Building a Custom Genesys Cloud Web Messaging Guest Client with TypeScript and React

What You Will Build

• A production-ready guest webchat interface that establishes a WebSocket connection to Genesys Cloud CX, renders conversation history using a virtualized list, handles text and file attachments, and manages connection lifecycles with full accessibility compliance.
• This tutorial uses the Genesys Cloud Conversations API (/api/v2/conversations/webchat) and the native WebSocket protocol for real-time message exchange.
• The implementation covers TypeScript, React 18, and @tanstack/react-virtual for high-performance rendering.

Prerequisites

• Node.js 18+ and package manager (npm or yarn)
• React 18+ with TypeScript 5+
• @tanstack/react-virtual@3.5.0 for list virtualization
• uuid@9.0.0 for generating deterministic local message identifiers
• Genesys Cloud Web Messaging configuration ID (retrieved from Admin > Channels > Web Messaging > Configurations)
• OAuth scopes: Guest webchat operates without OAuth tokens. If your application proxies requests through a backend service, the backend requires webchat:read and webchat:write scopes on the OAuth client.

Authentication Setup

Guest webchat clients do not use OAuth bearer tokens. Instead, they initiate an anonymous session by posting to the Genesys Cloud Conversations API. The server responds with a webSocketUrl, conversationId, and guestId. These values establish the session identity for the duration of the chat.

The initial handshake uses a standard HTTP POST request. You must pass your webchat configuration ID in the request body. The response contains the WebSocket endpoint that your client will use for all subsequent real-time communication.

// src/services/webchat.ts
const GENESYS_API_BASE = 'https://api.mypurecloud.com';

export interface WebchatSession {
  conversationId: string;
  guestId: string;
  webSocketUrl: string;
  status: string;
}

export async function initiateWebchatSession(configId: string): Promise<WebchatSession> {
  const response = await fetch(`${GENESYS_API_BASE}/api/v2/conversations/webchat`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Accept': 'application/json'
    },
    body: JSON.stringify({
      configId: configId,
      channel: 'webchat'
    })
  });

  if (!response.ok) {
    if (response.status === 400) {
      throw new Error('Invalid webchat configuration ID or malformed request payload.');
    }
    if (response.status === 429) {
      throw new Error('Rate limit exceeded. Implement exponential backoff before retrying.');
    }
    if (response.status >= 500) {
      throw new Error('Genesys Cloud server error. Retry with jitter after 2 seconds.');
    }
    throw new Error(`HTTP ${response.status}: ${response.statusText}`);
  }

  const data: WebchatSession = await response.json();
  return data;
}

The webSocketUrl returned is a secure wss:// endpoint specific to your tenant. You will store this value and use it to create the WebSocket instance. The conversationId and guestId are required in every outbound message payload to route traffic correctly.

Implementation

Step 1: WebSocket Connection Manager

The connection manager handles the WebSocket lifecycle, including initial connection, automatic reconnection with exponential backoff, and message serialization. Genesys Cloud expects outbound messages to follow a strict JSON schema with a type field and a message payload object.

Create a custom hook that manages connection state and provides a sendMessage function. The hook tracks connected, reconnecting, and disconnected states and exposes them to the UI.

// src/hooks/useWebchatConnection.ts
import { useState, useEffect, useCallback, useRef } from 'react';
import { v4 as uuidv4 } from 'uuid';

export type ConnectionStatus = 'disconnected' | 'connecting' | 'connected' | 'reconnecting';

export interface WebchatMessage {
  id: string;
  text?: string;
  fileName?: string;
  mimeType?: string;
  fileSize?: number;
  fileData?: string;
  sender: 'guest' | 'agent' | 'system';
  timestamp: string;
}

