WCIP-13: Use MQTT standard for peer communication

[abhriyaroy]

Problem

Walletconnect v1.0 uses non-standard socket implementation which needs to be handled effectively on following scenarios:

• Low-end devices, like most Android devices in India
• Devices with low-batteries
• On sleep mode devices

Having multiple connections for each DApp is an inefficient way of handling sockets where optimization is essential.

Solution

Use the MQTT standard with QoS=2 instead of custom socket implementations: https://mqtt.org/

The bridge will work as MQTT broker and maintain only one connection per device.

Benefits for using MQTT over custom socket implementation:

• Optimized for low-end devices and sleep mode
• Single socket connection per client
• Library/SDKs are available in different languages out of the box (no need to create the same custom socket implementation in each language). Less code, fewer bugs (in theory)
• Message caching when devices are offline when QoS=2. No need to write custom queueing for each device at bridge side
• Production ready

[ligi]

Thanks for the proposal - but as far as I see this WCIP needs more details like considerations on the upgrade path and backward compatibility.

[abhriyaroy]

I am not sure how to go about it without losing backward compatibility, but this is a necessary change. So, I am open to comments.

Current version needs to fix this one way or another when users start to use walletconnect with multiple DApps at once.

[ligi]

We can't just break WalletConnect backward compatibility at this point in time and need to offer a migration path.
Perhaps we use the 2.0 initiative where pluggable transports are planned to do this change - but just changing it for 1.0 and breaking existing workflows is no option IMHO - perhaps @pedrouid has some ideas here.