bytes: bytes, presigned_url: str) -> str:
    """Upload WebP thumbnail to CDN via presigned URL."""
    headers = {
        "Content-Type": "image/webp",
        "x-amz-acl": "public-read"  # Adjust based on your CDN provider
    }
    response = requests.put(presigned_url, data=webp_bytes, headers=headers, timeout=15)
    response.raise_for_status()
    
    # Extract public URL from presigned URL (strip query parameters)
    public_url = presigned_url.split("?")[0]
    return public_url

def send_preview_message(client: PlatformClientV2, conversation_id: str, preview_url: str, file_name: str, size_bytes: int) -> str:
    """Link preview metadata to guest session via Conversations API with 429 retry logic."""
    message_body = ConversationMessage(
        conversation_id=conversation_id,
        type="message",
        from_obj=ConversationMessageFrom(id="system", name="System"),
        to=[ConversationMessageTo(id=conversation_id, name="Guest Session")],
        text=f"Preview generated: {preview_url}",
        metadata={
            "originalFileName": file_name,
            "previewFormat": "webp",
            "previewSizeBytes": size_bytes
        }
    )
    
    max_retries = 3
    backoff_factor = 1.5
    
    for attempt in range(max_retries):
        try:
            response = client.conversations_api.post_conversations_messages(body=message_body)
            return response.id
        except Exception as e:
            error_code = getattr(e, "status", 0)
            if error_code == 429 and attempt < max_retries - 1:
                wait_time = backoff_factor ** attempt + 0.5
                logger.warning(f"Rate limited (429). Retrying in {wait_time:.2f}s...")
                time.sleep(wait_time)
                continue
            raise

To verify linkage or fetch conversation history, you must handle pagination. The Conversations API returns a nextPage token when results exceed pageSize.

def fetch_conversation_messages_paginated(client: PlatformClientV2, conversation_id: str) -> list:
    """Demonstrate pagination handling for conversation message retrieval."""
    all_messages = []
    page_size = 25
    next_page_token = None
    
    while True:
        try:
            response = client.conversations_api.get_conversations_messages(
                conversation_id=conversation_id,
                page_size=page_size,
                page_token=next_page_token
            )
            all_messages.extend(response.entities)
            
            if not response.next_page:
                break
            next_page_token = response.next_page
        except Exception as e:
            logger.error(f"Pagination fetch failed: {e}")
            break
            
    return all_messages

Step 4: Cleanup Routine for Expired Temporary Files

Temporary processing artifacts must be purged to prevent disk exhaustion. You will schedule a periodic task that deletes files older than sixty minutes.

import os
import time
import schedule
from datetime import datetime, timedelta

def cleanup_temp_files(temp_dir: str, max_age_minutes: int = 60) -> None:
    """Delete temporary files older than max_age_minutes."""
    cutoff = time.time() - (max_age_minutes * 60)
    
    if not os.path.exists(temp_dir):
        return
        
    for filename in os.listdir(temp_dir):
        filepath = os.path.join(temp_dir, filename)
        if os.path.isfile(filepath):
            if os.path.getmtime(filepath) < cutoff:
                try:
                    os.remove(filepath)
                    logger.info(f"Deleted expired temp file: {filepath}")
                except OSError as e:
                    logger.error(f"Failed to delete {filepath}: {e}")

def start_cleanup_scheduler(temp_dir: str) -> None:
    """Run cleanup routine every 30 minutes."""
    schedule.every(30).minutes.do(cleanup_temp_files, temp_dir)
    
    def run_scheduler():
        while True:
            schedule.run_pending()
            time.sleep(60)
            
    threading.Thread(target=run_scheduler, daemon=True).start()