export function useWebchatConnection(webSocketUrl: string | null, conversationId: string | null, guestId: string | null) {
  const [status, setStatus] = useState<ConnectionStatus>('disconnected');
  const [messages, setMessages] = useState<WebchatMessage[]>([]);
  const wsRef = useRef<WebSocket | null>(null);
  const reconnectTimeoutRef = useRef<number | null>(null);
  const maxRetries = 5;
  const retryCountRef = useRef(0);

  const connect = useCallback(() => {
    if (!webSocketUrl || !conversationId || !guestId) return;

    setStatus('connecting');
    const ws = new WebSocket(webSocketUrl);
    wsRef.current = ws;

    ws.onopen = () => {
      setStatus('connected');
      retryCountRef.current = 0;
      // Send initial guest presence ping
      ws.send(JSON.stringify({
        type: 'text',
        message: { text: '' },
        conversationId,
        guestId
      }));
    };

    ws.onmessage = (event: MessageEvent) => {
      try {
        const payload = JSON.parse(event.data);
        if (payload.type === 'text' || payload.type === 'file') {
          const newMessage: WebchatMessage = {
            id: payload.message.id || uuidv4(),
            text: payload.message.text,
            fileName: payload.message.name,
            mimeType: payload.message.mimeType,
            fileSize: payload.message.size,
            fileData: payload.message.data,
            sender: payload.sender === 'guest' ? 'guest' : payload.sender === 'agent' ? 'agent' : 'system',
            timestamp: new Date().toISOString()
          };
          setMessages(prev => [...prev, newMessage]);
        }
      } catch (error) {
        console.error('Failed to parse incoming webchat message:', error);
      }
    };

    ws.onclose = (event: CloseEvent) => {
      setStatus('disconnected');
      if (!event.wasClean) {
        scheduleReconnect();
      }
    };

    ws.onerror = (error: Event) => {
      console.error('WebSocket error:', error);
      setStatus('reconnecting');
    };
  }, [webSocketUrl, conversationId, guestId]);

  const scheduleReconnect = useCallback(() => {
    if (retryCountRef.current >= maxRetries) {
      setStatus('disconnected');
      return;
    }
    const delay = Math.min(1000 * Math.pow(2, retryCountRef.current), 10000);
    setStatus('reconnecting');
    reconnectTimeoutRef.current = window.setTimeout(() => {
      retryCountRef.current += 1;
      connect();
    }, delay);
  }, [connect]);

  const sendMessage = useCallback((content: { text?: string; file?: { name: string; type: string; data: string; size: number } } | null) => {
    if (!wsRef.current || wsRef.current.readyState !== WebSocket.OPEN) {
      throw new Error('WebSocket is not connected. Message queued for retry.');
    }

    const payload = content?.file
      ? {
          type: 'file',
          message: {
            name: content.file.name,
            mimeType: content.file.type,
            size: content.file.size,
            data: content.file.data
          },
          conversationId,
          guestId
        }
      : {
          type: 'text',
          message: { text: content?.text || '' },
          conversationId,
          guestId
        };

    wsRef.current.send(JSON.stringify(payload));
  }, [conversationId, guestId]);

  useEffect(() => {
    if (webSocketUrl) {
      connect();
    }
    return () => {
      if (reconnectTimeoutRef.current) clearTimeout(reconnectTimeoutRef.current);
      if (wsRef.current) wsRef.current.close();
    };
  }, [webSocketUrl, connect]);

  return { status, messages, sendMessage };
}

The connection manager implements exponential backoff to prevent 429 rate-limit cascades during network instability. It serializes both text and file payloads according to the Genesys Web Messaging protocol. The sendMessage function throws an error if the socket is closed, allowing the UI to queue messages locally if needed.

Step 2: Virtualized Message List and Accessibility

Rendering long conversation histories in React requires virtualization to maintain 60 FPS scroll performance. The @tanstack/react-virtual library calculates which items are visible in the viewport and renders only those rows. Accessibility requires proper ARIA roles, live regions for new messages, and keyboard navigation support.

