The file selector is a bridge between most VRE services and the NextCloud, allowing users to select data from their private workspace to be handed over to the processing service instances by the backend. Figure 1: Loosely-coupled structure of VRE services The second type of service is for the more computationally intensive tools, or for those that are not optimized for handling multiple users' sessions (this frequently occurs when desktop software is ported to the cloud). The services are loosely coupled to allow for easy extension: The VRE provides central services such as Single Sign-On and central web storage for users, but the services can also run as standalone services. [Extracted from the article]