org.rhq.core.pluginapi.inventory
Class ResourceContext<T extends ResourceComponent<?>>

java.lang.Object
  org.rhq.core.pluginapi.inventory.ResourceContext<T>

Type Parameters:

T - the parent resource component type for this component. This means you can nest a hierarchy of resource components that mimic the resource type hierarchy as defined in a plugin deployment descriptor.

Direct Known Subclasses:

ResourceUpgradeContext

public class ResourceContext<T extends ResourceComponent<?>>
extends Object

The context object that ResourceComponent objects will have access - it will have all the information that the resource components needs during their lifetime.

This context class is currently designed to be an immutable object. Instances of this context object are to be created by the plugin container only.

Constructor Summary

ResourceContext(Resource resource, T parentResourceComponent, ResourceDiscoveryComponent<T> resourceDiscoveryComponent, SystemInfo systemInfo, File temporaryDirectory, File dataDirectory, String pluginContainerName, EventContext eventContext, OperationContext operationContext, ContentContext contentContext, Executor availCollectorThreadPool, PluginContainerDeployment pluginContainerDeployment)
Creates a new ResourceContext object.

Method Summary

AvailabilityCollectorRunnable	createAvailabilityCollectorRunnable(AvailabilityFacet availChecker, long interval) Under certain circumstances, a resource component may want to perform asynchronous availability checks, as opposed to AvailabilityFacet.getAvailability() blocking waiting for the managed resource to return its availability status.
ContentContext	getContentContext() Returns a ContentContext that allows the plugin to access the content functionality provided by the plugin container.
File	getDataDirectory() Directory where plugins can store persisted data that survives plugin container restarts.
EventContext	getEventContext() Returns an EventContext, if the resource supports one or more types of Events, or null otherwise.
ProcessInfo	getNativeProcess() Returns the information on the native operating system process in which the managed resource is running.
List<ProcessScanResult>	getNativeProcessesForType() Scans the current list of running processes and returns information on all processes that may contain resources of the same type as this resource.
OperationContext	getOperationContext() Returns an OperationContext that allows the plugin to access the operation functionality provided by the plugin container.
T	getParentResourceComponent() The parent of the resource component that is associated with this context.
Configuration	getPluginConfiguration() Returns the resource's plugin configuration.
PluginContainerDeployment	getPluginContainerDeployment() Indicates where the plugin container (and therefore where the plugins) are deployed and running.
String	getPluginContainerName() The name of the plugin container in which the resource component is running.
String	getResourceKey() The resource key of the resource this context is associated with.
ResourceType	getResourceType() The resource type of the resource this context is associated with.
SystemInfo	getSystemInformation() Returns a SystemInfo object that contains information about the platform/operating system that the resource is running on.
File	getTemporaryDirectory() A temporary directory for plugin use that is destroyed at plugin container shutdown.
String	getVersion() The version of the resource this context is associated with.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ResourceContext

public ResourceContext(Resource resource,
                       T parentResourceComponent,
                       ResourceDiscoveryComponent<T> resourceDiscoveryComponent,
                       SystemInfo systemInfo,
                       File temporaryDirectory,
                       File dataDirectory,
                       String pluginContainerName,
                       EventContext eventContext,
                       OperationContext operationContext,
                       ContentContext contentContext,
                       Executor availCollectorThreadPool,
                       PluginContainerDeployment pluginContainerDeployment)

Creates a new ResourceContext object. The plugin container is responsible for instantiating these objects; plugin writers should never have to actually create context objects.

Parameters:

resource - the resource whose ResourceComponent will be given this context object of the plugin

parentResourceComponent - the parent component of the context's associated resource component

resourceDiscoveryComponent - the discovery component that can be used to detect other resources of the same type as this resource (may be null)

systemInfo - information about the system on which the plugin and its plugin container are running

temporaryDirectory - a temporary directory for plugin use that is destroyed at plugin container shutdown

dataDirectory - a directory where plugins can store persisted data that survives plugin container restarts

pluginContainerName - the name of the plugin container in which the discovery component is running. Components can be assured this name is unique across all plugin containers/agents running in the RHQ environment.

eventContext - an EventContext, if the resource supports one or more types of Events, or null otherwise

operationContext - an OperationContext the plugin can use to interoperate with the operation manager

contentContext - a ContentContext the plugin can use to interoperate with the content manager

availCollectorThreadPool - a thread pool that can be used by the plugin component should it wish or need to perform asynchronous availability checking. See the javadoc on AvailabilityCollectorRunnable for more information on this.

pluginContainerDeployment - indicates where the plugin container is running

Method Detail

getResourceKey

public String getResourceKey()

The resource key of the resource this context is associated with. This resource key is unique across all of the resource's siblings. That is to say, this resource key is unique among all children of the parent.

Returns:

resource key of the associated resource

getResourceType

public ResourceType getResourceType()

The resource type of the resource this context is associated with.

