strands_webtools

An interface to access the real and/or simulated robot via web applications. It is suggested that you run the server on a separate computer and have that computer connect to the robot's roscore, e.g. by setting export ROS_MASTER_URI="http://robot-ip:11311/" accordingly.

Useful Information

• Slides from ROSCon talk: here

• Source of examples from ROSCon talk: here

• ROS requirements on Ubuntu:

rosdep -y install -r strands_webtools

• ROS requirements from source (e.g. OS X): rosbridge_suite, rosauth, tf2_web_republisher, mjpeg_server, robot_pose_publisher

Running as standalone (not as part of a web server)

1. roslaunch strands_webtools webtools.launch
2. (optional) rosrun topic_republisher republish_ptu_jointstate.py (republishes the PTU joint state on /ptu, only needed for MORSE; The package topic_republisher can be found in the strands_utils repository)
3. Open in web browser: http://localhost/

Running the webtools behind a firewall in Apache (for the marathon)

Install Apache2

• sudo apt-get install apache2 libapache2-mod-proxy-html
• install the mod_wstunnel for apache (the script roscd strands_webtools; sudo ./build_wstunnel.sh automates the following)

Check apache version (should be 2.2.20 as of writing, if not adjust the next step)

dpkg -s apache2

Checkout apache source

svn checkout http://svn.apache.org/repos/asf/httpd/httpd/tags/2.2.20/ httpd-2.2.20

Get patch and apply it

wget http://cafarelli.fr/gentoo/apache-2.2.24-wstunnel.patch cd httpd-2.2.20 patch -p1 < ../apache-2.2.24-wstunnel.patch

Build Apache

svn co http://svn.apache.org/repos/asf/apr/apr/branches/1.4.x srclib/apr svn co http://svn.apache.org/repos/asf/apr/apr-util/branches/1.3.x srclib/apr-util ./buildconf ./configure --enable-proxy=shared --enable-proxy_wstunnel=shared make

Copy the module and recompiled mod_proxy (for new symbols) to the ubuntu apache installation and update the permissions to match the other modules

sudo cp modules/proxy/.libs/mod_proxy{_wstunnel,}.so /usr/lib/apache2/modules/ sudo chmod 644 /usr/lib/apache2/modules/mod_proxy{_wstunnel,}.so echo -e "# Depends: proxy\nLoadModule proxy_wstunnel_module /usr/lib/apache2/modules/mod_proxy_wstunnel.so" | sudo tee -a /etc/apache2/mods-available/proxy_wstunnel.load

  ```

• Afterwards, run: sudo a2enmod proxy* rewrite*

ROS setup

The marathon branch requires STRAND's own version of rosbridge_suite and mjpeg_server to added security features. Here's the rosinstall config:

- git: 
   local-name: rosbridge_suite
   uri: 'https://github.com/strands-project/rosbridge_suite.git'
   version: readonly_capabilities
   
- git: 
   local-name: mjpeg_server
   uri: 'https://github.com/strands-project/mjpeg_server.git'
   version: groovy-devel

Network and Server setup:

The setup is as follows:

• There is a webhost called WH in the following, which is accessible from the internet on port 80, which fulfills these requirements:
  • has Ubuntu 12.04LTS 64bit
  • runs (part of) the STRANDS ROS system (everything in strands_webtools is the minimum) and it can connect to the robot's network
  • it has a firewall in place to ensure that it only accepts port 80 from the outside worlds, but accepts everything from the robot (I use ufw to configure this easily)
• There is the robot, called Linda here, that can connect to that server on all ports
• WH uses Linda's ROS_MASTER_URI which needs to be configured to e.g. export ROS_MASTER_URI=http://linda:11311
• On WH the html, css, etc. files are served in a dedicated repository, e.g. /opt/strands/lib/www is assumed in the following.
• Apache needs to be configured to serve the files and act as a reverse proxy to allow to access ROS via port 80. Here's the Lincoln working file that resides under /etc/apache2/available-sites/strands.site

<VirtualHost *:80>
	DocumentRoot /var/www/
  # this tells apache that everything under "linda" is served from another location... that's where your html files should be
	Alias /linda /opt/strands/lib/www

	# just entering the server name will take you to your institutions website
	RedirectMatch permanent ^/$ http://robots.lincoln.ac.uk/
	
	# disable listing of directories in the strands dir
	<Directory /opt/strands/lib/www>
		Options -Indexes		
	</Directory>
	
	# rewrite engine is needed for the reverseproxy things to work
	RewriteEngine On
	
	Options -Indexes
	
	
	# serving mjpeg image streams under this URL. This needs to match the URL given in the HTML file. the mjpeg_server is running locally on port 8181 (as specified in the launch file)
	RewriteRule ^/linda/video http://localhost:8181/ [P]
	
  # reverse proxy for rosbridge (rosbridge is running locally on port 9090 (as specified in the launch file)
  ProxyPass /linda/rosws ws://localhost:9090/
  ProxyPassReverse /linda/rosws ws://localhost:9090/	
</VirtualHost>

You may want to adapt this (e.g. change 'linda' for something else), but be aware to change the marathon.html file correspondingly.

Running it

• run all the nodes on the robot, e.g. openni, mapserver, etc.
• On the robot make sure you run the nodes that throttle the network traffic: roslaunch strands_webtools webtools_robot.launch You want to include this in your usual robot setup. It just advertises a few other topics that have low bandwidth that WH is then connecting to.
• On WH run roslaunch strands_webtools webtools_safe.launch with ROS_MASTER_URI=http://linda:11311/ (or whatever your robot is called, e.g. just its IP address)
• goto the external URL (e.g. http://lcas.lincoln.ac.uk/linda/marathon.html) and check if everythin works