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Express and Seneca Actions on same Express server port.

seneca-express-actions-transport

Lead Maintainer: Diego Laucsen da Rosa
Sponsor: Par Mais
Node: 6.x

Motivation

This project was wrote to solve a specific problem.

Imagine the situation where your Express microservices are running in an environment that have only one open port in each machine, like 80 on most cases. On this case, you cannot create Seneca Listener in other ports.

This scenario is common when running a Single Instance on AWS Elastic Beanstalk, where only port 80 is available.

This Transport plugin was created to enable an Express App and Seneca Listener to run on same port.

Install

npm install --save seneca-express-actions-transport

Inportant: This Transport was designet to run with Express 4

Usage

Listener

import Seneca from 'seneca';
import ExpressActions from 'seneca-express-actions-transport';
 
Seneca()
  .use(ExpressActions)
  .listen({
    type: 'express-actions',
    pin: 'cmd:log,level:*',
    prefix: '/micro'
  })
  .add('cmd:log,level:*', (args, done) => {
    console[req.level](args.message);
    return done(null, { ok: true, when: Date.now() });
  });

Configuration

prefix: It is possible to inform a custom route to be used as comunication. If prefix is not ser, "act" is used as default value.

How it works

On case above, express-actions will add a route with with path /micro/:action/, that is used by clients to send information to this listener.

The option set by prefix is customizable to avoid url conflict.

Client

import Seneca from 'seneca';
import ExpressActions from 'seneca-express-actions-transport';
 
const client = Seneca()
  .use(ExpressActions)
  .client({
    type: 'express-actions',
    pin: 'cmd:log,level:*',
    
    host: 'www.server.rurl.com.br',
    port: 80,
    prefix: '/micro',
    action: 'level'
  });
 
setInterval(() => {
  client.act('cmd:log,level:log', {
    message: 'Hello World'
  }, (err, res) => {
    if (err) {
      // Handle error in some way
      throw err;
    }
    // Print out the response
    console.log(res);
  });
}, 2000);

Important: action is a mandatory field. Read about it below.

Configuration

host: Server host. 0.0.0.0 is a default value.
port: Server port. Default 80.
prefix: Same used on listener. If your listner is configured with a prefix, you client need it too.
action: Action to be executed on listener. As Listener is configured with ```/micro/:action/``', this ':action' will be replaced with given action on configurations.

How it works

Client basically send a post on configured http endpoint, supposing that a listener server is awaiting there for actions.

The action configuration is mandatory, because client must know how action will be executed on other side. Its happen because a listener may have more than one action configured on same server, and as everything is running on same port, a name must be specified.

Contributing

The Par Mais Tecnologia encourages participation. If you feel you can help in any way, be it with bug reporting, documentation, examples, extra testing, or new features feel free to create an issue, or better yet, [submit a Pull Request. For more information on contribution please see our Contributing guide.