[ros-users] Generic transport plugins and shared memory

[Cedric Pradalier]

On 06/06/2010 04:01 PM, Dejan Pangercic wrote:
> Dear Cedric,
>
> where are the packages
> message_transport
> sharedmem_transport
> coming from? Are those yours?
>
>    
Hi,

Yes I've developed these package myself.
However, if you're looking for shared-memory transfer, there seems to be 
more interest&potential in developing the nodelet architecture.
If you're interested in a generic transport plugin architecture, then I 
think my packages are doing the job (and also offering some 
shared-memory advantages).

I'm happy to share the packages if there is an interest. Note that there 
has not been many users yet ;)
We don't have an official ros svn yet, so you would have to contact me 
directly at this stage.

Cheers


> cheers, D.
> On Mon, May 10, 2010 at 11:09 PM, Cedric Pradalier
> <cedric.pradalier at mavt.ethz.ch>  wrote:
>    
>> Hi all,
>>
>> I'm not quite sure who will be interested by this message, but since we
>> don't have (yet) our official ros repository, I'll send the info here.
>> Please feel free to contact me or discuss on the list if you want more
>> information.
>>
>> Given the long travel time coming back from ICRA, and my experience with
>> the image_transport plugin architecture, I found that being only able to
>> make transport_plugin and shared memory only for sensor_msgs::Image was
>> a bit limiting.
>>
>> So I've adapted the image_transport framework using templates to make it
>> generic, and integrated a generic shared memory transport into the
>> framework. I've also ported the compressed and theora transport, but
>> still keeping them specialised to Image.
>>
>> The resulting framework allow to create a starting set of plugins (raw
>> and sharedmem) for (e.g) PointCloud using the following code:
>>
>> manifest.cpp:
>> #include<pluginlib/class_list_macros.h>
>> #include<message_transport/raw_publisher.h>
>> #include<message_transport/raw_subscriber.h>
>> #include<sharedmem_transport/sharedmem_publisher.h>
>> #include<sharedmem_transport/sharedmem_subscriber.h>
>> #include<sensor_msgs/PointCloud.h>
>>
>> // Raw class
>> PLUGINLIB_REGISTER_CLASS(raw_pub,
>>     message_transport::RawPublisher<sensor_msgs::PointCloud>,
>>     message_transport::PublisherPlugin<sensor_msgs::PointCloud>)
>> PLUGINLIB_REGISTER_CLASS(raw_sub,
>>     message_transport::RawSubscriber<sensor_msgs::PointCloud>,
>>     message_transport::SubscriberPlugin<sensor_msgs::PointCloud>)
>>
>> // Sharedmem class (the PointCloud message contains a header, which the
>> publisher uses)
>> PLUGINLIB_REGISTER_CLASS(sharedmem_pub,
>>
>> sharedmem_transport::SharedmemPublisherWithHeader<sensor_msgs::PointCloud>,
>>
>>     message_transport::PublisherPlugin<sensor_msgs::PointCloud>)
>> PLUGINLIB_REGISTER_CLASS(sharedmem_sub,
>>     sharedmem_transport::SharedmemSubscriber<sensor_msgs::PointCloud>,
>>     message_transport::SubscriberPlugin<sensor_msgs::PointCloud>)
>>
>> Note that a specialised list_transport must be compiled for each message
>> classes where plugins are developed:
>> list_transport.cpp:
>> #include<message_transport/list_transport.h>
>> #include<sensor_msgs/PointCloud.h>
>>
>> using namespace message_transport;
>>
>> int main(int argc, char** argv)
>> {
>>     LIST_TRANSPORT("pointcloud_transport",sensor_msgs::PointCloud);
>>
>>     return 0;
>> }
>>
>> As an instance, the plugin declaration for the compressed images starts
>> with:
>>
>> class CompressedPublisher : public
>>     message_transport::SimplePublisherPlugin<sensor_msgs::Image,
>>         sensor_msgs::CompressedImage>
>> { ...
>>
>> protected:
>>   virtual void publish(const sensor_msgs::Image&  message,
>>           const message_transport::SimplePublisherPlugin<sensor_msgs::Image,
>>                 sensor_msgs::CompressedImage>::PublishFn&  publish_fn)
>> const ;
>> };
>>
>>
>> For the moment, my message_transport stack contains -- i.e. written and
>> tested -- (indentation means dependency):
>> message_transport_common
>> ->sharedmem_transport
>>   ->pointcloud_transport
>>   ->imagem_transport
>>     ->compressed_imagem_transport
>>     ->theora_imagem_transport
>>
>> Other plugins are obviously possible and easy to write, to extend the
>> library for image and pointcloud or for other types of message.
>>
>> HTH
>>
>> --
>> Dr. Cedric Pradalier
>> http://www.asl.ethz.ch/people/cedricp
>>
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
>>      
>
>
>    


-- 
Dr. Cedric Pradalier
http://www.asl.ethz.ch/people/cedricp