4.4.2 TCP/SSL Remote Control

sat-nms M&C systems can be controlled remotely using a simple text based IP protocol. A remote application may use this protocol to query state information or device settings and to control the settings of each individual device. The M&C provides three flavours of this protocol on three different IP ports:

• Port 2015 accepts SSL connections giving monitor and control access to all parameters / devices in the M&C
• Port 2016 accepts plain TCP connections giving monitor and control access to all parameters / devices in the M&C
• Port 2017 accepts plain TCP connections like port 2016, but grants monitoring access only.

All three ports are disabled by default. In order to use them, they have to be enabled in the vlc.properties file:

    server.rcontrol.ssl.read-write=yes
    server.rcontrol.tcp.read-write=yes
    server.rcontrol.tcp.read-only=yes

To make changes in the vlc.properties file effective, you must restart the M&C server. The protocol itself is very simple, there are only three commands:

? *parameter-id*

Queries the actual state of a parameter. parameter-id is a textual string as used in the configuration of logical devices, e.g. BCRX-1.power identifies the power reading of a SatService beacon receiver named BCRX-1. The parameter may be any device setting or a status reading. If there is a value known for the given parameter-id, the parameter-id followed by a space character and the actual value is replied, numeric values are formatted in the same way as for presenting them at the sat-nms GUI. If the parameter-id is not known or if the device driver could read a value from the device since start of the program, nothing is replied.

@ *parameter-id*

Subscribes for updates on every change of a parameter. If there is a value known for the given parameter-id, the parameter-id followed by a space character and the actual value is replied, numeric values are formatted in the same way as for presenting them at the sat-nms GUI. If the parameter-id is not known or if the device driver could read a value from the device since start of the program, nothing is replied. Every time the value of this parameter changes, the M&C will send a line with the parameter-id followed by a space character and the actual value of the parameter.

! *parameter-id new-value*

Sets a parameter to the given value. new-value is parsed as if entered to a field in the sat-nms GUI. There is no reply to this command. If you want to check if the new value has been accepted, use the '?' or '@' commands. At the monitoring only port 2017 set commands are silently ignored.

Remarks

• Subscriptions remain active until the connection is closed, there is no 'unsubscribe' command.
• If you are using subscriptions, it is always possible that you receive a change message for a changed parameter before you receive the expected reply to a subscribe or query command. You always must be capable to receive messages in any sequence.