Remote Access to a Midas experiment: Difference between revisions

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mserver provides remote access to any MIDAS client. It is needed when one or more of the MIDAS clients for an experiment are running on a different host. In this case, an mserver client must be started on the host where the experiment resides.
<div style="column-count:4;-moz-column-count:4;-webkit-column-count:4">
* [[Feature_listing|Feature Listing]]
* [[mlogger|Midas server]]
* [[Online_Database|Online Database]]
</div>


For example, if there is no mserver client is running on host dasdevpc2, then an attempt to run a client on dasdevpc2 from a remote computer (isdaq01) will result in an error message:


[bnmr@isdaq01 ~/online]$ odb -e t2kgas -h dasdevpc2
Cannot connect to remote host
If an mserver client is now started on host dasdevpc2,


[suz@dasdevpc2 ~]$ mserver -D
As Midas support remote frontend, the method to connect the frontend to the backend is through a daemon '''[[mserver]]''' providing the necessary interface at the backend computer for accepting the frontend connection. This client requesting connection to a particular Midas experiment, will have to provide arguments such as::
mserver started interactively
* The backend node name to which it wants to connect
Becoming a daemon...
* The name of the Midas experiment to connect
Now one can connect to the remote experiment :
* The port through which it wants to connect (optional)


[bnmr@isdaq01 ~/online]$ odb -e t2kgas -h dasdevpc2
Possible restriction can be enforced to prevent undesired node to connect to the backend. The '''[[[mserver|Midas server]]''' will take as argument a list of clients nodes allowed to connect to any experiment on this backend node.
[dasdevpc2:t2kgas:S]/>quit
The mserver utility usually runs in the background and doesn't need to be modified. In the case where debugging is required, the mserver can be started with the -d flag which will write an entry for each transaction to a log file /tmp/mserver.log . The log entry contains the time stamp and RPC call request.
More than one mserver can be started on a system, provided they use different tcp ports. This is useful if, for example, different versions of MIDAS are in use on a single host at the same time. To start a version of mserver on a different port, use the -p argument, e.g. mserver -p XXXX -D
To connect a client to this version of mserver, use the format "hostname:port", e.g.
 
  fe_test -h lin08:7066 -e expt
 
mserver arguments
 
Arguments
[-h ] : help
[-s ] : Single process server
[-t ] : Multi thread server
[-m ] : Multi process server (default)
[-p ] : Port number; listen for connections on non-default tcp port
[-d ] : Write debug info to /tmp/mserver.log
[-D ] : Become a Daemon

Revision as of 19:53, 15 February 2014


As Midas support remote frontend, the method to connect the frontend to the backend is through a daemon mserver providing the necessary interface at the backend computer for accepting the frontend connection. This client requesting connection to a particular Midas experiment, will have to provide arguments such as::

  • The backend node name to which it wants to connect
  • The name of the Midas experiment to connect
  • The port through which it wants to connect (optional)

Possible restriction can be enforced to prevent undesired node to connect to the backend. The [[[mserver|Midas server]] will take as argument a list of clients nodes allowed to connect to any experiment on this backend node.

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