fuchsia.sys2

PROTOCOLS

Realm

Defined in fuchsia.sys2/realm.fidl

A protocol used by a component instance to manage its own realm, such as for binding to its children.

The component manager provides this service to components that use /svc/fuchsia.sys2.Realm.

BindChild

Binds to a child component instance, causing it to start running if it is not already. When this function successfully returns, child is running and exposed_dir is bound to a directory that contains the capabilities which the child exposed to its realm via ComponentDecl.exposes (specified via "expose" declarations in the component’s manifest).

exposed_dir is a valid channel as long as child is running. child will remain running until it either stops on its own, or DestroyChild causes the child instance to be destroyed.

For example, if the child exposes a service /svc/example.Echo then exposed_dir will contain that service at that path.

NOTE: BindChild does not support pipelining with CreateChild. If BindChild is called on an instance before CreateChild successfully returns, it may return INSTANCE_NOT_FOUND.

Errors: - INVALID_ARGUMENTS: child is not a valid child reference. - - INSTANCE_NOT_FOUND: child does not exist. - INSTANCE_CANNOT_START: child was not running and there was an error starting it. - INSTANCE_CANNOT_RESOLVE: child's component declaration failed to resolve.

Request

Name	Type
child	ChildRef
exposed_dir	request<fuchsia.io/Directory>

Response

Name	Type
result	Realm_BindChild_Result

CreateChild

Creates a child component instance dynamically. When this function returns successfully, the instance exists, but it may not be running.

Errors: - INVALID_ARGUMENTS: collection is not a valid reference or child is not a valid declaration. - COLLECTION_NOT_FOUND: collection does not exist. - INSTANCE_ALREADY_EXISTS: decl.name already exists in collection. - NO_SPACE: Could not allocate storage for the new instance.

Request

Name	Type
collection	CollectionRef
decl	ChildDecl

Response

Name	Type
result	Realm_CreateChild_Result

DestroyChild

Destroys a dynamically-created component instance. When this function returns, the client should assume the instance no longer exists. However, some cleanup (such as stopping the component instance or freeing its storage) may be performed in the background after the function returns.

Errors: - INVALID_ARGUMENTS: child is not a valid reference or does not refer to a dynamic instance. - INSTANCE_NOT_FOUND: child does not exist. - COLLECTION_NOT_FOUND: collection does not exist.

Request

Name	Type
child	ChildRef

Response

Name	Type
result	Realm_DestroyChild_Result

ListChildren

Returns an iterator that lists all instances in a collection.

NOTE: The results are not guaranteed to be consistent. Instances may be created or destroyed while the iterator is live, but those changes won't be observed by the iterator after this method returns.

Errors: - INVALID_ARGUMENTS: collection is not a valid reference. - COLLECTION_NOT_FOUND: collection does not exist.

Request

Name	Type
collection	CollectionRef
iter	request<ChildIterator>

Response

Name	Type
result	Realm_ListChildren_Result

ChildIterator

Defined in fuchsia.sys2/realm.fidl

A protocol to iterate over the list of children in a realm.

Next

Advance the iterator and return the next batch of children.

Returns a vector of ChildRef. Returns an empty vector when there are no more children.

Request

Name	Type

Response

Name	Type
children	vector<ChildRef>

ComponentResolver

Defined in fuchsia.sys2/component_resolver.fidl

An interface for resolving a URL to a component.

This interface is implemented by components that provide support for loading components with a particular URL scheme. For example, the Fuchsia package component resolver exposes a service with this interface to resolve component URLs using the "fuchsia-pkg://" scheme.

To use a resolver to resolve URLs within your realm, register it in your realm's manifest. (TODO: explain in more detail)

Resolve

Resolves a component with the given URL.

component_url is the unescaped URL of the component to resolve.

If successful, returns ZX_OK and information about the component that was resolved.

On failure, returns null info and... - ZX_ERR_INVALID_ARGS: The component's URL was malformed. - ZX_ERR_NOT_FOUND: The component does not exist. - ZX_ERR_UNAVAILABLE: The resolver was unable to retrieve or parse the component's resources.

Request

Name	Type
component_url	string

Response

Name	Type
status	int32
component	Component

ComponentRunner

Defined in fuchsia.sys2/component_runner.fidl

An interface for running components.

