The Cosync Server-Side is a collection of functions and triggers that are installed by the Cosync Portal during the configuration of a Cosync Application for the Cosync Storage module. The Cosync Server-Side code is written in Javascript, and is licensed under the terms of the Cosync Service Agreement, which can be found here SLA Agreement.

Although all of the Server-Side code is provided in source code form, alteration of the server-side code by the developer does invalidate the terms of the Cosync Service Level Agreement. This is the only non-open source portion of the Cosync product. If as a developer, you find a bug or request a feature in the server-side code, please let us know and we will evaluate your suggestions for a future release of the service.


The Server Side portion of the Cosync Storage module is responsible for interfacing with the Amazon S3 Storage service, for handling asset management on behalf a client device and collaborative application.

The Cosync Server Side triggers that are installed by the Cosync Portal during configuration of a MongoDB Realm Application for the Cosync Storage module include the following

  • CosyncAssetUploadTrigger
  • CosyncRemoveAssetTrigger

The Cosync Server Side functions that are installed include:

  • CosyncAssetUpload
  • CosyncCreatePresignedURL
  • CosyncRefreshAsset
  • CosyncRemoveAsset
  • CosyncSanitizeFileName

The module also includes two functions that are callable by the client application:

  • CosyncRefreshAsset
  • CosyncRemoveAsset

The CosyncRefreshAsset function is used to by a client Realm application to refresh expired readUrl(s) within a CosyncAsset object. The CosyncRemoveAsset is used to remove an asset from both the MongoDB Atlas data-base and from the Amazon S3 Storage bucket.