Flow Map

The ODSFlowMap class walks from the policies and processes in scope to the event consumables they react to, the operation consumables they issue, the events those operations raise, and the policies and processes those events wake in turn. Where a consumption names one of those operations in by, the walk carries on into the operation it calls, so a chain that crosses a bounded context is drawn whole. The flowMapToDigraph function draws it left to right: events as ellipses, policies as notes, processes as folders, operations as boxes.

An answer is drawn as one more edge from the operation that answers, labelled with the shape it came back as: a returned or rejected schema is the call coming back rather than something that happens on the way somewhere, so it gets no box of its own.

A process is drawn with its lifecycle: what starts an instance comes in on the left with everything else it waits for, and what ends one leaves it on a dashed ends edge. That edge is drawn and never walked, because an ending fact completes an instance rather than waking it again — which is why a process that ends on an event its own operations raise is no cycle.

import { writeFileSync } from "node:fs";
import { ODSFlowMap, Workspace } from "@open-domain-specification/core";
import { flowMapToDigraph } from "@open-domain-specification/graphviz";
import { describe, expect, it } from "vitest";

const ws = new Workspace("eCommerce", {
	description: "Flow map example",
	version: "0.1.0",
});
const ordering = ws.addBoundedContext("Ordering", { description: "" });
const order = ordering.addAggregate("Order", { description: "" });
const placed = order.provides("Order Placed", {
	description: "",
	type: "event",
	pattern: "published-language",
});
const approved = order.provides("Order Approved", {
	description: "",
	type: "event",
	internal: true,
});
const approve = order
	.provides("Approve Order", {
		description: "",
		type: "operation",
		internal: true,
	})
	.raises(approved);
const ship = ordering
	.addAggregate("Shipment", { description: "" })
	.provides("Create Shipment", {
		description: "",
		type: "operation",
		internal: true,
	});

ordering
	.addPolicy("Auto approve", { description: "" })
	.on(placed)
	.issues(approve);
ordering
	.addPolicy("Ship when approved", { description: "" })
	.on(approved)
	.issues(ship);

describe("Flow map", () => {
	it("renders the event → policy → operation chain", async () => {
		const digraph = flowMapToDigraph(ODSFlowMap.fromBoundedContext(ordering));
		const svg = await digraph.toSVG();
		writeFileSync("static/img/flow-map-example.svg", svg);
		expect(digraph.toDot()).toContain("Ship when approved");
	});
});