This interface is implemented by components that provide an execution environment for running particular classes of programs. For example, the Dart virtual machine exposes a service with this interface to run Dart programs.

To specify the runner needed to run your component, set the "runner_url" property in your component's manifest.

Start

Starts running a new component instance described by start_info.

The caller of this method takes responsibility for binding client connections and controlling the lifetime of the newly started component instance through the requested controller.

Request

Name	Type
start_info	ComponentStartInfo
controller	request<ComponentController>

ComponentController

Defined in fuchsia.sys2/component_runner.fidl

An interface for binding client connections and controlling the lifetime of a component instance started using ComponentRunner.Start().

When the controlled component instance terminates or becomes inaccessible for any reason, the server invokes OnEpitaph() and closes its endpoint of the controller interface.

LIFECYCLE

A component may exist in one of two states, Started or Stopped. The component is Started from time ComponentRunner.Start() is called until the ComponentRunner closes the ComponentController handle. The component then transitions to Stopped.

Stop() is called to indicate a ComponentRunner should end a component's execution. Kill() indicates that a runner must halt a component's execution immediately and close the ComponentController's server end. After the ComponentController is closed the component manager can tear down the namespace it hosts for the stopped component. The component manager may call Kill() without first having called Stop().

EPITAPH

This interface uses a FIDL epitaph to indicate that the controller component instance has terminated and to describe its final disposition.

The following epitaph status codes have particular significance:

• ZX_OK: The component instance was successfully terminated in response to Stop() and its runtime resources have been fully released.
• ZX_ERR_UNAVAILABLE: The runner was unable to start the component instance. e.g. The runner could not retrieve the component's assets.

• ERR_COMPONENT_DIED: The component instance was started but subsequently terminated unexpectedly.

  Other status codes (e.g. ZX_ERR_PEER_CLOSED) may indicate a failure of the component runner itself. The component manager may respond to such failures by terminating the component runner's job to ensure system stability.

Stop

Requests the runner to stop the controlled component instance.

After stopping the component instance, the server should report an epitaph then close its endpoint of the controller interface.

Request

Name	Type

Kill

Stop this component immediately. This ComponentRunner must immediately kill the component instance, set an epitaph set on the channel, and close the channel. After the channel closes, the component instance will be considered by the component manager to be Stopped and the component's namespace will be torn down.

Kill() may have been preceeded by Stop(), but that is not guaranteed.

Request

Name	Type

SystemController

Defined in fuchsia.sys2/system_controller.fidl

An interface implemented by ComponentManager that requests the ComponentManager stop all components and exit.

Shutdown

Stop all components, return an empty result, close this protocol's channel, and exit ComponentManager. If this is the root ComponentManager is exited we expect the system will reboot.

Request

Name	Type

Response

Name	Type

WorkScheduler

Defined in fuchsia.sys2/work_scheduler.fidl

Framework service: API for scheduling and canceling work. Each component instance can access work items that it has scheduled (but not others' scheduled work items). Work items are scheduled roughly at the specified time and frequency; the service implementation may specify its notion of roughly, and may provide a configuration API to tune this notion.

Each scheduled work item is identified by a client-provided WorkId. Each scheduled work item has a WorkId that is unique with respect to scheduled work items belonging to the same component instance.

ScheduleWork

Schedule a new work item identified by work_id. The work item is to be scheduled roughly at the time corresponding to work_request.start. When work_request.period is specified, reschedule work roughly every work_request.period until the the work item is canceled.

Request

Name	Type
work_id	string[100]
work_request	WorkRequest

Response

Name	Type
result	WorkScheduler_ScheduleWork_Result

CancelWork

Cancel the scheduled work item specified by work_id.

Request

Name	Type
work_id	string[100]

Response

Name	Type
result	WorkScheduler_CancelWork_Result

Worker

Defined in fuchsia.sys2/work_scheduler.fidl

Component-exposed service: Work scheduler connects to this service to invoke scheduled work item callbacks. The service implementation is responsible for invoking the code that corresponds to the scheduled work item identified by work_id.

