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# UNDER CONSTRUCTION
This library is under construction, so use at your own risk

### Why microsia?
Microsia is an lightweight microservices server with simple, familiar syntax that was inspired by [koa](https://github.com/koajs/koa) and [express](https://github.com/expressjs/express),
allow you to create transport layer for microservices as quick as possible.

Currently, microsia is building around [nats](https://github.com/nats-io/nats-server) as central messaging system.
Microsia also has local pubsub system, that allow services on same server communicate with each other fastest without remote messaging system (nats).


### Concept:
![Concept](https://i.imgur.com/U2NWxd5.jpg)

### Usages:
Install package
```
npm install --save microsia
# OR
yarn add microsia
```

Sample service `services/bar.js`:
```javascript
const broker = require('microsia')
const service = broker().createService({ name: 'bar' })

service.use(function (ctx, next) {
  console.log('bar was called')
  next()
})

service.subscribe('bar', function(ctx) {
  ctx.res.send({
    msg: `SERVICE bar: Hi, This is bar!`,
  })
})

// Call to other service using current context
// Metadata (requestId,...) will be past to other service, too
service.subscribe('call-to-other', async function(ctx) {
  const res = await ctx.call('baz.status')
  ctx.res.send({
    msg: `SERVICE bar: Status of baz`,
    data: res.body,
  })
})

// Call directly from service will create new context
service.call('foo.foo', {})
    .then(data => console.log(data))
```

Run group services with service runner:
```javascript
const loadServices = require('microsia/runner')

// Service path
const services = [
  'services/foo.js',
  'services/bar.js',
]
const options = {
  transporter: {
    name: 'nats',
    options: {
      servers: ['nats://demo.nats.io:4222'],
      timeout: 3000,
      pingInterval: 120000,
      reconnect: true,
      reconnectTimeWait: 2000,
      maxReconnectAttempts: 10,
      maxRequestRetryAttempts: 3,
    },
  },
}

loadServices(options, services)
```

You also can run only one service directly by `node`,
just pass config to `broker()` and then run `node services/bar.js`:
```javascript
const broker = require('microsia/broker')
const service = broker({
  transporter: {
    name: 'nats',
    options: {
      servers: ['nats://demo.nats.io:4222'],
      timeout: 3000,
      pingInterval: 120000,
      reconnect: true,
      reconnectTimeWait: 2000,
      maxReconnectAttempts: 10,
      maxRequestRetryAttempts: 3,
    },
  },
}).createService({ name: 'bar' })

...
```

Please see example code in `example` folder for more information.

### Run example code:
Internal Services using runner:
```
cd example
node index.js
```

ApiGateway using broker directly and using express as http server:
```
cd example/gateway
yarn
node index.js
```

Make request to ApiGateway
```
curl -i -H "Accept: application/json" "http://localhost:3000/api/bar" 
```

### TODO:
- Api Gateway
- Group route
- Middleware with route
- Streaming file
- Circuit Breaker (inside broker)
- Logger
- Nats authrorize
- Serialize (protobuf, ...)
- Polish code
- Unit test & code coverage
- Benchmark
- Optimize
- Improve documentation & example
- Kafka transporter
- Multi transporter in one broker (consider later)