org.apache.ignite.spi.deployment

Interface DeploymentSpi

All Superinterfaces:

IgniteSpi

All Known Implementing Classes:

LocalDeploymentSpi, UriDeploymentSpi

public interface DeploymentSpi
extends IgniteSpi

Grid deployment SPI is in charge of deploying tasks and classes from different sources.

Class loaders that are in charge of loading task classes (and other classes) can be deployed directly by calling register(ClassLoader, Class) method or by SPI itself, for example by asynchronously scanning some folder for new tasks. When method findResource(String) is called by the system, SPI must return a class loader associated with given class. Every time a class loader gets (re)deployed or released, callbacks DeploymentListener.onUnregistered(ClassLoader)} must be called by SPI.

If peer class loading is enabled (which is default behavior, see IgniteConfiguration.isPeerClassLoadingEnabled()), then it is usually enough to deploy class loader only on one grid node. Once a task starts executing on the grid, all other nodes will automatically load all task classes from the node that initiated the execution. Hot redeployment is also supported with peer class loading. Every time a task changes and gets redeployed on a node, all other nodes will detect it and will redeploy this task as well. Note that peer class loading comes into effect only if a task was not locally deployed, otherwise, preference will always be given to local deployment.

Ignite provides following GridDeploymentSpi implementations out of the box:

• LocalDeploymentSpi
• UriDeploymentSpi

NOTE: SPI methods should never be used directly. SPIs provide internal view on the subsystem and is used internally by Ignite. In rare use cases when access to a specific implementation of this SPI is required - an instance of this SPI can be obtained via Ignite.configuration() method to check its configuration properties or call other non-SPI methods. Note again that calling methods from this interface on the obtained instance can lead to undefined behavior and explicitly not supported.

Method Summary

Modifier and Type	Method and Description
DeploymentResource	findResource(String rsrcName) Finds class loader for the given class.
boolean	register(ClassLoader ldr, Class<?> rsrc) Registers a class loader with this SPI.
void	setListener(DeploymentListener lsnr) Sets or unsets deployment event listener.
boolean	unregister(String rsrcName) Unregisters all class loaders that have a class with given name or have a class with give ComputeTaskName value.

Methods inherited from interface org.apache.ignite.spi.IgniteSpi

getName, getNodeAttributes, onClientDisconnected, onClientReconnected, onContextDestroyed, onContextInitialized, spiStart, spiStop

Method Detail

findResource

DeploymentResource findResource(String rsrcName)

Finds class loader for the given class.

Parameters:

rsrcName - Class name or class alias to find class loader for.

Returns:

Deployed class loader, or null if not deployed.

register

boolean register(ClassLoader ldr,
                 Class<?> rsrc)
          throws IgniteSpiException

Registers a class loader with this SPI. This method exists to be able to add external class loaders to deployment SPI. Deployment SPI may also have its own class loaders. For example, in case of GAR deployment, every GAR file is loaded and deployed with a separate class loader maintained internally by the SPI.

The array of classes passed in should be checked for presence of ComputeTaskName annotations. The classes that have this annotation should be accessible by this name from findResource(String) method.

Parameters:

ldr - Class loader to register.

rsrc - Class that should be checked for aliases. Currently the only alias in the system is ComputeTaskName for task classes; in future, there may be others.

Returns:

True if resource was registered.

Throws:

IgniteSpiException - If registration failed.

unregister

boolean unregister(String rsrcName)

Unregisters all class loaders that have a class with given name or have a class with give ComputeTaskName value.

Parameters:

rsrcName - Either class name or ComputeTaskName value for a class whose class loader needs to be unregistered.

Returns:

True if resource was unregistered.

setListener

void setListener(DeploymentListener lsnr)

Sets or unsets deployment event listener. Grid implementation will use this listener to properly add and remove various deployments.

Parameters:

lsnr - Listener for deployment events. null to unset the listener.