DoWork

Request

Name	Type
work_id	string[100]

Response

Name	Type
result	Worker_DoWork_Result

WorkSchedulerControl

Defined in fuchsia.sys2/work_scheduler.fidl

Framework service: Administrative API for controlling parameters of the WorkScheduler framework service. So long as there are work items with deadlines in the next batch_period, the WorkScheduler will sleep for batch_period, then wake up and immediately dispatch a batch of work items: all those with past deadlines. It will repeat this process until no work items would be scheduled in the next batch_period, at which point it will go to sleep until the next deadline. This strategy ensures that each work item is dispatched approximately within batch_period of its deadline.

GetBatchPeriod

Get the current period between WorkScheduler attempts to dispatch a batch of work. batch_period is a non-negative 64-bit integer in the range [0, 2^63-1], representing a number of nanoseconds between dispatching batches of work.

Request

Name	Type

Response

Name	Type
result	WorkSchedulerControl_GetBatchPeriod_Result

SetBatchPeriod

Set the current period between WorkScheduler attempts to batch and dispatch a batch of work. batch_period is a non-negative 64-bit integer in the range [0, 2^63-1], representing a number of nanoseconds between dispatching batches of work.

Request

Name	Type
batch_period	int64

Response

Name	Type
result	WorkSchedulerControl_SetBatchPeriod_Result

STRUCTS

RealmRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to a component’s containing realm, i.e. the parent component.

Name	Type	Description	Default

SelfRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to the component itself.

Name	Type	Description	Default

ChildRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to one of the component's child instances.

Name	Type	Description	Default
name	string[100]	The name assigned to the child by its parent. If `collection` is set, `name` is scoped to `collection` and the child is a dynamic instance. Required.	No default
collection	string[100]?	The collection `name` belongs to. If omitted, `name` references a static instance. This field must be omitted if the `ChildRef` is being used in a component declaration. Optional.	No default

CollectionRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to one of the component's collections.

Name	Type	Description	Default
name	string[100]		No default

StorageRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to one of the component's storage sections.

Name	Type	Description	Default
name	string[100]		No default

FrameworkRef

Defined in fuchsia.sys2/relative_refs.fidl

A reference to the component framework itself.

Name	Type	Description	Default

Moniker

Defined in fuchsia.sys2/moniker.fidl

A moniker encodes the relationship between two component instances that exist in the component instance tree at runtime.

To understand this better, consider two component instances labeled "A" and "B" that are both children of a component instance labeled "P".

At runtime, when "B" requests a service from "A" through a channel established by the component manager, the component manager may provide "A" with a moniker that encodes "B's" identity relative to "A" itself. The moniker's encoded value describes the directed path to traverse from "A" (the moniker's origin) to "B" (the moniker's referent), passing through "P" (their common ancestor).

Name	Type	Description	Default
encoded_value	string[4096]	An opaque representation of the moniker's relation.	No default

Realm_BindChild_Response

generated

Name	Type	Description	Default

Realm_CreateChild_Response

generated

Name	Type	Description	Default

Realm_DestroyChild_Response

generated

Name	Type	Description	Default

Realm_ListChildren_Response

generated

Name	Type	Description	Default

ComponentNamespace

Defined in fuchsia.sys2/component_namespace.fidl

A namespace specifies the set of directories that a component instance receives at start-up. Each component instance's namespace is tailored to provide access to a set of files and services that are appropriate to that component instance's role in the system (its sandbox).

By convention, a component's namespace typically contains some or all of the following directories:

• "/svc": A directory containing services that the component requested to use via its "import" declarations.
• "/pkg": A directory containing the component's package, including its binaries, libraries, and other assets.

Name	Type	Description	Default
paths	vector<string>	The mount point for each of the directories below, each including a leading slash. For example, ["/pkg", "/svc", "/config/data"]. Each mount point must be unique and non-overlapping. For example, ["/foo", "/foo/bar"] is invalid.	No default
directories	vector<fuchsia.io/Directory>	The directories mounted at each path in the namespace.	No default

WorkScheduler_ScheduleWork_Response

generated

Name	Type	Description	Default

WorkScheduler_CancelWork_Response

generated

Name	Type	Description	Default

Worker_DoWork_Response

generated

Name	Type	Description	Default

WorkSchedulerControl_GetBatchPeriod_Response

generated

Name	Type	Description	Default
batch_period	int64		No default

WorkSchedulerControl_SetBatchPeriod_Response

generated

Name	Type	Description	Default

ENUMS

StartupMode

Type: uint32

Defined in fuchsia.sys2/child_decl.fidl

Name	Value	Description
LAZY	0	Start component instance only when another instance binds to it.
EAGER	1	Start component instance as soon as parent starts.

