AceBase realtime database engine

A fast, low memory, transactional, index & query enabled NoSQL database engine and server for node.js with realtime data change notifications. Includes built-in user authentication and authorization. Inspired by the Firebase realtime database, with additional functionality and less data sharding/duplication. Capable of storing up to 2^48 (281 trillion) object nodes in a binary database file that can theoretically grow to a max filesize of 8 petabytes. AceBase can run anywhere: in the cloud, NAS, local server, your PC/Mac, Raspberry Pi, wherever you want.

Natively supports storing of JSON objects, arrays, numbers, strings, booleans, dates and binary (ArrayBuffer) data. Custom classes can automatically be shape-shifted to and from plain objects by adding type mappings - Store a User, get a User. Store a Chat that has a collection of Messages, get a Chat with Messages back from the database. Any class specific methods can be executed directly on the objects you get back from the db, because they will be an instanceof your class.

Getting Started

AceBase is split up into multiple repositories:

• acebase: local AceBase database engine (github, npm)
• acebase-server: AceBase webserver endpoint to enable remote connections (github, npm)
• acebase-client: client to access an AceBase webserver (github, npm)

IMPORTANT: AceBase is in beta stage! If you run into errors, make sure you have the latest version of each package you are using. The database files created by older releases might be incompatible with newer versions, so you might have to start from scratch after updating. Do not use in production yet!

Prerequisites

AceBase currently only runs on Node, as it requires the 'fs' filesystem. AceBase cannot run in the browser yet, working on that!

Installing

All AceBase repositories are available through npm. You only have to install one of them, depending on your needs:

If you want to use a local AceBase database in your project, install the acebase repository.

npm i acebase

If you want to setup an AceBase server, install acebase-server.

npm i acebase-server

If you want to access a remote (or local) AceBase server, install the client software acebase-client.

npm i acebase-client

Example usage

The API is similar to that of the Firebase realtime database, with additions.

Creating a database

Creating a new database is as simple as connecting to it. If the database file doesn't exists, it will be created automatically.

const { AceBase } = require('acebase');
const db = new AceBase('mydb');  // Creates or opens a database with name "mydb"

db.ready(() => {
    // database is ready to use!
})

Loading data

Run .get on a reference to get the currently stored value. This is short for the Firebase syntax of .once("value")

db.ref('game/config')
.get(snapshot => {
    if (snapshot.exists()) {
        config = snapshot.val();
    }
    else {
        config = new MyGameConfig(); // use defaults
    }
});

Note: When loading data, the currently stored value will be wrapped and returned in a DataSnapshot object. Use snapshot.exists() to determine if the node exists, snapshot.val() to get the value.

Storing data

Setting the value of a node, overwriting if it exists:

db.ref('game/config')
.set({
    name: 'Name of the game',
    max_players: 10
})
.then(ref => {
    // stored at /game/config
})

Note: When storing data, it doesn't matter whether the target path, and/or parent paths exist already. If you store data in 'chats/somechatid/messages/msgid/receipts', it will create any nonexistent node in that path.

Updating data

Updating the value of a node merges the stored value with the new object. If the target node doesn't exist, it will be created with the passed value.

db.ref('game/config').update({
    description: 'The coolest game in the history of mankind'
})
.then(ref => {
    // config was updated, now get the value
    return ref.get(); // shorthand for firebase syntax ref.once("value")
})
.then(snapshot => {
    const config = snapshot.val();
    // config now has properties "name", "max_players" and "description"
});

Transactional updating

If you want to update data based upon its current value, and you want to make sure the data is not changed in between your get and update, use transaction. A transaction gets the current value, runs your callback with a snapshot. The value you return from the callback will be used to overwrite the node with. Returning null will remove the entire node, returning undefined will cancel the transaction.

db.ref('accounts/some_account')
.transaction(snapshot => {
    // some_account is locked until its new value is returned by this callback
    var account = snapshot.val();
    if (!snapshot.exists()) {
        // Create it
        account = {
            balance: 0
        };
    }
    account.balance *= 1.02;    // Add 2% interest
    return account; // accounts/some_account will be set to the return value
});

Note: transaction loads the value of a node including ALL child objects. If the node you want to run a transaction on has a large value (eg many nested child objects), you might want to run the transaction on a subnode instead. If that is not possible, consider structuring your data differently.

