diff --git a/packages/schema/src/interfaces.ts b/packages/schema/src/interfaces.ts
index 6a560bc9d..16d8b6a3e 100644
--- a/packages/schema/src/interfaces.ts
+++ b/packages/schema/src/interfaces.ts
@@ -10,6 +10,7 @@ import { IChangedArgs } from '@jupyterlab/coreutils';
 import { IDocumentManager } from '@jupyterlab/docmanager';
 import { DocumentRegistry, IDocumentWidget } from '@jupyterlab/docregistry';
 import { Contents, User } from '@jupyterlab/services';
+import { JSONObject } from '@lumino/coreutils';
 import { ISignal, Signal } from '@lumino/signaling';
 import { SplitPanel } from '@lumino/widgets';
 
@@ -26,7 +27,6 @@ import {
   SourceType
 } from './_interface/jgis';
 import { IRasterSource } from './_interface/rastersource';
-
 export { IGeoJSONSource } from './_interface/geojsonsource';
 
 export type JgisCoordinates = { x: number; y: number };
@@ -90,6 +90,9 @@ export interface IJupyterGISDoc extends YDocument<IJupyterGISDocChange> {
   readonly editable: boolean;
   readonly toJGISEndpoint?: string;
 
+  getSource(): JSONObject;
+  setSource(value: JSONObject | string): void;
+
   layerExists(id: string): boolean;
   getLayer(id: string): IJGISLayer | undefined;
   removeLayer(id: string): void;