Use one sentence per line

Author: ruffsl

ros/content.md

@@ -1,6 +1,8 @@
 # What is [ROS](https://www.ros.org/)?
 
-The Robot Operating System (ROS) is a set of software libraries and tools that help you build robot applications. From drivers to state-of-the-art algorithms, and with powerful developer tools, ROS has what you need for your next robotics project. And it's all open source.
+The Robot Operating System (ROS) is a set of software libraries and tools that help you build robot applications.  
+From drivers to state-of-the-art algorithms, and with powerful developer tools, ROS has what you need for your next robotics project.  
+And it's all open source.
 
 > [wikipedia.org/wiki/Robot_Operating_System](https://en.wikipedia.org/wiki/Robot_Operating_System)
 
@@ -25,7 +27,8 @@ RUN apt-get update && apt-get install -y \
 CMD ["ros2", "launch", "demo_nodes_cpp", "talker_listener.launch.py"]
 ```
 
-Note: all ROS images include a default entrypoint that sources the ROS environment setup before executing the configured command, in this case the demo packages launch file. You can then build and run the Docker image like so:
+Note: all ROS images include a default entrypoint that sources the ROS environment setup before executing the configured command, in this case the demo packages launch file.  
+You can then build and run the Docker image like so:
 
 ```console
 $ docker build -t my/ros:app .
@@ -105,19 +108,29 @@ RUN sed --in-place --expression \
 CMD ["ros2", "launch", "demo_nodes_cpp", "talker_listener.launch.py"]
 ```
 
-The example above starts by using [`vcstool`](https://github.com/dirk-thomas/vcstool) to clone source repos of interest into the cacher stage. One could similarly `COPY` code from the local build context into the source directory as well. Package manifest files are then cached in a temporary directory where the following builder stage may copy from to install necessary dependencies with [`rosdep`](https://github.com/ros-infrastructure/rosdep). This is done prior copying the rest of the source files to preserve the multi stage build cache, given unaltered manifests do not altered declared dependencies, saving time and bandwidth. The overlay is then built using [`colcon`](https://colcon.readthedocs.io/en/released/), the entrypoint updated to source the workspace, and the default command set to launch the demo.
+The example above starts by using [`vcstool`](https://github.com/dirk-thomas/vcstool) to clone source repos of interest into the cacher stage.  
+One could similarly `COPY` code from the local build context into the source directory as well.  
+Package manifest files are then cached in a temporary directory where the following builder stage may copy from to install necessary dependencies with [`rosdep`](https://github.com/ros-infrastructure/rosdep).  
+This is done prior copying the rest of the source files to preserve the multi stage build cache, given unaltered manifests do not altered declared dependencies, saving time and bandwidth.  
+The overlay is then built using [`colcon`](https://colcon.readthedocs.io/en/released/), the entrypoint updated to source the workspace, and the default command set to launch the demo.
 
-Note: `--from-paths` and `--packages-select` are set here as so to only install the dependencies and build for the demo C++ and Python packages, among many in the demo git repo that was cloned. To install the dependencies and build all the packages in the source workspace, merely change the scope by setting `--from-paths src/` and dropping the `--packages-select` arguments.
+Note: `--from-paths` and `--packages-select` are set here as so to only install the dependencies and build for the demo C++ and Python packages, among many in the demo git repo that was cloned.  
+To install the dependencies and build all the packages in the source workspace, merely change the scope by setting `--from-paths src/` and dropping the `--packages-select` arguments.
 
 For more advance examples such as daisy chaining multiple overlay workspaces to improve caching of docker image build layers, using tools such as ccache to accelerate compilation with colcon, or using buildkit to save build time and bandwidth even when dependencies change, the project `Dockerfile`s in the ROS2 [Navigation2](https://github.com/ros-planning/navigation2) repo are excellent resources.
 
 ## Deployment use cases
 
-This dockerized image of ROS is intended to provide a simplified and consistent platform to build and deploy distributed robotic applications. Built from the [official Ubuntu image](https://hub.docker.com/_/ubuntu/) and ROS's official Debian packages, it includes recent supported releases for quick access and download. This provides roboticists in research and industry with an easy way to develop, reuse and ship software for autonomous actions and task planning, control dynamics, localization and mapping, swarm behavior, as well as general system integration.
+This dockerized image of ROS is intended to provide a simplified and consistent platform to build and deploy distributed robotic applications.  
+Built from the [official Ubuntu image](https://hub.docker.com/_/ubuntu/) and ROS's official Debian packages, it includes recent supported releases for quick access and download.  
+This provides roboticists in research and industry with an easy way to develop, reuse and ship software for autonomous actions and task planning, control dynamics, localization and mapping, swarm behavior, as well as general system integration.
 
-Developing such complex systems with cutting edge implementations of newly published algorithms remains challenging, as repeatability and reproducibility of robotic software can fall to the wayside in the race to innovate. With the added difficulty in coding, tuning and deploying multiple software components that span across many engineering disciplines, a more collaborative approach becomes attractive. However, the technical difficulties in sharing and maintaining a collection of software over multiple robots and platforms has for a while exceeded time and effort than many smaller labs and businesses could afford.
+Developing such complex systems with cutting edge implementations of newly published algorithms remains challenging, as repeatability and reproducibility of robotic software can fall to the wayside in the race to innovate.  
+With the added difficulty in coding, tuning and deploying multiple software components that span across many engineering disciplines, a more collaborative approach becomes attractive.  
+However, the technical difficulties in sharing and maintaining a collection of software over multiple robots and platforms has for a while exceeded time and effort than many smaller labs and businesses could afford.
 
-With the advancements and standardization of software containers, roboticists are primed to acquire a host of improved developer tooling for building and shipping software. To help alleviate the growing pains and technical challenges of adopting new practices, we have focused on providing an official resource for using ROS with these new technologies.
+With the advancements and standardization of software containers, roboticists are primed to acquire a host of improved developer tooling for building and shipping software.  