// Run transaction on balance only, reduces amount of data being loaded, transferred, and overwritten
db.ref('accounts/some_account/balance')
.transaction(snapshot => {
    var balance = snapshot.val();
    if (balance === null) { // snapshot.exists() === false
        balance = 0;
    }
    return balance * 1.02;    // Add 2% interest
});

Removing data

You can remove data with the remove method

db.ref('animals/dog')
.remove()
.then(() => { /* removed successfully */ )};

Removing data can also be done by setting or updating its value to null. Any property that has a null value will be removed from the parent object node.

// Remove by setting it to null
db.ref('animals/dog')
.set(null)
.then(ref => { /* dog property removed */ )};

// Or, update its parent with a null value for 'dog' property
db.ref('animals')
.update({ dog: null })
.then(ref => { /* dog property removed */ )};

Adding user-generated data

For all user-generated data you add, you need to create keys that are unique and won't not clash with those created by other clients. To do this, you can have unique keys generated with push. Under the hood, push uses cuid to generated keys that a guaranteed to be unique.

db.ref('users')
.push({
    name: 'Ewout',
    country: 'The Netherlands'
})
.then(userRef => {
    // user is saved, userRef points to something 
    // like 'users/jld2cjxh0000qzrmn831i7rn'
};

The above example generates the unique key and stores the object immediately. You can also choose to have the key generated, but store the value later:

const postRef = db.ref('posts').push();
console.log(`About to add a new post with key "${postRef.key}"..`);
// ... do stuff ...
postRef.set({
    title: 'My first post'
})
.then(ref => {
    console.log(`Saved post "${postRef.key}"`);
};

Limit nested data loading

If your database structure is using nesting (eg storing posts in 'users/someuser/posts' instead of in 'posts'), you might want to limit to amount of data you are retrieving in most cases. Eg: if you want to get the details of a user, but don't want to load all nested data, you can explicitly limit the nested data retrieval by passing exclude, include, and child_objects options to .get:

// Exclude specific nested data:
db.ref('users/someuser')
.get({ exclude: ['posts', 'comments'] })
.then(snap => {
    // snapshot contains all properties except 
    // 'users/someuser/posts' and 'users/someuser/comments'
});

// Include specific nested data:
db.ref('users/someuser/posts')
.get({ include: ['*/title', '*/posted'] })
.then(snap => {
    // snapshot contains all posts, but each post 
    // only contains 'title' and 'posted' properties
})

Monitoring realtime data changes

You can subscribe to data events to get realtime notifications as the monitored node is being changed. When connected to a remote AceBase server, the events will be pushed to clients through a websocket connection. Supported events are:

• 'value': triggered when a node's value changes (including changes to any child value)
• 'child_added': triggered when a child node is added, callback contains a snapshot of the added child node
• 'child_changed': triggered when a child node's value changed, callback contains a snapshot of the changed child node
• 'child_removed': triggered when a child node is removed, callback contains a snapshot of the removed child node
• 'notify_*': notification only version of above events without data, see "Notify only events" below

// Firebase style: using callback
db.ref('users')
.on('child_added', function (newUserSnapshot) {
    // fires for all current children, 
    // and for each new user from then on
});

AceBase uses the same .on method signature as Firebase, but also offers a (more intuitive) way to subscribe to the events using the returned EventStream you can subscribe to. Additionally, subscribe callbacks only fire for future events, as opposed to .on, which also fires for current values of events 'value' and 'child_changed'.

