func (m *message) setZeroPayloadFlag() {
	m.Flags &^= FlagPayloadIsZero
	if len(m.Payload) == 0 && m.Payload != nil {
		m.Flags |= FlagPayloadIsZero
	}
}

type receiver interface {
	msgp.Unmarshaler
	Op() Op
}

type sender interface {
	msgp.MarshalSizer
	Op() Op
}

type connectReq struct {
	ID    [16]byte
	Host  string
	Time  time.Time
	Token string
}

the interface presents a list of user commands or options, such as a
menu, a prominent item in the list meets this criterion.

  1. Source Code.

  The "source code" for a work means the preferred form of the work
for making modifications to it.  "Object code" means any non-source
form of a work.

  A "Standard Interface" means an interface that either is an official

import org.gradle.api.specs.Spec
import org.gradle.util.GradleVersion
import java.io.File
import javax.inject.Inject


abstract class CachesCleaner : BuildService<CachesCleaner.Params> {
    interface Params : BuildServiceParameters {
        val gradleVersion: Property<String>
        val homeDir: DirectoryProperty
    }

    @get:Inject
    abstract val fileSystemOperations: FileSystemOperations

    private

/**
 * Handles serialization of a model into some kind of textual format like XML.
 *
 * @deprecated use {@code org.apache.maven.api.services.xml.ModelXmlFactory} instead
 */
@Deprecated(since = "4.0.0")
public interface ModelWriter {

    /**
     * Writes the supplied model to the specified file. Any non-existing parent directories of the output file will be
     * created automatically.
     *

            return new Settings(delegate.read(parser, strict, null));
        } catch (XMLStreamException e) {
            throw new XmlPullParserException(e.getMessage(), null, e);
        }
    }

    public interface ContentTransformer {
        /**
         * Interpolate the value read from the xpp3 document
         * @param source The source value

import org.apache.maven.settings.Settings;
import org.apache.maven.toolchain.model.PersistedToolchains;

/**
 * Assists in populating an execution request for invocation of Maven.
 *
 */
public interface MavenExecutionRequestPopulator {
    /**
     * Copies the values from the given toolchains into the specified execution request. This method will replace any

import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.repository.RemoteRepository;

/**
 * Collects settings required to resolve the version for a plugin.
 *
 * @since 3.0
 */
public interface PluginVersionRequest {

    /**
     * Gets the group id of the plugin.
     *
     * @return The group id of the plugin.
     */
    String getGroupId();

    /**
     * Sets the group id of the plugin.

import org.eclipse.aether.RepositorySystemSession;
import org.eclipse.aether.artifact.Artifact;

/**
 * Component collecting plugin validation issues and reporting them.
 *
 * @since 3.9.2
 */
public interface PluginValidationManager {
    enum IssueLocality {
        /**
         * Issue is "user actionable", is internal to the currently built project and is reparable from scope of it

/**
 * @deprecated As of 3.2.2, and there is no direct replacement. This is an internal class which was not marked as such,
 *             but should have been.
 *
 */
@Deprecated
public interface ProjectDependenciesResolver {

    /**
     * Resolves the transitive dependencies of the specified project.
     *
     * @param project         The project whose dependencies should be resolved, must not be {@code null}.

以及如何[使用 `CORSMiddleware` 处理 CORS](../tutorial/cors.md){.internal-link target=_blank}。

本章学习如何使用其它中间件。

## 添加 ASGI 中间件

因为 **FastAPI** 基于 Starlette，且执行 <abbr title="Asynchronous Server Gateway Interface，异步服务器网关界面">ASGI</abbr> 规范，所以可以使用任意 ASGI 中间件。

中间件不必是专为 FastAPI 或 Starlette 定制的，只要遵循 ASGI 规范即可。

总之，ASGI 中间件是类，并把 ASGI 应用作为第一个参数。

因此，有些第三方 ASGI 中间件的文档推荐以如下方式使用中间件：

```Python