Multiple-Tango Host

General Development
1

Hi All

How to define multiple TANGO_HOST ?

Thanks and Regards
TCS-GMRT Team

2

Hi TCS-GMRT,

good question. TANGO_HOST refers to the hos:port address of the TANGO database where a device is defined. The concept of multiple TANGO_HOST means that you can communicate with devices from multiple TANGO_HOST databases in the same client. You do this by specifying the TANGO_HOST in the name of the device e.g. a client can talk to (i.e. create a Device Proxy) to the following devices //host1:port1/my/device/1 and //host2:port2/my/device/2. The client is then connected to multiple TANGO_HOSTs. If the TANGO_HOST is not specified then it the default TANGO_HOST is used.

This should be confused with a related concept namely the possibility to have multiple DataBaseds device servers serving the same TANGO_HOST i.e. database. Each DataBaseds listens on a different port and/or host but connects to the same TANGO database. The multiple addresses are then specified in the same TANGO_HOST. The client tries to connect to each address in sequence and connects to the first one that replies. NOTE this is NOT what we mean by multiple TANGO_HOST. This feature is used to improve reliability of a large TANGO control system.

I hope my explanation is clear!

Andy

3

Hello Andy

Thank you for the instant reply. Got you point.Just want to ask how to specify multiple addresses in TANGO_HOST variable ?
For example:
TANGO_HOST=localhost:10000, 10.29.214.325:10000

Should the multiple host in the TANGO_HOST variable be comma separated or space separated or anything else ? I am not clear about the method of the above problem.

Thanks and Regards
TCS-GMRT Team

4

Hello TCS_GMRT,

I’ve never used this feature but I’ve learned from the manual that it uses comma as separator:
http://www.esrf.eu/computing/cs/tango/tango_doc/kernel_doc/ds_prog/node10.html#SECTION0010110000000000000000

Cheers,
Zibi

5

Hi Zibi

Thanks a lot. Will try this feature and let u know.

Thanks and Regards
TCS-GMRT team

6

Here is the example from the ESRF:

TANGO_HOST=hostname:11000,hostname:10000

Where hostname is the name of the host where the database servers are running. In our case they are the same but they don’t have to be.

Andy