+To help alleviate the growing pains and technical challenges of adopting new practices, we have focused on providing an official resource for using ROS with these new technologies.
 
 For a complete listing of supported architectures and base images for each ROS Distribution Release, please read the official REP on target platforms for either [ROS1](https://www.ros.org/reps/rep-0003.html) or for [ROS2](https://www.ros.org/reps/rep-2000.html).
 
@@ -130,11 +143,16 @@ The available tags include supported distros along with a hierarchy tags based o
 
 In the interest of keeping `ros-core` tag minimal in image size, developer tools such as `rosdep`, `colcon` and `vcstools` are not shipped in `ros_core`, but in `ros-base` instead.
 
-The rest of the common meta-packages such as `desktop` and `ros1-bridge` are hosted on automatic build repos under OSRF's Docker Hub profile [here](https://hub.docker.com/r/osrf/ros/). These meta-packages include graphical dependencies and hook a host of other large packages such as X11, X server, etc. So in the interest of keep the official images lean and secure, the desktop packages are just be hosted with OSRF's profile. For a extensive list of available variants, please read the official REP on target platforms for either [ROS1](https://ros.org/reps/rep-0150.html) or for [ROS2](https://www.ros.org/reps/rep-2001.html).
+The rest of the common meta-packages such as `desktop` and `ros1-bridge` are hosted on automatic build repos under OSRF's Docker Hub profile [here](https://hub.docker.com/r/osrf/ros/).  
+These meta-packages include graphical dependencies and hook a host of other large packages such as X11, X server, etc.  
+So in the interest of keep the official images lean and secure, the desktop packages are just be hosted with OSRF's profile.  
+For a extensive list of available variants, please read the official REP on target platforms for either [ROS1](https://ros.org/reps/rep-0150.html) or for [ROS2](https://www.ros.org/reps/rep-2001.html).
 
 ### Volumes
 
-ROS uses the `~/.ros/` directory for storing logs, and debugging info. If you wish to persist these files beyond the lifecycle of the containers which produced them, the `~/.ros/` folder can be mounted to an external volume on the host, or a derived image can specify volumes to be managed by the Docker engine. By default, the container runs as the `root` user, so `/root/.ros/` would be the full path to these files.
+ROS uses the `~/.ros/` directory for storing logs, and debugging info.  
+If you wish to persist these files beyond the lifecycle of the containers which produced them, the `~/.ros/` folder can be mounted to an external volume on the host, or a derived image can specify volumes to be managed by the Docker engine.  
+By default, the container runs as the `root` user, so `/root/.ros/` would be the full path to these files.
 
 For example, if one wishes to use their own `.ros` folder that already resides in their local home directory, with a username of `ubuntu`, we can simple launch the container with an additional volume argument:
 
@@ -144,21 +162,27 @@ $ docker run -v "/home/ubuntu/.ros/:/root/.ros/" %%IMAGE%%
 
 ### Devices
 
-Some application may require device access for acquiring images from connected cameras, control input from human interface device, or GPUS for hardware acceleration. This can be done using the [`--device`](https://docs.docker.com/engine/reference/commandline/run/#add-host-device-to-container---device) run argument to mount the device inside the container, providing processes inside hardware access.
+Some application may require device access for acquiring images from connected cameras, control input from human interface device, or GPUS for hardware acceleration.  
+This can be done using the [`--device`](https://docs.docker.com/engine/reference/commandline/run/#add-host-device-to-container---device) run argument to mount the device inside the container, providing processes inside hardware access.
 
 ### Networks
 
-ROS allows for peer-to-peer networking of processes (potentially distributed across machines) that are loosely coupled using the ROS communication infrastructure. ROS implements several different styles of communication, including synchronous RPC-style communication over services, asynchronous streaming of typed data over topics, combinations of both prior via request/reply and status/feedback over actions, and run-time settings via configuration over parameters. To abide by the best practice of [one process per container](https://docs.docker.com/articles/dockerfile_best-practices/), Docker networks can be used to string together several running ROS processes. For further details see the Deployment example further below.
+ROS allows for peer-to-peer networking of processes (potentially distributed across machines) that are loosely coupled using the ROS communication infrastructure.  
+ROS implements several different styles of communication, including synchronous RPC-style communication over services, asynchronous streaming of typed data over topics, combinations of both prior via request/reply and status/feedback over actions, and run-time settings via configuration over parameters.  
+To abide by the best practice of [one process per container](https://docs.docker.com/articles/dockerfile_best-practices/), Docker networks can be used to string together several running ROS processes.  
+For further details see the Deployment example further below.
 
-Alternatively, more permissive network setting can be used to share all host network interfaces with the container, such as [`host` network driver](https://docs.docker.com/network/host/), simplifying connectivity with external network participants. Be aware however that this removes the networking namespace separation between containers, and can affect the ability of DDS participants to communicate between containers, as documented [here](https://community.rti.com/kb/how-use-rti-connext-dds-communicate-across-docker-containers-using-host-driver).
+Alternatively, more permissive network setting can be used to share all host network interfaces with the container, such as [`host` network driver](https://docs.docker.com/network/host/), simplifying connectivity with external network participants.  
+Be aware however that this removes the networking namespace separation between containers, and can affect the ability of DDS participants to communicate between containers, as documented [here](https://community.rti.com/kb/how-use-rti-connext-dds-communicate-across-docker-containers-using-host-driver).
 
 ## Deployment example
 
 ### Docker Compose
 
 In this example we'll demonstrate using [`docker-compose`](https://docs.docker.com/compose/) to spawn a pair of message publisher and subscriber nodes in separate containers connected through shared software defined network.
 
-> Create the directory `~/ros_demos` and add the first `Dockerfile` example from above. In the same directory, also create file `docker-compose.yml` with the following that runs a C++ publisher with a Python subscriber:
+> Create the directory `~/ros_demos` and add the first `Dockerfile` example from above.  
+> In the same directory, also create file `docker-compose.yml` with the following that runs a C++ publisher with a Python subscriber:
 
