The Map Layers widget allows to manage the display of the Base Layer and ArcGIS MapService, ArcGIS FeatureService, WMS and WMTS layers. 

  

Use any GIS server (ESRI, open source MapServer, GeoServer, etc.) to compose your map in a third party application. Then, add new connections to the service through the Map Layers widget and access your GIS data.

For the complete documentation, please follow this link to the Map Layers widget.