The WAN Bridge & HTTP Gateway in the Cling Workbench
The Cling Workbench features an HTTP Gateway, so you can access all your UPnP devices with a webbrowser, either while you are at home or even remotely. The HTTP interface is RESTful and utilizes XHTML, thus enabling HATEOAS and easy programmatic client access. (It's not "pretty" for humans.)
Furthermore, the WAN Bridge maintains a durable live connection between two LANs, typically over a WAN. Endpoint connection management is implemented with RESTful HTTP interfaces. In other words, you can discover and control your friends UPnP devices over the public Internet, and they can discover and control yours. Devices from a remote LAN appear on your LAN and they act like they are connected directly on your LAN. (At this time GENA eventing is not supported and subscriptions to bridged remote devices will result in an error.)
The following screenshot shows the WAN Bridge configuration panel in the Cling Workbench with two connected endpoints. The local Workbench is connected to two other Workbench instances. In the background you see a proxy MediaServer device from one of the connected endpoints:
If available, the Workbench can create a NAT port mapping on your router and discover the external IP address automatically. After starting the bridge you may access the local URL with your webbrowser immediately, or send it to a friend who also has a running bridge. One of you will then create the link by entering and connecting to the other's URL. It doesn't matter who sends the URL and who creates the link, all UPnP devices from one LAN will be visible on the other LAN, respectively. Either side may disconnect the link at any time.
All communication by default is in clear-text with plain HTTP, no HTTPS or other protocols. Security is based on an authentication key embedded in the URL and all HTTP messages between two bridge endpoints.
Starting the bridge from the command-line
The extra package cling-workbench-bridge-cli.jar provides a command-line version of the WAN Bridge. You can start it directly from your shell:
java -jar cling-workbench-bridge-cli.jar \
-h 192.168.0.123 \
-url http://my.wan.hostname.and.port:8123 \
-demo
The options are the LAN interface for binding the HTTP gateway (192.168.0.123) and the WAN-reachable hostname and port, which will be send to other endpoints for connecting. The optional -demo argument can be provided to start a demo Binary Light device on the UPnP stack that runs the bridge, this helps with testing.
Security is also based on an authentication key, so you have to watch the startup log messages of the bridge for the generated key:
... INFO: <<< UPnP service started successfully INFO: Bridge configured with local URL: http://my.wan.hostname.and.port:8123/?auth=1surius3o7zuqf8qk1dp9qlc9
No port mapping on your NAT router will be created, you have to ensure that the configured WAN hostname and port is reachable and mapped to the LAN host (and same port) on which the HTTP gateway is bound. Open the local URL in your webbrowser to test this. Then access the minimal interface for bridge link management with http://my.wan.hostname.and.port:8123/link?auth=[key].
