The hemera from pward123

A Node.js microservices toolkit for the NATS messaging system

Node: v4.5 (Recommended v6+)
Documentation: https://hemerajs.github.io/hemera/
Website: https://hemerajs.github.io/hemera-site/
Lead Maintainer: Dustin Deus

📓 Getting Started

Hemera (/ˈhɛmərə/; Ancient Greek: Ἡμέρα [hɛːméra] "day") is a small wrapper around the NATS driver. NATS is a simple, fast and reliable solution for the internal communication of a distributed system. It chooses simplicity and reliability over guaranteed delivery. We want to provide a toolkit to develop micro services in an easy and powerful way. We provide a pattern matching RPC style. You don't have to worry about the transport. NATS is powerful.

With Hemera you have the best of both worlds. Efficient pattern matching to have the most flexibility in defining your RPC's. It doesn't matter where your server or client lives. You can add the same add as many as you want on different hosts to ensure maximal availability. The only dependency you have is a single binary of 7MB. Mind your own business NATS do the rest for you:

The key features of NATS in combination with Hemera are:

Lightweight: The Hemera core is small as possible and can be extended by extensions or plugins.
Location transparency: A service may be instantiated in different locations at different times. An application interacting with an service and does not know the service physical location.
Service Discovery: You don't need a service discovery all subscriptions are managed by NATS.
Load Balancing: Requests are load balanced (random) by NATS mechanism of "queue groups".
Packages: Providing reliable and modern plugins to the community.
High performant: NATS is able to handle million of requests per second.
Scalability: Filtering on the subject name enables services to divide work (perhaps with locality) e.g. topic:auth:germany. Queue group name allow load balancing of services.
Fault tolerance: Auto-heals when new services are added. Configure cluster mode to be more reliable.
Auto-pruning: NATS automatically handles a slow consumer and cut it off.
Pattern driven: Define the signatures of your RPC's in JSON and use the flexibility of pattern-matching.
Request & Reply: By default point-to-point involves the fastest or first to respond.
Publish & Subscribe: Hemera supports all features of NATS. This includes wildcards in subjects and normal publish and fanout mechanism.
Tracing: Any distributed system need good tracing capabilities. We provide support for Zipkin a tracing system which manages both the collection and lookup of this data.
Monitoring: Your NATS server can be monitored by cli or a dashboard.
Payload validation: Create your own validator or use existing plugins for Joi and Parambulator.
Serialization: Use JSON, Msgpack or Avro to serialize your data (dynamic or static).
Metadata: Transfer metadata across services or attach contextual data to tracing systems.
Dependencies: NATS is a single binary of 7MB and can be deployed in seconds.
Typescript: We provide a definition file to support auto-intellisense.

Built in protection

Process policy: Will exit the process when the policy (memory, event loop) could not be fullfilled (Option: heavy).
Message loop detection: Will return an error if you call a route recursively (Option: maxRecursion).

What Hemera code looks like

We support:

Async/Await (Node 7.6+)
Promise
Error-first-callback style

const Hemera = require('nats-hemera')
const HemeraJoi = require('hemera-joi')
const nats = require('nats').connect()

const hemera = new Hemera(nats, { logLevel: 'info' })
hemera.use(HemeraJoi)

hemera.ready(async () => {

  hemera.setOption('payloadValidator', 'hemera-joi')
  let Joi = hemera.joi

  hemera.add({ 
    topic: 'math',
    cmd: 'add',
    a: Joi.number().required(),
    b: Joi.number().required()
  }, async function (req) {
    return await req.a + req.b
  })

  const a = hemera.act({ topic: 'math', cmd: 'add', a: 10, b: 30 })
  const b = hemera.act({ topic: 'math', cmd: 'add', a: 10, b: 60 })

  const result = await Promise.all([a, b])
  hemera.log.info(result)

})

Documentation

Who's using Hemera?


appcom interactive	amerbank

Get Involved

Contributing: Pull requests are welcome!
- Read CONTRIBUTING.md and check out our help-wanted issues
- Submit github issues for any feature enhancements, bugs or documentation problems
Support: Join our gitter chat to ask questions to get support from the maintainers and other Hemera developers
- Questions/comments can also be posted as github issues
Discuss: Tweet using the #HemeraJs hashtag

Be aware of your requirements

Hemera has not been designed for high performance on a single process. It has been designed to create lots of microservices doesn't matter where they live. It choose simplicity and reliability as primary goals. It act together with NATS as central nervous system of your distributed system. Transport independency was not considered to be a relevant factor. In addition we use pattern matching which is very powerful. The fact that Hemera needs a broker is an argument which should be taken into consideration when you compare hemera with other frameworks. The relevant difference between microservice frameworks like senecajs, molecurer is not the performance or modularity its about the complexity you need to manage. Hemera is expert in providing an interface to work with lots of services in the network, NATS is the expert to deliver the message at the right place. Hemera is still a subscriber of NATS with some magic in routing and extensions. We don't have to worry about all different aspects in a distributed system like routing, load-balancing, service-discovery, clustering, health-checks ...

Characteristics

Max payload size 1MB but it's configurable in NATS Server
Messages are delivered at-most-once
SSL Support
Rely on a publish-subscribe (pub/sub) distribution model
Cluster support
Do you need reliable message delivery ? Look at hemera-nats-streaming

Packages

The hemera repo is managed as a monorepo, composed of multiple npm packages.

General	Version
nats-hemera
hemera-plugin
hemera-store
hemera-stats
hemera-controlplane
hemera-cli
hemera-mail
hemera-slackbot
hemera-graceful-shutdown

Tracer	Version
hemera-zipkin
hemera-jaeger

Messaging bridges	Version
hemera-nats-streaming
hemera-rabbitmq
hemera-nsq
hemera-web
hemera-sqs

Database adapter	Version
hemera-arango-store
hemera-sql-store
hemera-elasticsearch
hemera-couchbase-store
hemera-mongo-store
hemera-rethinkdb-store

Payload validation	Version
hemera-joi
hemera-parambulator

Data serialization	Version
hemera-msgpack
hemera-avro

Data compression	Version
hemera-snappy

Cache	Version
hemera-redis-cache

Granting / Authenticating	Version
hemera-jwt-auth

Performance

Platform info:
==============
   Windows_NT 10.0.15063 x64
   Node.JS: 8.4.0
   V8: 6.0.286.52
   Intel(R) Core(TM) i5-6600K CPU @ 3.50GHz × 4
==============
.\benchmark\request_rt.js
22436 request-responses/sec
Avg roundtrip latency: 22 microseconds

.\benchmark\request_rt_async_await.js
22002 request-responses/sec
Avg roundtrip latency: 22 microseconds

Changelog

See Releases

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Versioning

We use SemVer for versioning. Available versions tags on this repository.

Authors

Dustin Deus - StarpTech

See also the list of contributors who participated in this project.

License

This project is licensed under the MIT License - see the LICENSE file for details

Inspiration

Seneca - A microservices toolkit for Node.js.

Professional services

Hemera is free for any use (MIT license). If you are in production don't miss the professional support service. For courses and training send me an email to [email protected] or contact me private on

Support / Donate

We prefer a PR but if you have no time but want to give us something back you can support us with a starbucks coffee PaypalMe

pward123 / hemera Goto Github PK

hemera's Introduction