ASIO: Initial version based on IDF 5.0 with history

components/asio/examples/async_request/README.md

@@ -0,0 +1,52 @@
+| Supported Targets | ESP32 |
+| ----------------- | ----- |
+
+# Async request using ASIO
+
+(See the README.md file in the upper level 'examples' directory for more information about examples.)
+
+The application aims to show how to compose async operations using ASIO to build network protocols and operations.
+
+# Configure and Building example
+
+This example doesn't require any configuration, just build it with 
+
+```
+idf.py build
+```
+
+# Async operations composition and automatic lifetime control
+
+On this example we compose the operation by starting the next step in the chain inside the completion handler of the 
+previous operation. Also we pass the `Connection` class itself as the parameter of its final handler to be owned by 
+the following operation. This is possible due to the control of lifetime by the usage of `std::shared_ptr`.
+
+The control of lifetime of the class, done by `std::shared_ptr` usage, guarantee that the data will be available for 
+async operations until it's not needed any more. This makes necessary that all of the async operation class must start 
+its lifetime as a `std::shared_ptr` due to the usage of `std::enable_shared_from_this`.
+
+
+     User creates a shared_ptr──┐
+     of AddressResolution and   │
+     ask for resolve.           │
+     The handler for the       ┌▼─────────────────────┐
+     complete operation is sent│   AddressResolution  │  In the completion of resolve a connection is created.
+                               └─────────────────┬────┘  AddressResolution is automaticly destroyed since it's
+                                                 │       no longer needed
+                                               ┌─▼────────────────────────────────────┐
+                                               │         Connection                   │
+                                               └──────┬───────────────────────────────┘
+  Http::Session is created once we have a Connection. │
+  Connection is passed to Http::Session that holds it │
+  avoiding it's destruction.                          │
+                                                    ┌─▼───────────────────────────────┐
+                                                    │       Http::Session             │
+                                                    └────────┬────────────────────────┘
+                                After the HTTP request is    │
+                                sent the completion handler  │
+                                is called.                   │
+                                                             └────►Completion Handler()
+
+
+The previous diagram shows the process and the life span of each of the tasks in this examples. At each stage the 
+object responsible for the last action inject itself to the completion handler of the next stage for reuse.