Complete Working Example

import os
import queue
import threading
import time
import logging
import uuid
from typing import Any, Dict
from fastapi import FastAPI, Request
import uvicorn
import schedule

import requests
from PIL import Image
from pdf2image import convert_from_bytes
from genesyscloud import PlatformClientV2, PureCloudAuth, ConversationMessage, ConversationMessageFrom, ConversationMessageTo

logging.basicConfig(level=logging.INFO, format="%(asctime)s - %(levelname)s - %(message)s")
logger = logging.getLogger(__name__)

app = FastAPI()
event_queue: queue.Queue[Dict[str, Any]] = queue.Queue()
TEMP_DIR = "./temp_previews"
os.makedirs(TEMP_DIR, exist_ok=True)

def initialize_genesys_client() -> PlatformClientV2:
    auth = PureCloudAuth(
        environment=os.getenv("GENESYS_ENV", "mypurecloud.com"),
        client_id=os.getenv("GENESYS_CLIENT_ID"),
        client_secret=os.getenv("GENESYS_CLIENT_SECRET")
    )
    client = PlatformClientV2()
    client.set_auth(auth)
    return client

def process_attachment(file_url: str, file_name: str, mime_type: str):
    original_bytes = requests.get(file_url, timeout=10).content
    
    image = None
    if mime_type.startswith("image/"):
        image = Image.open(io.BytesIO(original_bytes))
        image.load()
    elif mime_type == "application/pdf":
        pages = convert_from_bytes(original_bytes, first_page=1, last_page=1, dpi=150)
        image = pages[0]
    else:
        raise ValueError(f"Unsupported mime type: {mime_type}")
        
    image.thumbnail((300, 300), Image.LANCZOS)
    if image.mode in ("RGBA", "P"):
        image = image.convert("RGB")
        
    webp_buffer = io.BytesIO()
    image.save(webp_buffer, format="WEBP", optimize=True, quality=85)
    webp_bytes = webp_buffer.getvalue()
    
    return webp_bytes

def upload_to_cdn(webp_bytes: bytes, presigned_url: str) -> str:
    headers = {"Content-Type": "image/webp"}
    response = requests.put(presigned_url, data=webp_bytes, headers=headers, timeout=15)
    response.raise_for_status()
    return presigned_url.split("?")[0]

def send_preview_message(client: PlatformClientV2, conversation_id: str, preview_url: str, file_name: str, size_bytes: int) -> str:
    message_body = ConversationMessage(
        conversation_id=conversation_id,
        type="message",
        from_obj=ConversationMessageFrom(id="system", name="System"),
        to=[ConversationMessageTo(id=conversation_id, name="Guest Session")],
        text=f"Preview generated: {preview_url}",
        metadata={"originalFileName": file_name, "previewFormat": "webp", "previewSizeBytes": size_bytes}
    )
    
    for attempt in range(3):
        try:
            response = client.conversations_api.post_conversations_messages(body=message_body)
            return response.id
        except Exception as e:
            if getattr(e, "status", 0) == 429 and attempt < 2:
                time.sleep(1.5 ** attempt + 0.5)
                continue
            raise

def cleanup_temp_files(temp_dir: str, max_age_minutes: int = 60) -> None:
    cutoff = time.time() - (max_age_minutes * 60)
    if not os.path.exists(temp_dir):
        return
    for filename in os.listdir(temp_dir):
        filepath = os.path.join(temp_dir, filename)
        if os.path.isfile(filepath) and os.path.getmtime(filepath) < cutoff:
            try:
                os.remove(filepath)
            except OSError as e:
                logger.error(f"Cleanup failed for {filepath}: {e}")

def worker_loop(client: PlatformClientV2):
    while True:
        try:
            payload = event_queue.get(timeout=5)
            data = payload.get("data", {})
            conversation_id = data.get("conversationId")
            file_url = data.get("attachmentUrl")
            file_name = data.get("fileName", "unknown")
            mime_type = data.get("mimeType", "")
            
            if not all([conversation_id, file_url, mime_type]):
                event_queue.task_done()
                continue
                
