The current state synchronization of the Waku2 store protocol is empowered by the Waku FT-store protocol.
Store nodes (while being online) listen to the network and store all the messages of the community.
Store nodes are allowed to go offline and then recover the gap in their message history by performing time-based queries from another store node that has been online for that duration.
Waku2 FT-store works based on the following assumptions
At any time, there is at least one online store node from which the history can be retrieved
Nodes (including store nodes and other regular nodes who publish messages) have synchronized clocks with a +-20 seconds error margin
There is no network partition, that is all the store nodes will ultimately receive all the messages transmitted in the network
Under the aforementioned assumptions, Waku2 FT-store protocol provides eventual consistency. However, the message state of store nodes may diverge for some points in time due to network delay.
However, we are seeking a better solution to get past the current assumptions and limitations, namely:
No reliance on the synchronization of nodes' clocks
Enforces replicated message state across store nodes for some configurable intervals
Better network partition tolerance
Solution ideas and ongoing efforts
There is ongoing research and development on a more advanced state synchronization protocol. The initial proposal is provided in https://github.com/vacp2p/research/issues/73. This proposal has a potential scalability issue and is prone to snowball effect which can eat up a large portion of store nodes bandwidth.
Further solution proposal with better scalability is currently underway (I will link it to this issue when it gets ready).
Problem
The current state synchronization of the Waku2 store protocol is empowered by the Waku FT-store protocol.
Under the aforementioned assumptions, Waku2 FT-store protocol provides eventual consistency. However, the message state of store nodes may diverge for some points in time due to network delay.
However, we are seeking a better solution to get past the current assumptions and limitations, namely:
Solution ideas and ongoing efforts
There is ongoing research and development on a more advanced state synchronization protocol. The initial proposal is provided in https://github.com/vacp2p/research/issues/73. This proposal has a potential scalability issue and is prone to snowball effect which can eat up a large portion of store nodes bandwidth. Further solution proposal with better scalability is currently underway (I will link it to this issue when it gets ready).