# Handling Errors

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

import org.apache.maven.InternalErrorException;
import org.apache.maven.Maven;
import org.apache.maven.api.Constants;
import org.apache.maven.api.cli.extensions.CoreExtension;
import org.apache.maven.api.services.MessageBuilder;
import org.apache.maven.api.services.MessageBuilderFactory;
import org.apache.maven.building.FileSource;
import org.apache.maven.building.Problem;
import org.apache.maven.building.Source;

import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Supplier;

import org.apache.maven.api.services.ModelBuilder;
import org.apache.maven.internal.impl.DefaultModelUrlNormalizer;
import org.apache.maven.internal.impl.DefaultModelVersionParser;
import org.apache.maven.internal.impl.DefaultModelXmlFactory;

# Settings and Environment Variables

In many cases your application could need some external settings or configurations, for example secret keys, database credentials, credentials for email services, etc.

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

/// tip

                  }
                }
              }
            },
            "metadata": {
              "filter_metadata": {
                "istio": {
                  "services": [
                    {
                      "name": "httpbin",
                      "namespace": "default",
                      "host": "httpbin.default.svc.cluster.local"
                    }

import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.apache.maven.api.feature.Features;
import org.apache.maven.api.model.Model;
import org.apache.maven.api.services.Lookup;
import org.apache.maven.eventspy.EventSpy;
import org.apache.maven.execution.ExecutionEvent;
import org.apache.maven.execution.MavenSession;
import org.apache.maven.internal.impl.resolver.MavenWorkspaceReader;

             * because we might close the socket during a
             * request. However the chances are slim and the
             * retry code should ensure the overall request
             * is serviced. The alternative complicates things
             * more than I think is worth it.
             */

            if ( this.socket != null ) {
                this.socket.close();
                this.socket = null;

* Cách thiết lập **các ràng buộc cho validation** như `maximum_length` hoặc `regex`.
* Một hệ thống **<abbr title="cũng được biết đến như components, resources, providers, services, injectables">Dependency Injection</abbr> vô cùng mạnh mẽ và dễ dàng sử dụng.
* Bảo mật và xác thực, hỗ trợ **OAuth2**(với **JWT tokens**) và **HTTP Basic**.

**剧透警告**： 教程 - 用户指南中的内容有：

* 对来自不同地方的参数进行声明，如：**请求头**、**cookies**、**form 表单**以及**上传的文件**。
* 如何设置**校验约束**如 `maximum_length` 或者 `regex`。
* 一个强大并易于使用的 **<abbr title="也被称为 components, resources, providers, services, injectables">依赖注入</abbr>** 系统。
* 安全性和身份验证，包括通过 **JWT 令牌**和 **HTTP 基本身份认证**来支持 **OAuth2**。
* 更进阶（但同样简单）的技巧来声明 **多层嵌套 JSON 模型** （借助 Pydantic）。
* 许多额外功能（归功于 Starlette）比如：
    * **WebSockets**
    * **GraphQL**

    name = "is_cuda_enabled",
    actual = if_oss(
        "@local_config_cuda//:is_cuda_enabled",
        "@local_config_cuda//cuda:using_config_cuda",
    ),
)

# Config setting that is satisfied when CUDA device code should be compiled
# with clang. It does not imply that CUDA support has been enabled.
alias(
    name = "is_cuda_compiler_clang",
    actual = if_oss(
        "@local_config_cuda//:is_cuda_compiler_clang",