Difference between revisions of "ROS2"

Latest revision as of 15:00, 3 January 2019

About

Use ROS2 in Elphel single or multi-camera systems. The cameras are 10393 system boards based on Xilinx Zynq, ARM.

Goals

Notes:

Controlling and initializing of multi-camera systems is already implemented using PHP API (autocampars.php), Python and lighttpd.
Using ROS2 is intended to simplify/standardize the above.
Using ROS2 is intended to make cameras compatible with other hardware supported by ROS1/2.

Having ROS2 cross-compiled and installed on each camera:

Initialize cameras in a pre-defined multi-camera system - sync and sequence critical init
Control multiple cameras from any camera of the system - parameters, recording
Control multiple cameras from a PC (with ROS2 for PC installed).
Control multiple cameras from a network device (w/o ROS2 installed, but with a browser) - by accessing a web server running on a camera interfaced with ROS2 of the camera. Can use nodejs or just lighttpd+php.

Status

Development

News

[2019/01/03] Updated the cross-compiled version from ardent to bouncy. PC was already at bouncy because rclnodejs will work with bouncy only (not yet compatible with crystal).

Updated because bouncy would not 'see' ardent nodes & services and vice versa.

Interfaces

ROS2 nodes communicate over:

1 GigE LAN or (possibly) wifi (camera1-camera2..N, pc-camera1..N, pc1-pc2..M)
within a single device

Notes:

image sensors, IMS (or GPS & IMU), any other sensors are attached to cameras via a custom interface or USB, with appropriate driver support.
normally cameras in the system are synced with a custom trigger cable - this is setup over network
any device attached to PC?

ROS2 on Zynq

Installation

For Embedded Linux (but not Ubuntu Distro) use meta-ros.git. What about meta-ros2?

TODO: Include meta-ros.git in elphel393 build system.

DONE: included a forked version okdzhimiev/meta-ros

Include meta-ros to elphel393

Add path to bblayers.conf
Add to "IMAGE_INSTALL_append" of core-image-elphel393.bb:

packagegroup-ros2-world \

Notes

Cross-compilation for ARM
ROS2 for python populates /usr/lib/python3.5/site-packages/ so python scripts can live anywhere.
For command line apps, like ros2 ..., if AMENT_PREFIX_PATH is not set then:

OSError: Environment variable 'AMENT_PREFIX_PATH' is not set or empty

Useful commands (command line):

export AMENT_PREFIX_PATH=/usr

ros2 pkg list
ros2 node list
ros2 srv list
ros2 srv show std_srvs/Trigger
ros2 msg list
ros2 msg show std_msgs/String

Demos

talker-listener cpp

# terminal 1:
export AMENT_PREFIX_PATH=/usr
ros2 run demo_nodes_cpp talker

# terminal 2:
export AMENT_PREFIX_PATH=/usr
ros2 run demo_nodes_cpp listener

Workflow

Use example recipes from meta-ros.git
bitbake package-name, check output and logs in the poky build tree
List package in core-image-elphel393.bb's IMAGE_INSTALL_append

TODO:

Add target-scp and an example empty recipe

ROS2 on PC

Installation

Google and follow the general instructions.

Notes

Switched to installing from a fat archive
Terminal setup:

source /path/setup.bash

Workflow

Create a workspace
Create some packages inside or clone - they have a vcs tool to clone all repos from a text file.
Install colcon
Then build with colcon
New packages will not get installed anywhere. They live in their folders.
To use a package:

source ~/ros2_ws/some-package/install/setup.bash
ros2 pkg list
then run anything in this terminal

Python scripts can live anywhere - just run them from that sourced terminal

ROS2 in Docker

docker pull osrf/ros2:bouncy-desktop
docker run -i -t osrf/ros2:bouncy-desktop 
No network, no colcon, no ament...

ROS2 General Notes

Notes

SROS is Secure ROS or something

Useful links

ErleRobotics Tutorials on ROS2 - very useful

Ament tutorial - build system for new packages
- works and supported in meta-ros
- will not work for PC because repo hashes moved on?

Colcon tutorial - newest build system for new packages
- works for PC, even in 16.04
- not supported in meta-ros (as of 2018/12/07)
- colcon docs

About meta-ros and about meta-ros2 - are they merged?

