# Readme /pubsub
This directory represents a ROS package due to its internal structure and files. The files inside `pubsub/pubsub/` are the Python scripts written by the package developer and can be called using the command line `ros2 run pubsub <entry_point_name>`. The `<entry_point_name>` has to be defined in _setup.py_.

## Files
This section describes the content and purpose of the files inside this directory.  
`ros2 run` callable files:  
* *topic\_talker.py* : Example for creating a `MinimumPublisher` and sending topics 
* *topic\_listener.py* : Example for creating a `MinimumSubscriber` and receiving topics
* *service\_host.py* : Example for creataing a `MinimumServiceProvider` and hosting a service
* *service\_client.py* : Example for creating a `MinimumServiceClient` and calling a service
* *statemachine\_host\_example.py* : Example application of State Machine (SM) hosting a service to call for a change of state
* *statemachine\_client\_example.py* : Example application of a service client calling for the change of SM state

Library files:  
* \[*pubsub\_library* ; *pubsub\_library\_v2*\] : old versions
* *pubsub\_library\_v3* : Library containing
   * `MinimalPublisher` class
   * `MinimalSubscriber` class
   * `MinimalServiceProvider` class
   * `MinimalServiceClient` class
   
## How to use
You can use the `Minimal<X>` classes in three ways:  
* Create `Minimal<X>` in your script (eg. [topic_listener.py](None) where data is echanged between the script environment and the class environment)
* Implement `Minimal<X>` inside your device class the same way as implementing in your main script (__<-- ToDo !!!__)
* Build device class upon `Minimal<X>` class (eg. [statemachine_host_example.py](None) where a device class is built upon the `MinimalServiceProvider` class) by implementing this structure
```python
class Child_Class(Parent_Class):
```
For example:
```python
class StateMachineCMDServiceProvider(MinimalServiceProvider):
```