Discourje: Automatically validated message exchange patterns in Clojure

The core.async library provides many high-level features for async programming, but does not protect against classical concurrency problems. Discourje extends core.async and offers high-level abstractions to define message exchange patterns that are run-time validated and enforced between threads.

Transcript

1. Discourje Automatically validated message exchange patterns in Clojure.
2. Context  Interested in concurrent programming  Clojure  Implement Message Exchange Pattern (MEP) framework in Clojure
3. Example: MEP global protocol BuyGoods (role Buyer, role Seller) { QuoteRequest from Buyer to Seller; choice at Seller { Quote from Seller to Buyer; Order from Buyer to Seller; OrderAcknowledgement from Seller to Buyer; } or { OutOfStock from Seller to Buyer; } } * https://github.com/scribble/scribble-language-guide/tree/master/defineprotocol
4. Clojure  Advantages of Clojure  No research done towards embedded (DSL) MEP languages.  Core.async
5. Core.async  Do not reinvent the wheel.  Provide facilities for independent threads of activity, communicating via queue-like channels.*  Note that, unlike other Clojure concurrency constructs, channels, like all communications, are subject to deadlocks.*  Validation? *https://clojure.org/news/2013/06/28/clojure-clore-async-channels
6. Discourje  Extends core.async channel operations  Monitors communication between threads  DSL for message exchange patterns (MEP)
7. Supported features:  Atomic send & receive operations  Sequencing  Parallelism  Branching  Recursion  Nesting (branching & recursion)
8. Discourje: Step 1 Define message exchange pattern.
9. Discourje: Step 2 Add infrastructure to MEP Generate default channels (buffer size 1) or create your own channels.
10. Discourje: Step 3 Communicate through Discourje abstractions
11. Demo Time for a Demo!
12. Demo – Step 0
13. Demo – Step 1
14. Demo – Step 2
15. Demo – Step 3
16. Future work  More supported core.async abstractions  Compile-time validation of MEP  clojure.spec
17. Conclusion  Separation of concerns  Build as DSL, no special compiler or syntax  Protection against communication mismatches and deadlocks
18. Questions? (def Q&A (mep (rec :questions? (-->> "Questions?" "Ruben" "Audience") (choice [(-->> "Yes" "Audience" "Ruben") (-->> "Answer" "Ruben" "Audience") (continue :questions?)] [(-->> "No" "Audience" "Ruben")]) (-->> "Thank you for your attention!" "Ruben" "Audience")))) https://gitlab.com/ruben.hamers/Discourje