| # Component URLs {#component-urls} |
| |
| A component URL is a [URL][wiki-url] that locates a component, including its |
| declaration, program, and assets. Component URLs are resolved to |
| [component declarations][doc-manifests-declaration] by a |
| [resolver][doc-resolvers]. |
| |
| ## Usage |
| |
| The primary use of component URLs is to identify a component in the definition |
| of a component instance, as part of a |
| [child declaration][doc-manifests-children]. |
| |
| You should not use component URLs to identify component *instances*, as multiple |
| component instances can share the same URL. For that purpose, instead use |
| [monikers][doc-monikers]. |
| |
| ## Format |
| |
| A component URL can, in principle, have any [scheme][rfc-uri-scheme]. Some |
| common schemes you may encounter are: |
| |
| - [fuchsia-pkg](#fuchsia-pkg) |
| - [fuchsia-boot](#fuchsia-boot) |
| - [http(s)](#http) |
| |
| ### fuchsia-pkg {#fuchsia-pkg} |
| |
| A `fuchsia-pkg` component URL is a [package URL][doc-package-url] that locates a |
| component distributed in a [Fuchsia package][doc-package]. |
| |
| It has the same format as [package URL][doc-package-url], with a |
| [resource path][doc-package-url-resource-path] relative to the package root that |
| locates a [component manifest][doc-manifests]. 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 {#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`](#fuchsia-pkg) [resolver][doc-resolvers] is |
| available. It has the following format: |
| |
| ``` |
| fuchsia-boot:///<path-to-manifest-in-bootfs> |
| ``` |
| |
| Example: |
| |
| ``` |
| fuchsia-boot:///#meta/driver_manager.cm |
| ``` |
| |
| ### http(s) {#http} |
| |
| 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][doc-runners], for |
| example. |
| |
| Example: |
| |
| ``` |
| https://en.wikipedia.org/wiki/Hippos |
| ``` |
| |
| [doc-manifests]: component_manifests.md |
| [doc-manifests-children]: component_manifests.md#children |
| [doc-manifests-declaration]: component_manifests.md#component-declaration |
| [doc-monikers]: monikers.md |
| [doc-resolvers]: resolvers.md |
| [doc-package]: /docs/concepts/packages/package.md |
| [doc-package-url]: /docs/concepts/packages/package_url.md |
| [doc-package-url-resource-path]: /docs/concepts/packages/package_url.md#resource-paths |
| [doc-resolvers]: resolvers.md |
| [doc-runners]: runners.md |
| [wiki-url]: https://en.wikipedia.org/wiki/URL |
| [rfc-uri-scheme]: https://tools.ietf.org/html/rfc3986#section-3.1 |
