@sealsystems/mongo-notification

An event emitter and receiver that uses MongoDB capped collections.

Installation

``shell
$ npm install @sealsystems/mongo-notification
`

Quick start

First you need to add a reference to @sealsystems/mongo-notification to your application.

`javascript
const mongoNotification = require('@sealsystems/mongo-notification');
`

Then connect to a MongoDB by calling the function mongoNotification. Provide an options object and returns a notification event emitter:

`javascript
const notification = await mongoNotification({
url: 'mongodb://...',
topic: 'messages',
collectionSize: '1MB',
writeOnly: false
});
`

The options contain:
- url mandatory, a connection string,
- topic mandatory, the name of a topic collection
- collectionSize optional, the size of the capped collection, default: 1MB
- writeOnly optional, the open mode, default: false
- Additional @sealsystems/mongo options

Emit events

Call the emit function for actually emitting an event:

`javascript
notification.emit('foo', { foo: 'bar' });
`

Optionally you may specify a callback to get notified when the event has been persisted:

`javascript
notification.emit('foo', { foo: 'bar' }, (err) => {
// ...
});
`

Receive events

If you want to receive events send by your application use the on function:

`javascript
notification.on('foo', (payload) => {
// ...
});
`

Write only mode

If you only want to emit events but not receive any you can set the writeOnly option to true when connecting.

`javascript
const notification = await mongoNotification({
...
writeOnly: true
});
`

Running the build

To build this module use roboter.

`shell
$ bot
``