• reverflow

[[https://npmjs.org/package/reverflow][file:https://img.shields.io/npm/v/reverflow.svg?style=flat]] [[https://travis-ci.org/zweifisch/reverflow][file:https://img.shields.io/travis/zweifisch/reverflow.svg?style=flat]]

reversible flow for building robust application with javascript

• explicit(serial/concurrent) flow construction
• multi step rollback made easy
• works with both sync and async(returns promise) functions

** usage

*** for nodejs < v6 require the transpiled version

: var reverflow = require("reverflow/legacy");

*** a simple serial flow

#+BEGIN_SRC dot :file graph/compositing-1.png :exports results digraph { rankdir=LR node [shape=circle fontname="Fira Code" fontcolor="#999999" color=white style="filled" fillcolor="#f0f0f0"] edge [penwidth="0.7" fillcolor="#c9c9c9" color="#c9c9c9"] 1 -> 2 2 -> 4 } #+END_SRC

#+RESULTS: [[file:graph/compositing-1.png]]

#+BEGIN_SRC js :exports both const {serial} = require('reverflow'); serial(x => x + 1, x => x * 2)(1).then(console.log); #+END_SRC

#+RESULTS: : 4

*** creating flow by composition

#+BEGIN_SRC dot :file graph/compositing-2.png :exports results digraph { rankdir=LR node [shape=circle fontname="Fira Code" fontcolor="#999999" color=white style="filled" fillcolor="#f0f0f0"] edge [penwidth="0.7" fillcolor="#c9c9c9" color="#c9c9c9"] 1 -> 2 2 -> 4 4 -> 7 1 -> 3 3 -> 7 } #+END_SRC

#+RESULTS: [[file:graph/compositing-2.png]]

#+BEGIN_SRC js :exports both const {serial, concurrent} = require('reverflow'); serial(concurrent(serial(x => x + 1, x => x * 2), x => x * 3), ([x, y]) => x + y)(1).then(console.log); #+END_SRC

#+RESULTS: : 7

*** rollbackable serial operations

#+BEGIN_SRC dot :file graph/serial.png :exports results digraph { rankdir=LR node [shape=circle fontname="Fira Code" fontcolor="#999999" color=white style="filled" fillcolor="#f0f0f0"] edge [penwidth="0.7" fillcolor="#c9c9c9" color="#c9c9c9"] C [style=filled fontcolor=white fillcolor="#ff4444"] A -> B B -> C } #+END_SRC

#+RESULTS: [[file:graph/serial.png]]

when ~C~ fails, ~B~ should be rolled back, then ~A~.

reverflow does this auotmatically, you can make an operation rollbackable with the ~rollbackable~ function

#+BEGIN_SRC javascript import {serial, rollbackable} from reverflow

serial(rollbackable(A, undoA), rollbackable(B, undoB), rollbackable(C, undoC))(input); #+END_SRC

*** rollbackable concurrent operations

#+BEGIN_SRC dot :file graph/concurrent.png :exports results digraph { rankdir=LR node [shape=circle fontname="Fira Code" fontcolor="#999999" color=white style="filled" fillcolor="#f0f0f0"] edge [penwidth="0.7" fillcolor="#c9c9c9" color="#c9c9c9"] B C [color=white fontcolor=white fillcolor="#ff4444"] A -> B A -> C A -> D } #+END_SRC

#+RESULTS: [[file:graph/concurrent.png]]

when ~C~ fails, ~B~ and ~D~ should be rolled back, then ~A~.

#+BEGIN_SRC javascript import {rollbackable, serial, concurrent} from reverflow serial(rollback(A, undoA), concurrent(rollbackable(B, undoB), rollbackable(C, undoC), rollbackable(D, undoD)))(input); #+END_SRC

*** miscs

**** passing param to the rollback function

#+BEGIN_SRC javascript rollbackable(input => save({id: uuid.v4()}), ({id}) => remove(id)); #+END_SRC

**** arrays can be passed to serial and concurrent

~serial(a,b,c)~ is equivelant to ~serial([a, b, c])~

**** normal functions can be passed to serial or concurrent