MongoDB Sync Connector
Bi-directional Data Sync with MongoDB - on-premise and to the cloud
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Bi-directional Data Sync with MongoDB - on-premise and to the cloud
Last updated
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ObjectBox Data Sync syncs data with MongoDB using the integrated . Changes made on ObjectBox clients are synchronized in real-time to MongoDB and vice versa.
ObjectBox Sync brings your data in MongoDB to the edge (e.g. mobile and IoT devices, big and small servers) and synchronizes changes back to MongoDB. By using ObjectBox Sync, you can make your MongoDB data always available: continue to work offline and sync in real-time when online.
While ObjectBox Sync is an established product, the MongoDB Connector is in its early stages. You can still get started with POCs or integrations right away. The timeline below enables you to align your development with ours and pick up speed. Once new features are out, you profit immediately.
Oktober 2024
Alpha 1
Two-way sync between MongoDB and ObjectBox for changes that are happening live.
January 2025
Alpha 2
JWT authentication, Mapping for all MongoDB data types
February 2025
Alpha 3
Relation mapping (to-one and many-to-many)
March 2025
Alpha 4
Support for additional MongoDB ID types
April 2025
Alpha 5 (2025-04-01)
Use MongoDB transactions, better change tracking, improved error handling, improved MongoDB Admin page
May 2025
Beta 1 (2025-05-05)
Import initial data from MongoDB, pick-up sync at any point. New admin page for full-syncs.
End of May 2025
Beta 2
Server-side rules to select data for sync per user
June 2025
1.0
Initial release incorporating most important user feedback
We'll update the plan regularly.
ObjectBox and MongoDB have many similarities. Nevertheless, it's important to understand some differences in terminology and concepts between the two databases. The following table illustrates these differences. It serves as background information on how to map things between the two systems:
Database containing the data
A store, grouped into types (data classes).
A database, grouped into collections.
What your application "opens"
Using a name or directory a single store (database) is opened locally on device. (In the case of Sync, this is the "client database".) Multiple stores can be opened, which are strictly separate.
A client is used to connect to a MongoDB server. All databases can be accessed on the server remotely.
Arranging data in a database (e.g. data sets)
A box holds all objects of the same type. A type typically matches a data class in programming languages. It's part of a strict schema (data model) that is enforced. The type definition consists of a fixed set of properties.
Collections are used to group documents together. By default, no strict rules are imposed (schema-less).
Data record
An object is an instance of a type. It can have data values for the properties defined in the type.
A document is a set of data values called fields. It's very similar to a JSON file.
Modelling related data
Objects can have to-one and to-many relationships to other objects. Relationships are bidirectional. Data is typically normalized.
Typically, a document embeds all "related data" into itself resulting in larger documents. Data is typically not normalized. Alternatively, one can also choose to use references, which is more similar to relationships.
Many-to-many relationships
Fully supported. Unlike to-one relationships, the data is stored outside the object. Updating relations is very efficient. There's no user-defined order and no duplicates.
Alternative modelling by embedding or referencing documents. Inside the document, you can have an array of IDs in a user-defined order allowing duplicates.
Nested data records
Nested data is supported by flex properties. E.g. these allow maps, which can contain nested data structures (JSON-like).
Documents contain nested data by default.
Identifiers (IDs)
IDs are 64-bit integers. They are unique within its box and database instance.
MongoDB uses Object ID (short: OID; 12 bytes) by default and supports other ID types. OIDs are unique within their collection and likely globally unique.
Setup a MongoDB instance, either locally or in the cloud.
Setup an ObjectBox Server instance and configure the MongoDB Sync Connector.
Import data from MongoDB to ObjectBox initially.
Now, two-way data synchronization between MongoDB and ObjectBox automatically happens.
If you are coming from Atlas Device Sync, you already now that it on September 30, 2025. Thus, it's a good idea to to get started with your migration.
