Package org.apache.ignite.services

Interface Service

  • All Superinterfaces:
    Serializable
    public interface Service
extends Serializable
    An instance of grid-managed service. Grid-managed services may be deployed from IgniteServices facade or directly from grid configuration at startup.

    Deployment

    Whenever service is deployed, Ignite will automatically calculate how many instances of this service should be deployed on each node within the cluster. Whenever service is deployed on a cluster node, Ignite will call execute() method on that service. It is up to the user to control whenever the service should exit from the execute method. For example, user may choose to implement service as follows: 
     public class MyIgniteService implements Service {
      ...
      // Example of ignite resource injection. All resources are optional.
      // You should inject resources only as needed.
      @IgniteInstanceResource
      private Ignite ignite;

      @ServiceContextResource
      private ServiceContext ctx;
      ...
      @Override public void cancel() {
          // No-op.
      }

      @Override public void execute() {
          // Loop until service is cancelled.
          while (!ctx.isCancelled()) {
              // Do something.
              ...
          }
      }
  }
    Consecutively, this service can be deployed as follows: 
     ...
 IgniteServices svcs = ignite.services();

 svcs.deployClusterSingleton("mySingleton", new MyIgniteService());
    Or from grid configuration on startup: 
     IgniteConfiguration gridCfg = new IgniteConfiguration();

 IgniteServiceConfiguration svcCfg = new IgniteServiceConfiguration();

 // Configuration for cluster-singleton service.
 svcCfg.setName("mySingleton");
 svcCfg.setMaxPerNodeCount(1);
 svcCfg.setTotalCount(1);
 svcCfg.setService(new MyIgniteService());

 gridCfg.setServiceConfiguration(svcCfg);
 ...
 Ignition.start(gridCfg);

    Cancellation

    Services can be cancelled by calling any of the cancel methods on IgniteServices API. Whenever a deployed service is cancelled, Ignite will automatically call cancel() method on that service.

    Note that Ignite cannot guarantee that the service exits from execute() method whenever cancel() is called. It is up to the user to make sure that the service code properly reacts to cancellations.

    • Method Detail

      • cancel

        default void cancel()
        Cancels this service. Ignite will automatically call this method whenever any of the cancel methods on IgniteServices API are called.

        Note that Ignite cannot guarantee that the service exits from execute() method whenever cancel() method is called. It is up to the user to make sure that the service code properly reacts to cancellations.

        See Also:
        ServiceContextResource

      • init

        default void init()
           throws Exception
        Pre-initializes service before execution. This method is guaranteed to be called before service deployment is complete (this guarantees that this method will be called before method execute() is called).
        Throws:
        Exception - If service initialization failed.
        See Also:
        ServiceContextResource

      • execute

        default void execute()
              throws Exception
        Starts execution of this service. This method is automatically invoked whenever an instance of the service is deployed on a grid node. Note that service is considered deployed even after it exits the execute method and can be cancelled (or undeployed) only by calling any of the cancel methods on IgniteServices API. Also note that service is not required to exit from execute method until cancel() method was called.
        Throws:
        Exception - If service execution failed. Not that service will still remain deployed, until IgniteServices.cancel(String) method will be called.
        See Also:
        ServiceContextResource

      • cancel

        @Deprecated
default void cancel​(ServiceContext ctx)
        Deprecated.
        Use cancel() instead.
        Cancels this service. Ignite will automatically call this method whenever any of the cancel methods on IgniteServices API are called.

        Note that Ignite cannot guarantee that the service exits from execute(ServiceContext) method whenever cancel(ServiceContext) method is called. It is up to the user to make sure that the service code properly reacts to cancellations.

        Parameters:
        ctx - Service execution context.

      • init

        @Deprecated
default void init​(ServiceContext ctx)
           throws Exception
        Deprecated.
        Use init() instead.
        Pre-initializes service before execution. This method is guaranteed to be called before service deployment is complete (this guarantees that this method will be called before method execute(ServiceContext) is called).
        Parameters:
        ctx - Service execution context.
        Throws:
        Exception - If service initialization failed.

      • execute

        @Deprecated
default void execute​(ServiceContext ctx)
              throws Exception
        Deprecated.
        Use execute() instead.
        Starts execution of this service. This method is automatically invoked whenever an instance of the service is deployed on a grid node. Note that service is considered deployed even after it exits the execute method and can be cancelled (or undeployed) only by calling any of the cancel methods on IgniteServices API. Also note that service is not required to exit from execute method until cancel(ServiceContext) method was called.
        Parameters:
        ctx - Service execution context.
        Throws:
        Exception - If service execution failed. Not that service will still remain deployed, until IgniteServices.cancel(String) method will be called.