orbit-db/README.md

# OrbitDB

## Introduction

Distributed, peer-to-peer Key-Value Store and Event Log on IPFS.

- Stores all data in IPFS, including the database index
- Aggregation happens on client side and data is eventually consistent
- Uses a LWW-element-set [CRDT](https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type) and (sort of) Vector Clocks for partial ordering
- Designed to work offline first and to be easily embeddable to applications

_Currently requires [orbit-server](https://github.com/haadcode/orbit-server) for pubsub communication. This will change in the future as soon as IPFS provides pubsub._

_OrbitDB calls its namespaces channels. A channel is similar to "table", "keyspace", "topic", "feed" or "collection" in other db systems._

## Install
```
npm install orbit-db
```

## Examples
Before running the examples, install dependencies with:
```
npm install
```

Key-Value store example:
```
node examples/keyvalue.js <host> <username> <channel> <key> <value>
node examples/keyvalueReader.js <host> <username> <channel> <key>
```

Event log example (run several in separate shells):
```
node examples/reader.js <host> <username> <channel> <data> <interval in ms>
```

Benchmark writes:
```
node examples/benchmark.js <host> <username> <channel>;
```

## API
_See usage example below_

    connect(host, port, username, password)

    channel(name, password)

        .add(data: String) // Insert an event to a channel, returns <ipfs-hash> of the event

        .iterator([options]) // Returns an iterator of events

            // options : { 
            //   gt: <ipfs-hash>,   // Return events newer than <ipfs-hash>
            //   gte: <ipfs-hash>,  // Return events newer then <ipfs-hash> (inclusive)
            //   lt: <ipfs-hash>,   // Return events older than <ipfs-hash>
            //   lte: <ipfs-hash>,  // Return events older than <ipfs-hash> (inclusive)
            //   limit: -1,         // Number of events to return, -1 returns all, default 1
            //   reverse: true      // Return items oldest first, default latest first
            // }

        .put(key, data: String) // Insert (key,value) to a channel

        .get(key) // Retrieve value

        .del({ key: <key or hash> }) // Remove entry

        .delete() // Deletes the channel, all data will be "removed" (unassociated with the channel, actual data is not deleted from ipfs)

## Usage
```javascript
const async       = require('asyncawait/async');
const OrbitClient = require('./OrbitClient');

// orbit-server
const host = 'localhost';
const port = 3333;

async(() => {
    // Connect
    const orbit = OrbitClient.connect(host, port, username, password);

    const channelName = 'hello-world';
    const db = orbit.channel(channelName);

    /* Event Log */
    const hash = db.add('hello'); // <ipfs-hash>

    // Remove event
    db.remove(hash);

    // Iterator options
    const options = { limit: -1 }; // fetch all messages

    // Get events
    const iter = db.iterator(options); // Symbol.iterator
    const next = iter.next(); // { value: <item>, done: false|true}

    // OR:
    // var all = iter.collect(); // returns all elements as an array

    // OR:
    // for(let i of iter)
    //   console.log(i.hash, i.item);

    /* KV Store */
    db.put('key1', 'hello world');
    db.get('key1'); // returns "hello world"
    db.del('key1');

    /* Delete channel */
    const result = db.delete(); // true | false
})();
```

### Development
#### Source Code
The entry point for the code is [src/OrbitClient.js](https://github.com/haadcode/orbit-db/blob/master/src/OrbitClient.js) and the DB implementation is [src/OrbitDB.js](https://github.com/haadcode/orbit-db/blob/master/src/OrbitDB.js)

#### Run Tests
```
npm test
```

Keep tests running while development:
```
mocha -w
```

#### Lint
*Work in progress! Throws an error "Parsing error: The keyword 'await' is reserved".*
```
npm run lint
```

### TODO
- Fix encryption
- Logging
- Caching
- Performance optimisations: 
  - local caching
  - remove asyncawait and use promises or callbacks
  - merge POST and OP (one less object.put)

## Notes
### Data structure description
*For future [IPLD](https://github.com/ipfs/ipld-examples) references*

List snapshots are posted to pubsub:
```
> QmRzWAiFdLkdkwBDehzxhHdhfwbDKDnzqBnX53va58PuQu
> ...
```

**Get a list snapshot**

`ipfs object get QmRzWAiFdLkdkwBDehzxhHdhfwbDKDnzqBnX53va58PuQu`
```json
{
  "Links": [],
  "Data": {
    "id": "writer",
    "seq": 1301,
    "ver": 3,
    "items": {
      "writer.1301.0": "QmNwREbsgGgiQPXxpvGanD55inFjUXjpEqjiPtpa39P7Mn",
      "writer.1301.1": "QmQxndNEzWxKT5KRqRsty7JDGcbPVazaYPCqfB5z1mxmon",
      "writer.1301.2": "QmUN1X97M2t8MX55H8VoPGXu2fLBpr91iCAzHkXudSMvDE"
    }
  }
}
```

**Get the item**

`ipfs object get QmNwREbsgGgiQPXxpvGanD55inFjUXjpEqjiPtpa39P7Mn`
```json
{
  "Links": [],
  "Data": {
    "id": "writer",
    "seq": 1301,
    "ver": 0,
    "data": "QmasZEUwc67yftPvdSxRLWenmvF8faLnS7TMphQpn4PCWZ",
    "next": {
      "writer.1300.9": "QmS17ABxzFEVoHv5WEvATetNEZhN2vkNApRPcFQUaJfij3"
    }
  }
}
```

**Get the item's data (operation)**

`ipfs object get QmasZEUwc67yftPvdSxRLWenmvF8faLnS7TMphQpn4PCWZ`
```json
{
  "Links": [],
  "Data": {
    "op": "PUT",
    "key": "default",
    "value": "QmaAPEKDdaucQZRseJmKmWwZhgftBSwj8TD1xEomgcxo1X",
    "meta":{
      "type": "text",
      "size": -1,
      "from": "writer",
      "ts": 1456494484094
    }
  }
}
```

**Get the value**

`ipfs object get QmaAPEKDdaucQZRseJmKmWwZhgftBSwj8TD1xEomgcxo1X`
```json
{
  "Links": [],
  "Data": {
    "content": "LambOfGod 347",
    "ts": 1456494484089
  }
}
```