此页面由 Cloud Translation API 翻译。

连接组件

协议句柄是众所周知的对象，可提供可使用组件命名空间检测到的 FIDL 协议。组件框架有助于在 Google Cloud 和 Google Cloud 组件功能功能路由描述了哪个组件应充当。找出合适的组件后组件管理器使用在每个组件中找到的句柄在组件之间该组件的命名空间。

请参考以下示例，了解 fuchsia.example.Foo 协议：

展示连接组件如何成为功能组合的示意图
提供路由和协议服务组件必须提供
向其他组件提供的协议

下图突出显示了执行连接所涉及的主要元素：

提供程序组件以静态方式声明 capabilities 部分。这样，组件框架就可以执行功能路由。
客户端组件在 use 部分中以静态方式请求协议。这将创建 /svc/fuchsia.example.Foo 协议条目（如果功能路由成功）。
提供程序代码会在运行时发布实现。这会创建提供商外拨电话中 /svc/fuchsia.example.Foo 处的协议条目目录。
客户端代码在运行时会连接到协议句柄。这会打开一个与提供程序组件中运行的实现的 FIDL 连接。

发布协议实现

实现 FIDL 协议的组件会声明和公开作为一项功能添加到其组件清单中。这样，该组件以便执行从该组件到请求该功能的拓扑。

{
    // ...
    capabilities: [
        { protocol: "fuchsia.example.Foo" },
    ],
    expose: [
        {
            protocol: "fuchsia.example.Foo",
            from: "self",
        },
    ],
}

功能路由描述的是协议的访问权限没有为连接建立必要的端点。组件必须发布使用/svc/ fuchsia.io 协议。通过生成的 FIDL 绑定会封装此句柄，并使提供程序能够连接请求句柄，以开始接收 FIDL 消息。

Rust

let mut service_fs = ServiceFs::new_local();

// Serve the protocol
service_fs.dir("svc").add_fidl_service(PROTOCOL_NAME);
service_fs.take_and_serve_directory_handle().context("failed to serve outgoing namespace")?;

C++

// Serve the protocol
FooImplementation instance;
fidl::Binding<fuchsia::example::Foo> binding(&instance);
instance.event_sender_ = &binding.events();
fidl::InterfaceRequestHandler<fuchsia::example::Foo> handler =
    [&](fidl::InterfaceRequest<fuchsia::example::Foo> request) {
      binding.Bind(std::move(request));
    };
context->outgoing()->AddPublicService(std::move(handler));

连接到协议实现

客户端组件将协议声明为组件清单。这样，组件框架就可以确定该组件有权访问协议实施。如果为有效路线存在，则该组件的命名空间包含相应的 /svc/ 句柄。

{
    // ...
    use: [
        { protocol: "fuchsia.example.Foo" },
    ],
}

客户端组件使用 fuchsia.io 协议与协议实现建立连接并打开一个通道。通过生成的 FIDL 绑定会封装此通道，并使客户端能够开始发送向提供程序发送这些消息

Rust

// Connect to FIDL protocol
let protocol = connect_to_protocol::<FooMarker>().expect("error connecting to echo");

C++

// Connect to FIDL protocol
fuchsia::example::FooSyncPtr proxy;
auto context = sys::ComponentContext::Create();
context->svc()->Connect(proxy.NewRequest());

练习：Echo 服务器和客户端

在本部分中，您将使用生成的 FIDL 绑定， fidl.examples.routing.echo，用于在 Rust 中实现客户端和服务器组件。

启动模拟器

如果您尚未运行实例，请启动模拟器：

启动新的模拟器实例：

ffx emu start --headless

启动完成后，模拟器将输出以下消息和返回：

Logging to "$HOME/.local/share/Fuchsia/ffx/emu/instances/fuchsia-emulator/emulator.log"
Waiting for Fuchsia to start (up to 60 seconds)........
Emulator is ready.

