nextql-configuration

NextQL plugin for complex model modular and distribution.

NextQL

NextQL is JSON query language for APIs and a robust and extensible runtime for resolve those queries. Equivalent with Facebook's GraphQL, but much more simple.

Why?

In real life applications, number of models (or types) could be numerous. For example Github's GraphQL API have more than 150 types. ERP system like Odoo could have thousands models. NextQL-Configuration is a pattern to organize models into different modules and sources.

Usage

	const nextql = new NextQL();
	nextql.use(configurationPlugin);
	await nextql.configure({
		modules: [
			{
				loader: "json",
				source: path.resolve(__dirname, "./fixtures/json/*.json")
			}
		]
	});

How?

Modules

Module is a group of relevant models (or extension models).

{
	"name": "Module A",
	"models": {
		"modelA": {
			"fields": {},
			"methods": {},
			"computed": {}
		},
		"modelB": {
			"fields": {},
			"methods": {},
			"computed": {}
		},
	},
	"dependencies": ["Module B"]
}

Extension models

Module not only group relevant models, also extension models which defined in other modules. This is a useful pattern to organize complex relationship models.

For example: we have a User model which grouped into Base module

{
	name: "base",
	models: {
		user: {
			fields: {
				name: 1
			},
			methods: {
				getById(){}
			}
		},
		group: {}
	}
}

Later we develop Mail module which provide mail stuff for user

{
	name: "mail",
	models: {
		message: {//define model for single mail's message
			fields: { content: 1}
		}, 
		user: { // extend user model for mail features
			fields: {
				mailAddress: 1 // inject mailAddress field into above user model
			},
			methods: {
				getInbox(){} // inject getInbox method into above user model
			}
		}
	},
	dependencies: ["user"]
}

Notice: to make sure module user loaded before module mail, module mail should define dependencies key.

Nextql query

{
	user: {
		getById: {
			$params: {id: "giapnh" },
			name: 1,
			mailAddress: 1

		},
		getInbox: {
			$params: {id: "giapnh"},
			content: 1
		}
	}
}

Sources/Loaders

Source is where modules configuration stored. Source could be:

• JSON, Js files
• Databases
• KV Store: consul, etcd
• Orchestrator: Dockers, Kubernetes
• Or anything as long as you write a loader for them.

{
	modules: [
		{ // source configuration
			source: path.resolve(__dirname, "./fixtures/modules/*.js"),
			loader: "json" 
		},
		{
			source: "unix:///var/run/docker.sock",
			loader: "docker"
		},
		{
			source: "moduleCollection",
			loader: "mongodb"
		},
		resolveLoader: {
			paths: []
		}  
	]
}

Source configuration should consist a loader key to define name of source's loader. Rest of keys is parameters for the loader.

Source's loader

Loader is simple nodejs function return a Promise which resolved when the loader complete load modules.

function loader (modules, options) {
	return new Promise(function (ok, fail){
		// 1. load modules from databases, files, kv stores or rest api.
		// 2. update modules list.
		// 3. call ok() or fail()
		ok();
	});
}

How nextql-configuration resolve loaders.

Nextql-configuration follow below order to resolve loaders

• resolveLoader.paths
• node_modules
• default loaders

Default loaders

• json: Load json files based on source pattern. A module defined as a json file.
• js: Load js modules based on source pattern. A module defined as a js module.

APIs

Next-configuration plugin inject 2 api into nextql object

nextql.configuration:

Load all modules from sources. Build models from modules. Finally, load all models into nextql.

nextql.configuration({ modules:[], resolveLoader: {}});

nextql.reload

Reload all modules from sources, rebuild nextql's models. The method use to reload configure when module's sources changes For example: after detect source's changes, we send SIGUSR2 signal tell nextql-configuration reload modules and rebuild models.

process.on('SIGUSR2',function(){
	console.log("Received SIGUSR2");
	nextql.reload(); //reload all modules from sources and rebuild models
});