diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index b89290d05fa..d139918f061 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -523,6 +523,27 @@ declare module 'vscode' {
 
 	//#region André: debug
 
+	/**
+	 * A DebugSource is an opaque stand-in type for the type [Source](https://microsoft.github.io/debug-adapter-protocol/specification#Types_Source) defined in the Debug Adapter Protocol.
+	 */
+	export interface DebugSource {
+		// opaque contents
+	}
+
+	export namespace debug {
+
+		/**
+		 * Converts a "Source" object received via the Debug Adapter Protocol into a Uri that can be used to load its contents.
+		 *
+		 * If the "Source" object has insufficient information to create a uri, an error is thrown.
+		 *
+		 * @param source An object conforming to the [Source](https://microsoft.github.io/debug-adapter-protocol/specification#Types_Source) type defined in the Debug Adapter Protocol.
+		 * @param session An optional debug session that will be used to locate the Debug Adapter Protocol.
+		 * @return A uri that can be used to load the contents of the source.
+		 */
+		function asDebugSourceUri(source: DebugSource, session?: DebugSession): Uri;
+	}
+
 	// deprecated
 
 	export interface DebugConfigurationProvider {
diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index c872655f012..448923b1044 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -778,7 +778,6 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				if (!parentSessionOrOptions || (typeof parentSessionOrOptions === 'object' && 'configuration' in parentSessionOrOptions)) {
 					return extHostDebugService.startDebugging(folder, nameOrConfig, { parentSession: parentSessionOrOptions });
 				}
-				checkProposedApiEnabled(extension);
 				return extHostDebugService.startDebugging(folder, nameOrConfig, parentSessionOrOptions || {});
 			},
 			addBreakpoints(breakpoints: vscode.Breakpoint[]) {
@@ -786,6 +785,10 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			},
 			removeBreakpoints(breakpoints: vscode.Breakpoint[]) {
 				return extHostDebugService.removeBreakpoints(breakpoints);
+			},
+			asDebugSourceUri(source: vscode.DebugSource, session?: vscode.DebugSession): vscode.Uri {
+				checkProposedApiEnabled(extension);
+				return extHostDebugService.asDebugSourceUri(source, session);
 			}
 		};
 
diff --git a/src/vs/workbench/api/common/extHostDebugService.ts b/src/vs/workbench/api/common/extHostDebugService.ts
index f079be622ee..a80504d6c0f 100644
--- a/src/vs/workbench/api/common/extHostDebugService.ts
+++ b/src/vs/workbench/api/common/extHostDebugService.ts
@@ -30,5 +30,6 @@ export interface IExtHostDebugService extends ExtHostDebugServiceShape {
 	registerDebugConfigurationProvider(type: string, provider: vscode.DebugConfigurationProvider): vscode.Disposable;
 	registerDebugAdapterDescriptorFactory(extension: IExtensionDescription, type: string, factory: vscode.DebugAdapterDescriptorFactory): vscode.Disposable;
 	registerDebugAdapterTrackerFactory(type: string, factory: vscode.DebugAdapterTrackerFactory): vscode.Disposable;
+	asDebugSourceUri(source: vscode.DebugSource, session?: vscode.DebugSession): vscode.Uri;
 }
 
diff --git a/src/vs/workbench/api/node/extHostDebugService.ts b/src/vs/workbench/api/node/extHostDebugService.ts
index 1b9b233961a..82d87ead799 100644
--- a/src/vs/workbench/api/node/extHostDebugService.ts
+++ b/src/vs/workbench/api/node/extHostDebugService.ts
@@ -138,6 +138,32 @@ export class ExtHostDebugService implements IExtHostDebugService, ExtHostDebugSe
 		});
 	}
 
+	public asDebugSourceUri(src: vscode.DebugSource, session?: vscode.DebugSession): URI {
+
+		const source = <any>src;
+
+		if (typeof source.sourceReference === 'number') {
+			// src can be retrieved via DAP's "source" request
+
+			let debug = `debug:${encodeURIComponent(source.path || '')}`;
+			let sep = '?';
+
+			if (session) {
+				debug += `${sep}session=${encodeURIComponent(session.id)}`;
+				sep = '&';
+			}
+
+			debug += `${sep}ref=${source.sourceReference}`;
+
+			return vscode.Uri.parse(debug);
+		} else if (source.path) {
+			// src is just a local file path
+			return vscode.Uri.file(source.path);
+		} else {
+			throw new Error(`cannot create uri from DAP 'source' object; properties 'path' and 'sourceReference' are both missing.`);
+		}
+	}
+
 	private registerAllDebugTypes(extensionRegistry: ExtensionDescriptionRegistry) {
 
 		const debugTypes: string[] = [];