Networking:

ROS on DDS

... 
if you are concerned about latency, like for soft real-time, you can basically tune DDS to be just a UDP blaster. In another scenario you might need something that behaves like TCP, but needs to be more 
tolerant to long dropouts, and with DDS all of these things can be controlled by changing the QoS parameters.
...

ROS2 Services:

Reference ROS repos

ROS1

Won't build. More info.

Difference between revisions of "ROS2"

Latest revision as of 15:00, 3 January 2019

Contents

About

Goals

Status

News

Interfaces

ROS2 on Zynq

Installation

Include meta-ros to elphel393

Notes

Demos

talker-listener cpp

Workflow

ROS2 on PC

Installation

Notes

Workflow

ROS2 in Docker

ROS2 General Notes

Notes

Useful links

Reference ROS repos

ROS1

Navigation menu

Personal tools

Namespaces

Variants

Views

More

Search

Navigation

Tools

@@ Line 3: / Line 3: @@
 ==<font color='blue'>Goals</font>==
-<font color='green'>Notes:
+<font color='green'>'''Notes:'''
 * Controlling and initializing of multi-camera systems is already implemented using PHP API (autocampars.php), Python and lighttpd.
 * Using ROS2 is intended to simplify/standardize the above.
@@ Line 17: / Line 17: @@
 ==<font color='blue'>Status</font>==
 Development
+==<font color='blue'>News</font>==
+* [2019/01/03] Updated the cross-compiled version from '''ardent''' to '''bouncy'''. PC was already at '''bouncy''' because rclnodejs will work with '''bouncy''' only (not yet compatible with '''crystal''').
+Updated because ''bouncy'' would not 'see' ''ardent'' nodes & services and vice versa.
 ==<font color='blue'>Interfaces</font>==
@@ Line 32: / Line 35: @@
 ===Installation===
 * For Embedded Linux (but not Ubuntu Distro) use [https://github.com/bmwcarit/meta-ros.git meta-ros.git]. What about <font color='red'>[https://github.com/erlerobot/meta-ros2 meta-ros2]</font>?
-<font color='green'>'''TODO:''' Include [https://github.com/bmwcarit/meta-ros.git meta-ros.git] in [https://git.elphel.com/Elphel/elphel393 elphel393] build system.</font>
+<font color='green'><s>'''TODO:''' Include [https://github.com/bmwcarit/meta-ros.git meta-ros.git] in [https://git.elphel.com/Elphel/elphel393 elphel393] build system.</s></font>
+<font color='green'>'''DONE:''' included a forked version [https://github.com/okdzhimiev/meta-ros/ okdzhimiev/meta-ros]</font>
+====Include meta-ros to elphel393====
+* Add path to bblayers.conf
+* Add to "IMAGE_INSTALL_append" of core-image-elphel393.bb:
+ <font size='2'>packagegroup-ros2-world \</font>
+===Notes===
+* Cross-compilation for ARM
+* ROS2 for python populates '''/usr/lib/python3.5/site-packages/''' so python scripts can live anywhere.
+* For command line apps, like ''ros2 ...'', if AMENT_PREFIX_PATH is not set then:
+ <font size='1' color='red'>'''OSError: Environment variable 'AMENT_PREFIX_PATH' is not set or empty'''</font>
+* Useful commands (command line):
+ <font size='2'>export AMENT_PREFIX_PATH=/usr</font>
+ <font size='2'>ros2 pkg list
+ ros2 node list
+ ros2 srv list
+ ros2 srv show std_srvs/Trigger
+ ros2 msg list
+ ros2 msg show std_msgs/String</font>
+===Demos===
+====talker-listener cpp====
+ <font size='2'>''# terminal 1:''
+ export AMENT_PREFIX_PATH=/usr
+ ros2 run demo_nodes_cpp talker
+ ''# terminal 2:''
+ export AMENT_PREFIX_PATH=/usr
+ ros2 run demo_nodes_cpp listener</font>
 ===Workflow===
+* Use example recipes from [https://github.com/bmwcarit/meta-ros.git meta-ros.git]
+* ''bitbake package-name'', check output and logs in the poky build tree