// src/components/MessageList.tsx
import { useRef, useEffect } from 'react';
import { useVirtualizer } from '@tanstack/react-virtual';
import { WebchatMessage } from '../hooks/useWebchatConnection';

interface MessageListProps {
  messages: WebchatMessage[];
}

export function MessageList({ messages }: MessageListProps) {
  const parentRef = useRef<HTMLDivElement>(null);

  const virtualizer = useVirtualizer({
    count: messages.length,
    getScrollElement: () => parentRef.current,
    estimateSize: () => 60,
    overscan: 5
  });

  // Auto-scroll to bottom on new message
  useEffect(() => {
    if (parentRef.current && messages.length > 0) {
      virtualizer.scrollToIndex(messages.length - 1, { align: 'end' });
    }
  }, [messages.length, virtualizer]);

  return (
    <div
      ref={parentRef}
      role="log"
      aria-live="polite"
      aria-label="Conversation messages"
      style={{
        height: '400px',
        width: '100%',
        overflowY: 'auto',
        position: 'relative',
        border: '1px solid #d1d5db',
        borderRadius: '8px',
        padding: '8px'
      }}
    >
      <div
        style={{
          height: `${virtualizer.getTotalSize()}px`,
          width: '100%',
          position: 'relative'
        }}
      >
        {virtualizer.getVirtualItems().map((virtualRow) => {
          const message = messages[virtualRow.index];
          const isGuest = message.sender === 'guest';
          return (
            <div
              key={virtualRow.key}
              data-index={virtualRow.index}
              ref={virtualizer.measureElement}
              style={{
                position: 'absolute',
                top: 0,
                left: 0,
                width: '100%',
                height: `${virtualRow.size}px`,
                transform: `translateY(${virtualRow.start}px)`
              }}
            >
              <div
                role="listitem"
                aria-label={`${isGuest ? 'You' : 'Agent'} said: ${message.text || 'Sent a file'}`}
                style={{
                  display: 'inline-block',
                  maxWidth: '70%',
                  padding: '8px 12px',
                  margin: '4px 0',
                  borderRadius: '12px',
                  backgroundColor: isGuest ? '#2563eb' : '#f3f4f6',
                  color: isGuest ? '#ffffff' : '#111827',
                  alignSelf: isGuest ? 'flex-end' : 'flex-start',
                  marginLeft: isGuest ? 'auto' : '0',
                  marginRight: isGuest ? '0' : 'auto'
                }}
              >
                {message.text && <p style={{ margin: 0 }}>{message.text}</p>}
                {message.fileName && (
                  <div style={{ marginTop: '4px', fontSize: '0.875rem', opacity: 0.9 }}>
                    📎 {message.fileName} ({message.fileSize ? `${Math.round(message.fileSize / 1024)} KB` : ''})
                  </div>
                )}
              </div>
            </div>
          );
        })}
      </div>
    </div>
  );
}

The virtualizer calculates row heights dynamically. The role="log" and aria-live="polite" attributes inform screen readers when new messages arrive without interrupting the user. Each bubble includes an aria-label that describes the sender and content. The layout uses flex alignment to position guest messages on the right and agent messages on the left.

Step 3: Input Form with Rich Media Attachments

The input form captures text and file selections. It converts files to base64 strings for transmission over the WebSocket connection. Genesys Cloud enforces a 2 MB limit for base64-encoded attachments in real-time webchat. The form implements keyboard navigation, allowing users to press Enter to send and Shift+Enter to create a new line.

