The NoSQL Object (or NO2, AKA Nitrite) database is an open-source NoSQL embedded document database written in Java with a MongoDB-like API. It supports both in-memory and single file-based persistent stores.

Nitrite is a serverless embedded database ideal for desktop, mobile, or small web applications.

Features

• Embedded key-value/document and object stores.
• In-memory or single data file.
• Very fast and lightweight MongoDB-like API.
• Indexing.
• Full-text search capability.
• Full Android compatibility.
• Observable store.
• Two-way replication via Nitrite DataGate server.

Nitrite is not an RDBMS. It is also not a distributed NoSQL database like MongoDB or Cassandra. It does not have any server for external applications to connect to. It does not support sharding or ACID transaction.

How to Install

To use Nitrite in any Java application, just add the below dependency:

Maven

<dependency>
    <groupId>org.dizitart</groupId>
    <artifactId>nitrite</artifactId>
    <version>1.0</version>
</dependency>

Gradle

compile 'org.dizitart:nitrite:1.0'

Usage

Let's now start with some quick examples.

Initialize Database

Nitrite db = Nitrite.builder()
        .compressed()
        .filePath("/tmp/test.db")
        .openOrCreate("user", "password");

For more options on opening a database, visit here.

Data in Nitrite is stored as a document in a collection called NitriteCollection. A document is nothing but a map of key-value pairs.

A POJO can also be stored directly in an ObjectRepository. Under the hood, a POJO is converted into a document using Jackson's ObjectMapper and is stored in a NitriteCollection. 

Create a Collection

// Create a Nitrite Collection
NitriteCollection collection = db.getCollection("test");

// Create an Object Repository
ObjectRepository<Employee> repository = db.getRepository(Employee.class);

Construct a Document

// create a document to populate data
Document doc = createDocument("firstName", "John")
     .put("lastName", "Doe")
     .put("birthDay", new Date())
     .put("data", new byte[] {1, 2, 3})
     .put("fruits", new ArrayList<String>() {{ add("apple"); add("orange"); add("banana"); }})
     .put("note", "a quick brown fox jump over the lazy dog");

CRUD operations are very easy and are very much similar to the Mongo Java API.

Insert/Modify/Remove a Document

// insert the document
collection.insert(doc);

// update the document
collection.update(eq("firstName", "John"), createDocument("lastName", "Wick"));

// remove the document
collection.remove(doc);

Details of CRUD operations for NitriteCollection can be found here for ObjectRepository here.

Query a Collection

Nitrite comes with an easy API for querying a collection efficiently.

Cursor cursor = collection.find(
                        // and clause
                        and(
                            // firstName == John
                            eq("firstName", "John"),
                            // elements of data array is less than 4
                            elemMatch("data", lt("$", 4)),
                            // elements of fruits list has one element matching orange
                            elemMatch("fruits", regex("$", "orange")),
                            // note field contains string 'quick' using full-text index
                            text("note", "quick")
                            )
                        );

for (Document document : cursor) {
    // process the document
}

// create document by id
Document document = collection.getById(nitriteId);

Nitrite supports indexing. It takes advantage of indexing during searching. More on this can be found here.

Replication

In our connected world, seamless replication over devices is a must. Nitrite supports replication with the help of Nitrite DataGate server. Setting up replication is very easy in Nitrite once a DataGate server instance is up and running.

// connect to a DataGate server localhost 9090 port
DataGateClient dataGateClient = new DataGateClient("http://localhost:9090")
        .withAuth("userId", "password");
DataGateSyncTemplate syncTemplate
        = new DataGateSyncTemplate(dataGateClient, "remote-collection@userId");

// create sync handle
SyncHandle syncHandle = Replicator.of(db)
        .forLocal(collection)
        // a DataGate sync template implementation
        .withSyncTemplate(syncTemplate)
        // replication attempt delay of 1 sec
        .delay(timeSpan(1, TimeUnit.SECONDS))
        // both-way replication
        .ofType(ReplicationType.BOTH_WAY)
        // sync event listener
        .withListener(new SyncEventListener() {
            @Override
            public void onSyncEvent(SyncEventData eventInfo) {

            }
        })
        .configure();

// start sync in the background using handle
syncHandle.startSync();

We will discuss more on setting up a DataGate server in another article.

Further Reading

There is a lot more to it and I can not squeeze everything into a single article. We will discuss those things in coming days. In the meantime, if you feel interested head out to the Nitrite's project page or GitHub repo. If you want to dig into Nitrite's capabilities in more details, please go to its documentation page, where you will find all the tiny details with lots of examples.