BPMN: ISO/IEC 19510:2015 Erlang/OTP
===================================
[](https://github.com/synrc/bpe/actions)
[](https://hex.pm/packages/bpe)
Overview
--------
BPMN is a Business Process Model Notation Engine that brings BPMN to Erlang and Erlang to Enterprises.
It provides infrastructure for Workflow Definitions, Process Orchestration,
Rule Based Production Systems and Distributed Storage.
<img src="https://bpe.n2o.dev/man/img/camunda.png" width=600/>
Requirements
------------
* Based on HRL files so Erlang also can work
* Raw KV backend Storage
* Mnesia Storage
Sample Session
--------------
```
iex(1)> {_,p} = :bpe.start :bpe_xml.def, []
{:ok, '76900759556000'}
iex(2)> :bpe.next p
{:complete, 'either'}
iex(3)> :bpe.next p
{:complete, 'left'}
iex(4)> :bpe.next p
{:complete, 'right'}
iex(5)> :bpe.next p
{:complete, 'join'}
iex(6)> :bpe.next p
{:complete, 'join'}
iex(7)> :bpe.next p
{:complete, 'epilog'}
iex(8)> :bpe.next p
{:complete, 'finish'}
iex(9)> :bpe.next p
:Final
```
```
> :kvs.all '/bpe/flow/77012724426000'
[
{:sched, {:step, 0, '77012724426000'}, 1, ['x1']},
{:sched, {:step, 1, '77012724426000'}, 1, ['x2', 'x3']},
{:sched, {:step, 2, '77012724426000'}, 2, ['x4', 'x3']},
{:sched, {:step, 3, '77012724426000'}, 1, ['x4', 'x5']},
{:sched, {:step, 4, '77012724426000'}, 1, ['x5']},
{:sched, {:step, 5, '77012724426000'}, 1, ['x6']},
{:sched, {:step, 6, '77012724426000'}, 1, ['x7']},
{:sched, {:step, 7, '77012724426000'}, 1, []}
]
```
Formal Spec
===========
Processes
---------
Processes are main entities of BPE, they map one-to-one to Erlang processes.
Basically, BPE process is an algorithm or function, that is executed entirely in the
context of Erlang process. The arguments for such algorithms are:
values from infinite streams (KVS chains);
values from Erlang messages being sent to BPE process.
```erlang
-record(step, { id = 0 :: integer(), proc = "" :: list() }).
-record(role, { id = [] :: list(), name :: binary(), tasks = [] :: term() }).
-record(sched, { id = [] :: [] | #step{},
prev=[] :: [] | integer(),
next=[] :: [] | integer(),
pointer = -1 :: integer(),
state = [] :: list(list()) }).
-record(hist, { id = [] :: [] | #step{},
prev=[] :: [] | integer(),
next=[] :: [] | integer(),
name=[] :: [] | binary() | list(),
task=[] :: [] | atom() | list() | #sequenceFlow{} | condition(),
docs=[] :: list(tuple()),
time=[] :: [] | #ts{} }).
-record(process, { id = [] :: procId(),
prev=[] :: [] | integer(),
next=[] :: [] | integer(),
name=[] :: [] | binary() | string() | atom(),
feeds=[] :: list(),
roles = [] :: term(),
tasks = [] :: list(tasks()),
events = [] :: list(events()),
flows = [] :: list(#sequenceFlow{}),
docs = [] :: list(tuple()),
options = [] :: term(),
module = ?DEFAULT_MODULE :: [] | atom(),
xml = [] :: list(),
timer = [] :: [] | reference(),
notifications=[] :: [] | term(),
result = [] :: [] | binary(),
started = [] :: [] | #ts{},
beginEvent = [] :: list() | atom(),
endEvent = [] :: list() | atom() }).
```
During execution of the process, all steps are being written to the persistent storage,
by which execution logic is restorable and reproducible. The process definition is actually
diagram or graph where points represented by `task` and edges by `sequenceFlow`.
Tasks and Flows
---------------
The step itself is represented as `task` (point). The transition between steps is
represented as `sequenceFlow` (edge).
```erlang
-define(TASK, id=[] :: list(),
name=[] :: list() | binary(),
in=[] :: list(list()),
out=[] :: list(list()),
prompt=[] :: list(tuple()),
roles=[] :: list(atom()),
etc=[] :: list({term(),term()}) ).
-record(beginEvent , { ?TASK }).
-record(endEvent, { ?TASK }).
-record(task, { ?TASK }).
-record(userTask, { ?TASK }).
-record(serviceTask, { ?TASK }).
-record(receiveTask, { ?TASK, reader=[] :: #reader{} }).
-record(sendTask, { ?TASK, writer=[] :: #writer{} }).
```
The history record of process execution is
represented as `hist` and captures the `sequenceFlow` information.
```erlang
-type condition() :: {compare,BpeDocParam ::
{ atom(),
term()},
Field :: integer(),
ConstCheckAgainst :: term()
}
| {service,atom()}.
-record(sequenceFlow, { id=[] :: list(),
name=[] :: list() | binary(),
condition=[] :: [] | condition() | binary(),
source=[] :: list(),
target=[] :: list(integer()) | list(list()) }).
```
Events
------
While Tasks are deterministic, where you're getting a new task from previous one,
the Events are non-deterministic, where you could get a new task by external
event from the system to the process.
```erlang
-define(EVENT, id=[] :: list() | atom(),
name=[] :: list() | binary(),
prompt=[] :: list(tuple()),
etc=[] :: list({term(),term()}),
payload=[] :: [] | binary(),
timeout=[] :: [] | #timeout{} ).
-define(CYCLIC, timeDate=[] :: [] | binary(),
timeDuration=[] :: [] | binary(),
timeCycle=[] :: [] | binary() ).
-record(messageEvent, { ?EVENT }).
-record(messageBeginEvent, { ?EVENT }).
-record(boundaryEvent,{ ?EVENT, ?CYCLIC }).
-record(timeoutEvent, { ?EVENT, ?CYCLIC }).
```
Gateways
--------
Gateways represent multiplexors and demultiplexors which cause non-linear trace and multiple
current states as leaves of execution graph.
```erlang
-type gate() :: exclusive | parallel | inclusive | complex | event.
-record(gateway, { ?TASK, type= parallel :: gate() }).
```
Full set of BPMN 2.0 fields could be obtained
at [http://www.omg.org/spec/BPMN/2.0](http://www.omg.org/spec/BPMN/2.0), page 3-7.
Authors
-------
* Максим Сохацький
* Євгеній Гадібіров
* Георгій Мельник-Веттштайн
