# Host Component Resources ###API Summary - [List host components](host-components.md) - [View host component information](host-component.md) - [Create host component](create-hostcomponent.md) - [Update host component](update-hostcomponent.md) ###Properties

Property	Description
HostRoles/role_id	The host component id
HostRoles/cluster_name	The name of the parent cluster
HostRoles/host_name	The name of the parent host
HostRoles/component_name	The name of the parenbt component
HostRoles/state	The state of the host component
HostRoles/actual_configs	The actual configuration
HostRoles/desired_configs	The desired configuration
HostRoles/stack_id	The stack id (e.g. HDP-1.3.0)

###States The current state of a host component resource can be determined by looking at the ServiceComponentInfo/state property. GET api/v1/clusters/c1/services/HDFS/components/NAMENODE?fields=ServiceComponentInfo/state 200 OK { "href" : "http://your.ambari.server/api/v1/clusters/c1/services/HDFS/components/NAMENODE?fields=ServiceComponentInfo/state", "ServiceComponentInfo" : { "cluster_name" : "c1", "component_name" : "NAMENODE", "state" : "INSTALLED", "service_name" : "HDFS" } } The following table lists the possible values of the service resource ServiceComponentInfo/state property.

State	Description
INIT	The initial clean state after the component is first created.
INSTALLING	In the process of installing the component.
INSTALL_FAILED	The component install failed.
INSTALLED	The component has been installed successfully but is not currently running.
STARTING	In the process of starting the component.
STARTED	The component has been installed and started.
STOPPING	In the process of stopping the component.
UNINSTALLING	In the process of uninstalling the component.
UNINSTALLED	The component has been successfully uninstalled.
WIPING_OUT	In the process of wiping out the installed component.
UPGRADING	In the process of upgrading the component.
MAINTENANCE	The component has been marked for maintenance.
UNKNOWN	The component state can not be determined.

###Starting a Host Component A component can be started through the API by setting its state to be STARTED (see [update host component](update-hostcomponent.md)). ###Stopping a Host Component A component can be stopped through the API by setting its state to be INSTALLED (see [update host component](update-hostcomponent.md)). ###Maintenance The user can update the desired state of a host component through the API to be MAINTENANCE (see [update host component](update-hostcomponent.md)). When a host component is into maintenance state it is basically taken off line. This state can be used, for example, to move a component like NameNode. The NameNode component can be put in MAINTENANCE mode and then a new NameNode can be created for the service.