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Component URLs

A component URL is a URL that identifies a component.

This section describes the syntax used for displaying URLs to users.

URL Format

A component URL can, in principle, have any scheme. Some common schemes you may encounter are:

fuchsia-pkg

A fuchsia-pkg component URL is a package URL that locates a component distributed in a Fuchsia package.

It has the same format as package URL, with a resource path relative to the package root that locates a component manifest. This path is usually of the form meta/<manifest_name>.cm.

fuchsia-pkg://<repo-hostname>[/<pkg-name>[/<pkg-variant>][?hash=<pkg-hash>][#<path-to-manifest>]]

Example:

fuchsia-pkg://fuchsia.com/stash#meta/stash_secure.cm

fuchsia-boot

A fuchsia-boot component URL locates a component in the system boot image. This scheme is used to identify components that must be resolved during early boot before a fuchsia-pkg resolver is available. It has the following format:

fuchsia-boot:///<path-to-manifest-in-bootfs>

Example:

fuchsia-boot:///#meta/driver_manager.cm

http(s)

An http(s) component URL identifies a web page as a component. Such a component could be executed as a web page in a web runner, for example.

Example:

https://en.wikipedia.org/wiki/Hippos

Relative URLs

The Component Framework supports a subset of relative URLs (Relative URLs are defined in URL RFC 3986). Specifically, Component Framework supports relative path URLs (plus a URL fragment with the path to the component manifest) to subpackaged components, and fragment-only URLs.

The path to the component manifest is the only content allowed in a relative component URL fragment (#meta/<component>.cm). If the fragment contains any other content, or if a relative component includes URL query parameters (?key=value), the component will not resolve.

Relative path URLs to subpackaged components

A relative path URL is resolved at runtime based on a known "context". For components resolving a child component by relative URL, the context is a resolver-supplied value associated with the parent component. The URL path is interpreted as the name of one of the declared subpackage s of the parent component's package.

Relative subpackage path URLs start with a relative package URL and have the following format:

<subpackage-path>#<path-to-manifest>

Example:

child#meta/default.cm

For more information on subpackages and subpackaged components, see the documentation on Fuchsia Subpackages.

Relative fragment-only URLs

A relative fragment-only URL is resolved at runtime based on the URL of the parent component's package. Fragment-only URLs have the following format:

#<path-to-manifest>

Example:

#meta/child.cm

For a fuchsia-pkg parent component with the following URL:

fuchsia-pkg://fuchsia.com/package#meta/component.cm

The relative URL resolves to:

fuchsia-pkg://fuchsia.com/package#meta/child.cm