Daniel,

If your goal is to check whether or not an action server is processing a
goal, there's no tool currently to give you that information. It would be
simple to write something that listens to status and lets you know if any
goals for a given server are marked as active, and it wouldn't be
unreasonable to put this logic into the action client. You should feel free
to create a ticket for this feature request. With that said, action servers
have a number of different policies when it comes to handling goals, as
Blaise mentioned, and will do different things when you send a goal to them.
I can, however, see use cases where you might not want to send a goal to an
action server when it is already processing a request.

Hope all is well,

Eitan

On Fri, Oct 22, 2010 at 8:53 AM, Blaise Gassend <blaise@willowgarage.com>wrote:

> Hi Daniel,
>
> getState() is telling you the state of the client's current goal, not
> the state of the server. Hence, if there is no goal, getState is
> meaningless. This makes sense because a server could have the ability
> to handle multiple goals in parallel. Hence, there isn't a single
> state for the server that you can query.
>
> I imagine that what you are trying to do is determine if a server that
> can only handle a single goal is currently busy. I don't think that
> there is a general answer to that question. Some servers might reject
> your goal if they are already busy. Others might interrupt the
> existing goal. Let's see what others have to reply.
>
> Blaise
>
> On Fri, Oct 22, 2010 at 12:51 AM, Daniel Stonier <d.stonier@gmail.com>
> wrote:
> >
> > Just a quick question with regards to the simple action client - why is
> > using the getState() method considered improper when there is no goal
> > (action client outputs an ROS_ERROR when you do so). Is there another
> means
> > of querying the server to know whether it is currently handling a goal or
> > not?
> > Or perhaps, am I mistaken in thinking that I should be needing to?
> > Regards,
> > Daniel Stonier.
> > --
> > Phone : +82-10-5400-3296 (010-5400-3296)
> > Home: http://snorriheim.dnsdojo.com/
> > Yujin Robot: http://www.yujinrobot.com/
> > Eros: http://www.ros.org/wiki/eros
> > Embedded Control Libraries:
> http://snorriheim.dnsdojo.com/redmine/wiki/ecl
> >
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