Flow Based Programming in Elixir

An application is defined

as its processes

communicating

via Information Packets

with externally defined connections.

This talk was held at the #52 Elixir User Group Berlin on October 11, 2018.

https://github.com/suitepad-gmbh/pipette
https://hexdocs.pm/pipette/Pipette.html

Google Bot Verification Example
hexdocs.pm/pipette/google_bot_verification.html

Transcript

1. FBP
3. Earlier this year...
8. SuitePad is awesome!
9. Many thanks to Paul, Hilde & Mario.
12. Flow based programming
13. Initial author is J Paul Morrison
14. He favoured reuse-ability,
 rapid prototyping
 and was a visual thinker.
15. Let me show you some examples
18. Visual applications
19. Quickly changing connections
20. IOT and data processing
23. How to design a FBP application
24. An application is defined
 as its processes
 communicating
 via Information Packets
 with externally defined connections.
25. Does that sound familiar to Elixir?
26. Elixir so far has Flow
27. Do not confuse Flow as
 a FBP framework! Flow provides Stream processing.
28. There is more to FBP than just Flow
31. Read File
32. Read File In
33. Read File OUT
34. OUT B A OUT IN IN IN IN
35. Stages represent code.
36. Stages represent reuse-able code.
37. Network defines connections
40. Example: Google Bot Verification
41. https://hexdocs.pm/pipette/google_bot_verification.html
42. Run a reverse DNS lookup (type PTR) Domain name ends in googlebot.com. or google.com. Run a forward DNS lookup (type A) Verify that response to the same IP
44. defmodule GoogleBotVerification do @subscribe ptr_query: :IN @subscribe verify_domain: :ptr_query @subscribe dns_query: :verify_domain @subscribe verify: :dns_query @subscribe OUT: :verify end
46. def ptr_query(ip_addr) do domain = DNSLookup.ptr(ip_addr) %{ip_addr: ip_addr, domain: domain} end
47. @gdomains ~w[google.com. googlebot.com.]
 def verify_domain(%{domain: domain} = state) do if String.ends_with?(domain, @gdomains) do {:ok, state} else {:error, :invalid_ptr} end end
48. PTR
 query verify ... ... OUT :error :ok IN IN IN
49. @subscribe log_errors: {:*, :error}
 
 @stage log_errors: %Stage.Consumer{handler: fn error -> Logger.error("error: #{inspect error}") end}
51. Quick adjustments through routing
52. {:ok, "value"} %IP{route: :ok, value: "value"}
54. {:error, :something_went_wrong} %IP{route: :error, ...}
56. {:verified, "a value"} %IP{route: :verified, ...}
57. Ok Stage
58. Ok Nope Stage
60. Recap
61. You can build reuse-able components
62. And mix them within a FBP framework
63. Iterate rapidly
64. Extend dynamically
65. Data processing applications benefit
66. Event processing applications benefit
67. Thank you Lukas Rieder, @Overbryd I write programs. I give talks. FBP {:pipette, "~> 0.1.0"} https://github.com/suitepad-gmbh/pipette