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Real-time Architecture

ChurchApps uses a single WebSocket-based delivery framework for every real-time surface — group chat, private messages, content notes, the live stream chat, and presence/attendance. This page documents the protocol, the server, and the client primitives that consumers use.

Overview​

┌────────────────────┐                ┌────────────────────────────┐
│ Browser / B1Admin  │                │  MessagingApi (Lambda)     │
│ Browser / B1App    │ ─── WS ─────▶  │  ┌───────────────────────┐ │
│  - SocketHelper    │                │  │ SocketHelper (server) │ │
│  - SubscriptionMgr │   POST /msg ──▶│  │ MessageController     │ │
│  - ConversationStore│  POST /conn ─▶│  │ ConnectionController  │ │
│  - PresenceStore   │ ◀── action ──  │  │ DeliveryHelper        │ │
└────────────────────┘                │  └───────────────────────┘ │
                                      └────────────────────────────┘

The protocol has three pieces:

  1. One persistent WebSocket per browser tab, opened by SocketHelper.
  2. Connection rows (POST /messaging/connections) recorded in the connections table — these mark a (socketId, churchId, conversationId) tuple as a subscriber to a room.
  3. Server-side fan-out by DeliveryHelper.sendConversationMessages() — when a message is saved (POST /messaging/messages/send), the server reads the matching connection rows and pushes a typed payload to each open socket.

There is no Socket.IO, no long-polling fallback, and no separate microservice. The WebSocket runs in the same process as the REST API (web Lambda for HTTP, socket Lambda for WebSocket in AWS; one combined process locally and on Railway).

Ports and transport​

EnvironmentHTTPWebSocket
Local dev8084ws://localhost:8087 (separate WebSocketServer)
Railway / single-port hostssharedshared HTTP server (SocketHelper.attachToServer())
AWS LambdaAPI Gateway HTTPAPI Gateway WebSocket ($connect / $disconnect / $default routes)

The transport selector is the deliveryProvider config:

  • local → raw ws library; clients connect to MessagingApiSocket from CommonEnvironmentHelper.
  • aws → API Gateway WebSocket; the server posts payloads to active connections via @aws-sdk/client-apigatewaymanagementapi.

The client never has to know which is in use — it speaks the same JSON protocol either way.

Wire protocol​

Every frame is JSON of shape PayloadInterface:

interface PayloadInterface {
  churchId: string;
  conversationId: string;  // the "room" — usually a UUID, sometimes "alerts" or "content-{type}-{id}"
  action: PayloadAction;
  data: unknown;
}

type PayloadAction =
  | "socketId"            // server → client, after connect, carries the socketId to use for room joins
  | "message"             // server → client, new message
  | "deleteMessage"       // server → client, message removed
  | "privateMessage"      // server → client, new message in a private conversation
  | "conversationActivity"// server → client, secondary "something happened" signal for content-room subscribers
  | "attendance"          // server → client, viewer list / presence snapshot
  | "notification"        // server → client, generic notification (counts, etc.)
  | "reconnect"           // client-internal, fired by SocketHelper when a fresh socket replaces a dropped one
  | "alert" | "callout";  // legacy, see Connections endpoint reference

Handshake​

  1. Client opens the socket and sends the literal string "getId".
  2. Server replies with { action: "socketId", data: "<id>" }.
  3. Client stores the socketId and uses it as the third coordinate of every room subscription.

Joining a room​

A "room" is just a (churchId, conversationId) tuple. To subscribe, the client posts a Connection row:

POST /messaging/connections
[
  {
    "churchId": "CHU00000001",
    "conversationId": "CON123…",
    "socketId": "abc123",
    "personId": null,            // optional; null for anonymous live stream viewers
    "displayName": "Anonymous4823"
  }
]

Posting also triggers an attendance broadcast on the conversation so existing subscribers learn a new viewer joined.

Sending a message​

POST /messaging/messages/send (anonymous-allowed) or POST /messaging/messages/ (auth-required):

[
  { "churchId": "CHU00000001", "conversationId": "CON123…", "displayName": "John Smith", "content": "Hello!", "messageType": "comment" }
]

The server saves the message, then DeliveryHelper.sendConversationMessages() looks up every connection row for that conversationId and sends each socket a { action: "message", data: <message> } frame.

For content-bound conversations (e.g., notes attached to a person), a second broadcast with action: "conversationActivity" fires on the synthetic "content-{type}-{id}" room so list-view consumers know to refresh without holding the underlying conversation open.

Leaving a room​

DELETE /messaging/connections/:churchId/:conversationId/:socketId

Clears the connection row and triggers a final attendance broadcast.

Server-side components​

FileRole
Api/src/modules/messaging/helpers/SocketHelper.tsOwns the WebSocketServer. Assigns socketId on connect. Cleans up dead sockets and triggers an attendance rebroadcast on disconnect
Api/src/modules/messaging/helpers/DeliveryHelper.tssendConversationMessages(payload) reads connections for the room and routes each frame to the local socket or the AWS API Gateway connection. sendAttendance(churchId, conversationId) builds and broadcasts the viewer snapshot
Api/src/modules/messaging/controllers/ConnectionController.tsPOST / joins, DELETE /:churchId/:conversationId/:socketId leaves, POST /setName updates display name
Api/src/modules/messaging/controllers/MessageController.tsPOST /send (anonymous) and POST / (authed) save then fan out
Api/src/modules/messaging/repositories/ConnectionRepo.tsloadForConversation(churchId, conversationId) is the source of truth for who's subscribed

Client-side primitives (@churchapps/apphelper)​

All five primitives are static singletons in apphelper/src/helpers/. They cooperate so that each tab opens one WebSocket no matter how many components mount on the page.

