graph-entity

Graph Entity service to track linked services and change events, idea is loosely based on Graph Database but more Entity and event driven.

Overview

Service is designed to track linked service nodes and their change events (by adding/removing nodes and edges and nodes emitting change events). This allow tracking changes as example NodeJS => Express => Logins: [User1, User2, User3] / Logouts. Or track other services like Redis, MongoDB, etc. and those relations and events.

Example

import {EventEmitter} from 'events';
import type {type GraphNodeEventMapping, type IGraphBaseEntityNode, type IGraphEventEntityNode} from '@luolapeikko/graph-entity-types';
import {GraphManager} from '@luolapeikko/graph-entity';

export const GraphTypeEnum = {
	NodeJS: 0,
	Express: 10,
	ExpressRouter: 11,
	MognoDB: 20,
	Redis: 30,
} as const;

const manager = new GraphManager<ExpressJs | NodeJsNode>();

type NodeJsNode = IGraphBaseEntityNode<typeof GraphTypeEnum.NodeJS, {version: string}>;
export const rootNodejsGraphNode: NodeJsNode = {
	nodeType: GraphTypeEnum.NodeJS,
	getNodeId: () => 'nodejs',
	getNodeProps: () => ({version: process.versions.node}),
};
manager.addNode(rootNodejsGraphNode); // add nodejs node to manager

export class ExpressJs
	extends EventEmitter<GraphNodeEventMapping>
	implements IGraphEventEntityNode<typeof GraphTypeEnum.Express, {port: string | number | undefined; status?: 'running' | 'stopped'}>
{
	public nodeType = GraphTypeEnum.Express;
	public getNodeId = () => 'express';
	private port: string;
	private status: 'running' | 'stopped' = 'stopped';
	public constructor(port: string) {
		super();
		this.port = port;
		manager.addEdge(rootNodejsGraphNode, this); // here constructor work easy way to add edge to nodejs root node
		// after start server, set status to running and notify with this.emit('nodeUpdated') event
	}
	public getNodeProps() {
		return {
			port: this.port,
			status: this.status,
		};
	}
}

// hook to manager events and output the node hierarchy structure
manager.on('graphUpdate', async (node) => {
	console.log(await manager.getNodeStructure(node));
});