aedes-persistence-cassandra

[Aedes][aedes] [persistence][persistence], backed by [Cassandra][cassandra].

See [aedes-persistence][persistence] for the full API, and [Aedes][aedes] for usage.

Disclaimer

Be sure to understand applicability and limitations before using this package in production.

In most cases aedes-persistence-mongodb should be considered a better alternative to this.

Please understand that Cassandra is not suited for implementing queues as in most cases this results in reading lots of tombstones (cassandra-anti-patterns-queues-and-queue-datasets).

This package is suitable when:

* You have a small sets of subscriptions with low traffic
* You already have a deployed Cassandra cluster and can't afford to deploy another persistence solution (e.g. MongoDB or Redis)
* You are regularly performing compactions/repair on the used keyspace

Install

``bash
npm install aedes aedes-persistence-cassandra --save
`

or

`bash
yarn add aedes aedes-persistence-cassandra
`

Target keyspace must be initialized with aedes.cql script.

API

$3

Creates a new instance of aedes-persistence-cassandra.

$3

- ttl: Used to set a ttl (time to live) to documents stored in collections
- packets: Could be an integer value that specify the ttl in seconds of all packets collections or an Object that specifies for each collection its ttl in seconds. Packets collections are: incoming, outgoing, retained, will.
- susbscriptions: Set a ttl (in seconds)
- cassandra: Extra options to pass to Cassandra driver (see cassandra-driver) (alternative to client)
- client: Existing cassandra-driver client instance (alternative to cassandra)

If neither cassandra or client option are supplied, connection to localhost:9042 will be attempted with local datacenter datacenter1 and keyspace aedes.

Supplying an external client it's recommended.

$3

`js
const AedesPersistenceCassandra = require("aedes-persistence-cassandra");

AedesPersistenceCassandra({
cassandra: {
contactPoints: ["localhost:9042"],
localDataCenter: "datacenter1",
keyspace: "aedes"
},
// Optional ttl settings
ttl: {
packets: 300, // Number of seconds
subscriptions: 300,
}
})
`

With the previous configuration all packets will have a ttl of 300 seconds. You can also provide different ttl settings for each packet type:

`js
ttl: {
packets: {
incoming: 100,
outgoing: 100,
will: 300,
retained: -1
}, // Number of seconds
subscriptions: 300,
}
`

If you want a specific packet type to be persistent just set corresponding ttl to null or undefined`.

Acknowledgements

Implementation inspired after aedes-persistence-mongodb.

License

MIT

[aedes]: https://github.com/moscajs/aedes
[persistence]: https://github.com/moscajs/aedes-persistence
[cassandra]: https://cassandra.apache.org/_/index.html