[ros-users] trigger goal from inside actionlib server

[Blaise Gassend]

BTW, to solve this you probably want whatever is calling
triggerGoalInternallyCallback to be on a different queue. Or you could
spin up a thread to do the action triggering, and return immediately.

On Mon, Oct 18, 2010 at 12:35 PM, Blaise Gassend
<blaise at willowgarage.com> wrote:
> Where is your triggerGoalInternallyCallback being called from? If it
> is being called from ROS on the same queue that your ActionServer is
> using then I would expect this code to deadlock. Indeed, ROS would be
> waiting for triggerGoalInternallyCallback to return before calling
> subsequent callbacks, and those callbacks are necessary for the action
> to get carried out.
>
> Blaise
>
> On Mon, Oct 18, 2010 at 12:27 PM, Axelrod, Benjamin <baxelrod at irobot.com> wrote:
>> Thanks.  I did try to create a client inside the server.  For some reason I
>> thought it didn’t work. But maybe I messed something up.  I think it would
>> hang when I called tempclient.waitForServer().
>>
>>
>>
>> Vijay: I don’t want the server to be active on a null goal.  I do want a
>> goal.  I want to provide the goal from inside the client.  This is to
>> simplify testing and debugging.
>>
>>
>>
>> This is the pattern I am looking for:
>>
>>
>>
>> void MyActionServer::goalCallback()
>>
>> {
>>
>>     // accept goal from client
>>
>>     goal_ = *server_.acceptNewGoal();
>>
>>     this->performAction(goal_);
>>
>> }
>>
>>
>>
>> void MyActionServer::triggerGoalInternallyCallback()
>>
>> {
>>
>>     // create a goal for internal testing
>>
>>     MyActionServerGoal tempGoal;
>>
>>     tempGoal.foo = “bar”;
>>
>>     this->performAction(tempGoal);
>>
>> }
>>
>>
>>
>> However, I have no performAction() method.  And because the service routine
>> uses a timer, and relies on the server being active, it is not so easy to
>> split out.
>>
>>
>>
>> So, ideally, I would have this:
>>
>>
>>
>> void MyActionServer::triggerGoalInternallyCallback()
>>
>> {
>>
>>     // create a goal for internal testing
>>
>>     MyActionServerGoal tempGoal;
>>
>>     tempGoal.foo = “bar”;
>>
>>     this->server_->setGoal(tempGoal);
>>
>> }
>>
>>
>>
>> Which would then trigger the MyActionServer::goalCallback().
>>
>>
>>
>>
>>
>>
>>
>> From: ros-users-bounces at code.ros.org [mailto:ros-users-bounces at code.ros.org]
>> On Behalf Of Vijay Pradeep
>> Sent: Monday, October 18, 2010 1:21 PM
>> To: User discussions
>> Subject: Re: [ros-users] trigger goal from inside actionlib server
>>
>>
>>
>> Hi Ben,
>>
>> If this is what you want to do, I would go with Blaise's suggestion and send
>> a goal using the action client with no callbacks registered.
>>
>> However, I'm not really sure why you would want to have the
>> SimpleActionServer be active on null goal.  Understanding your use case
>> would help us get a feel for exactly what functionality you need.
>>
>> Vijay
>>
>> On Mon, Oct 18, 2010 at 9:44 AM, Blaise Gassend <blaise at willowgarage.com>
>> wrote:
>>
>> Hi Ben,
>>
>> On Mon, Oct 18, 2010 at 9:06 AM, Axelrod, Benjamin <baxelrod at irobot.com>
>> wrote:
>>> I have an actionlib server and I would like to be able to trigger its own
>>> goal.  I don’t need any callbacks for goal accepted, feedback, or even
>>> result.  I just want to manually set the server to be active.  Is this
>>> possible?  I can’t figure out a way to do this.
>>
>> Why don't you use a SimpleActionClient to set the goal? If you don't
>> specify the callbacks when setting you call sendGoal, those callbacks
>> default to being null. Is that not what you want?
>>
>> http://www.ros.org/doc/api/actionlib/html/classactionlib_1_1SimpleActionClient.html#ae6a2e6904495e7c20c59e96af0d86801
>>
>>> It might be nice if  actionlib::SimpleActionServer::acceptNewGoal() was
>>> overloaded to accept a goal parameter.  That would set the server active,
>>> but with NULL callbacks.
>>
>> Is there a strong reason for wanting to do this without explicitly
>> having a client?
>>
>> Blaise
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>>
>>
>> --
>> Vijay Pradeep
>> Systems Engineer
>> Willow Garage, Inc.
>> vpradeep at willowgarage.com
>>
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>>
>>
>