Paper: Logic and Lattices for Distributed Programming

Neil Conway from Berkeley CS is giving an advanced level talk at a meetup today in San Francisco on a new paper: Logic and Lattices for Distributed Programming - extending set logic to support CRDT-style lattices.

The description of the meetup is probably the clearest introduction to the paper:

In this talk, I'll discuss work from our group at UC Berkeley that aims to make it easier to write distributed programs without relying on strong consistency. Bloom is a declarative programming language for distributed computing, while CALM is an analysis technique that identifies programs that are guaranteed to be eventually consistent. I'll then discuss our recent work on extending CALM to support a broader range of programs, drawing upon ideas from CRDTs (A Commutative Replicated Data Type).

If you have an eye towards understanding the future then this is for you.

Abstract from the paper:

In recent years there has been interest in achieving application-level consistency criteria without the latency and availability costs of strongly consistent storage infrastructure. A standard technique is to adopt a vocabulary of commutative operations; this avoids the risk of inconsistency due to message reordering. A more powerful approach was recently captured by the CALM theorem, which proves that logically monotonic programs are guaranteed to be eventually consistent. In logic languages such as Bloom, CALM analysis can automatically verify that program modules achieve consistency without coordination.
In this paper we present BloomL, an extension to Bloom that takes inspiration from both these traditions. BloomL generalizes Bloom to support lattices and extends the power of CALM analysis to whole programs containing arbitrary lattices. We show how the Bloom interpreter can be generalized to support efficient evaluation of lattice-based code using well-known strategies from logic programming. Finally, we use BloomL to develop several practical distributed programs, including a key-value store similar to Amazon Dynamo, and show how BloomL encourages the safe composition of small, easy-to-analyze lattices into larger programs.