Returns:

type of the associated resource

getVersion

public String getVersion()

The version of the resource this context is associated with.

Returns:

the resource's version string

getParentResourceComponent

public T getParentResourceComponent()

The parent of the resource component that is associated with this context.

Returns:

parent component of the associated resource component

getSystemInformation

public SystemInfo getSystemInformation()

Returns a SystemInfo object that contains information about the platform/operating system that the resource is running on. With this object, you can natively obtain things such as the operating system name, its hostname,and other things. Please refer to the javadoc on SystemInfo for more details on the types of information you can access.

Returns:

system information object

getPluginConfiguration

public Configuration getPluginConfiguration()

Returns the resource's plugin configuration. This is used to configure the subsystem that is used to actually talk to the managed resource. Do not confuse this with the resource configuration, which is the actual configuration settings for the managed resource itself.

Returns:

plugin configuration

getNativeProcess

public ProcessInfo getNativeProcess()

Returns the information on the native operating system process in which the managed resource is running. If native support is not available or the process for some reason can no longer be found, this may return null.

Returns:

information on the resource's process

getNativeProcessesForType

public List<ProcessScanResult> getNativeProcessesForType()

Scans the current list of running processes and returns information on all processes that may contain resources of the same type as this resource. More specifically, this method will scan all the processes and try to match them up with the PIQL queries associated with this resource's type.

Returns:

information on the processes that may be running this resource or other resources of the same type

See Also:

ResourceType.getProcessScans()

getTemporaryDirectory

public File getTemporaryDirectory()

A temporary directory for plugin use that is destroyed at plugin container shutdown. Plugins should use this if they need to write temporary files that they do not expect to remain after the plugin container is restarted. This directory is shared among all plugins - plugins must ensure they write unique files here, as other plugins may be using this same directory. Typically, plugins will use the File.createTempFile(String, String, File) API when writing to this directory.

Returns:

location for plugin temporary files

getDataDirectory

public File getDataDirectory()

Directory where plugins can store persisted data that survives plugin container restarts. Each plugin will have their own data directory. The returned directory may not yet exist - it is up to each individual plugin to manage this directory as they see fit (this includes performing the initial creation when the directory is first needed).

Returns:

location for plugins to store persisted data

getPluginContainerName

public String getPluginContainerName()

The name of the plugin container in which the resource component is running. Components can be assured this name is unique across all plugin containers/agents running in the RHQ environment.

Returns:

the name of the plugin container

getPluginContainerDeployment

public PluginContainerDeployment getPluginContainerDeployment()

Indicates where the plugin container (and therefore where the plugins) are deployed and running. See PluginContainerDeployment for more information on what the return value means.

Returns:

indicator of where the plugin container is deployed and running

getEventContext

public EventContext getEventContext()

Returns an EventContext, if the resource supports one or more types of Events, or null otherwise.

Returns:

an EventContext, if the resource supports one or more types of Events, or null otherwise

getOperationContext

public OperationContext getOperationContext()

Returns an OperationContext that allows the plugin to access the operation functionality provided by the plugin container.

Returns:

operation context object

getContentContext

public ContentContext getContentContext()

Returns a ContentContext that allows the plugin to access the content functionality provided by the plugin container.

Returns:

content context object

createAvailabilityCollectorRunnable

public AvailabilityCollectorRunnable createAvailabilityCollectorRunnable(AvailabilityFacet availChecker,
                                                                         long interval)

Under certain circumstances, a resource component may want to perform asynchronous availability checks, as opposed to AvailabilityFacet.getAvailability() blocking waiting for the managed resource to return its availability status. Using asynchronous availability checking frees the resource component from having to guarantee that the managed resource will provide availability status in a timely fashion. If the resource component needs to perform asynchronous availability checking, it should call this method to create an instance of AvailabilityCollectorRunnable inside the ResourceComponent.start(org.rhq.core.pluginapi.inventory.ResourceContext) method. It should then call the returned object's AvailabilityCollectorRunnable.start() method within the same resource component ResourceComponent.start(ResourceContext) method. The resource component should call the AvailabilityCollectorRunnable.stop() method when the resource component stops. The resource component's AvailabilityFacet.getAvailability() method should simply return the value returned by AvailabilityCollectorRunnable.getLastKnownAvailability(). This method will be extremely fast since it simply returns the last availability that was retrieved by the given availability checker. Only when the availability checker finishes checking for availability of the managed resource (however long it takes to do so) will the last known availability state change. For more information, read the javadoc in AvailabilityCollectorRunnable.

Parameters:

availChecker - the object that will perform the actual check of the managed resource's availability

interval - the interval, in milliseconds, between availability checks. The minimum value allowed for this parameter is AvailabilityCollectorRunnable.MIN_INTERVAL.

Returns:

the availability collector runnable that will perform the asynchronous checking