启动软件包服务器，使模拟器能够加载软件包：
```
fx serve
```

创建服务器组件

首先，创建一个新的组件项目来实现 echo 服务器。这个组件将提供 Echo 协议并处理传入请求。

在echo-server //vendor/fuchsia-codelab 目录：

mkdir -p vendor/fuchsia-codelab/echo-server

Rust

//vendor/fuchsia-codelab/echo-server
                        |- BUILD.gn
                        |- meta
                        |   |- echo.cml
                        |
                        |- src
                            |- main.rs

C++

//vendor/fuchsia-codelab/echo-server
                        |- BUILD.gn
                        |- meta
                        |   |- echo.cml
                        |
                        |- main.cc

将以下构建规则添加到 BUILD.gn 文件中，以构建并打包服务器组件：

Rust

echo-server/BUILD.gn：

import("//build/components.gni")
import("//build/rust/rustc_binary.gni")


rustc_binary("bin") {
  output_name = "echo-server"
  edition = "2021"

  deps = [
    "//vendor/fuchsia-codelab/echo-fidl:echo_rust",
    "//src/lib/diagnostics/inspect/runtime/rust",
    "//src/lib/diagnostics/inspect/rust",
    "//src/lib/fuchsia",
    "//src/lib/fuchsia-component",
    "//third_party/rust_crates:anyhow",
    "//third_party/rust_crates:futures",
  ]

  sources = [ "src/main.rs" ]
}

# Unpackaged component "#meta/echo_server.cm"
fuchsia_component("echo_server_cmp") {
  component_name = "echo_server"
  manifest = "meta/echo_server.cml"
  deps = [ ":bin" ]
}

fuchsia_package("echo-server") {
  package_name = "echo-server"
  deps = [ ":component" ]
}

C++

echo-server/BUILD.gn：

import("//build/components.gni")


executable("bin") {
  output_name = "echo-server"
  sources = [ "main.cc" ]

  deps = [
    "//vendor/fuchsia-codelab/echo-fidl:echo_hlcpp",
    "//sdk/lib/async-loop:async-loop-cpp",
    "//sdk/lib/async-loop:async-loop-default",
    "//sdk/lib/inspect/component/cpp",
    "//sdk/lib/sys/cpp",
  ]
}

# Unpackaged component "#meta/echo_server.cm"
fuchsia_component("echo_server_cmp") {
  component_name = "echo_server"
  manifest = "meta/echo_server.cml"
  deps = [ ":bin" ]
}

fuchsia_package("echo-server") {
  package_name = "echo-server"
  deps = [ ":component" ]
}

将 Echo 协议声明为服务器组件提供的功能。并将其公开，以供父域使用：

Rust

echo-server/meta/echo_server.cml：

{
    include: [
        "inspect/client.shard.cml",
        "syslog/client.shard.cml",
    ],

    // Information about the program to run.
    program: {
        // Use the built-in ELF runner.
        runner: "elf",

        // The binary to run for this component.
        binary: "bin/echo-server",
    },

    // Capabilities provided by this component.
    capabilities: [
        { protocol: "fidl.examples.routing.echo.Echo" },
    ],
    expose: [
        {
            protocol: "fidl.examples.routing.echo.Echo",
            from: "self",
        },
    ],
}

C++

echo-server/meta/echo_server.cml：

{
    include: [
        "inspect/client.shard.cml",
        "syslog/client.shard.cml",
    ],

    // Information about the program to run.
    program: {
        // Use the built-in ELF runner.
        runner: "elf",

        // The binary to run for this component.
        binary: "bin/echo-server",
    },

    // Capabilities provided by this component.
    capabilities: [
        { protocol: "fidl.examples.routing.echo.Echo" },
    ],
    expose: [
        {
            protocol: "fidl.examples.routing.echo.Echo",
            from: "self",
        },
    ],
}

实现服务器

打开主源文件，并将 import 语句替换为以下代码：

Rust

echo-server/src/main.rs：

use anyhow::Context;
use fidl_fidl_examples_routing_echo::{EchoRequest, EchoRequestStream};
use fuchsia_component::server::ServiceFs;
use fuchsia_inspect::component;
use fuchsia_inspect::health::Reporter;
use futures::prelude::*;