+* List package in core-image-elphel393.bb's ''IMAGE_INSTALL_append''
+<font color='green'>'''TODO:'''
+* Add ''target-scp'' and an example empty recipe</font>
 ==<font color='blue'>ROS2 on PC</font>==
 ===Installation===
 * Google and follow the [https://index.ros.org/doc/ros2/ general instructions].
-<font color='green'>'''Notes:'''
-* '''apt install ros-bouncy-desktop''' available in 18.04, <font color='red'>n/a in 16.04</font>
-* '''apt install ros-ardent-desktop''' available in 16.04</font>
-===Workflow===
+===Notes===
-* ROS2 will get installed to '''/opt/ros/<name>''', <name> = ardent, bouncy.
+* Switched to installing from a ''fat'' archive
 * Terminal setup:
-  source /opt/ros/bouncy/setup.bash
+  <font size='2'>''source /path/setup.bash''</font>
- or
- source /opt/ros/bouncy/local_setup.bash
+===Workflow===
 * Create a workspace
 * Create some packages inside or clone - they have a [https://github.com/dirk-thomas/vcstool vcs tool] to clone all repos from a text file.
 * Install [https://colcon.readthedocs.io/en/released/user/quick-start.html colcon]
 * Then build with colcon
-* Packages will not get installed to /opt/ros/bouncy/... Instead they will stay in their folders.
+* New packages will not get installed anywhere. They live in their folders.
 * To use a package:
-  source /opt/ros/bouncy/setup.bash
+  <font size='2'>source ~/ros2_ws/some-package/install/setup.bash
- source ~/ros2_ws/some-package/install/local_setup.bash
   ros2 pkg list
-  then run anything in this terminal
+  then run anything in this terminal</font>
 * Python scripts can live anywhere - just run them from that sourced terminal
-* [https://erlerobotics.gitbooks.io/erle-robotics-python-gitbook-free/udp_and_tcp/a_simple_tcp_client_and_server.html Good book about UDP?]
+==<font color='blue'>ROS2 in Docker</font>==
+ docker pull osrf/ros2:bouncy-desktop
+ docker run -i -t osrf/ros2:bouncy-desktop
+ No network, no colcon, no ament...
 ==<font color='blue'>ROS2 General Notes</font>==
 ===Notes===
 * SROS is Secure ROS or something
 ===Useful links===
-* [http://docs.erlerobotics.com/robot_operating_system/ros2/tutorials/tutorial_10 Tutorials ErleRobotics]
-* [https://github.com/intel/ros2_intel_realsense Intel RealSense]
-* [https://index.ros.org/doc/ros2/Ament-Tutorial/ Ament tutorial] - will not work for PC because it's outdated, will work in Yocto
-* [https://index.ros.org/doc/ros2/Colcon-Tutorial/ Colcon tutorial] - this one worked for PC
-* [https://discourse.ros.org/t/suggestions-for-std-srvs/1079/16 STD-SRVS '''discussion'''] & [https://github.com/ros2/examples/issues/4 ROS2 examples(?)]
-* [https://discourse.ros.org/search?q=meta-ros%20order%3Alatest About meta-ros]
-===Docker===
+* [http://docs.erlerobotics.com/robot_operating_system/ros2 ErleRobotics Tutorials on ROS2] - very useful
- docker pull osrf/ros2:bouncy-desktop
- docker run -i -t osrf/ros2:bouncy-desktop
+* [https://index.ros.org/doc/ros2/Ament-Tutorial/ Ament tutorial] - build system for new packages
- ...no network, no colcon, no ament...
+** works and supported in meta-ros
+** will not work for PC because repo hashes moved on?
+* [https://index.ros.org/doc/ros2/Colcon-Tutorial/ Colcon tutorial] - newest build system for new packages
+** works for PC, even in 16.04
+** not supported in meta-ros (as of 2018/12/07)
+** [https://colcon.readthedocs.io/en/released/user/how-to.html#build-only-a-single-package-or-selected-packages colcon docs]
+* [https://discourse.ros.org/search?q=meta-ros%20order%3Alatest About meta-ros] and [https://discourse.ros.org/search?q=meta-ros2%20order%3Alatest about meta-ros2] - are they merged?