// AceBase style: using .subscribe
db.ref('users')
.on('child_added')
.subscribe(newUserSnapshot => {
    // .subscribe only fires for new children from now on
})

db.ref('users')
.on('child_removed')
.subscribe(removedChildSnapshot => {
    // removedChildSnapshot contains the removed data
});

db.ref('users')
.on('child_changed')
.subscribe(userRef => {
    // Got new value for any user that was updated
});

db.ref('users/some_user')
.on('value', true) // passing true will trigger .subscribe for current value as well
.subscribe(userRef => {
    // Got current value (1st call), or new value (2nd+ call) for some_user
});

The EventStream returned by .on can also be used to subscribe more than once:

const newPostStream = db.ref('posts').on('child_added');
const subscription1 = newPostStream.subscribe(childSnapshot => { /* do something */ });
const subscription2 = newPostStream.subscribe(childSnapshot => { /* do something else */ });
// To stop 1's subscription:
subscription1.stop(); 
// or, to stop all active subscriptions:
newPostStream.stop();

Notify only events

In additional to the events mentioned above, you can also subscribe to their notify_ counterparts which do the same, but with a reference to the changed data instead of a snapshot. This is quite useful if you want to monitor changes, but are not interested in the actual values. Doing this also saves serverside resources, and results in less data being transferred from the server. Eg: notify_child_changed will run your callback with a reference to the changed node.

Querying data

When running a query, all child nodes of the referenced path will be matched against your set criteria and returned in any requested sort order. Pagination of results is also supported, so you can skip and take any number of results. Queries do not require data to be indexed, although this is recommended if your data becomes larger.

To filter results, multiple where(key, operator, compare) statements can be added. The filtered results must match all conditions set (logical AND). Supported query operators are:

• '<': value must be smaller than compare
• '<=': value must be smaller or equal to compare
• '==': value must be equal to compare
• '!=': value must not be equal to compare
• '>': value must be greater than compare
• '>=': value must be greater or equal to compare
• 'between': value must be between the 2 values in compare array (compare[0] <= value <= compare[1]). If compare[0] > compare[1], their values will be swapped
• '!between': value must not be between the 2 values in compare array (value < compare[0] or value > compare[1]). If compare[0] > compare[1], their values will be swapped
• matches: value must be a string and must match the regular expression compare
• !matches: value must be a string and must not match the regular expression compare
• 'in': value must be equal to one of the values in compare array
• '!in': value must not be equal to any value in compare array
• 'has': value must be an object, and it must have property compare.
• '!has': value must be an object, and it must not have property compare
• 'contains': value must be an array and it must contain a value equal to compare
• '!contains': value must be an array and it must not contain a value equal to compare

NOTE: A query does not require any where criteria, you can also use a query to simply paginate your data using skip, take and order

db.query('songs')
.where('year', 'between', [1975, 2000])
.where('title', 'matches', /love/i)  // Songs with love in the title
.take(50)                   // limit to 50 results
.skip(100)                  // skip first 100 results
.order('rating', false)     // highest rating first
.order('title')             // order by title ascending
.get(snapshots => {
    // ...
});

To quickly convert a snapshots array to the values it encapsulates, you can call snapshots.getValues(). This is a convenience method, you can also do it yourself with values = snapshots.map(snap => snap.val()):

db.query('songs')
.where('year', '>=', 2018)
.get(snapshots => {
    const songs = snapshots.getValues();
});

By default, queries will return snapshots of the matched nodes, but you can also get references only by passing the option { snapshots: false }

// ...
.get({ snapshots: false }, references => {
    // now we have references only, so we can decide what data to load
});

Instead of using the callback of .get, you can also use the retuned Promise which comes in very handy in promise chains:

// ... in some promise chain
.then(fromYear => {
    return db.query('songs')
    .where('year', '>=', fromYear)
    .get();
})
.then(snapshots => {
    // Got snapshots from returned promise
})

Removing data with a query

To remove all nodes that match a query, sinply call remove instead of get:

db.query('songs')
.where('year', '<', 1950)
.remove(() => {
    // Old junk gone
}); 

Indexing data

Indexing data will dramatically increase the speed of any query you might run against your data, especially as it increases in size. Any indexes you create will be updated automatically when underlaying data is changed, added or removed. NOTE: If you are connected to an external AceBase server (using AceBaseClient), indexes can only be created if you are signed in as the admin user.

