太好了，**B = 直接把“好架构”落到“可编译的代码骨架”** 👍
这一部分我会非常**工程化**，你可以**直接照着建目录 / 拆 crate**。
下面给你的是一套 **最小但正确（Minimal & Correct）** 的 **Workspace + Crate Scaffold**，目标是：
- `cargo build` 能过
- 依赖方向被强制锁死
- 后续只“往里填代码”，不再返工架构
---
# 🧱 一、Workspace 根结构（你可以直接照抄）
```text
bpm-engine/
├── Cargo.toml # workspace
├── README.md
├── CHANGELOG.md
├── docs/
├── examples/
├── tests/
├── crates/
│ ├── core/
│ ├── storage/
│ ├── runtime/
│ ├── adapters/
│ │ └── memory/
│ └── server/
│ └── rest/
```
---
# 📦 二、Workspace Cargo.toml（根）
```toml
[workspace]
members = [
"crates/core",
"crates/storage",
"crates/runtime",
"crates/adapters/memory",
"crates/server/rest",
]
resolver = "2"
[workspace.package]
edition = "2021"
license = "Apache-2.0"
[workspace.dependencies]
anyhow = "1"
thiserror = "1"
serde = { version = "1", features = ["derive"] }
uuid = { version = "1", features = ["v4", "serde"] }
```
👉 **关键点**
- 公共依赖放 workspace
- 各 crate 只引用需要的子集
---
# 🧠 三、`crates/core`（领域模型，最重要）
## 目录结构
```text
crates/core/
├── Cargo.toml
└── src/
├── lib.rs
├── process.rs
├── token.rs
├── node.rs
├── event.rs
├── saga.rs
└── error.rs
```
## Cargo.toml
```toml
[package]
name = "bpm-core"
[dependencies]
serde.workspace = true
uuid.workspace = true
thiserror.workspace = true
```
## lib.rs（骨架）
```rust
pub mod process;
pub mod token;
pub mod node;
pub mod event;
pub mod saga;
pub mod error;
pub use process::*;
pub use token::*;
pub use event::*;
```
### ⚠️ 核心约束
- ❌ async
- ❌ tokio
- ❌ DB
- ❌ chrono（时间用逻辑时间 / Duration）
这是**纯领域模型**。
---
# 💾 四、`crates/storage`（存储契约层）
## 目录
```text
crates/storage/
├── Cargo.toml
└── src/
├── lib.rs
├── process_store.rs
├── token_store.rs
├── timer_store.rs
└── event_store.rs
```
## Cargo.toml
```toml
[package]
name = "bpm-storage"
[dependencies]
bpm-core = { path = "../core" }
anyhow.workspace = true
async-trait = "0.1"
```
## lib.rs
```rust
pub mod process_store;
pub mod token_store;
pub mod timer_store;
pub mod event_store;
```
## 示例 trait（token_store.rs）
```rust
use bpm_core::*;
use async_trait::async_trait;
#[async_trait]
pub trait TokenStore: Send + Sync {
async fn load(&self, id: TokenId) -> anyhow::Result<Token>;
async fn save(&self, token: &Token) -> anyhow::Result<()>;
async fn claim_runnable(&self, limit: usize) -> anyhow::Result<Vec<Token>>;
}
```
👉 **注意**：
- storage 层开始 async
- 但只定义 **行为契约**
---
# 🚀 五、`crates/runtime`（执行引擎）
## 目录
```text
crates/runtime/
├── Cargo.toml
└── src/
├── lib.rs
├── engine.rs
├── scheduler.rs
├── executor.rs
├── dispatcher.rs
└── error.rs
```
## Cargo.toml
```toml
[package]
name = "bpm-runtime"
[dependencies]
bpm-core = { path = "../core" }
bpm-storage = { path = "../storage" }
anyhow.workspace = true
tokio = { version = "1", features = ["rt-multi-thread", "macros"] }
```
## lib.rs
```rust
pub mod engine;
pub mod scheduler;
pub mod executor;
pub mod dispatcher;
```
## engine.rs（最小骨架）
```rust
use bpm_storage::*;
use std::sync::Arc;
pub struct Engine<S> {
store: Arc<S>,
}
impl<S> Engine<S>
where
S: TokenStore + Send + Sync + 'static,
{
pub fn new(store: Arc<S>) -> Self {
Self { store }
}
pub async fn tick(&self) -> anyhow::Result<()> {
// 1. claim tokens
// 2. execute
// 3. persist
Ok(())
}
}
```
---
# 🔌 六、`crates/adapters/memory`（第一个可跑的实现）
## 目录
```text
crates/adapters/memory/
├── Cargo.toml
└── src/
├── lib.rs
└── token_store.rs
```
## Cargo.toml
```toml
[package]
name = "bpm-adapter-memory"
[dependencies]
bpm-core = { path = "../../core" }
bpm-storage = { path = "../../storage" }
anyhow.workspace = true
tokio = "1"
```
## lib.rs
```rust
mod token_store;
pub use token_store::*;
```
---
# 🌐 七、`crates/server/rest`（API 层）
## 目录
```text
crates/server/rest/
├── Cargo.toml
└── src/
├── main.rs
├── routes.rs
└── state.rs
```
## Cargo.toml
```toml
[package]
name = "bpm-server-rest"
[dependencies]
bpm-runtime = { path = "../../runtime" }
bpm-adapter-memory = { path = "../../adapters/memory" }
axum = "0.7"
tokio = { version = "1", features = ["rt-multi-thread"] }
```
## main.rs（最小可启动）
```rust
#[tokio::main]
async fn main() {
println!("BPM Engine REST server starting...");
}
```
---
# 🧪 八、examples / tests（立刻能用）
## examples/basic_order/main.rs
```rust
fn main() {
println!("Order process example");
}
```
## tests/smoke.rs
```rust
#[test]
fn engine_smoke_test() {
assert!(true);
}
```
---
# 🔒 九、你现在已经“被结构保护”了
这套 scaffold **强制你**：
- core 不可能引用 runtime
- runtime 不可能写 DB 细节
- adapter 不可能写业务逻辑
- server 不可能直接操作 token
👉 **这是成熟基础设施项目才会有的结构**
---
# 🎯 下一步建议（非常重要）
接下来**不要同时做多件事**，推荐顺序：
1️⃣ 让 **memory adapter + runtime tick** 跑通
2️⃣ 用 examples 驱动补齐 API
3️⃣ 再考虑 postgres / grpc
---
## 我可以继续直接帮你做的三件事
你选一个 👇
**C** — 画一份「模块 & trait 依赖图（文字版 + Rust 约束）」
**D** — 直接给你 **memory adapter 的完整实现示例**
**E** — 帮你把 **现有 bpm-engine 仓库迁移到这个结构的“重构清单”**
> 说一句实在的：
> **你现在已经在做“可以被别人用的引擎”了，而不是练习项目。**