Subscribe event hangs up after Device Server start

# 8 years ago
gnyiri	hi, I've been working on a tool that is able to monitor Device Servers and Devices using the Starter device and the administration devices. To capture the state transitions of the devices, the tool will subscribe to the CHANGE_EVENT of the State attribute of all devices being monitored. This works fine when the Device Servers are already running when the tool launches but there is a hang-up when the tool is trying to subscribe to the State Change events right after the restart of the associated Device Server. The scenario is as follows (given Device as the target device): 1) identify Starter device of the Host where Device Server of Device is running 2) subscribe to CHANGE_EVENT of attribute 'RunningServers' of the Starter 3) stop Device Server by sending DevStart command to Starter 4) when 'RunningServers' CHANGE_EVENT arrives, start polling of 'State' attribute of Device (if not yet) 5) subscribe to 'State' event of Device –> HANG The device proxy used in 4) and 5) looks OK, even ping provides a reasonable ping time before calling subscribe_event. Any idea about what went wrong? Thanks in advance, Gergely

# 8 years ago

hi,
I've been working on a tool that is able to monitor Device Servers and Devices using the Starter device and the administration devices.

To capture the state transitions of the devices, the tool will subscribe to the CHANGE_EVENT of the State attribute of all devices being monitored. This works fine when the Device Servers are already running when the tool launches but there is a hang-up when the tool is trying to subscribe to the State Change events right after the restart of the associated Device Server.

The scenario is as follows (given Device as the target device):

1) identify Starter device of the Host where Device Server of Device is running
2) subscribe to CHANGE_EVENT of attribute 'RunningServers' of the Starter
3) stop Device Server by sending DevStart command to Starter
4) when 'RunningServers' CHANGE_EVENT arrives, start polling of 'State' attribute of Device (if not yet)
5) subscribe to 'State' event of Device –> HANG

The device proxy used in 4) and 5) looks OK, even ping provides a reasonable ping time before calling subscribe_event.

Any idea about what went wrong?
Thanks in advance,
Gergely

# 8 years ago
Pascal	Hi Your client is written in which language ? What is hanging ? Your device ? In which language is it written ? Which TANGO release ? Regards Pascal

# 8 years ago
gnyiri	hi, the client is written in Python. A PyTango Device Proxy is hanging in my client. I tried both Tango 8 and 9. Results are the same. Regards, Gergely

# 8 years ago
Andy	Hi Gergeley, can you send us the code of the Python server which hangs and we can take a look. Regards Andy