Update developer documentation

source/developers/add_new_platform.markdown

@@ -21,11 +21,38 @@ For example, the built-in `switch` component consists of the following files in
 
 If you are planning to add support for a new type of device to an existing component, you can get away with only writing platform logic. Have a look at how the component works with other platforms and create a similar file for the platform that you would like to add.
 
-<p class='note'>
+### {% linkable_title Interfacing with devices %}
-Platform logic should not interface directly with the devices but use a third-party Python 3 library that speaks the actual API.
+
-</p>
+One of the rules for Home Assistant is that platform logic should never interface directly with
+devices but use a third-party Python 3 library to do so. This way Home Assistant is able to share
+code with the Python community and we can keep the project maintainable.
+
+Platforms can specify dependencies and requirements the same way as a component does. Please see
+[the component page](/developers/creating_components.html#dependencies) for more information.
+
+### {% linkable_title Creating Entities %}
+
+Home Assistant will call a function with the following signature to initialize
+your new platform. This function must exist in the platform module you create.
+
+```python
+def setup_platform(hass, config, add_devices, discovery_info=None)
+```
+
+In this function, your platform should create the appropriate entities and
+register them with the Home Assistant core. Entities are Home Assistant's
+representation of lights, switches, sensors, etc. and are derived from the
+[Entity Abstract Class](https://github.com/balloob/home-assistant/blob/master/homeassistant/helpers/entity.py).
+This abstract class contains logic for integrating most standard features into
+your entities, such as visibility, entity IDs, updates, and many more.
+
+A list of entities can be registered with Home Assistant using the *add_devices*
+function that is provided as an input to *setup_platform*. Once entities are
+registered with with Home Assistant their updates will be provided to the core
+and the core will have control over them. For more information on how Entities
+can be customized, take a look at the [Entity Abstract
+Class](https://github.com/balloob/home-assistant/blob/master/homeassistant/helpers/entity.py#L18).
 
-<a name='discovery'></a>
 ## {% linkable_title Allowing your platform to be discovered %}
 
 Home Assistant has a discovery service running in the background to discover new devices. Whenever a new device is discovered, an `SERVICE_DISCOVERED` event will be fired with the found service and the information. The `discovery` component has some knowledge about which components handle which type of services and will ensure those are loaded and listening before firing the `SERVICE_DISCOVERED` event.
@@ -61,28 +88,3 @@ The Discovery component is capable of setting up your components before firing t
 <p class='note warning'>
 This option is currently limited to built-in components.
 </p>
-
-### {% linkable_title Creating Entities %}
-
-Home Assistant will call a function with the following signature to initialize
-your new platform. This function must exist in the platform module you create.
-
-```python
-def setup_platform(hass, config, add_devices, discovery_info=None)
-```
-
-In this function, your platform should create the appropriate entities and
-register them with the Home Assistant core. Entities are Home Assistant's
-representation of lights, switches, sensors, etc. It is best practice for all
-new entities to inherit the
-[Entity Abstract Class](https://github.com/balloob/home-assistant/blob/master/homeassistant/helpers/entity.py#L18).
-This abstract class contains logic for integrating most standard features into
-your entities, such as visibility, entity IDs, updates, and many more. That is
-why it is best practice to reference the existing class.
-
-A list of entities can be registered with Home Assistant using the *add_devices*
-function that is provided as an input to *setup_platform*. Once entities are
-registered with with Home Assistant their updates will be provided to the core
-and the core will have control over them. For more information on how Entities
-can be customized, take a look at the [Entity Abstract
-Class](https://github.com/balloob/home-assistant/blob/master/homeassistant/helpers/entity.py#L18).

source/developers/creating_components.markdown

@@ -42,6 +42,22 @@ You can override a built-in component by having a component with the same name i
 Home Assistant will use the directory that contains your config file as the directory that holds your customizations. By default this is the <code>config</code> folder in your current work directory. You can use a different folder by running Home Assistant with the --config argument: <code>python3 homeassistant --config /YOUR/CONFIG/PATH/</code>.
 </p>
 
+## {% linkable_title Dependencies %}
+
+Home Assistant allows components and platforms to specify their dependencies and requirements using the variables
+`DEPENDENCIES` and `REQUIREMENTS`. Both are lists that contain strings.
+
+Dependencies are other Home Assistant components that should be setup before the platform is loaded.
+An example is the MQTT sensor component, which requires an active connection to a MQTT broker. If
+Home Assistant is unable to load and setup the MQTT component, it will not setup the MQTT sensor
+component.
+
+Requirements are Python libraries that you would normally install using `pip`. Each entry in a
+requirement list is a pip compatible string. For example, the media player Cast platform depends
+on the Python package PyChromecast thus `REQUIREMENTS = ['pychromecast==0.6.12']`. If Home
+Assistant is unable to install the package or verify it is installed, the component will fail to
+load.
+
 ## {% linkable_title Initializing components %}
 
 After loading, the bootstrapper will call `setup(hass, config)` method on the component to initialize it. The following parameters are passed in:

source/developers/index.markdown

@@ -9,9 +9,49 @@ sharing: true
 footer: true
 ---
 
-Home Assistant is build from the ground-up to be easily extensible by other developers using components. It uses [Python 3](https://www.python.org/) for the backend and [Polymer (Webcomponents)](https://www.polymer-project.org/) for the frontend. 
+Home Assistant is build from the ground-up to be easily extensible by other developers using
+components. It uses [Python 3](https://www.python.org/) for the backend and
+[Polymer (Webcomponents)](https://www.polymer-project.org/) for the frontend.
+
+Home Assistant is open-source and MIT licensed. The source can be found here:
+
+ - [home-assistant](https://github.com/home-assistant) - Python server-backend
+ - [home-assistant-js](https://github.com/home-assistant-js) - javascript-backend powering the client
+ - [home-assistant-polymer](https://github.com/home-assistant-polymer) - Polymer UI
+
+### {% linkable_title Starting development %}
+
+You will need to setup a development environment if you want to start developing a new feature or
+component for Home Assistant.
+
+ 1. Clone the Home Assistant repository:<br>
+    `git clone https://github.com/balloob/home-assistant.git`
+ 2. Setup your computer for development:<br>
+    `python3 setup.py develop`
+
+After following these steps, running `hass` will invoke your local installation.
+
+### {% linkable_title Submitting improvements %}
+
+Improvements to Home Assistant should be submitted one feature at a time using Github pull
+requests.
+
+ 1. Go to [the Home Assistant repository](https://github.com/balloob/home-assistant)
+    and click fork in the top right.
+ 2. Follow steps in the previous section but with your forked repository.
+ 3. Create a new branch to hold your changes<br>
+    `git checkout -b some-feature`
+ 4. Make the changes you want
+ 5. Commit the changes<br>
+    `git add .`<br>
+    `git commit -m "Added some-feature"`
+ 6. Push your commited changes back to your fork on Github<br>
+    `git push origin HEAD`
+ 7. Follow [these steps](https://help.github.com/articles/creating-a-pull-request/) to create your
+    pull request.
+
+### {% linkable_title Further reading %}
 
-For further reading, see:
 <ul>
   <li><a href="{{ root_url }}/developers/architecture.html">
     Home Assistant Architecture