-==<font color='blue'>ROS2 on Zynq</font>==
+Networking:
-Cross-compiled and installed in Yocto
-===Other links===
 * [http://design.ros2.org/articles/ros_on_dds.html ROS on DDS]
   <font size='2'>...
@@ Line 92: / Line 131: @@
 * [http://www.eprosima.com/index.php/resources-all/performance/40-eprosima-fast-rtps-performance FastRTPS benchmarks]
 * [http://docs.eprosima.com/en/latest/advanced.html FastRTPS max message size]
-* [https://wiki.ros.org/Services Request-Response is done with '''service''']. Format [https://wiki.ros.org/srv srv]
+* [https://erlerobotics.gitbooks.io/erle-robotics-python-gitbook-free/udp_and_tcp/a_simple_tcp_client_and_server.html Good book about UDP?]
-===Build===
+ROS2 Services:
-* Add path to bblayers.conf
-* Add to "IMAGE_INSTALL_append" of core-image-elphel393.bb:
- packagegroup-ros2-world \
-<font color='green'>'''Notes:'''
+* [https://wiki.ros.org/Services Request-Response is done with '''service''']. Format [https://wiki.ros.org/srv srv]
-* -</font>
+* [https://discourse.ros.org/t/suggestions-for-std-srvs/1079/16 STD-SRVS '''discussion'''] & [https://github.com/ros2/examples/issues/4 ROS2 examples(?)]
-===Work===
-====Available packages====
-* SSH session:
- root@elphel393:~# export AMENT_PREFIX_PATH=/usr
- root@elphel393:~# ros2 pkg list
- <font size='1'>builtin_interfaces
- demo_nodes_cpp
- example_interfaces
- geometry_msgs
- rcl
- rcl_interfaces
- rclcpp
- rclpy
- rcutils
- rmw
- rmw_fastrtps_cpp
- rosidl_cmake
- rosidl_generator_c
- rosidl_generator_cpp
- rosidl_parser
- rosidl_typesupport_interface
- rosidl_typesupport_introspection_c
- rosidl_typesupport_introspection_cpp
- sensor_msgs</font>
-====Test Talker and Listener====
-* SSH session 1:
- root@elphel393:~# export AMENT_PREFIX_PATH=/usr
- root@elphel393:~# ros2 run demo_nodes_cpp talker
-* SSH session 2:
- root@elphel393:~# export AMENT_PREFIX_PATH=/usr
- root@elphel393:~# ros2 run demo_nodes_cpp listener
-<font color='green'>'''Notes:'''</font>
-* It populates '''/usr/lib/python3.5/site-packages/''' so python scripts can be pretty much standalone
-* <font color='green'>If AMENT_PREFIX_PATH is not set (only for command line apps) then:</font>
- <font size='1'>Traceback (most recent call last):
-   File "/usr/bin/ros2", line 11, in <module>
-     load_entry_point('ros2cli==0.4.0', 'console_scripts', 'ros2')()
-   File "/usr/lib/python3.5/site-packages/ros2cli/cli.py", line 64, in main
-     rc = extension.main(parser=parser, args=args)
-   File "/usr/lib/python3.5/site-packages/ros2run/command/run.py", line 59, in main
-     executable_name=args.executable_name)
-   File "/usr/lib/python3.5/site-packages/ros2run/api/__init__.py", line 30, in get_executable_path
-     paths = get_executable_paths(package_name=package_name)
-   File "/usr/lib/python3.5/site-packages/ros2pkg/api/__init__.py", line 41, in get_executable_paths
-     prefix_path = get_prefix_path(package_name)
-   File "/usr/lib/python3.5/site-packages/ros2pkg/api/__init__.py", line 34, in get_prefix_path
-     prefix_path = get_package_prefix(package_name)
-   File "/usr/lib/python3.5/site-packages/ament_index_python/packages.py", line 49, in get_package_prefix
-     content, package_prefix = get_resource('packages', package_name)
-   File "/usr/lib/python3.5/site-packages/ament_index_python/resources.py", line 37, in get_resource
-     for path in get_search_paths():
-   File "/usr/lib/python3.5/site-packages/ament_index_python/search_paths.py", line 30, in get_search_paths
