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Get message metadata within rosjava

asked 2014-05-21 09:22:10 -0500

Using rosjava, how would one get the timestamp and other metadata for a message?

Answering in the form of an adaptation of the Listener class in the rosjava tutorial would be particularly useful.

Thanks!

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answered 2014-05-27 07:04:09 -0500

After talking with a colleague, I have a rough understanding of this issue now. My understanding is below, though I haven't verified it via further internet research.

Headers are a field type that can be added to a message definition. A pre-defined message cannot simply have a header added to it at runtime (as I thought it could). Because of this, the Message class in rosjava does not have the ability to get the header from the message. Rather, a specific message class that inherits from Message could have a getHeader() method written in for it.

Please feel free to correct any misconceptions here.

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answered 2014-05-21 11:42:35 -0500

damonkohler gravatar image

ROS messages don't have metadata. Timestamps are encoded in the Header sub-message of "stamped" messages. So, message.getHeader().getStamp().

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Good to hear from you, Damon. Thanks for your timely response. There is apparently no getHeader() method in org.ros.internal.message.Message, either in my local copy or at http://docs.rosjava.googlecode.com/hg/rosjava_core/html/javadoc/org/ros/internal/message/Message.html. Any suggestions?

bradknox gravatar imagebradknox ( 2014-05-21 12:42:21 -0500 )edit

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Asked: 2014-05-21 09:22:10 -0500

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Last updated: May 27 '14