2008-Oct-16 JMB

How to setup an NGAS Server to subscribe to new data files being archived
on another NGAS server.

For example :

NGAS server : evlangas-1.evla.nrao.edu
Ingests data from the EVLA backend via NGAMS_ARCHIVE_CLIENT

For subscriptions, this host is the 'data provider'.


NGAS Server : newtech-4.aoc.nrao.edu
Receives data files from evlangas-1 by subsscription service.

This host is the 'data subscriber', the client in the subscription
process..


The subscriber-client (newtech-4) configures itself by entries
in its ngamsServer.conf file.


Set ngamsServer.conf on data subscriber (client : newtech-4) to automatically start
a subscription when ngas is started...

  <SubscriptionDef AutoUnsubscribe="1"
                   BackLogExpTime="28T00:00:00"
                   Enable="1"
                   SuspensionTime="0T00:03:00">
    <Subscription  HostId="evlangas-1.evla.nrao.edu"
                   PortNo="7777"
                   Priority="1"
                   SubscriberUrl="http://newtech-4.aoc.nrao.edu:7777/ARCHIVE"
                   FilterPlugIn="ngamsMimeTypeFilterPI"
                   FilterPlugInPars="mime_types=application/x-vla"/>
  </SubscriptionDef>


Now on newtech-4, /etc/init.d/ngamsServer stop 

Note this removes the row in db: evlangas, table: ngas_subscribers if one was
present.

Now on newtech-4, /etc/init.d/ngamsServer start

A new row appears in the db: evlangas, table: ngas_subscribers

This works. A new row is entered in the Oracle db : evlangas on evlangas-1 
table ngas_subscriber. Look's correct.

Push a new .dat file into evlangas-1, it gets copied to newtech-4.

Note: Thus far I have not successfully used ngamsCClient  ... -cmd SUBSCRIBE ...

Making changes to the ngamsServer.conf (on newtech-4, the data subscriber)
works........