-     "Environment variable '{}' is not set or empty".format(AMENT_PREFIX_PATH_ENV_VAR))
- <font color='red'>'''OSError: Environment variable 'AMENT_PREFIX_PATH' is not set or empty'''</font></font>
-==<font color='blue'>ROS2 on PC</font>==
+===Reference ROS repos===
-* [https://index.ros.org/doc/ros2/Linux-Install-Debians/ Linux-Install-Debians]
+* [https://github.com/inertialsense/inertial_sense_ros.git inertial_sense_ros.git] - cpp
+* [https://github.com/intel/ros2_intel_realsense.git ros2_intel_realsense.git] - cpp
-<font color='green'>'''Notes:'''
+* [https://github.com/ros-drivers/axis_camera.git axis_camera.git] - python
-* '''apt install ros-bouncy-desktop''' available in 18.04, n/a in 16.04
+* [https://github.com/bmwcarit/meta-ros.git meta-ros.git] - layer for Yocto
-* '''apt install ros-ardent-desktop''' available in 16.04</font>
 ==<font color='blue'>ROS1</font>==
+<font color='red'>'''Won't build'''</font>. [[ROS1|More info]].
-===Build===
-<font color='red'>'''Won't build'''</font>
- <font size='1'>Build Configuration:
- BB_VERSION           = "1.37.0"
- BUILD_SYS            = "x86_64-linux"
- NATIVELSBSTRING      = "universal"
- TARGET_SYS           = "arm-poky-linux-gnueabi"
- MACHINE              = "elphel393"
- DISTRO               = "poky"
- DISTRO_VERSION       = "2.4+snapshot-20181204"
- TUNE_FEATURES        = "arm armv7a vfp neon cortexa9"
- TARGET_FPU           = "softfp"
- meta
- meta-poky
- meta-yocto-bsp       = "HEAD:72867393fe2004ab9f0ee23eb09a975c82938b9e"
- meta-ezynq           = "rocko:046de13c06cc248b725cb7b9928f35d4a369b50f"
- meta-elphel393       = "rocko:0cea9b9b8776f0fe725316f1be1501396c95feb4"
- meta-ros             = "HEAD:72068b17e4192b51e09c8dc633805a35edac8701"
- meta-xilinx-bsp      = "HEAD:a18947c20dba2c0c38db8bde1ad4684995df4bbd"
- meta-oe
- meta-python
- meta-networking
- meta-webserver       = "HEAD:34aa4c3202b427f59f843dc43a4e1afda4f81d13"</font>
-* Error 1:
-** ROS_USE_PYTHON3 = "yes"
-** IMAGE_INSTALL += "roslaunch"
- <font size='1'>NOTE: Resolving any missing task queue dependencies
- ERROR: Nothing RPROVIDES 'python3-pycrypto' (but /home/oleg/GIT/elphel393_rocko_clean_install/meta/meta-ros/recipes-devtools/python/python3-paramiko_1.16.0.bb RDEPENDS on or otherwise requires it)
- NOTE: Runtime target 'python3-pycrypto' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['python3-pycrypto']
- NOTE: Runtime target 'python3-paramiko' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['python3-paramiko', 'python3-pycrypto']
- NOTE: Runtime target 'roslaunch' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['roslaunch', 'python3-paramiko', 'python3-pycrypto']
- ERROR: Required build target 'core-image-elphel393' has no buildable providers.
- Missing or unbuildable dependency chain was: ['core-image-elphel393', 'roslaunch', 'python3-paramiko', 'python3-pycrypto']</font>
-* Successful build:
-** IMAGE_INSTALL += "roslaunch"
- <font size='1'>NOTE: Resolving any missing task queue dependencies
- ERROR: Nothing RPROVIDES 'python3-pycrypto' (but /home/oleg/GIT/elphel393_rocko_clean_install/meta/meta-ros/recipes-devtools/python/python3-paramiko_1.16.0.bb RDEPENDS on or otherwise requires it)
- NOTE: Runtime target 'python3-pycrypto' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['python3-pycrypto']
- NOTE: Runtime target 'python3-paramiko' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['python3-paramiko', 'python3-pycrypto']
- NOTE: Runtime target 'roslaunch' is unbuildable, removing...
- Missing or unbuildable dependency chain was: ['roslaunch', 'python3-paramiko', 'python3-pycrypto']