Durability

Type: uint32

Defined in fuchsia.sys2/collection_decl.fidl

The durability of component instances created in a collection.

Name	Value	Description
PERSISTENT	1	An instance exists until either it or its parent is destroyed.
TRANSIENT	2	An instance exists until either its parent instance is stopped or it is explicitly destroyed.

StorageType

Type: uint32

Defined in fuchsia.sys2/storage_decl.fidl

The type of storage offered by this component.

Name	Value	Description
DATA	1	General data storage.
CACHE	2	Cache storage that may be deleted at any time by the system.
META	3	Meta storage that will be used by component manager to persist metadata and other information about the component

Error

Type: uint32

Defined in fuchsia.sys2/error.fidl

Standard error codes for component framework protocols.

Name	Value	Description
INTERNAL	1	Component manager encountered an otherwise unspecified error while performing the operation.
INVALID_ARGUMENTS	2	At least one argument had an invalid format.
UNSUPPORTED	3	The feature is not yet supported.
INSTANCE_NOT_FOUND	4	The component instance was not found.
INSTANCE_ALREADY_EXISTS	5	The component instance already exists.
INSTANCE_CANNOT_START	6	The component instance could not be started.
INSTANCE_CANNOT_RESOLVE	7	Failed to resolve the component's declaration.
COLLECTION_NOT_FOUND	8	The component collection was not found.
NO_SPACE	9	There was insufficient space to perform the operation.

TABLES

ChildDecl

Defined in fuchsia.sys2/child_decl.fidl

Statically declares a child component instance.

Ordinal	Name	Type	Description
1	name	string[100]	The name assigned to the child by its parent. Must be non-empty, unique among all siblings, and contain only the following characters: [a-z0-9-_.].
2	url	string[4096]	The child component's URL. Must be non-empty and a well-formed URL.
3	startup	StartupMode	The startup mode for the component instance.

CollectionDecl

Defined in fuchsia.sys2/collection_decl.fidl

Statically declares a component instance collection.

Ordinal	Name	Type	Description
1	name	string[100]	The name of the collection. Instances created in the collection are scoped to this name.
2	durability	Durability	The durability of instances in the collection.

ComponentDecl

Defined in fuchsia.sys2/component_decl.fidl

A component declaration.

This information is typically encoded in the component manifest (.cm file) if it has one or may be generated at runtime by a component resolver for those that don't.

Ordinal	Name	Type	Description
1	program	fuchsia.data/Dictionary	Information about the program to run when the component is executed. The component manager provides the contents of this dictionary to the component runner when executing the program. Each component runner can freely define the contents of this dictionary as needed. The system's default runner understands the following entries: - "binary": string The path of the executable relative to the root of the package. Typically an ELF binary. - "args": vector of strings The command-line arguments to provide to the executable at runtime. - "env": dictionary of strings The environment variables to provide to the executable at runtime. Other runners may define different entries.
2	uses	vector<UseDecl>	List of capabilities used by the component. These consist of capabilities offered to the component that are installed in its incoming namespace. The used capabilities must be unique and non-overlapping.
3	exposes	vector<ExposeDecl>	List of capabilities exposed by the component. These consist of capabilities that are made visible to the containing realm. The parent may `offer` these capabilities to its children, but not `use` them. The exposed capabilities must be unique and non-overlapping.
4	offers	vector<OfferDecl>	List of capabilities offered to the component’s children. These consist of capabilities that the given children may `use`, which may come from a child, the containing realm, or the component's own outgoing namespace. The offered capabilities must be unique and non-overlapping.
5	facets	fuchsia.data/Dictionary	Additional metadata about the component.
6	children	vector<ChildDecl>	The component's statically instantiated children. The children must have unique names.
7	collections	vector<CollectionDecl>	The component's collections. The collections must have unique names.
8	storage	vector<StorageDecl>	List of storage capabilities created by this component. Storage capabilities can be offered to children.
9	runners	vector<RunnerDecl>	List of runner capabilities created by this component. Runner capabilities can be exposed to the parent's realm or offered to children.

