Extends senecajs microservice library: offhandedly, with respect
When i started building application using senecajs framework, i didn't find the easy ways to solve some of problems:
- ability to use promises
- throw errors on server and catch them by client (with custom payload)
- initialize plugins on asynchronius way before load them into framework
- log messages in own format instead of verbose seneca output
- some other stuff
This wrapper try to solve most of this troubles, offering common interface without changing the basic functionality in my own way.
WARN: this module don't works in nodejs <6.x (no time for babel, feel free to pull reques with babel support if you need earlier versions support)
$ npm install seneca-extended
$ npm run test
const ld = require('lodash')
const seneca = require('../src')()
// `seneca` is fully usable seneca instance with build-in additional features
/** default senecajs plugin **/
const basicPlugin = function (config) {
this.add({ role: 'example', method: 'ping' }, (message, done) => {
// in case of exception here - error will not pass to remote client
done(null, { ping: 'pong'} )
})
this.add('role:example,method:error', (message, done) => {
this.emitError(new Error('this error will be passed to client'), done)
})
}
/** extended plugin **/
const route = {
ping: 'role:example,method:ping',
error: 'role:example,method:error'
}
const extendedPlugin = {
name: 'example', // exported routes will be available in: seneca.routes.example.*
routes: ld.pick(route, ['ping']) // will export only route 'ping' for example
init: function (senecaInstance, config) {
// this method will be called on plugin load, async code can be used here
return Promise.delay(300)
},
seneca: function (config) {
// basoc seneca route add
this.add('role:example,method:sometest', (message, done) => done(null, { ping: 'sometes'} ))
this.addAsync(route.ping, message => {
// we are in promise now, so can just return result - all error will be handled
return { ping: 'pong' }
})
this.addAsync(route.error, message => {
const error = new Error('this error will be passed to client')
error.payload = { additional: 'payload' } // we can evend add payload
throw error
})
},
someOther: function () {
// we can export other method for futher usage
// ex.: route schemas/specifications, helper methods etc
}
}
const sampleOptions = { some: 'config' }
// now seneca able to load not only synchronous code...
seneca.useAsync(basicPlugin, sampleOptions) // same as synchronous seneca.use
seneca.actAsync('role:example,method:error').catch(err => {
console.log('catched from error:', err.message)
})
// ... but also preload plugins methods as promises
seneca.useAsync(extendedPlugin, sampleOptions).then(() => {
console.log('async plugins loaded and usable now')
// 'role:example,method:ping'
seneca.actAsync(seneca.example.ping, { some: 'payload' }).then(res => {
console.log('got from ping:', res)
})
})
// Output:
// async plugins loaded and usable now
// catched from error: this error will be passed to client
// got from ping: { ping: 'pong' }
Advanced example: custom microservice with deployment into kubernetes, configuration files and common launcher - micro-test (maybe outdated)
Core documentation available at oficial API page. Following methods are added by seneca-extended
and not usable without this module:
Extened version of seneca.add
with promisified callback.
Extened version of seneca.use
with ability to load promisified plugins.
this.add('...', (message, done) => {
try {
// some code
done()
} catch (err) {
// now remote clients will catch this error
this.emitError(err, done)
}
})
Extended version of seneca.act
with error catching (useful if you dont need response)
Promisified version of seneca.actCustom
.
seneca.actAsync('some:route').then(console.log).catch(console.log)
Lightweight logger without default seneca verbosity (should be, just lightweight now :) .