- ERROR: Required build target 'core-image-elphel393' has no buildable providers.
- Missing or unbuildable dependency chain was: ['core-image-elphel393', 'roslaunch', 'python3-paramiko', 'python3-pycrypto']</font>
-* Error 2:
-** <font color='red'>Seems like '''rostopic''' causes:</font>
- <font size='1'>ERROR: python-imaging-1.1.7-r5 do_package_qa: QA Issue: python-imaging: The compile log indicates that host include and/or library paths were used.
-          Please check the log '/home/oleg/GIT/elphel393_rocko_clean_install/poky/build/tmp/work/cortexa9-neon-poky-linux-gnueabi/python-imaging/1.1.7-r5/temp/log.do_compile' for more information. [compile- host-path]
- ERROR: python-imaging-1.1.7-r5 do_package_qa: QA run found fatal errors. Please consider fixing them.
- ERROR: python-imaging-1.1.7-r5 do_package_qa: Function failed: do_package_qa
- ERROR: Logfile of failure stored in: /home/oleg/GIT/elphel393_rocko_clean_install/poky/build/tmp/work/cortexa9-neon-poky-linux-gnueabi/python-imaging/1.1.7-r5/temp/log.do_package_qa.19425
- ERROR: Task (/home/oleg/GIT/elphel393_rocko_clean_install/meta/meta-openembedded/meta-python/recipes-devtools/python/python-imaging_1.1.7.bb:do_package_qa) failed with exit code '1'</font>
- potential links:
-  https://github.com/intel-aero/meta-intel-aero/issues/81
-  https://github.com/bmwcarit/meta-ros/issues/395
- removed python3-imaging from '''rosbag''' - everything builds but then not really working.
- with '''ROS_USE_PYTHON3 = "yes"''' stopped at finding an appropriate '''python-pycrypto''' lib
-===Work===
-* <font color='red'>'''Won't work'''</font>
-** There's no '''rosrun''' (does not exist?)
-** SSH session 1:
-*** Add to /etc/hosts:
-.0.0.1	elphel393.localdomain		elphel393
-*** Export vars:
- export ROS_ROOT=/opt/ros
- export ROS_DISTRO=indigo
- export ROS_PACKAGE_PATH=/opt/ros/indigo/share
- export PATH=$PATH:/opt/ros/indigo/bin
- export LD_LIBRARY_PATH=/opt/ros/indigo/lib
- export PYTHONPATH=/opt/ros/indigo/lib/python2.7/site-packages
- export ROS_MASTER_URI=http://localhost:11311
- export CMAKE_PREFIX_PATH=/opt/ros/indigo
- touch /opt/ros/indigo/.catkin
-*** Roscore
- roscore
-** SSH session 2:
- root@elphel393:~# rosnode list
-  <font size='1'>/rosout</font>
- root@elphel393:~# rospack list
-  <font size='1'>cpp_common /opt/ros/indigo/share/cpp_common
-  genmsg /opt/ros/indigo/share/genmsg
-  genpy /opt/ros/indigo/share/genpy
-  rosbag /opt/ros/indigo/share/rosbag
-  rosbag_storage /opt/ros/indigo/share/rosbag_storage
-  rosclean /opt/ros/indigo/share/rosclean
-  rosconsole /opt/ros/indigo/share/rosconsole
-  roscpp /opt/ros/indigo/share/roscpp
-  roscpp_serialization /opt/ros/indigo/share/roscpp_serialization
-  roscpp_tutorials /opt/ros/indigo/share/roscpp_tutorials
-  rosgraph /opt/ros/indigo/share/rosgraph
-  rosgraph_msgs /opt/ros/indigo/share/rosgraph_msgs
-  roslaunch /opt/ros/indigo/share/roslaunch
-  roslib /opt/ros/indigo/share/roslib
-  roslz4 /opt/ros/indigo/share/roslz4
-  rosmaster /opt/ros/indigo/share/rosmaster
-  rosnode /opt/ros/indigo/share/rosnode
-  rosout /opt/ros/indigo/share/rosout
-  rospack /opt/ros/indigo/share/rospack
-  rosparam /opt/ros/indigo/share/rosparam
-  rospy /opt/ros/indigo/share/rospy
-  rospy_tutorials /opt/ros/indigo/share/rospy_tutorials
-  rostime /opt/ros/indigo/share/rostime
-  rostopic /opt/ros/indigo/share/rostopic
-  std_msgs /opt/ros/indigo/share/std_msgs
-  topic_tools /opt/ros/indigo/share/topic_tools
-  xmlrpcpp /opt/ros/indigo/share/xmlrpcpp</font>