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Why rxgraph needs to open many port continuously?

asked 2012-03-12 17:49:10 -0600

Hi, I want to know the data transferring between master and nodes.

I use Wireshark and set filter to tcp.port == 11311(that is, only to catch data from port 11311) to catch the data packets of master.

The weird thing is, when I execute rxgraph, master sends data to different ports(always increase by 2 or 4; For instance, 11311 send data to 40081, 40085, 40087, ...etc) of rxgraph.

I am wondering why rxgraph keeps opening new port instead of fixing to one port?

Thanks in advance.

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Due to a bug I cannot post an 'answer', but the reason why it opens so many connections is that it must poll each node to determine status. The Master is not responsible for making connections, as ROS is peer to peer, so determining the graph requires contacting each peer.

kwc gravatar imagekwc ( 2012-03-12 18:51:11 -0600 )edit

Is rxgraph needs to get a list from master every period of time, and use that list to connect all nodes to draw all relations graph? So when rxgraph get the latest list then it will open new ports to connect to nodes even the list still the same. Is that right?

sam gravatar imagesam ( 2012-03-13 05:30:59 -0600 )edit

Yes, it has to keep polling, otherwise it cannot find broken connections

kwc gravatar imagekwc ( 2012-03-13 06:32:58 -0600 )edit

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answered 2012-03-12 23:17:34 -0600

This is the answer from kwc.

"Due to a bug I cannot post an 'answer', but the reason why it opens so many connections is that it must poll each node to determine status. The Master is not responsible for making connections, as ROS is peer to peer, so determining the graph requires contacting each peer."

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Asked: 2012-03-12 17:49:10 -0600

Seen: 138 times

Last updated: Mar 12 '12