ExposeServiceDecl

Defined in fuchsia.sys2/expose_decl.fidl

Declares a service exposed to a component's containing realm, such as a service exposed by the component or one of its children at runtime.

To learn more about services, see: https://fuchsia.dev/fuchsia-src/glossary#service

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `self` or `child`.
2	source_path	string[1024]	Path identifying the service, by which it was presented to this component. Must be an absolute path starting with /.
3	target	Ref	The destination to which the service is exposed: either the component's realm or the framework.
4	target_path	string[1024]	The path by which the capability is being exposed. Must be an absolute path starting with /.

ExposeLegacyServiceDecl

Defined in fuchsia.sys2/expose_decl.fidl

Declares a legacy service exposed to a component's containing realm, such as a legacy service exposed by the component or one of its children at runtime.

A legacy service is a service with a single instance, provided by a single FIDL protocol.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `self` or `child`.
2	source_path	string[1024]	Path identifying the legacy service, by which it was presented to this component.
3	target	Ref	The destination to which the legacy service is exposed: either the component's realm or the framework.
4	target_path	string[1024]	The path by which the capability is being exposed. Must be an absolute path starting with /.

ExposeDirectoryDecl

Defined in fuchsia.sys2/expose_decl.fidl

Declares a directory exposed to a component's containing realm, such as a directory exposed by the component or one of its children at runtime.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `self` or `child`.
2	source_path	string[1024]	Path identifying the directory, by which it was presented to this component.
3	target	Ref	The destination to which the directory is exposed: either the component's realm or the framework.
4	target_path	string[1024]	The path by which the capability is being exposed. Must be an absolute path starting with /.

ExposeRunnerDecl

Defined in fuchsia.sys2/expose_decl.fidl

Declares a runner exposed to a component's containing realm, such as a runner exposed by the component or one of its children at runtime.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `self` or `child`.
2	source_name	string[100]	The name of the runner, by which it was presented to this component.
3	target	Ref	The destination to which the runner is exposed: either the component's realm or the framework.
4	target_name	string[100]	The name by which the capability is being exposed.

OfferServiceDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a service offered by a component to one of its children, which may have been offered by the component's containing realm, the component itself, or one of its other children.

To learn more about services, see: https://fuchsia.dev/fuchsia-src/glossary#service

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `realm`, `self`, or `child`.
2	source_path	string[1024]	Path identifying the service being offered. Must be an absolute path starting with /.
3	target	Ref	Reference to the target. Must be `child` or `collection`.
4	target_path	string[1024]	The path under which the capability is being offered. Must be an absolute path starting with /.

OfferLegacyServiceDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a legacy service offered by a component to one of its children, which may have been offered by the component's containing realm, the component itself, or one of its other children.

A legacy service is a service with a single instance, provided by a single FIDL protocol.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `realm`, `self`, or `child`.
2	source_path	string[1024]	Path identifying the legacy service being offered.
3	target	Ref	Reference to the target. Must be `child` or `collection`.
4	target_path	string[1024]	The path under which the capability is being offered. Must be an absolute path starting with /.

OfferDirectoryDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a directory offered by a component to one of its children, which may have been offered by the component's containing realm, the component itself, or one of its other children.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `realm`, `self`, or `child`.
2	source_path	string[1024]	Path identifying the directory being offered.
3	target	Ref	Reference to the target of the capability. Must be `child` or `collection`.
4	target_path	string[1024]	The path under which the capability is being offered. Must be an absolute path starting with /.

OfferStorageDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a storage capability offered by a component to one of its children, such as meta storage offered by the component's containing realm or cache storage offered by the component itself.

Ordinal	Name	Type	Description
1	type	StorageType	The type of storage being offered.
2	source	Ref	The source of the storage capability. Must be `realm` or `storage`.
3	target	Ref	Reference to the target of the capability. Must be `child` or `collection`.

OfferRunnerDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a runner offered by a component to one of its children, which may have been offered by the component's containing realm, the component itself, or one of its other children.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the capability relative to the component itself. Must be `realm`, `self`, or `child`.
2	source_name	string[100]	Name of the runner being offered.
3	target	Ref	Reference to the target of the capability. Must be `child` or `collection`.
4	target_name	string[100]	Name under which the capability is being offered.

