Merge pull request #228 from patrikspiess/Add-the-layers-of-fotoobo-i…

…n-arch-docs-#227

📝 Add layers of fotoobo

WHATSNEW.md

@@ -1,5 +1,7 @@
 ### Added
 
+- Add the layers of fotoobo into the architecture documentation
+
 ### Changed
 
 ### Removed

docs/source/developer/architecture/5_building_block_view.rst

@@ -7,10 +7,65 @@
 5. Building Block View
 ======================
 
+The layers of fotoobo
+---------------------
+
+There are three designated layers in **fotoobo**. These are the interface layer, the business logic
+layer and the infrastructure layer.
+
+.. image:: diagrams/fotoobo_layers.drawio.svg
+  :width: 100%
+  :alt: The layers of fotoobo visualized
+
+In this diagram you see the designated paths to use when accessing a Fortinet device. Although these 
+are the recommended ways to use it, you may also access the layers in other ways. Just keep in mind 
+there always should be a rational and understandable approach.
+
+
+The Interface Layer
+^^^^^^^^^^^^^^^^^^^
+
+This is the main entry point for interaction with **fotoobo** when you installed it as an
+application on your system. It acts as a frontend for users and automation tools. At the Moment only
+the CLI part is implemented. In future version a REST API may be available if there is a need for
+it.
+
+Call **fotoobo** with its command(s) directly from the command line or from any automation engine
+like cron jobs, Rundeck or others.
+
+The Business Logic Layer
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+At this level you have access to specific use cases. These are called **tools** in **fotoobo**. Any
+CLI command or API endpoint should point to such a **tool** which then interacts with the
+infrastructure layer.
+
+Whenever you use **fotoobo** as a module in your own code (instead of using it as an installed
+application) you may directly access this layer.
+
+The Infrastructure Layer
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+In this lowest level of **fotoobo** we directly interact with the infrastructure, meaning we handle 
+the authentication and API calls to the devices like FortiGate, FortiManger and others. The 
+interface layer should not directly access this infrastructure layer. Instead there should always 
+be a **tool** in the business logic layer which connects these two. No other layer than the 
+infrastructure layer should directly access any fortinet device.
+
+As a module in your own code you may also directly use the infrastructure layer.
+
+
 Package structure
 -----------------
 
-The package structure describes the internal structure of **fotoobo**.
+The package structure describes the internal structure of **fotoobo**. The following diagram
+visualizes the top level modules in the code. There are direct associations for these modules to 
+the layers of **fotoobo**:
+
+* cli: Interface Layer
+* tools: Business Logic Layer
+* fortinet: Infrastructure Layer
+
 
 .. image:: diagrams/package_structure.drawio.svg
   :width: 100%