Какие особенности протокола DDP?

DDP (Distributed Data Protocol) is a protocol used in Meteor.js for real-time data synchronization between client and server.

• Publish-Subscribe (Pub/Sub): The server "publishes" data collections, and clients can "subscribe" to them. When data on the server changes, it is automatically "pushed" to subscribed clients.
• RPC (Remote Procedure Call): Clients can invoke functions defined on the server as if they were local.
• Optimistic UI: The client can immediately display changes in the user interface as if they have already occurred on the server. If conflicts or errors occur, the UI reverts to the previous state.
• Stateful: DDP maintains the connection state between client and server, allowing real-time data synchronization.
• Uses WebSockets: Usually operates over WebSockets for efficient real-time data exchange but can also use other mechanisms if WebSockets are unavailable.
• JSON format: Data is transmitted in JSON format.

Example of calling an RPC method on the client:

// Calling the server method 'addTask' with parameters
Meteor.call('addTask', 'New task', function(error, result) {
  if (error) {
    console.error('Error adding task:', error);
  } else {
    console.log('Task successfully added, ID:', result);
  }
});