 ```yaml
 version: '3'
@@ -175,7 +199,8 @@ services:
     command: ros2 run demo_nodes_py listener
 ```
 
-> Use docker-compose inside the same directory to launch our ROS nodes. Given the containers created derive from the same docker compose project, they will coexist on shared project network:
+> Use docker-compose inside the same directory to launch our ROS nodes.  
+> Given the containers created derive from the same docker compose project, they will coexist on shared project network:
 
 ```console
 $ docker-compose up -d
@@ -204,7 +229,8 @@ $ docker-compose rm
 
 ### ROS1 Bridge
 
-+To ease ROS2 migration, [`ros1_bridge`](https://index.ros.org/p/ros1_bridge/github-ros2-ros1_bridge) is a ROS2 package that provides bidirectional communication between ROS1 and ROS2. As a minimal example, given the ROS2 Dockerfile above, we'll create the ROS1 equivalent below, and name the Dockerfile appropriately.
++To ease ROS2 migration, [`ros1_bridge`](https://index.ros.org/p/ros1_bridge/github-ros2-ros1_bridge) is a ROS2 package that provides bidirectional communication between ROS1 and ROS2.  
+As a minimal example, given the ROS2 Dockerfile above, we'll create the ROS1 equivalent below, and name the Dockerfile appropriately.
 
 ```dockerfile
 FROM %%IMAGE%%:noetic
@@ -219,7 +245,8 @@ RUN apt-get update && apt-get install -y \
 CMD ["roslaunch", "roscpp_tutorials", "talker_listener.launch"]
 ```
 
-The compose file bellow spawns services for both talker listener demos while connecting the two via a dynamic bridge. You may then view the log output from both pairs of talker and listener nodes cross talking over the `/chatter` topic.
+The compose file bellow spawns services for both talker listener demos while connecting the two via a dynamic bridge.  
+You may then view the log output from both pairs of talker and listener nodes cross talking over the `/chatter` topic.
 
 ```yaml
 version: '3'