| # Component declarations (Components v2) |
| |
| <<../_v2_banner.md>> |
| |
| A component declaration describes what a component can do, the capabilities |
| it uses and exposes, its children, and other information needed to run the |
| component. |
| |
| Every component has a declaration. For components that are distributed in |
| [packages][glossary-package], the declaration typically takes the form of |
| a [component manifest file][doc-component-manifests] that is located using a |
| [component URL][doc-component-urls]. |
| |
| Components can also be distributed in other forms such as web applications |
| with the help of a [resolver][doc-resolvers] to retrieve the component |
| declaration and a [runner][doc-runners] to run the component. |
| |
| For example, the declaration for a calculator component might specify the |
| following information: |
| |
| - The [location of the calculator program within its package][doc-component-manifests-program]. |
| - The name of the [runner][doc-runners] used to run the program. |
| - A [request for persistent storage][doc-storage-capability] to save the |
| contents of the calculator's accumulator across restarts. |
| - A request to [use capabilities][doc-component-manifests-use] to present |
| a user interface. |
| - A request to [expose capabilities][doc-component-manifests-expose] to |
| allow other components to access the calculator's accumulator register |
| using inter-process communication. |
| |
| [doc-component-urls]: /docs/concepts/components/component_urls.md |
| [doc-component-manifests]: /docs/concepts/components/v2/component_manifests.md |
| [doc-component-manifests-program]: /docs/concepts/components/v2/component_manifests.md#program |
| [doc-component-manifests-use]: /docs/concepts/components/v2/component_manifests.md#use |
| [doc-component-manifests-expose]: /docs/concepts/components/v2/component_manifests.md#expose |
| [doc-resolvers]: /docs/concepts/components/v2/resolvers.md |
| [doc-runners]: /docs/concepts/components/v2/runners.md |
| [doc-storage-capability]: /docs/concepts/components/v2/capabilities/storage.md |
| [glossary-package]: /docs/glossary.md#package |
