How to create a server and connect it to another server?

[Xie-Tian]

Hi, I ran into a problem: I need to construct a server using labrad, and meanwhile, treat it as a client, connecting it to another server. Here's my easy code.

from labrad.server import LabradServer, setting
import labrad

SERVERNAME = 'tian'

cxn = labrad.connect('192.xxx.xxx.xx', password='xxxxxxxxx', tls_mode='off')

class Tian_Server(LabradServer):

    name = SERVERNAME

    def initServer(self):
        pass

if __name__ == "__main__":
    from labrad import util
    util.runServer( Tian_Server() )
```python

But it seems that there is a twisted.internet.error.

[maffoo]

There's no need to call labrad.connect when running a server. Instead you should pass the configuration such as the manager host and password as command line arguments, or set them in environment variables. When the server starts it will connect to the labrad manager on its own using that configuration.

[Xie-Tian]

Thanks for your quick reply! If I want to set them in environment variables, is in this way:?

from labrad.server import LabradServer, setting
import labrad

SERVERNAME = 'tian'

class Tian_Server(LabradServer):

    name = SERVERNAME

    def initServer(self):
        cxn = labrad.connect('192.xxx.xxx.xx', password='xxxxxxxxx', tls_mode='off')
        dac = cxn.laserdac_server
        pass

if __name__ == "__main__":
    from labrad import util
    server = Tian_Server()
    util.runServer( server )

But it raises a timeout error when initiating.

[DanielSank]

To run a command in bash with environment variables, do this

LABRADHOST=whatever LABRADPASSWORD=whatever python myserver.py

[maffoo]

Environment variables are set in your shell before launching python, for example using the export command in bash, or the set command in windows (alternately, in windows you can set environment variables in the system configuration dialogs so that they will be available if you launch servers in other ways). You can also pass command-line arguments to the program when you run it.

So, suppose you save the server in a script called tian_server.py, then you could do the following in a windows command prompt:

set LABRADHOST=192.xxx.xxx.xxx
set LABRADPASSWORD=xxxxxxxx
python tian_server.py

or, with command line arguments:

python tian_server.py --host=192.xxx.xxx.xxx --password=xxxxxxx

In the server itself, as I said, there is no need to call labrad.connect. The server will connect to the labrad manager and you can just reuse the connection that it has, which is available as self.client.

[Xie-Tian]

Thanks for kind instructions. I do the following in a windows command prompt: set LABRADHOST=192.xxx.xxx.xxx set LABRADPASSWORD=xxxxxxxx python tian_server.py

It now could run. But how could I use it by self.client? I try in this way to connect:

from labrad.server import LabradServer, setting
import labrad

SERVERNAME = 'tian'

class Tian_Server(LabradServer):

    name = SERVERNAME

    def initServer(self):

        pass

    @setting(1, "test")
    def test(self,c):
        cxn = yield self.client
        dac = cxn.laserdac_server

if __name__ == "__main__":
    from labrad import util
    server = Tian_Server()
    util.runServer( server )

I want use dac, but I shows that: dac = cxn.laserdac_server exceptions.AttributeError: 'ClientAsync' object has no attribute 'laserdac_server' [payload=None]

Thanks a lot!