</ph> 针对 Rust 的 FIDL 绑定会生成以 FIDL 命名的 Rust 库 crate。 library。对于 fidl.examples.routing.echo 库，生成的 crate 名称为 fidl_fidl_examples_routing_echo。对于请参见 Rust 绑定。

C++

echo-server/main.cc：

#include <fidl/examples/routing/echo/cpp/fidl.h>
#include <lib/async-loop/cpp/loop.h>
#include <lib/async-loop/default.h>
#include <lib/fidl/cpp/binding.h>
#include <lib/inspect/component/cpp/component.h>
#include <lib/sys/cpp/component_context.h>

将以下代码添加到 main() 以提供 Echo 协议：

Rust

echo-server/src/main.rs：

// Wrap protocol requests being served.
enum IncomingRequest {
    Echo(EchoRequestStream),
}

#[fuchsia::main(logging = false)]
async fn main() -> Result<(), anyhow::Error> {
    let mut service_fs = ServiceFs::new_local();

    // Initialize inspect
    component::health().set_starting_up();
    let _inspect_server_task = inspect_runtime::publish(
        component::inspector(),
        inspect_runtime::PublishOptions::default(),
    );

    // Serve the Echo protocol
    service_fs.dir("svc").add_fidl_service(IncomingRequest::Echo);
    service_fs.take_and_serve_directory_handle().context("failed to serve outgoing namespace")?;

    // Component is serving and ready to handle incoming requests
    component::health().set_ok();

    // Attach request handler for incoming requests
    service_fs
        .for_each_concurrent(None, |request: IncomingRequest| async move {
            match request {
                IncomingRequest::Echo(stream) => handle_echo_request(stream).await,
            }
        })
        .await;

    Ok(())
}

此代码执行以下步骤以提供 Echo 协议：

初始化 ServiceFs 并在下面添加一个条目传出目录中的 /svc/fidl.examples.routing.echo.Echo。
提供该目录并开始监听传入的连接。
将 handle_echo_request() 函数作为任何匹配 Echo 个请求。

C++

echo-server/main.cc：

int main(int argc, const char** argv) {
  async::Loop loop(&kAsyncLoopConfigAttachToCurrentThread);
  auto context = sys::ComponentContext::CreateAndServeOutgoingDirectory();

  // Initialize inspect
  inspect::ComponentInspector inspector(loop.dispatcher(), inspect::PublishOptions{});
  inspector.Health().StartingUp();

  // Serve the Echo protocol
  EchoImplementation echo_instance;
  fidl::Binding<fidl::examples::routing::echo::Echo> binding(&echo_instance);
  echo_instance.event_sender_ = &binding.events();
  fidl::InterfaceRequestHandler<fidl::examples::routing::echo::Echo> handler =
      [&](fidl::InterfaceRequest<fidl::examples::routing::echo::Echo> request) {
        binding.Bind(std::move(request));
      };
  context->outgoing()->AddPublicService(std::move(handler));

  // Component is serving and ready to handle incoming requests
  inspector.Health().Ok();

  return loop.Run();
}

此代码执行以下步骤以提供 Echo 协议：

初始化 ComponentContext 并在下面添加一个条目传出目录中的 /svc/fidl.examples.routing.echo.Echo。
提供该目录并开始监听传入的连接。
将 EchoImplementation 实例作为任何匹配 Echo 个请求。

添加以下代码以实现协议请求处理程序：

Rust

echo-server/src/main.rs：

// Handler for incoming service requests
async fn handle_echo_request(mut stream: EchoRequestStream) {
    while let Some(event) = stream.try_next().await.expect("failed to serve echo service") {
        let EchoRequest::EchoString { value, responder } = event;
        responder.send(value.as_ref().map(|s| &**s)).expect("failed to send echo response");
    }
}

EchoRequestStream 中的每个请求都按方法名称输入 (EchoString) 并包含一个用于发回返回值的响应器接口。

C++

echo-server/main.cc：

// Handler for incoming service requests
class EchoImplementation : public fidl::examples::routing::echo::Echo {
 public:
  void EchoString(fidl::StringPtr value, EchoStringCallback callback) override { callback(value); }
  fidl::examples::routing::echo::Echo_EventSender* event_sender_;
};