SocketHelper​

Owns the single WebSocket connection. Re-entrant init() is idempotent — multiple components can call it without opening duplicate sockets. Exposes:

  • init() — open (or re-use) the socket and complete the getId handshake.
  • addHandler(action, id, fn) / removeHandler(id) — register/unregister listeners by action. Multiple handlers can listen to the same action.
  • setPersonChurch({ personId, churchId }) — for authenticated callers; triggers an "alerts" room subscription so push notifications arrive on this socket.
  • onSocketIdReady(fn) — fires once when the handshake completes; used by SubscriptionManager to flush pending joins.

SubscriptionManager​

Ref-counted room membership. Multiple components subscribing to the same conversation only register one server-side connection row.

import { SubscriptionManager } from "@churchapps/apphelper";

await SubscriptionManager.joinRoom(conversationId, churchId, personId, displayName);
// ... component renders, receives socket frames via ConversationStore.subscribe ...
await SubscriptionManager.leaveRoom(conversationId, churchId);

Three behaviors that consumers get for free:

  • Debounced leave (300 ms) — survives React StrictMode's double mount/unmount and short remount cycles without dropping the server-side subscription.
  • Reconnect rejoin — listens for SocketHelper's "reconnect" event and re-issues every active connection row.
  • Late-binding socketId — joinRoom records intent before the socket finishes its handshake; the actual POST /connections fires on onSocketIdReady.

ConversationStore​

In-memory cache keyed by conversationId. Registers message / deleteMessage / privateMessage socket handlers exactly once and applies inbound frames to whichever conversations are currently open.

import { ConversationStore } from "@churchapps/apphelper";

const conv = await ConversationStore.loadByConversationId(conversationId, churchId);
// ↑ uses /messages/conversation/:id when authenticated, /messages/catchup/:churchId/:id when anonymous

const unsubscribe = ConversationStore.subscribe(conversationId, (conv) => {
  setMessages(conv.messages);  // re-render with the latest snapshot
});
// ...
unsubscribe();
ConversationStore.forget(conversationId);  // optional explicit cleanup

Authenticated callers also get people hydration — personIds on incoming messages are resolved to PersonInterface objects via a cached GET /people/ids lookup. Anonymous callers skip this.

PresenceStore​

Mirrors ConversationStore's pattern for the attendance action. Subscribers receive a PresenceSnapshot { conversationId, totalViewers, viewers } whenever the server rebroadcasts presence. Identical snapshots are deduped before notify, so reconnect storms don't trigger unnecessary re-renders.

import { PresenceStore } from "@churchapps/apphelper";

const unsubscribe = PresenceStore.subscribe(conversationId, (snapshot) => {
  setViewerCount(snapshot.totalViewers);
});

NotificationService​

Top-level boot for authenticated callers. Wraps SocketHelper.init(), sets the person/church context (which auto-joins the "alerts" room), and calls ConversationStore.ensureHandlers() / PresenceStore.ensureHandlers() / SubscriptionManager.setupRejoin() exactly once.

await NotificationService.getInstance().initialize(userContext);

Anonymous flows (the live stream chat is the canonical example) skip NotificationService and call the primitives directly — see B1App/src/helpers/StreamChatManager.ts for a reference implementation.

Live stream chat​

The live stream is the largest anonymous consumer of the framework. It uses two contentTypes for room scoping:

  • streamingLive — the public chat tab on /stream (one room per streamingService).
  • streamingLiveHost — a private room visible only to staff with the contentApi.chat.host permission. The room id is encrypted on the server (GET /streamingServices/:id/hostChat) so casual scraping doesn't reveal it.

B1App/src/helpers/StreamChatManager.ts boots both rooms via the unified primitives — there is no live-stream-specific socket code anymore.

Patterns and pitfalls​

  • Don't open your own WebSocket. SocketHelper is a singleton for a reason. If you need to listen for a custom action, register a handler on the existing socket via SocketHelper.addHandler.
  • Don't bypass SubscriptionManager. Direct POST /connections calls work but lose ref counting, debounced leave, and reconnect rejoin. Group chat and PM consumers all go through SubscriptionManager.
  • Handler ids must be unique per action. SocketHelper.addHandler(action, id, fn) keys by (action, id); reusing the same id for two listeners replaces the first. The unified stores use ids like "ConversationStore-Message" and "PresenceStore-Attendance" to stay clear of consumer ids.
  • Room ids are opaque strings. Most are conversation UUIDs but the system also supports "alerts" (per-person notifications), "content-{type}-{id}" (synthetic activity rooms), and the encrypted streamingLiveHost ids.
  • Authentication is checked at the REST boundary, not the socket. Joining a room by POST /connections is anonymous-allowed; access control happens at message-send time (the message controller decides what messageTypes an anonymous caller may send).