RunnerDecl

Defined in fuchsia.sys2/runner_decl.fidl

Declares a runner capability backed by a service.

Ordinal	Name	Type	Description
1	name	string[100]	The name of this runner.
2	source	Ref	The provider of the underlying service relative to the component itself. Must be `realm`, `self`, or `child`.
3	source_path	string[1024]	The path of the capability within the specified source.

StorageDecl

Defined in fuchsia.sys2/storage_decl.fidl

Declares a storage capability backed by a directory from which data, cache, or meta storage can be offered.

Ordinal	Name	Type	Description
1	name	string[100]	The name of this storage
2	source	Ref	The provider of the underlying directory capability relative to the component itself. Must be `realm`, `self`, or `child`.
3	source_path	string[1024]	The incoming path to the directory capability. If "source == SELF", this is a path in the component's outgoing directory. Otherwise, it is the path by which the capability was presented to the component.

UseServiceDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares a service used by a component, which was offered to the component's environment.

To learn more about services, see: https://fuchsia.dev/fuchsia-src/glossary#service

Ordinal	Name	Type	Description
1	source	Ref	The provider of the service relative to the component itself. Must be |realm| or |framework|.
2	source_path	string[1024]	Path identifying the service, by which it was presented to this component. Must be an absolute path starting with /.
3	target_path	string[1024]	The path where the capability should be installed in the component's namespace. Must be an absolute path starting with /.

UseLegacyServiceDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares a legacy service used by a component, which was offered to the component's environment.

A legacy service is a service with a single instance, provided by a single FIDL protocol.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the legacy service relative to the component itself. Must be |realm| or |framework|.
2	source_path	string[1024]	Path identifying the legacy service, by which it was presented to this component.
3	target_path	string[1024]	The path where the capability should be installed in the component's namespace. Must be an absolute path starting with /.

UseDirectoryDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares a directory used by a component, which was offered to the component's environment.

Ordinal	Name	Type	Description
1	source	Ref	The provider of the directory relative to the component itself. Must be |realm| or |framework|.
2	source_path	string[1024]	Path identifying the directory, by which it was presented to this component.
3	target_path	string[1024]	The path where the capability should be installed in the component's namespace. Must be an absolute path starting with /.

UseStorageDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares storage used by a component, which was offered to the component's environment.

Ordinal	Name	Type	Description
1	type	StorageType	Type of storage used by the component.
2	target_path	string[1024]	The path where the capability should be installed in the component's namespace. Must not be set if `type` is `META`. Must be an absolute path starting with /.

UseRunnerDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares a runner used by a component, which was offered to the component's environment.

Ordinal	Name	Type	Description
1	name	string[100]	The name of the runner, as it was presented to this component.

Component

Defined in fuchsia.sys2/component.fidl

A component is a unit of executable software.

This object provides the component's declaration, access to its package's content, and relevant metadata.

Ordinal	Name	Type	Description
1	resolved_url	string	The resolved URL of the component. This is the canonical URL obtained by the component resolver after after following redirects and resolving relative paths.
2	decl	ComponentDecl	The component's declaration. This information is typically obtained from the component's manifest or generated by the component resolver.
3	package	Package	The package that contains the component. By convention, the component's package is mapped to "/pkg" in its namespace at runtime. This is null if the component is not represented as a package. In that case, it is the runner's responsibility to load the component's resource from the `resolved_url`. This mechanism is used for web applications.

ComponentStartInfo

Defined in fuchsia.sys2/component_runner.fidl

Parameters for starting a new component instance.

Ordinal	Name	Type	Description
1	resolved_url	string	The resolved URL of the component. This is the canonical URL obtained by the component resolver after after following redirects and resolving relative paths.
2	program	fuchsia.data/Dictionary	The component's program declaration. This information originates from `ComponentDecl.program`.
3	ns	ComponentNamespace	The namespace to provide to the component instance.
4	outgoing_dir	request<fuchsia.io/Directory>	The directory this component serves.
5	runtime_dir	request<fuchsia.io/Directory>	The directory served by the runner to present runtime information about the component.

