bpm-engine 0.1.0

Lightweight embeddable BPM runtime for long-running, stateful workflows with tokens, timers, Saga compensation, and crash recovery
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131

//! ServiceTask chain: Start → step1 → step2 → step3 → End.
//!
//! Run: `cargo run --example service_task_chain`
//!
//! Demonstrates a linear sequence of ServiceTasks; each step runs in order and the process completes in one run.

use bpm_engine::engine::{
    payloads, BpmEngine, EngineContext, EngineEvent, ProcessCompletedHandler, ProcessStartHandler,
    TokenArrivedHandler,
};
use bpm_engine::model::*;
use bpm_engine::persistence::{InstanceRepo, ProcessDefStore, ProcessInstanceRepo};
use std::collections::HashMap;
use std::sync::Arc;

fn step1(instance: &mut ProcessInstance) {
    instance.variables.insert("step".into(), "1".into());
    println!("  step1");
}

fn step2(instance: &mut ProcessInstance) {
    instance.variables.insert("step".into(), "2".into());
    println!("  step2");
}

fn step3(instance: &mut ProcessInstance) {
    instance.variables.insert("step".into(), "3".into());
    println!("  step3");
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let process = ProcessDefinition {
        id: "service_task_chain",
        start: "start",
        nodes: HashMap::from([
            (
                "start",
                Node {
                    id: "start",
                    node_type: NodeType::Start,
                    outgoing_edges: vec![OutgoingEdge {
                        target: "step1",
                        condition: None,
                    }],
                },
            ),
            (
                "step1",
                Node {
                    id: "step1",
                    node_type: NodeType::ServiceTask(step1),
                    outgoing_edges: vec![OutgoingEdge {
                        target: "step2",
                        condition: None,
                    }],
                },
            ),
            (
                "step2",
                Node {
                    id: "step2",
                    node_type: NodeType::ServiceTask(step2),
                    outgoing_edges: vec![OutgoingEdge {
                        target: "step3",
                        condition: None,
                    }],
                },
            ),
            (
                "step3",
                Node {
                    id: "step3",
                    node_type: NodeType::ServiceTask(step3),
                    outgoing_edges: vec![OutgoingEdge {
                        target: "end",
                        condition: None,
                    }],
                },
            ),
            (
                "end",
                Node {
                    id: "end",
                    node_type: NodeType::End,
                    outgoing_edges: vec![],
                },
            ),
        ]),
    };

    let repo = Arc::new(InstanceRepo::new(":memory:")?);
    let def_store = ProcessDefStore::new();
    def_store.register(process.clone());

    let mut ctx = EngineContext {
        process_repo: Some(Box::new(Arc::clone(&repo))),
        token_repo: Some(Box::new(Arc::clone(&repo))),
        process_def_repo: Some(Box::new(def_store)),
        task_repo: None,
        parallel_join_repo: Some(Box::new(Arc::clone(&repo))),
        timer_repo: Some(Box::new(Arc::clone(&repo))),
        compensation_repo: Some(Box::new(Arc::clone(&repo))),
        run_in_tx: Some(Box::new(|event, handlers, ctx, queue| {
            for handler in handlers {
                let new_events = handler.handle(event, ctx);
                queue.extend(new_events);
            }
        })),
    };

    let engine = BpmEngine::new(vec![
        Box::new(ProcessStartHandler),
        Box::new(TokenArrivedHandler::new()),
        Box::new(ProcessCompletedHandler),
    ]);

    let instance_id = uuid::Uuid::new_v4().to_string();
    engine.run(
        EngineEvent::ProcessStarted(payloads::ProcessStarted {
            process_id: process.id.to_string(),
            instance_id: instance_id.clone(),
        }),
        &mut ctx,
    );

    let inst = repo.load(&instance_id).expect("instance exists");
    assert!(inst.completed());
    assert_eq!(inst.variables.get("step").map(String::as_str), Some("3"));
    println!("OK: instance completed after step1 → step2 → step3");
    Ok(())
}