每个 Echo 协议方法都有一个对应的替换函数 (EchoString()) 并包含一个回调接口，用于发回返回值。

此实现只是“回显”请求返回的相同字符串值。

创建客户端组件

再创建一个新的组件项目来实现 echo 客户端。这个组件将连接到协议实现并发送请求。

在echo-client //vendor/fuchsia-codelab 目录：

mkdir -p vendor/fuchsia-codelab/echo-client

Rust

//vendor/fuchsia-codelab/echo-client
                        |- BUILD.gn
                        |- meta
                        |   |- echo.cml
                        |
                        |- src
                            |- main.rs

C++

//vendor/fuchsia-codelab/echo-client
                        |- BUILD.gn
                        |- meta
                        |   |- echo.cml
                        |
                        |- main.cc

将以下构建规则添加到 BUILD.gn 文件，以构建并打包客户端组件：

Rust

echo-client/BUILD.gn：

import("//build/components.gni")
import("//build/rust/rustc_binary.gni")


rustc_binary("bin") {
  output_name = "echo-client"
  edition = "2021"
  deps = [
    "//vendor/fuchsia-codelab/echo-fidl:echo_rust",
    "//src/lib/fuchsia",
    "//src/lib/fuchsia-component",
    "//third_party/rust_crates:anyhow",
    "//third_party/rust_crates:tracing",
  ]

  sources = [ "src/main.rs" ]
}

# Unpackaged component "#meta/echo_client.cm"
fuchsia_component("echo_client_cmp") {
  component_name = "echo_client"
  manifest = "meta/echo_client.cml"
  deps = [ ":bin" ]
}

fuchsia_package("echo-client") {
  package_name = "echo-client"
  deps = [ ":component" ]
}

C++

echo-client/BUILD.gn：

import("//build/components.gni")


executable("bin") {
  output_name = "echo-client"
  sources = [ "main.cc" ]

  deps = [
    "//vendor/fuchsia-codelab/echo-fidl:echo_hlcpp",
    "//sdk/lib/async-loop:async-loop-cpp",
    "//sdk/lib/async-loop:async-loop-default",
    "//sdk/lib/sys/cpp",
    "//sdk/lib/syslog/cpp",
  ]
}

# Unpackaged component "#meta/echo_client.cm"
fuchsia_component("echo_client_cmp") {
  component_name = "echo_client"
  manifest = "meta/echo_client.cml"
  deps = [ ":bin" ]
}

fuchsia_package("echo-client") {
  package_name = "echo-client"
  deps = [ ":component" ]
}

配置客户端的组件清单以请求服务器公开的 fidl.examples.routing.echo.Echo 功能：

Rust

echo-client/meta/echo_client.cml：

{
    include: [
        // Enable logging on stdout
        "syslog/client.shard.cml",
    ],

    // Information about the program to run.
    program: {
        // Use the built-in ELF runner.
        runner: "elf",

        // The binary to run for this component.
        binary: "bin/echo-client",

        // Program arguments
        args: [ "Hello Fuchsia!" ],
    },


    // Capabilities used by this component.
    use: [
        { protocol: "fidl.examples.routing.echo.Echo" },
    ],
}

C++

echo-client/meta/echo_client.cml：

{
    include: [
        // Enable logging.
        "syslog/client.shard.cml",
    ],

    // Information about the program to run.
    program: {
        // Use the built-in ELF runner.
        runner: "elf",

        // The binary to run for this component.
        binary: "bin/echo-client",

        // Program arguments
        args: [ "Hello Fuchsia!" ],
    },


    // Capabilities used by this component.
    use: [
        { protocol: "fidl.examples.routing.echo.Echo" },
    ],
}