Package

Defined in fuchsia.sys2/package.fidl

A package is a signed collection of immutable files.

This object provides access to a package's content and relevant metadata.

Ordinal	Name	Type	Description
1	package_url	string	The URL of the package itself.
2	package_dir	fuchsia.io/Directory	The package's content directory.

WorkRequest

Defined in fuchsia.sys2/work_scheduler.fidl

Parameters for a new piece of work to be scheduled.

Ordinal	Name	Type	Description
1	start	Start	Time when corresponding work item should be _first_ scheduled.
2	period	int64	Delay between repeated schedulings of corresponding work item. This is left unspecified for one-shot work that should not repeat. Repeating work items are rescheduled indefinitely until it is canceled.

UNIONS

Realm_BindChild_Result

generated

Name	Type	Description
response	Realm_BindChild_Response
err	Error

Realm_CreateChild_Result

generated

Name	Type	Description
response	Realm_CreateChild_Response
err	Error

Realm_DestroyChild_Result

generated

Name	Type	Description
response	Realm_DestroyChild_Response
err	Error

Realm_ListChildren_Result

generated

Name	Type	Description
response	Realm_ListChildren_Response
err	Error

WorkScheduler_ScheduleWork_Result

generated

Name	Type	Description
response	WorkScheduler_ScheduleWork_Response
err	Error

WorkScheduler_CancelWork_Result

generated

Name	Type	Description
response	WorkScheduler_CancelWork_Response
err	Error

Worker_DoWork_Result

generated

Name	Type	Description
response	Worker_DoWork_Response
err	Error

WorkSchedulerControl_GetBatchPeriod_Result

generated

Name	Type	Description
response	WorkSchedulerControl_GetBatchPeriod_Response
err	Error

WorkSchedulerControl_SetBatchPeriod_Result

generated

Name	Type	Description
response	WorkSchedulerControl_SetBatchPeriod_Response
err	Error

XUNIONS

ExposeDecl

Defined in fuchsia.sys2/expose_decl.fidl

Declares a capability exposed to either a component's containing realm or to the framework. For example, a legacy service exposed by the component at runtime.

Name	Type	Description
service	ExposeServiceDecl
legacy_service	ExposeLegacyServiceDecl
directory	ExposeDirectoryDecl

OfferDecl

Defined in fuchsia.sys2/offer_decl.fidl

Declares a capability offered by a component to one of its children, which may have been offered by the component's containing realm, the component itself, or one of its other children.

Name	Type	Description
service	OfferServiceDecl
legacy_service	OfferLegacyServiceDecl
directory	OfferDirectoryDecl
storage	OfferStorageDecl

Ref

Defined in fuchsia.sys2/relative_refs.fidl

A reference to a capability source or destination relative to this component.

Name	Type	Description
realm	RealmRef
self	SelfRef
child	ChildRef
collection	CollectionRef
storage	StorageRef
framework	FrameworkRef

UseDecl

Defined in fuchsia.sys2/use_decl.fidl

Declares a capability used by a component, which was offered to the component's environment.

Name	Type	Description
service	UseServiceDecl
legacy_service	UseLegacyServiceDecl
directory	UseDirectoryDecl
storage	UseStorageDecl

Start

Defined in fuchsia.sys2/work_scheduler.fidl

Different ways to specify when to schedule a work item for the first time.

Name	Type	Description
delay	int64	A non-negative delay to wait before scheduling work.
monotonic_time	int64	A fixed point in time to start scheduling work, interpreted like `ZX_CLOCK_MONOTONIC`: number of nanoseconds since the system was powered on.

CONSTANTS

Name	Value	Type	Description
MAX_FACET_NAME_LENGTH	100	uint32
MAX_CHILD_NAME_LENGTH	100	uint32
MAX_COLLECTION_NAME_LENGTH	100	uint32
MAX_RUNNER_NAME_LENGTH	100	uint32
MAX_STORAGE_NAME_LENGTH	100	uint32
MAX_PATH_LENGTH	1024	uint32
MAX_URL_LENGTH	4096	uint32
MAX_MONIKER_LENGTH	4096	uint32
ERR_COMPONENT_DIED	1	int32	Error produced when a component terminates unexpected.
MAX_WORK_ID_LENGTH	100	uint32