About Upload Transports

About upload Transports

DDP (WebSockets)

DDP (Distributed Data Protocol) build by MDG (Meteor Dev Group) on top of WebSockets via SockJS library. DDP provides authentication, data standardization (via EJSON), and of course fallback to http, with long polling, if WebSockets is not available or not supported by browser.

The pros:

• Persistent connection;
• Common way for Meteor to communicate with the server.

The cons:

• “magic” overhead inside DDP and EJSON;
• Only one data-transfer per time unit (blocks other DDP requests, like methods, subs, etc.);
• It's synchronous.

HTTP (TCP/IP)

Well known way to exchange data between browser and server. To solve issue with opening connection and first-byte exchange use HTTP/2, SSL/TLS, SSL session cache and OCSP stapling.

From Is TLS Fast Yet:

Unlike HTTP/1.1, HTTP/2 requires only a single connection per origin, which means fewer sockets, memory buffers, TLS handshakes, and so on.

The pros:

• Asynchronous, unordered and simultaneous requests (depends from browser, usually up to 10 simultaneous connections);
• No data-processing/encoding, we send data as it is;
• Speed.

The cons:

• HTTP (Hypertext Transfer Protocol) as you see from full name of the protocol it was initially created to transfer hypertext, other words HTML markup. So it was created for text-based data, not binary (files).

RTC Data Chanel (UDP)

This transport supported only in webrtc-data-channel branch. It's in testing mode, we're waiting for community feedback, before merging to master. If you're interested in RTC/DC uploads, try this branch locally. Any feedback on RTC/DC usage for uploads is highly appreciated!

The pros:

• Single socket connection;
• Direct tunneled connection from Client to Server;
• Pure binary data support;
• Native implementation and support on mobile devices;
• It's UDP.

The cons:

• No mobile browsers support;
• Chunk size limited to 64KB;
• Only single stream is supported (so, it's currently uses synchronous chunk uploads. If RTC/DC will be accepted by community we will implement asynchronous chunks upload).