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SWTbahn client-server command line interface

This is a client-server command line interface for the SWTbahn. The server is connected to the BiDiB interface and provides a REST API. The client side provides a command line interface which connects to the web service to execute the commands. The command line interface was developed by Nicolas Gross as part of his work for the libbidib project.

Dependencies

Server

  • A C compiler
  • Libraries: onion, libpam, libgnutls, libgcrypt, libpthread, libglib-2.0, libyaml, libbidib

Client

  • python3
  • Libraries: click, requests, pyaml (pip3 install click requests pyaml)

Build

  1. Clone the repository
  2. Adjust server/CMakeLists.txt according to your installations of the dependencies
  3. Navigate to the directory where the build files should be generated
  4. Execute cmake <path-to-project-root>/server
  5. Execute make

Usage

Server

  1. Build the executable (see section Build)
  2. Create the configuration files for your track (see libbidib documentation)
  3. Connect the BiDiB interface to the server
  4. Check on which serial device the board is connected: dmesg | grep tty
  5. Start the server: ./swtbahn-server <serial-device> <config-directory> <IP> <port> (IP is the IP-address under which the server can be reached and port specifies on which port the server listens)
    For example: ./swtbahn-server /dev/ttyUSB0 ../../configurations/swtbahn-lite/ 141.13.106.27 2048
  6. Quit the server with Ctrl-C if you're done

Client (Command Line)

  1. The client is located under <project-root>/client/swtbahn

  2. Use the --help flag to get information about parameters, options, ...

  3. Use the config command to setup the client: swtbahn config <hostname> <port> <default-track-output>, where hostname is the IP and port the port which you used when you started the server. The is the name of the track output which should be used if no track output is explicitly specified when issuing a command.
    For example: ./swtbahn config 141.13.106.27 2048 master
    This will create a config file in the current working directory. Dont use the client from a different working directory for the current session, otherwise it won't find the configuration file. If you really want to use two logically different clients on the same device, you could just run the clients from different working directories which will lead to distinct configs.

  4. Now you can use the commands from the categories swtbahn admin, swtbahn controller, swtbahn driver and swtbahn monitor. If the system was not started by swtbahn admin startup, all the other commands won't work.

    For example:
    ./swtbahn admin startup
    ./swtbahn monitor get_segments
    ./swtbahn monitor get_trains
    ./swtbahn driver grab cargo
    ./swtbahn driver set_dcc_speed -b 5

  5. If you're done, you should shut the system down gracefully by invoking swtbahn admin shutdown

Client (Web Interface)

  1. Use a web browser to navigate to <IP>:<port>/assets/client.html
  2. Set the main track output (default is master).
  3. Click the Startup button.
  4. To be a train driver, select a train and click the Grab button. Enter a speed between 0 (stop) and 127 (max speed), and click the Drive button.
  5. To control a point, type the name of a point (see the YAML configuration file), select a position, and click the Set button.
  6. To control a signal, type the name of a signal (see the YAML configuration file), select an aspect, and click the Set button.

Logging into the Raspberry Pi remotely

Use ssh to the log in remotely. Suppose the Raspberry Pi is located at 141.13.106.30. Then use the command ssh [email protected].

Strategy for finding the IP address of the Raspberry Pi

There are two Raspberry Pis with the hostnames raspberrypi1 and raspberrypi2. The Raspberry Pi documentation lists several strategies for finding the IP address of a Raspberry Pi. If you change the Raspberry Pi's hostname, e.g., by editing /etc/hostname or by using the Raspberry Pi Configuration application, Avahi will automatically change the .local mDNS address. The MAC address of all Raspberry Pis begin with b8:27:eb.

  1. macOS: Try and resolve the Raspberry Pi's hostname, e.g., raspberrypi1.local, with multicast DNS:

    ping raspberrypi1.local

    If this fails, try the strategy for Linux.

  2. Linux: Use ifconfig to find your subnet, e.g., 192.168.1._. Use the nmap command to scan your subnet for connected devices, and look for the Raspberry Pi's hostname in the results:

    nmap -sn 192.168.1.0/24

  3. Windows: Use ipconfig to find your subnet, e.g., 192.168.1._. Install nmap and open the command line as an administrator for nmap to display the hostnames in its results. Use the nmap command to scan your subnet for connected devices, and look for the Raspberry Pi's hostname in the results:

    nmap -sn 192.168.1.0/24

    Use the command nmap -sn 192.168.1.0/24 | findstr /i "b8:27:eb" to quickly see a list of Raspberry Pis (MAC addresses only).

Sending files from the Raspberry Pi to a client computer:

Use scp on your client computer. For example, suppose the Raspberry Pi is located at 141.13.106.30 and has the user pi. To copy the the file /var/log/syslog from the Raspberry Pi via the user pi, use the command scp [email protected]:/var/log/syslog syslog

Grab-id and session-id behaviour

Grab-ids are used as tokens for trains. A client needs to grab a train before he can invoke commands for controlling the train. A train could only be grabbed by one client at a time.
Session-ids are used to check wether a grab-id was given out to the client on the current session or on a previous session.

Server side

When is a new session-id created?

  • If a user issues swtbahn admin startup and the system is not running already

When is the session-id invalidated?

  • If a user issues swtbahn admin shutdown

When is a grab-id created?

  • If a client issues swtbahn driver grab <train> and the train is available

When is a grab-id invalidated?

  • If a client issues swtbahn driver release and the train was grabbed by this client

Client side

When is the session-id fetched?

  • If the user issues swtbahn driver grab <train> and the train is available and the client has not already grabbed a train

When is the session-id reset?

  • If the user issues swtbahn driver release
  • If the user issues any swtbahn driver command and the session-id or grab-id is not the same as the one at the server
  • If the user issues swtbahn admin shutdown and the system was running
  • If the user issues swtbahn config

When is a grab-id fetched?

  • If the user issues swtbahn driver grab <train> and the train is available and the client has not already grabbed a train

When is a grab-id reset?

  • If the user issues swtbahn driver release
  • If the user issues any swtbahn driver command and the session-id or grab-id is not the same as the one at the server
  • If the user issues swtbahn admin shutdown and the system was running
  • If the user issues swtbahn config