Introduction to MongoDB Realm

MongoDB Realm is a 1-tier architecture based embedded, object-oriented, highly available, scalable database, meant to provide 24/7 service without any downtime. It is meant to be tightly integrated and available in the same device as of the mobile application that uses the database.

Realm Database to MongoDB Realm

Initially, the MongoDB Realm database usually called as Realm database. It was an alternative to SQLite and another similar kinds of databases. Realm was object-oriented, and it let developers to handle data as objects rather than rows and columns. It was easy to use, and highly performant, so developers like to use it.

In 2019, MongoDB acquired Realm. At that time MongoDB wanted to make its strong presence in the Mobile database market, and more importantly to provide mobile app,  a robust and seamless connection between the mobile and server environments, so it acquired Realm and Realm became MongoDB realm.

MongoDB Realm Features

• Automatic bidirectional sync between the MongoDB Realm and MongoDB database

• Serverless Functions, as MongoDB Realm syncs data between the mobile app and MongoDB in the cloud, execute the custom logic in response to app events without any dedicated server setup. MongoDB cloud manages the infrastructure for us.

• GraphQL Integration

• MongoDB Realm supports third-party OAuth2 providers, email passwords, API keys kind of many Authorization methods and User Management.

•  Data Access Controls, who can access and what data.

MongoDB with MongoDB Realm provides a continuous and seamless data sync between the mobile and MongoDB on the cloud.

Offline-First Applications by MongoDB Realm

The idea is that a mobile application should be able to work, when even the internet connection is not stable, or unavailable. So this is the kind of functionality supported by MongoDB Realm. Suppose a mobile app is used by field workers or technicians in remote areas, they started their job, and marked complaints InProgress / completed, now MongoDB Realm your embedded database makes its marking process operational offline when the internet is unavailable, and push the updates to MongoDB server when it comes online. It also handles data conflicts if it happens while data syncing.

Real-time Data Synchronization with Realm Sync

How the data sync between multiple MongoDB Realms and central MongoDB Atlas. Thanks to Realm Sync. It has the following features:- 

• Initialization of Realm Sync, It then establishes a connection with the Realm Object server and specifies which subset of the data needs to be synced.

• Bidirectional Syncing

• Conflict resolution in data if it happens, this is the real-world scenario

• Offline-First, we already discussed

• Real-time data access control, It has robust fine-grained control of who can access what

• Real-time updates in the data. If some data changes in the central MongoDB Atlas server instance, updates are pushed to relevant client MongoDB Realm instances.

• Since MongoDB Realm is an embedded database, it is mobile-optimized.

Performance of MongoDB Realm in comparison to its competitors

MongoDB Realm competitors are Firebase by Google, AWS Amplify, Azure Mobile Apps, Couchbase Mobile, Parse, open source database, Realm(prior version before acquisition by MongoDB), PouchDB and CouchDB.

MongoDB Realm uses a Zero-copy design approach to eliminate the need to copy the data from one buffer to another buffer which in turn saves CPU usage for these operations, instead, it passes the pointers and reference to the data when needed, this allows to access the data from its original location only. It benefits the performance, reduces latency and increases the efficiency of the system. 

However, this is a kind of new database as it was acquired in 2019 by MongoDB, so maybe some of the features it does not provide yet, which are offered by its competitors.

Cross-platform development with MongoDB Realm

Cross platform means a single codebase can run on multiple platforms either it be the Web, Android or IOS. MongoDB Realm uses the Consistent Data layer and backend services across these platforms. Data operations remain the same in each platform because of its Consistent API. It also supports a variety of programming languages like JavaScript(React Native), and Kotlin/Java for Android development.

As a Backend Service, it supports, Unified GraphQL API, serverless functions, and triggers, an automatic kind of callbacks or functionalities that react to particular data changes.

Data Encryption and Security Features of MongoDB Realm

MongoDB Realm has built-in encryption mechanisms. It supports file-level AES-256 encryption with 64 byte encryption key for opening a database. So this key has to be key secure and is required to read the data. Also, it uses SSL/TLS for data syncing and communication between the Realm Object Server and Realm SDK on the client side.

Basically, Realm Object Server syncs the Realms between devices, and supports authentication, access control services, and serverless event processing.

How to use Kotlin with MongoDB Realm for Android Development

Perquisites:-

- Ensure you have already Android Studio installed

- You created a Kotlin Based Project

Adding MongoDB Realm

implementation 'io.realm:realm-gradle-plugin:latest_version'

Applying the Realm android

apply plugin: 'realm-android'

MongoDB Realm Initialization

class MyApplication: Application(){
	Override fun onCreate(){
		Super.onCreate()
		Realm.init(this)
    }
}

Define the Data Model

open class Employee{
	var name: String="",
	var id: String=""
}:RealmObject()

CRUD OPERATIONS

- Create

val realm: Realm = Realm.getDefaultInstance()
realm.executeTransaction { realm ->
    val employee = realm.createObject(Employee::class.java)
    employee.name = "Tushar"
    employee.id = "EMPID101"
}

- Read

val employees: RealmResults<Employee> = realm.where(Employee::class.java).findAll()

- Update

realm.executeTransaction {realm ->
    val employee= realm.where(Employee::class.java).equalTo("id", "EMPID101").findFirst()
    employee?.name = "Tushar Agarwal"
}

- Delete

realm.executeTransaction {realm ->
    val employee= realm.where(Employee::class.java).equalTo("id", "EMPID101").findFirst()
    employee?.deleteFromRealm()
}

- Close

realm.close()

Summary: MongoDB Realm DB and its integration with Kotlin

In this story, we learned about the MongoDB Realm, it is the embedded, 1-Tier, object-oriented database tightly coupled with the application itself, and runs in mobile as a mobile database. MongoDB Realm is a highly scalable, 24/7 available database without downtime.

We learned about its history, Realm was acquired by MongoDB back in 2019 to make its strong presence in the mobile database market and to provide a seamless connection between the mobile data and MongoDB in the cloud.

We learned about its features like an Offline-first database (so how it can work offline and benefit the working of the mobile application even in locations where internet connection is very unstable), automatic bidirectional sync between MongoDB Realm mobile data and MongoDB database on cloud i.e. it pushes the data from mobile database to MongoDB database on cloud, or if something changed in the data in the MongoDB cloud, then it push the updates back to the mobile database MongoDB Realm.

Also, we learned about conflict resolution while syncing the data, serverless functions and how MongoDB cloud manages the infrastructure which is why it is serverless. It also supports GraphQL, third-party OAuth2 Authentication providers, email-password authentication, API key authentication, and various methods of authentication MongoDB supports. Also, MongoDB has fine-grained Data Access Control to control who can access and what.

We also discussed that MongoDB Realm is cross-platform due to its Consistent API and backend services across platforms.

We discussed about the security of data, the Built-in encryption mechanisms using file-level AES-256 encryption with a 64-byte encryption key and how it uses the SSL/TLS encryption while transiting the data between the Realm Object Server and client Realm. Realm Object Server is used in Realm Sync to sync the data between different mobile Realms. We also learned about the performance of the MongoDB Realm as it uses the zero-copy approach to read the data eliminating the need to copy the data between the servers. We also saw how to use it with Kotlin for Android development. We saw doing the CRUD operations using MongoDB Realm.

In conclusion, MongoDB provides a robust solution of mobile database i.e. MongoDB Realm and MongoDB server database with real-time bidirectional sync between the data of the server and client mobile with offline work capability.