实现客户端

与 echo-args 类似，客户端以消息形式传递程序参数发送到服务器。将以下程序参数添加到 echo_client.cml：

Rust

echo-client/meta/echo_client.cml：

// Information about the program to run.
program: {
    // Use the built-in ELF runner.
    runner: "elf",

    // The binary to run for this component.
    binary: "bin/echo-client",

    // Program arguments
    args: [ "Hello Fuchsia!" ],
},

C++

echo-client/meta/echo_client.cml：

// Information about the program to run.
program: {
    // Use the built-in ELF runner.
    runner: "elf",

    // The binary to run for this component.
    binary: "bin/echo-client",

    // Program arguments
    args: [ "Hello Fuchsia!" ],
},

打开主源文件，并将 import 语句替换为以下代码：

Rust

echo-client/src/main.rs：

use fidl_fidl_examples_routing_echo::EchoMarker;
use fuchsia_component::client::connect_to_protocol;

C++

echo-client/main.cc：

#include <fidl/examples/routing/echo/cpp/fidl.h>
#include <lib/fidl/cpp/string.h>
#include <lib/sys/cpp/component_context.h>
#include <lib/syslog/cpp/log_settings.h>
#include <lib/syslog/cpp/macros.h>

#include <cstdlib>
#include <iostream>
#include <string>

将以下代码添加到 main() 以连接到 Echo 协议并发送请求：

Rust

echo-client/src/main.rs：

#[fuchsia::main]
async fn main() -> Result<(), anyhow::Error> {
    // Parse arguments, removing binary name
    let mut args: Vec<String> = std::env::args().collect();
    args.remove(0);

    // Connect to FIDL protocol
    let echo = connect_to_protocol::<EchoMarker>().expect("error connecting to echo");

    // Send messages over FIDL interface
    for message in args {
        let out = echo.echo_string(Some(&message)).await.expect("echo_string failed");
        tracing::info!("Server response: {}", out.as_ref().expect("echo_string got empty result"));
    }

    Ok(())
}

EchoMarker 提供了一个封装容器，用于通过并为打开的 EchoProxy 接口返回一个句柄。此代理包含 echo_string() FIDL 协议方法。

C++

echo-client/main.cc：

int main(int argc, const char* argv[], char* envp[]) {
  // Set tags for logging.
  fuchsia_logging::LogSettingsBuilder builder;
  builder.WithTags({"echo_client"}).BuildAndInitialize();

  // Connect to FIDL protocol
  fidl::examples::routing::echo::EchoSyncPtr echo_proxy;
  auto context = sys::ComponentContext::Create();
  context->svc()->Connect(echo_proxy.NewRequest());

  // Send messages over FIDL interface for each argument
  fidl::StringPtr response = nullptr;
  for (int i = 1; i < argc; i++) {
    ZX_ASSERT(echo_proxy->EchoString(argv[i], &response) == ZX_OK);
    if (!response.has_value()) {
      FX_LOG_KV(INFO, "echo_string got empty result");
    } else {
      FX_LOG_KV(INFO, "Server response", FX_KV("response", response->c_str()));
    }
  }

  return 0;
}

EchoSyncPtr 提供了一个封装容器，用于通过 name 并向开放代理接口返回一个句柄。此代理包含 EchoString() FIDL 协议方法。

集成组件

服务器提供的功能必须通过组件框架为此，您需要实现一个 Realm 组件作为父项并管理 capability 路由。

为大区产品定义创建一个新的项目目录：

mkdir -p vendor/fuchsia-codelab/echo-realm

//vendor/fuchsia-codelab/echo-realm
                        |- BUILD.gn
                        |- meta
                        |   |- echo_realm.cml

创建一个包含以下内容的新组件清单文件 meta/echo_realm.cml：以下内容：

echo-realm/meta/echo_realm.cml：

{
    // Two children: a server and client.
    children: [
        {
            name: "echo_server",
            url: "#meta/echo_server.cm",
        },
        {
            name: "echo_client",
            url: "#meta/echo_client.cm",
        },
    ],
    offer: [
        // Route Echo protocol from server to client.
        {
            protocol: "fidl.examples.routing.echo.Echo",
            from: "#echo_server",
            to: "#echo_client",
        },

