Component resolvers

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Component resolvers extend the component framework through an [environment][glossary.environment] to resolve a [component URL][glossary.component-url] into a component.

Component manager resolves component URLs by finding a resolver that supports a matching URL scheme in the relevant environment and sending a request using the [fuchsia.component.resolution.Resolver][fidl-resolver] protocol.

If resolution succeeds, the component resolver returns a [ComponentDecl][fidl-decl], the FIDL representation of a [component manifest][component-manifest]. If the component being resolved has an associated package, the component resolver also returns a [fuchsia.io.Directory][fidl-directory] handle for the package directory.

Providing resolver capabilities {#provide}

To provide a resolver capability, a component must declare a resolver capability, whose path designates a FIDL protocol implementing [fuchsia.component.resolution.Resolver][fidl-resolver] served from the component's [outgoing directory][glossary.outgoing-directory].

{
    capabilities: [
        {
            resolver: "my_resolver",
            path: "/svc/fuchsia.component.resolution.Resolver",
        },
    ],
}

Component manager submits requests to resolve a component URL to this protocol.

Routing resolver capabilities {#route}

Components route resolver capabilities by exposing them to their parent and offering them to their children.

For more details on how the framework routes component capabilities, see [capability routing][capability-routing].

Exposing {#expose}

Exposing a resolver capability gives the component's parent access to that capability:

{
    expose: [
        {
            resolver: "my_resolver",
            from: "self",
        },
    ],
}

Offering {#offer}

Offering a resolver capability gives a child component access to that capability:

{
    offer: [
        {
            resolver: "my_resolver",
            from: "self",
            to: [ "#child-a" ],
        },
    ],
}

Registering a component resolver {#register}

Component resolvers are made available to components through their [environment][environment]. To register a new resolver within an environment, add a new entry to the resolvers section of the environments declaration:

environments: [
    {
        name: "my-environ",
        extends: "realm",
        resolvers: [
            {
                resolver: "my_resolver",
                scheme: "my-scheme",
                from: "parent",
            }
        ],
    },
]

The registered resolver will be used to resolve component URLs whose URL scheme matches the provided scheme.

For more details on how to apply environments to components, see the [environments documentation][environment].

Framework resolvers {#framework}

Component framework provides the following built-in component resolvers to support standard Fuchsia URL schemes:

Resolver	URL scheme
boot_resolver	[fuchsia-boot][url-boot]
base_resolver	[fuchsia-pkg][url-pkg]
universe_resolver	[fuchsia-pkg][url-pkg]

glossary.component-url /glossary/README.md#environment glossary.outgoing-directory /concepts/components/v2/capabilities/README.md#routing component-manifestenvironmentfidl-resolverfidl-declfidl-directoryurl-boot /reference/components/url.md#fuchsia-pkg

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最后更新: 2022 年 12 月 31 日（Saturday） 21:06 CST