Add info about centrifugo in example

.gitignore

@@ -75,4 +75,7 @@ log.pana.json
 # Test
 .coverage/
 /test/**/*.json
-/test/.test_coverage.dart
+/test/.test_coverage.dart
+
+# Centifuge
+config.json

examples/console/README.md

@@ -0,0 +1,126 @@
+# Example console chat app
+
+## Getting started with Centrifugo
+
+Before running this example make sure you created `chat` namespace in Centrifugo configuration and allowed publishing into channel.
+
+1. Call `centrifugo genconfig` to create a basic `config.json` at the first time.
+
+2. Update the `config.json` file with tokens and namespaces, e.g.:
+
+```json
+{
+  "token_hmac_secret_key": "<TOKEN HMAC SECRET KEY>",
+  "admin_password": "<ADMIN PASSWORD>",
+  "admin_secret": "<ADMIN SECRET>",
+  "api_key": "<API KEY>",
+  "allowed_origins": ["http://localhost:8000"],
+  "namespaces": [
+    {
+      "name": "chat",
+      "anonymous": false,
+      "publish": true,
+      "join_leave": true,
+      "presence": true,
+      "presence_stats": true,
+      "allow_publish_for_subscriber": true,
+      "allow_subscribe_for_client": true
+    }
+  ]
+}
+```
+
+3. When you use your own configuration, please re-generate the tokens registered in `example.dart`:
+
+- Use `centrifugo gentoken --user dart` to generate the user's JWT token.
+- Use `centrifugo gensubtoken --user dart --channel chat:index` to generate the user's subscription JWT token.
+
+4. Run Centrifugo with the admin option, to later send messages to all subscribers:
+
+```bash
+centrifugo --admin
+```
+
+For testing purposes only, you can also run Centrifugo in insecure client mode, so that the validity of JWT tokens
+are not checked:
+
+```bash
+centrifugo --client_insecure --admin
+```
+
+5. Now check the IP address if your system with `ipconfig` on Windows and `ip adds` on Unix-like systems and change the `serverAddr` variable in `example.dart` accordingly.
+
+6. When the configuration is correct, you can launch the console app with `dart example.dart`.
+
+7. When you have started centrifugo with the `--admin` option, you can also open `http://localhost:8000/#/actions` to send a message to your console app with the
+   following settings:
+
+- Method: Publish
+- Channel: `chat:index`
+- Data: `{"message": "hello world", "username": "admin"}`
+
+Congratulations, you have a running centrifugo system and a Flutter console app that connects to it!
+
+## Centrifugo with Docker
+
+### Configurate Centrifugo
+
+First, you need to create a config file for Centrifugo. You can do this with Docker:
+
+1. Generate config file:
+
+Bash:
+
+```bash
+docker run -it --rm --volume ${PWD}:/centrifugo \
+    --name centrifugo centrifugo/centrifugo:latest centrifugo genconfig
+```
+
+PowerShell:
+
+```powershell
+docker run -it --rm --volume ${PWD}:/centrifugo `
+    --name centrifugo centrifugo/centrifugo:latest centrifugo genconfig
+```
+
+2. Generate user token
+   with `centrifugo gentoken --user dart` to generate the user's JWT token.
+   `centrifugo gensubtoken --user dart --channel chat:index` to generate the user's subscription JWT token.
+
+Bash:
+
+```bash
+docker run -it --rm --volume ${PWD}/config.json:/centrifugo/config.json:ro \
+    --name centrifugo centrifugo/centrifugo:latest \
+    centrifugo gensubtoken --user dart --channel chat:index
+```
+
+PowerShell:
+
+```powershell
+docker run -it --rm --volume ${PWD}/config.json:/centrifugo/config.json:ro `
+    --name centrifugo centrifugo/centrifugo:latest `
+    centrifugo gensubtoken --user dart --channel chat:index
+```
+
+### Run Centrifugo
+
+You can also run the example with Docker. First, build the image:
+
+Bash:
+
+```bash
+docker run -d -it --rm --ulimit nofile=65536:65536 --port 8000:8000 \
+    --volume ${PWD}/config.json:/centrifugo/config.json:ro \
+    --name centrifugo centrifugo/centrifugo:latest centrifugo \
+    --client_insecure --admin --admin_insecure --log_level=debug
+```
+
+PowerShell:
+
+```powershell
+docker run -d -it --rm --ulimit nofile=65536:65536 --port 8000:8000 `
+    --volume ${PWD}/config.json:/centrifugo/config.json:ro `
+    --name centrifugo centrifugo/centrifugo:latest centrifugo `
+    --client_insecure --admin --admin_insecure --log_level=debug
+```

lib/src/client/centrifuge_interface.dart

@@ -8,10 +8,20 @@ abstract interface class ICentrifuge {
   /// Stream of client states.
   abstract final Stream<CentrifugeState> states;
 
+  /* abstract final Stream<Object> publications; */
+
   /// Connect to the server.
   /// [url] is a URL of endpoint.
   Future<void> connect(String url);
 
+  // Send asynchronous message to a server. This method makes sense
+  // only when using Centrifuge library for Go on a server side. In Centrifugo
+  // asynchronous message handler does not exist.
+  //Future<void> send(List<int> data);
+
+  /// Publish data to the channel.
+  /* Future<PublishResult> publish(String channel, List<int> data); */
+
   /// Disconnect from the server.
   Future<void> disconnect();