Flow-based programming is a programming paradigm that defines applications as networks of black-box processes that exchange data through message passing. These processes can be reconnected without internal changes to form different applications. Flow-based programming was invented in the 1970s and has been used continuously in a major bank since. The paradigm promotes writing programs as text streams that communicate, following the Unix philosophy. Flow-based programming can be used in Node.js apps through the NoFlo library, which allows specifying flows as a DSL and running flows in a web-based interface or for integration with external systems.

1. Flow-Based Programming for Node.js

2. http://bergie.iki.fi
henri.bergius@iki.fi
@bergie

3. Call-Return

4. Continuation-Passing Style

5. JavaScript, the Ugly Parts

6. Promises

7. Hooks

8. How to make your code manageable?

9. Clean separation of concerns

10. Visualized connections between
components

11. Flow-based programming
“Flow-based programming (FBP) is a programming
paradigm that defines applications as networks of 'black
box' processes, which exchange data across predefined
connections by message passing, where the connections
are specified externally to the processes. These black
box processes can be reconnected endlessly to form
different applications without having to be changed
internally. FBP is thus naturally component-oriented.”
- Wikipedia

12. Flow-based programming

13. “Flow-Based Programming was invented by
John Paul Morrison [from IBM] in the early
1970s, and an early implementation of this
technology has been in continuous production
use at a major Canadian bank since that time.”
- Wikipedia

14. Software
archeology?

15. “This is the Unix philosophy: Write programs
that do one thing and do it well. Write
programs to work together. Write programs
to handle text streams, because that is a
universal interface.”
- Doug McIlroy

16. “I thought of objects being like biological
cells and/or individual computers on a
network, only able to communicate with
messages (so messaging came at the very
beginning -- it took a while to see how to do
messaging in a programming language
efficiently enough to be useful).”
- Alan Kay

18. send options 'a, u & x' to command 'ps',
send option 'firefox' to command 'grep'
direct standard output of 'ps' to 'grep'

19. NoFlo components

20. Using NoFlo in your Node.js app

21. Using NoFlo in your Node.js app

22. DSL for specifying flows

23. DSL for specifying flows
send string 'package.json' to source port of Read
send output of Read to Split (by lines)
send output of Split to Count
send output of Count to Display

24. NoFlo shell

25. NoFlo in integration
email External
partners
CouchDB
+
CouchApp
Project NoFlo
Controller
External
systems
github.com/iks/proggis

26. NoFlo in integration
github.com/iks/proggis

27. NoFlo in real world

28. What happens next?
●
Web-based drawing ●
Hook.io support
●
Web-based ●
Component loading
monitoring & debug from NPM

29. Flow-Based Programming, the book
amzn.com/1451542321

30. Flow-Based Programming for Node.js
github.com/bergie/noflo

31. github.com/bergie/noflo
Screenshot: github.com, couple of weeks ago