It register a name for the view inside a namespace. All the "Akanda Networking" panel is registered as the "networking" namespace inside the Project dashboard whose namespace is "project" inside Horizon default namespace "horizon". Registering the network_topology/urls.py in akanda/horizon/urls.py as url(r'topology/', include(topology_urls, namespace='topology'),), I'm defining a the "topology" namespace for all the views in it. So to the get the url I just need to reverse horizon:project:networking:topology:json in the template.