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[DEPRECATED] Hub

Definition

The hub is a virtual filesystem that represents a realm and contains relevant directories of all component instances under that realm.

Structure of the hub

A hub has the following filesystem layout:

hub
├── children
|   ├── foo
|   |   └── ...
|   └── bar
|       └── ...
├── exposed
├── ns
├── out
└── runtime

When a component instance is resolved, the following directories are present in its hub:

  • children: Hub directories of the children of this component instance.
  • exposed: Capabilities exposed by this component instance in its manifest.
  • ns: Capabilities used by this component instance in its manifest.

When a component instance is running, the following directories are also present:

  • out: Capabilities served by the program of this component instance.
  • runtime: Debug information served by the runner of this component instance.

Accessing the root hub

A hub scoped to the root component is available in the serial shell and fx shell under the directory /hub-v2.

(host)$ fx shell
$ cd hub-v2
$ ls
children
exposed
ns

Example: List all capabilities exposed by a component

To list all capabilities exposed by the component with moniker /bootstrap/archivist, do the following:

(host)$ fx shell
$ cd /hub-v2/children/bootstrap/children/archivist/exposed
$ ls
diagnostics
fuchsia.diagnostics.ArchiveAccessor
fuchsia.diagnostics.FeedbackArchiveAccessor
fuchsia.diagnostics.LegacyMetricsArchiveAccessor
fuchsia.diagnostics.LoWPANArchiveAccessor
fuchsia.diagnostics.LogSettings
fuchsia.logger.Log
fuchsia.logger.LogSink

Example: See the namespace of a component

To see the namespace of the component with moniker /core/memory_monitor, do the following:

(host)$ fx shell
$ cd /hub-v2/children/core/children/memory_monitor/ns
$ ls
cache
config
dev
pkg
svc