        // Route diagnostics protocols to both children.
        {
            protocol: [
                "fuchsia.inspect.InspectSink",
                "fuchsia.logger.LogSink",
            ],
            from: "parent",
            to: [
                "#echo_client",
                "#echo_server",
            ],
        },
    ],
}

这将创建一个以服务器和客户端作为子组件的组件领域，并将 fidl.examples.routing.echo.Echo 协议功能路由到客户端。

添加 BUILD.gn 文件，为 Realm 组件创建构建目标：

echo-realm/BUILD.gn：

import("//build/components.gni")

fuchsia_component("echo_realm") {
  manifest = "meta/echo_realm.cml"
}

fuchsia_package("echo-realm") {
  deps = [
    ":echo_realm",
    "//vendor/fuchsia-codelab/echo-server:component",
    "//vendor/fuchsia-codelab/echo-client:component",
  ]
}

更新 build 配置以包含新组件：

fx set workstation_eng.x64 \
    --with //vendor/fuchsia-codelab/echo-server \
    --with //vendor/fuchsia-codelab/echo-client \
    --with //vendor/fuchsia-codelab/echo-realm

再次运行 fx build 以构建组件：

fx build

将组件添加到拓扑中

您需要将您的组件添加到受限集合 ffx-laboratory 中用于在产品的核心领域进行开发。借助集合在运行时动态创建和销毁的组件。

通过传递 echo-realm 组件网址和将 ffx-laboratory 内的相应名称添加到 ffx component create：

ffx component create /core/ffx-laboratory:echo-realm \
    fuchsia-pkg://fuchsia.com/echo-realm#meta/echo_realm.cm

然后，使用 ffx component resolve 解析 echo-realm 组件：

ffx component resolve /core/ffx-laboratory:echo-realm

验证服务器和客户端的实例也被创建为子级组件：ffx component show

ffx component show echo

               Moniker: /core/ffx-laboratory:echo-realm/echo_client
                   URL: #meta/echo_client.cm
                  Type: CML static component
       Component State: Unresolved
       Execution State: Stopped

               Moniker: /core/ffx-laboratory:echo-realm/echo_server
                   URL: #meta/echo_server.cm
                  Type: CML static component
       Component State: Unresolved
       Execution State: Stopped

               Moniker: /core/ffx-laboratory:echo-realm
                   URL: fuchsia-pkg://fuchsia.com/echo-realm#meta/echo_realm.cm
                  Type: CML dynamic component
       Component State: Resolved
       Execution State: Stopped
           Merkle root: 666c40477785f89b0ace22b30d65f1338f1d308ecceacb0f65f5140baa889e1b

验证组件交互

使用 ffx component start 启动现有客户端组件实例：

ffx component start /core/ffx-laboratory:echo-realm/echo_client

打开另一个终端窗口，验证客户端组件的日志输出：

ffx log --filter echo

您应该会在设备日志中看到以下输出：

[echo_client][I] Server response: Hello, Fuchsia!

在客户端连接到 fidl.examples.routing.echo.Echo功能并继续运行其他 FIDL 请求。

使用 ffx component show 查看在组件中运行的 echo 服务器实例树：

ffx component show echo_server

               Moniker: /core/ffx-laboratory:echo-realm/echo_server
                   URL: #meta/echo_server.cm
                  Type: CML static component
       Component State: Resolved
 Incoming Capabilities: fuchsia.logger.LogSink
  Exposed Capabilities: diagnostics
                        fidl.examples.routing.echo.Echo
       Execution State: Running
                Job ID: 474691
            Process ID: 474712
           Running for: 2026280474361 ticks
           Merkle root: 666c40477785f89b0ace22b30d65f1338f1d308ecceacb0f65f5140baa889e1b
 Outgoing Capabilities: diagnostics
                        fidl.examples.routing.echo.Echo

销毁实例

使用以下命令清理 echo-realm 实例：

ffx component destroy /core/ffx-laboratory:echo-realm

Fuchsia 接口定义语言

集成测试