// src/components/MessageForm.tsx
import { useState, useRef, FormEvent, KeyboardEvent, ChangeEvent } from 'react';

interface MessageFormProps {
  onSend: (content: { text?: string; file?: { name: string; type: string; data: string; size: number } } | null) => void;
  isDisabled: boolean;
}

export function MessageForm({ onSend, isDisabled }: MessageFormProps) {
  const [text, setText] = useState('');
  const [attachment, setAttachment] = useState<{ name: string; type: string; data: string; size: number } | null>(null);
  const fileInputRef = useRef<HTMLInputElement>(null);
  const textareaRef = useRef<HTMLTextAreaElement>(null);

  const handleFileChange = async (e: ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (!file) return;

    if (file.size > 2 * 1024 * 1024) {
      alert('File size exceeds 2 MB limit. Please select a smaller file.');
      return;
    }

    const reader = new FileReader();
    reader.onload = () => {
      const base64 = reader.result as string;
      setAttachment({
        name: file.name,
        type: file.type,
        data: base64.split(',')[1],
        size: file.size
      });
    };
    reader.readAsDataURL(file);
  };

  const handleSubmit = (e: FormEvent) => {
    e.preventDefault();
    if (!text.trim() && !attachment) return;

    onSend({
      text: text.trim() || undefined,
      file: attachment || undefined
    });

    setText('');
    setAttachment(null);
    if (fileInputRef.current) fileInputRef.current.value = '';
    textareaRef.current?.focus();
  };

  const handleKeyDown = (e: KeyboardEvent<HTMLTextAreaElement>) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      handleSubmit(e as unknown as FormEvent);
    }
  };

  return (
    <form onSubmit={handleSubmit} style={{ display: 'flex', flexDirection: 'column', gap: '8px', marginTop: '12px' }}>
      {attachment && (
        <div
          aria-live="assertive"
          style={{ fontSize: '0.875rem', color: '#059669', padding: '4px 8px', backgroundColor: '#ecfdf5', borderRadius: '4px' }}
        >
          Attached: {attachment.name}
        </div>
      )}
      <div style={{ display: 'flex', gap: '8px', alignItems: 'flex-end' }}>
        <input
          type="file"
          ref={fileInputRef}
          onChange={handleFileChange}
          aria-label="Attach file"
          tabIndex={-1}
          style={{ display: 'none' }}
        />
        <button
          type="button"
          onClick={() => fileInputRef.current?.click()}
          aria-label="Select file to attach"
          disabled={isDisabled}
          style={{ padding: '8px 12px', cursor: isDisabled ? 'not-allowed' : 'pointer' }}
        >
          📎
        </button>
        <textarea
          ref={textareaRef}
          value={text}
          onChange={(e) => setText(e.target.value)}
          onKeyDown={handleKeyDown}
          aria-label="Type a message"
          placeholder="Type a message or press Shift+Enter for new line"
          rows={1}
          disabled={isDisabled}
          style={{
            flex: 1,
            padding: '10px',
            borderRadius: '8px',
            border: '1px solid #d1d5db',
            resize: 'none',
            minHeight: '44px'
          }}
        />
        <button
          type="submit"
          disabled={isDisabled || (!text.trim() && !attachment)}
          aria-label="Send message"
          style={{
            padding: '10px 16px',
            backgroundColor: '#2563eb',
            color: 'white',
            border: 'none',
            borderRadius: '8px',
            cursor: 'pointer'
          }}
        >
          Send
        </button>
      </div>
    </form>
  );
}

The form disables submission when the WebSocket is disconnected. The file input is hidden and triggered via an accessible button to maintain a clean UI. Base64 encoding removes the data URI prefix before transmission. Keyboard navigation is explicit: Enter submits, Shift+Enter creates a newline.

Complete Working Example

The following component orchestrates the session initiation, connection manager, virtualized list, and input form into a single runnable module. Replace YOUR_CONFIG_ID with your actual Genesys Cloud Web Messaging configuration ID.