Promise.all([
    // creates indexes if they don't exist
    db.createIndex('songs', 'year'),
    db.createIndex('songs', 'genre')
])
.then(() => {
    return db.query('songs')
    .where('year', '==', 2010) // uses the index on key year
    .where('genre', 'in', ['jazz','rock','blues']) // uses the index on key genre
    .get();
})
.then(snapshots => {
    let songs = snapshots.map(snap => snap.val()); // Converts snapshots array to values array
    console.log(`Got ${songs.length} songs`);
});

Indexing scattered data with wildcards

Because nesting data is recommended in AceBase (as opposed to Firebase that discourages this), you are able to index and query data that is scattered accross your database in a structered manner. For example, you might want to store posts for each user under their own user node, and index (and query) all posts by any user:

db.createIndex('users/*/posts', 'date') // Index date of any post by any user
.then(() => {
    let now = new Date();
    let today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
    return db.query('users/*/posts') // query with the same wildcard
    .where('date', '>=', today)
    .get();
})
.then(postSnapshots => {
    // Got all today's posts, of all users
});

NOTE: Wildcard queries always require an index - they will not execute if there is no corresponding index.

Mapping data to custom classes

Mapping data to your own classes allows you to store and load objects to/from the database without them losing their class type. Once you have mapped a database path to a class, you won't ever have to worry about serialization or deserialization of the objects.

// User class implementation
class User {
    constructor(plainObject) {
        this.name = plainObject.name;
    }

    serialize() {
        // (optional) method to manually serialize
        return {
            name: this.name
        }
    }
}

// Bind to all children of users node
db.types.bind("users", User);

// Create a user
let user = new User();
user.name = 'Ewout';

// Store the user in the database
db.ref('users')
.push(user)
.then(userRef => {
    // The object returned by user.serialize() was stored in the database
    return userRef.get();
})
.then(userSnapshot => {
    let user = userSnapshot.val();
    // user is an instance of class User!
})

If you are unable (or don't want to) to change your class constructor, add a static method to deserialize the plain object and bind to it:

class Pet {
    // Constructor that takes multiple arguments
    constructor(animal, name) {
        this.animal = animal;
        this.name = name;
    }
    // Static method that instantiates a Pet object
    static from(obj) {
        return new Pet(obj.animal, obj.name);
    }
}
// Bind to all pets of any user, using Pet.from as deserializer
db.types.bind("users/*/pets", Pet.from, { instantiate: false }); 

Note: { instantiate: false } informs AceBase that Pet.from should not be called using the new keyword. Also note that class Pet did not implement a serialize method. In this case, AceBase will serialize the object's properties automatically. If your class contains properties that should not be serialized (eg get properties), make sure to implement a serialize method.

Authors

• Ewout Stortenbeker - Initial work - me@appy.one

Contributing

If you would like to contribute to help move the project forward, you are welcome to do so! What can you help me with?

• Bugfixes - if you find bugs please create a new issue on github. If you know how to fix one, feel free to submit a pull request or drop me an email
• Database GUI - it would be great to have a web-based GUI to browse and/or edit database content. The reflect API method can be used to get info about particular database nodes and their children, so it is already possible to selectively load info.
• Ports - If you would like to port AceBaseClient to other languages (Java, Swift, C#, etc) that would be awesome!
• Ideas - I love new ideas, share them!
• Money - I am an independant developer and many working hours were put into developing this. Being new to open sourcing my code, giving it away for free was not easy! I also have a family to feed so if you like AceBase, feel free to send me a donation 👌 My BTC address: 3EgetGDnG9vvfJzjLYdKwWvZpHwePKNJYc