Refs #21094: Update ReadMe file

Signed-off-by: elianalf <62831776+elianalf@users.noreply.github.com>

examples/cpp/custom_payload_pool/README.md

@@ -1,13 +1,89 @@
-# Objetive
+# Custom Payload Pool example
 
-This example has been developed to allow setting the endpoints' payload pool from the DDS layer.
-In that way, a custom payload pool is mandatory to be implemented, and passed to the endpoints in the publisher and subscriber implementations.
+The *eProsima Fast DDS Custom payload pool* example is a simple application intended to demonstrate how to set the endpoints' payload pool from the DDS layer.
 
-# Launch
+This example is part of the suite of examples designed by eProsima that aims to illustrate the features and possible configurations of DDS deployments through *eProsima Fast DDS*.
 
-To launch this test open two different consoles:
+In this example, a custom payload pool is implemented instead of the default one, and passed to the endpoints in the publisher and subscriber implementations.
 
-In the first one launch: `./HelloWorldExample publisher` (or `HelloWorldExample.exe publisher` on Windows).
-In the second one: `./HelloWorldExample subscriber` (or `HelloWorldExample.exe subscriber` on Windows).
+* [Description of the example](#description-of-the-example)
+* [Run the example](#run-the-example)
 
-The endpoints will match and communicate with the custom payload pool.
+## Description of the example
+A Payload is the data the user wants to transmit between a DataWriter and a DataReader. In order to manage the lifecycle of the Payloads, DataReaders and DataWriters use a pool object, an implementation of the `IPayloadPool` interface. The user can define different pool implementations, to obtain different kind of optimizations to manage the Payloads. A custom Payload pool can be given to `create_datawriter()` and `create_datareader()` functions, and DataWriters and DataReaders will use the provided pool when a new change in their history is requested or released. The example provides a simple payload pool that reserves and frees memory each time.
+
+## Run the example
+
+To launch this example, two different terminals are required.
+One of them will run the publisher example application, and the other will run the subscriber application.
+
+### Custom payload pool publisher
+
+* Ubuntu ( / MacOS )
+
+    ```shell
+    user@machine:example_path$ ./custom_payload_pool publisher
+    Publisher running. Please press Ctrl+C to stop the Publisher at any time.
+    ```
+
+* Windows
+
+    ```powershell
+    example_path> custom_payload_pool.exe publisher
+    Publisher running. Please press Ctrl+C to stop the Publisher at any time.
+    ```
+
+### Custom payload pool subscriber
+
+* Ubuntu ( / MacOS )
+
+    ```shell
+    user@machine:example_path$ ./custom_payload_pool subscriber
+    Subscriber running. Please press Ctrl+C to stop the Subscriber at any time.
+    ```
+
+* Windows
+
+    ```powershell
+    example_path> custom_payload_pool.exe subscriber
+    Subscriber running. Please press Ctrl+C to stop the Subscriber at any time.
+    ```
+
+All the example available flags can be queried running the executable with the ``-h`` or ``--help`` flag.
+
+### Expected output
+
+Regardless of which application is run first, since the publisher will not start sending data until a subscriber is discovered, the expected output both for publishers and subscribers is a first displayed message acknowledging the match, followed by the amount of samples sent or received until Ctrl+C is pressed.
+
+### Custom payload pool publisher
+
+```shell
+Publisher running. Please press Ctrl+C to stop the Publisher at any time.
+Publisher matched.
+Message: 'Hello world' with index: '1' SENT
+Message: 'Hello world' with index: '2' SENT
+Message: 'Hello world' with index: '3' SENT
+...
+```
+
+### Custom payload pool subscriber
+
+```shell
+Subscriber running. Please press Ctrl+C to stop the Subscriber at any time.
+Subscriber matched.
+Message: 'Hello world' with index: '1' RECEIVED
+Message: 'Hello world' with index: '2' RECEIVED
+Message: 'Hello world' with index: '3' RECEIVED
+...
+```
+
+When Ctrl+C is pressed to stop one of the applications, the other one will show the unmatched status, displaying an informative message, and it will stop sending / receiving messages.
+The following is a possible output of the publisher application when stopping the subscriber app.
+
+```shell
+...
+Message: 'Hello world' with index: '9' SENT
+Message: 'Hello world' with index: '10' SENT
+Message: 'Hello world' with index: '11' SENT
+Publisher unmatched.
+```