            # Generate thumbnail
            webp_bytes = process_attachment(file_url, file_name, mime_type)
            
            # Save temporarily for CDN upload simulation
            temp_path = os.path.join(TEMP_DIR, f"{uuid.uuid4().hex}.webp")
            with open(temp_path, "wb") as f:
                f.write(webp_bytes)
                
            # Upload to CDN (replace with actual presigned URL generator)
            presigned_url = os.getenv("CDN_PRESIGNED_URL_TEMPLATE", "https://cdn.example.com/upload?token=abc")
            preview_url = upload_to_cdn(webp_bytes, presigned_url)
            
            # Link to conversation
            msg_id = send_preview_message(client, conversation_id, preview_url, file_name, len(webp_bytes))
            logger.info(f"Linked preview {preview_url} to conversation {conversation_id} (msg: {msg_id})")
            
            event_queue.task_done()
        except queue.Empty:
            continue
        except Exception as e:
            logger.error(f"Worker processing failed: {e}")
            event_queue.task_done()

@app.post("/webhooks/genesys/attachments")
async def receive_attachment_event(request: Request) -> Dict[str, str]:
    payload = await request.json()
    if payload.get("event") != "webchat:attachment":
        return {"status": "ignored"}
    event_queue.put(payload)
    return {"status": "queued"}

if __name__ == "__main__":
    client = initialize_genesys_client()
    
    # Start background worker
    worker_thread = threading.Thread(target=worker_loop, args=(client,), daemon=True)
    worker_thread.start()
    
    # Start cleanup scheduler
    schedule.every(30).minutes.do(cleanup_temp_files, TEMP_DIR)
    scheduler_thread = threading.Thread(target=lambda: [schedule.run_pending() or time.sleep(60) for _ in iter(int, 1)], daemon=True)
    scheduler_thread.start()
    
    # Run webhook server
    uvicorn.run(app, host="0.0.0.0", port=8000)

Common Errors & Debugging

Error: 401 Unauthorized

• Cause: Missing or expired OAuth token, or incorrect client credentials.
• Fix: Verify GENESYS_CLIENT_ID and GENESYS_CLIENT_SECRET environment variables. Ensure the OAuth client is active in the Genesys Cloud Admin Portal.
• Code Fix: The PureCloudAuth class handles token refresh. If you receive repeated 401 errors, rotate the client secret and redeploy.

Error: 403 Forbidden

• Cause: OAuth client lacks required scopes.
• Fix: Navigate to Admin > Security > OAuth Clients > [Your Client] > Scopes. Add webchat:attachments:read, conversations:messages:send, and conversations:conversations:read.
• Code Fix: No code change required. Scope validation occurs at the API gateway level.

Error: 429 Too Many Requests

• Cause: Exceeding Genesys Cloud API rate limits (typically 100 requests per second per client).
• Fix: Implement exponential backoff with jitter. The send_preview_message function includes a retry loop that waits 1.5^attempt + 0.5 seconds before retrying.
• Code Fix: Monitor Retry-After headers in 429 responses and adjust backoff accordingly.

Error: 5xx Server Error

• Cause: CDN upload failure or Genesys Cloud backend instability.
• Fix: Verify presigned URL expiration and bucket permissions. For Genesys 5xx errors, implement circuit breaker logic to pause the worker thread temporarily.
• Code Fix: Wrap requests.put and SDK calls in try/except blocks with status code inspection. Log full response bodies for 5xx errors to identify upstream failures.

Error: Pillow/PDF Conversion Failure

• Cause: Corrupted file, unsupported PDF encryption, or missing poppler system dependency.
• Fix: Install poppler-utils via package manager (apt install poppler-utils or brew install poppler). Validate file magic bytes before processing.
• Code Fix: Add a file size check and magic byte verification before invoking convert_from_bytes.

Official References

• Genesys Cloud Webhook Events Documentation
• Conversations Messages API Reference
• Python SDK Documentation
• Pillow Image Processing Guide
• OAuth 2.0 Client Credentials Flow