This is cool! There seems to be some room for a recommendation on how to apply these data structures effectively in practice, especially around the distribution mechanism. For instance, I can imagine storing these in an atom and using watchers to push changes out over zero-mq. Or is that the Worst Idea Ever™? I feel like the transit layer probably has *some* impact on whether CRDTs are the right solution to the problem, and I'm interested to know what those boundaries are.
Have you used them in production over the network, and if so, what solution did you use? Thanks again! > On Apr 18, 2018, at 5:57 PM, Alex Redington <areding...@gmail.com> wrote: > > Good evening! > > I submit for your evaluation and reasoned feedback a library I've been > working on to provide a set of convergent replicated data types to Clojure > and ClojureScript: > > https://github.com/aredington/schism > [com.holychao/schism "0.1.0"] > > Schism provides convergent collections for sets, vectors, lists, and maps, > along with edn readers and writers out of the gate. My intent is to provide > you with all the tools necessary to replicate a collection across two or more > computing nodes. > > Replication is a hard problem, so there are a few caveats to these tools as I > provide them: > > - You must identify nodes within your cluster. You may choose to identify > nodes with a random UUID, in which case schism will help you to do so. Node > identifiers must be clojure serializable data. > - Schism purposefully avoids carrying around a monotonically increasing > historical collection of data about deleted entries. Consequently there are > some ambiguities during convergence that may not exactly mirror local > modification. > - Schism is only solving the problem of synchronizing two in memory sets. > Maintaining identity of those two sets, tracking state changes, and long term > durability are responsibilities left to the schism user. > > Schism collections are persistent collections, so you should feel free to > work with them as a drop in replacement for a function which would work > against a Clojure collection. The usual utilities such as conj, assoc, > dissoc, disj, and rest are pure functions which will return you derived > copies, implicitly soing the convergence bookkeeping necessary in the > background. As you work with it, schism will maintain node and timestamp > information, with the goal of convergence providing the same result as if all > previous invocations had occurred on one local collection in memory. Schism's > requirements are your expectations of a Clojure collection, so hash, =, and > support for meta are all included, as well as many other functions defined > against Clojure's own collections. Particularly with hash and =, you can > expect a schism collection to return the same hashcode as its Clojure > equivalent, and to determine equality in the same way as its Clojure > equivalent would. > > I've built schism in the absence of a direct itch to scratch with it. Should > you find that it betrays your expectations of Clojure collections, I'd > greatly appreciate a bug report and will work to correct schism quickly. > > I hope that it assists you in solving your own problems. > > -Alex > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with your > first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > <http://groups.google.com/group/clojure?hl=en> > --- > You received this message because you are subscribed to the Google Groups > "Clojure" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clojure+unsubscr...@googlegroups.com > <mailto:clojure+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