// src/App.tsx
import { useState, useCallback } from 'react';
import { initiateWebchatSession } from './services/webchat';
import { useWebchatConnection } from './hooks/useWebchatConnection';
import { MessageList } from './components/MessageList';
import { MessageForm } from './components/MessageForm';

const CONFIG_ID = 'YOUR_CONFIG_ID';

export default function App() {
  const [webSocketUrl, setWebSocketUrl] = useState<string | null>(null);
  const [conversationId, setConversationId] = useState<string | null>(null);
  const [guestId, setGuestId] = useState<string | null>(null);
  const [error, setError] = useState<string | null>(null);

  const startSession = useCallback(async () => {
    try {
      setError(null);
      const session = await initiateWebchatSession(CONFIG_ID);
      setWebSocketUrl(session.webSocketUrl);
      setConversationId(session.conversationId);
      setGuestId(session.guestId);
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Failed to initialize webchat session.');
    }
  }, []);

  const { status, messages, sendMessage } = useWebchatConnection(webSocketUrl, conversationId, guestId);

  if (!webSocketUrl) {
    return (
      <div style={{ padding: '24px', fontFamily: 'system-ui, sans-serif' }}>
        <h1>Genesys Cloud Webchat</h1>
        {error && <p style={{ color: '#dc2626' }}>{error}</p>}
        <button
          onClick={startSession}
          style={{ padding: '12px 24px', backgroundColor: '#2563eb', color: 'white', border: 'none', borderRadius: '6px', cursor: 'pointer' }}
        >
          Start Chat
        </button>
      </div>
    );
  }

  return (
    <div style={{ padding: '24px', fontFamily: 'system-ui, sans-serif', maxWidth: '600px', margin: '0 auto' }}>
      <div style={{ marginBottom: '12px', fontSize: '0.875rem', color: '#6b7280' }}>
        Status: {status} | Conversation: {conversationId}
      </div>
      <MessageList messages={messages} />
      <MessageForm
        onSend={sendMessage}
        isDisabled={status === 'disconnected' || status === 'connecting' || status === 'reconnecting'}
      />
    </div>
  );
}

This example handles the full lifecycle. Clicking Start Chat initiates the HTTP session, retrieves the WebSocket URL, and mounts the connection manager. The UI disables input during reconnection attempts and displays the current connection state.

Common Errors & Debugging

Error: HTTP 400 Bad Request during session initiation

• Cause: The configuration ID is invalid, expired, or the request body omits the configId field.
• Fix: Verify the configuration ID in the Genesys Cloud Admin console. Ensure the POST body matches the exact schema: {"configId": "...", "channel": "webchat"}.
• Code adjustment: Add explicit schema validation before sending the request.

Error: WebSocket closes with code 1006 or 4001

• Cause: The WebSocket URL expired or the session was terminated by the server due to inactivity. Genesys Cloud invalidates webchat URLs after 24 hours or when the conversation is archived.
• Fix: Implement a heartbeat mechanism or detect onclose events with non-clean codes. Trigger a fresh POST /api/v2/conversations/webchat request to generate a new session.
• Code adjustment: Extend the scheduleReconnect function to call initiateWebchatSession again after 3 failed WebSocket attempts.

Error: 429 Too Many Requests on WebSocket messages

• Cause: Rapid message dispatching exceeds tenant-level rate limits. Genesys Cloud enforces limits on outbound webchat events.
• Fix: Implement client-side message throttling. Queue messages in a FIFO array and dispatch them at a maximum rate of 5 messages per second.
• Code adjustment: Wrap sendMessage in a throttle utility that delays subsequent calls until the socket is ready.

Error: Base64 attachment transmission fails silently

• Cause: The encoded string exceeds the WebSocket frame limit or the Genesys Cloud 2 MB attachment threshold.
• Fix: Validate file size before encoding. For files larger than 2 MB, use the Genesys Cloud File Upload API to obtain a pre-signed URL, then send the URL reference instead of raw data.
• Code adjustment: Add if (file.size > 2 * 1024 * 1024) return; before FileReader execution.

Official References

• Genesys Cloud Conversations Webchat API Documentation
• Genesys Cloud Web Messaging WebSocket Protocol Guide
• @tanstack/react-virtual Documentation
• WCAG 2.1 Accessibility Guidelines for Live Regions