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server.ts
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server.ts
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import { createLogger } from '@restorecommerce/logger';
import { Logger } from 'winston';
import * as _ from 'lodash';
import { EventEmitter } from 'events';
import { BindConfig } from './transport/provider/grpc';
const transports: Record<string, any> = {};
/**
* register transport provider
*
* @param {string} name transport provider identifier
* @param {constructor} provider transport provider constructor function
*/
export const registerTransport = (name: string, provider: any): void => {
transports[name] = provider;
};
// register included providers
const grpc = require('./transport/provider/grpc');
registerTransport('grpc', grpc.Server);
/**
* Initializes all configured transports.
* @param {object} config Configuration
* @param {object} logger
* @return {object} Transport
*/
const setupTransport = (config: any, logger: Logger): any => {
const transport = {};
logger.debug('available transport providers',
Object.keys(transports).join(','));
for (let i = 0; i < config.length; i += 1) {
const transportCfg = config[i];
const providerName = transportCfg.provider;
if (_.isNil(providerName)) {
throw new Error('transport configuration without a provider');
}
const transportName = transportCfg.name;
if (_.isNil(providerName)) {
throw new Error('transport configuration without a name');
}
const TransportProvider = transports[providerName];
if (_.isNil(TransportProvider)) {
throw new Error(`transport provider ${providerName} does not exist`);
}
const provider = new TransportProvider(transportCfg, logger);
transport[transportName] = provider;
}
logger.debug('using transports', Object.keys(transport).join(','));
return transport;
};
/**
* Server is a microservice server chassis.
* It enables business logic to be accessed over transports and listen to events.
* Default event providers: 'kafka'
* Default transports: 'grpc'
* @class
*/
export class Server extends EventEmitter {
config: any;
logger: Logger;
middleware: any;
transport: any;
/**
* @constructor
* @param {object} config Server config.
* @param {Logger} logger
*/
constructor(config?: any, logger?: Logger) {
super();
if (_.isNil(config)) {
throw new Error('mising argument config');
}
this.config = config;
// logger
if (_.isNil(logger)) {
if (_.isNil(this.config.logger)) {
this.logger = createLogger();
} else {
const loggerCfg = this.config.logger;
this.logger = createLogger(loggerCfg);
}
} else {
this.logger = logger;
}
// services
this.logger.debug('setting up service endpoints');
// transports
this.logger.debug('setting up transports');
try {
this.transport = setupTransport(this.config.transports, this.logger);
} catch (error) {
this.logger.error('setupTransports', { code: error.code, message: error.message, stack: error.stack });
throw error;
}
}
/**
* bind connects the service to configured transports.
*
* @param {string} name Service name.
* @param {BindConfig} bindConfig A business logic service.
*/
async bind(name: string, bindConfig: BindConfig<any>): Promise<void> {
if (_.isNil(name)) {
throw new Error('missing argument name');
}
if (!_.isString(name)) {
throw new Error('argument name is not of type string');
}
if (_.isNil(bindConfig)) {
throw new Error('missing argument bindConfig');
}
this.logger.debug('binding endpoints to transports');
const transportNames = Object.keys(this.transport);
const transport = this.transport;
for (let i = 0; i < transportNames.length; i += 1) {
const transportName = transportNames[i];
const provider = transport[transportName];
await provider.bind(bindConfig);
this.emit('bound', name, bindConfig, provider);
}
}
/**
* start launches the server by starting transports and listening to events.
*/
async start(): Promise<any> {
const transportNames = Object.keys(this.transport);
for (let i = 0; i < transportNames.length; i += 1) {
const name = transportNames[i];
const provider = this.transport[name];
await provider.start();
this.logger.info(`transport ${name} started`);
}
this.emit('serving', this.transport);
}
/**
* Shuts down all transport provider servers.
*/
async stop(): Promise<any> {
const transportNames = _.keys(this.transport);
for (let i = 0; i < transportNames.length; i += 1) {
const name = transportNames[i];
if (this.transport[name].end) {
await this.transport[name].end();
}
}
this.emit('stopped', this.transport);
}
}