### Install Control plane

This can run in any cluster. A mesh should have at least one cluster should run Pilot or equivalent XDS server,
and it is recommended to have Pilot running in each region and in multiple availability zones for multi cluster.

```bash
iop istio-control istio-discovery $IBASE/istio-control/istio-discovery \
            --set global.istioNamespace=istio-system

# Second istio-discovery, using master version of istio

import java.io.PrintWriter;

import org.apache.maven.api.annotations.Nullable;
import org.apache.maven.api.cli.Logger;

/**
 * Proto {@link Logger}. Uses provided {@link PrintStream}s or {@link System} ones as fallback.
 * Supports only two levels: ERROR and WARNING, that is emitted to STDERR and STDOUT.
 */
public class ProtoLogger implements Logger {

    private final PrintWriter out;
    private final PrintWriter err;

#### Operation

"Operation" here refers to one of the HTTP "methods".

One of:

* `POST`
* `GET`
* `PUT`
* `DELETE`

...and the more exotic ones:

* `OPTIONS`
* `HEAD`
* `PATCH`
* `TRACE`

In the HTTP protocol, you can communicate to each path using one (or more) of these "methods".

---

It will all be combined and included in your OpenAPI, and shown in the API docs:

<img src="/img/tutorial/additional-responses/image01.png">

## Combine predefined responses and custom ones

You might want to have some predefined responses that apply to many *path operations*, but you want to combine them with custom responses needed by each *path operation*.

In short:

* `100` and above are for "Information". You rarely use them directly.  Responses with these status codes cannot have a body.
* **`200`** and above are for "Successful" responses. These are the ones you would use the most.
    * `200` is the default status code, which means everything was "OK".
    * Another example would be `201`, "Created". It is commonly used after creating a new record in the database.

     * filter is applied (like in Maven 3).
     * <br/>
     * Supported filters:
     * <ul>
     *     <li>"h" or "h(num)" - highest version or top list of highest ones filter</li>
     *     <li>"l" or "l(num)" - lowest version or bottom list of lowest ones filter</li>
     *     <li>"s" - contextual snapshot filter</li>
     *     <li>"e(G:A:V)" - predicate filter (leaves out G:A:V from range, if hit, V can be range)</li>
     * </ul>

Create a PassLib "context". This is what will be used to hash and verify passwords.

/// tip

The PassLib context also has functionality to use different hashing algorithms, including deprecated old ones only to allow verifying them, etc.

For example, you could use it to read and verify passwords generated by another system (like Django) but hash any new passwords with a different algorithm like Bcrypt.

        // Those two public constants are initialized here, as they need all the private constants
        // above to be initialized first, but the code style imposes the public constants to be
        // defined above the private ones...
        OS_FAMILY = getOsFamily();
        IS_WINDOWS = isFamily(FAMILY_WINDOWS);
    }

    private Os() {}

    /**
     * Determines if the OS on which Maven is executing matches the

`secrets.compare_digest()` needs to take `bytes` or a `str` that only contains ASCII characters (the ones in English), this means it wouldn't work with characters like `á`, as in `Sebastián`.

To handle that, we first convert the `username` and `password` to `bytes` encoding them with UTF-8.

- asking to use a plugin for which you do not have a version defined - tools to easily select versions
- goal not found in a plugin (probably could list the ones that are)

 */

// PluginNotFoundException, PluginResolutionException, PluginDescriptorParsingException,
// CycleDetectedInPluginGraphException;

/**
 * Transform an exception into useful end-user message.
 */