This is a Proof of Concept (POC) demonstrating the implementation of Change Streams in Meteor, based on Pull Request #13787.

This project demonstrates the usage of Meteor's new streaming APIs:

• Meteor.publish.stream - Publishing change streams on the server
• Meteor.subscribeStream - Subscribing to streams on the client

⚠️ API Note: The subscribeStream API will be transformed to subscribe.stream in the next commits.

This Developer Experience (DX) was inspired by the excellent Jam pub/sub package, which already implements similar patterns for change streams.

In the server/main.js file, we use Meteor.publish.stream to create a publication that monitors changes in the collection:

Meteor.publish.stream('streamLinks', function (sub) {
  const changeStream = LinksCollection.watch([
    { $match: { operationType: 'insert' } }
  ]);
  
  changeStream.on('change', (change) => {
    sub.stream(change);
  });
  
  sub.onStop(() => changeStream.close());
});

Features:

• Uses MongoDB Change Streams natively
• Allows specific filters (in the example, only insert operations)
• Automatically manages connection lifecycle
• Calls sub.stream(data) to send data to clients

In the imports/ui/Info.jsx file, we use Meteor.subscribeStream to receive real-time events:

useEffect(() => {
  // Subscribe to the change stream
  const sub = Meteor.subscribeStream('streamLinks');
  
  sub.onData((data) => {
    setStreamEvents(evts => [data, ...evts]);
  });
  
  return () => sub.stop();
}, []);

Features:

• Simple and reactive API
• onData callback to process received events
• Automatic cleanup with sub.stop()
• Perfect integration with React hooks

├── client/                 # Meteor client
├── server/                 # Meteor server
├── imports/
│   ├── api/
│   │   └── links.js       # Collection and methods
│   └── ui/
│       ├── App.jsx        # Main component
│       ├── Hello.jsx      # Button to insert data
│       └── Info.jsx       # Change events display
├── mongo-replica/         # MongoDB replica set data
└── package.json

• Meteor.js
• MongoDB (configured as replica set for change streams)

1. Start the MongoDB replica set:

   ./start-meteor-mongo-replica.sh

2. Run the Meteor application:

   meteor run

3. Test the functionality:

   • Click the "Click Me" button to insert new links
   • Watch the change events appear in real-time in the "Change Stream Events" section

4. To stop MongoDB:

   ./stop-meteor-mongo-replica.sh

Change Streams are ideal for:

• Real-time notifications - Notify users about relevant changes
• Audit and logging - Track all operations on specific collections
• Synchronization - Keep external systems synchronized
• Analytics - Process data events in real-time
• Cache invalidation - Invalidate caches when data changes

• Feature discussion on Meteor Forums
• MongoDB Change Streams Documentation
• Meteor Pub/Sub Guide
• Jam Pub/Sub Package