Investigate/implement IPFS-based implementation of BlockStore

[pchiusano]

See #86 for some context.

IPFS is big project, but the part we are most interested in is the distributed, content-addressed file-system, which could work as a nice backend for BlockStore. It would have the advantage that IPFS-backed Unison nodes would all share a common Universe, which eliminates the hash-syncing step of the distributed evaluation protocol. It also has a solution to the hash distribution problem - common hashes are replicated based on demand across the IPFS network, which can minimize bottlenecks and bring the data closer to where it is needed.

Something I was rather concerned about was this issue, but it looks like the IPFS folks are on the case.

The goal is to investigate and possibly implement an IPFS-based BlockStore. At first glance, IPFS doesn't look like a natural fit for the Series concept that BlockStore has. Perhaps it could be implemented using IPNS, or perhaps we don't rely on IPFS for that aspect of the implementation.

/cc @jbenet - Juan, not sure if you get this notification, but hello! IPFS seems like a great project. We may be building atop it. Also, looking forward to meeting you at Full Stack Fest this year.

[jbenet]

Hey @pchiusano :) fan of unison too, i was excited when it was announced. In short:

• we need to fix the resource limits, but that's purely optimization
• you can use IPNS i think. and aim not 100% sure, but i think you want what we're calling "authenticated streams" (think of a co-recursive merkle-dag, meaning you listen on H and get a stream of objects, all of which have H as a descendant (well, ancestor in merkle-dag terms, since arrows point back in time).
• yeah let's definitely chat at FullStack Fest
• Highly recommend looking into our IPLD work-- i think it may be super relevant to unison.
• In general, dive into our abstraction pool-- there's lots of good stuff there.
• And, highly recommend to use something like https://github.com/multiformats/multihash ( https://github.com/multiformats/multiformats ) to ensure interop for a long time :)