Expand description
A lightweight, fast, tiny, extensiable workflow engine
Yao workflow engine
yao
is a fast, tiny, extensiable workflow engine, which provides the abilities to execute workflow based on simple yml model.
The yml workflow model is not as same as the tranditional flow. such as bpmn. It is inspired by Github actions. As a contrast, it added branch defination for more complex flow, for the purpose of business approval flow, it defines the subject
property in step to support the top absolute rules for user, org and role.
Fast
Uses rust to create the lib, there is no virtual machine, no db dependencies. The default store uses rocksdb for local storage.
Tiny
The lib size is only 3mb (no local db)
Extensiable
Supports the plugin to extend the functions
Examples
Here are some examples:
How to start
First, you should load a ymal workflow model, and call engine.start
to start and call engine.close
to stop it.
use yao::{Engine, Vars, Workflow};
#[tokio::main]
async fn main() {
let engine = Engine::new();
let text = include_str!("../examples/simple/model.yml");
let mut workflow = Workflow::from_str(text).unwrap();
let mut vars = Vars::new();
vars.insert("input".into(), 3.into());
workflow.set_env(vars);
engine.push(&workflow);
let e = engine.clone();
engine.on_workflow_complete(move |w: &Workflow| {
println!(
"on_workflow_complete: {:?}, cost={}ms",
w.outputs(),
w.cost()
);
e.close();
});
engine.start().await;
}
How to create model
Notices the struct of the yaml, there are different type of node, which is constructed by Workflow
, Job
, Branch
and Step
. Every workflow can have more jobs, every job can have more steps, a step can have more branches and a branch can have if
property to judge the condition.
The env
property can be set in each node, in the run
scripts, you can use env
moudle to get(env.get
) or set(env.set
) the value
The run
property is the script based on rhai script
name: model name
jobs:
- id: job1
env:
value: 0
steps:
- name: step 1
run: |
print("step 1")
- name: step 2
branches:
- name: branch 1
if: ${ env.get("value") > 100 }
run: |
print("branch 1");
- name: branch 2
if: ${ env.get("value") <= 100 }
steps:
- name: step 3
run: |
print("branch 2")
In the Workflow
, you can set the outputs
to output the env to use.
name: model name
outputs:
output_key:
jobs:
- id: job1
steps:
- name: step1
run: |
env.set("output_key", "output value");
The subject
is used to create the user Act
, which can wait util calling the post_message
to complete by user.
name: model name
jobs:
- id: job1
steps:
- name: step1
subject:
matcher: any
users: |
let a = ["u1"];
let b = ["u2"];
a.union(b)
It will generate the user act and send message automationly according to the sub users.
The matcher
tells the workflow how to pass the step act when you post_message
to workflow, there are several match rules.
- matcher
-
one to generate or check only one user
-
any to match any of the users
-
some(rule_name) to match some users by giving rule name, which can be registed by
register_some_rule
function. -
ord or ord(rule_name) to generate the act message one by one by giving rule name, which can be registed by
register_ord_rule
function
- users Used to generate the step participants, the final results are the user ids, which can be generated by org or role rule.
The code role("test_role")
uses the role rule to get the users from the role test_role
users: |
let users = role("test_role");
users
The following code uses the user("test_user")
the get the user and then throght the relate
rule to find the user’s owner of the department (d.owner
).
users: |
let users = user("test_user").relate("d.owner");
users
Use builder to create model
use yao::{Workflow};
let mut workflow = Workflow::new()
.with_name("workflow builder")
.with_output("result", 0.into())
.with_job(|job| {
job.with_id("job1")
.with_env("index", 0.into())
.with_env("result", 0.into())
.with_step(|step| {
step.with_id("cond")
.with_branch(|branch| {
branch
.with_if(r#"env.get("index") <= env.get("count")"#)
.with_step(|step| {
step.with_id("c1")
.with_action(|env| {
let result =
env.get("result").unwrap().as_i64().unwrap();
let index = env.get("index").unwrap().as_i64().unwrap();
env.set("result", (result + index).into());
env.set("index", (index + 1).into());
})
.with_next("cond")
})
})
.with_branch(|branch| {
branch.with_if(r#"env.get("index") > env.get("count")"#)
})
})
.with_step(|step| {
step.with_name("step2")
.with_action(|env| println!("result={:?}", env.get("result").unwrap()))
})
});
Register plugin
See the example of ActPlugin
.
Register store adapter
See the example of StoreAdapter
.
Register org adapter
See the example of OrgAdapter
.
Register role adapter
See the example of RoleAdapter
.
Register rule adapter
See the example of RuleAdapter
.