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AWS Flow Framework for Java
Developer Guide (API Version 2012-01-25)

AWS Flow Framework for Java Annotations

@Activities

This annotation can be used on an interface to declare a set of activity types. Each method in an interface annotated with this annotation represents an activity type. An interface can't have both @Workflow and @Activities annotations-

The following parameters can be specified on this annotation:

activityNamePrefix

Specifies the prefix of the name of the activity types declared in the interface. If set to an empty string (which is the default), the name of the interface followed by '.' is used as the prefix.

version

Specifies the default version of the activity types declared in the interface. The default value is 1.0.

dataConverter

Specifies the type of the DataConverter to use for serializing/deserializing data when creating tasks of this activity type and its results. Set to NullDataConverter by default, which indicates that the JsonDataConverter should be used.

@Activity

This annotation can be used on methods within an interface annotated with @Activities.

The following parameters can be specified on this annotation:

name

Specifies the name of the activity type. The default is an empty string, which indicates that the default prefix and the activity method name should be used to determine the name of the activity type (which is of the form {prefix}{name}). Note that when you specify a name in an @Activity annotation, the framework will not automatically prepend a prefix to it. You are free to use your own naming scheme.

version

Specifies the version of the activity type. This overrides the default version specified in the @Activities annotation on the containing interface. The default is an empty string.

@ActivityRegistrationOptions

Specifies the registration options of an activity type. This annotation can be used on an interface annotated with @Activities or the methods within. If specified in both places, then the annotation used on the method takes effect.

The following parameters can be specified on this annotation:

defaultTasklist

Specifies the default task list to be registered with Amazon SWF for this activity type. This default can be overridden when calling the activity method on the generated client using the ActivitySchedulingOptions parameter. Set to USE_WORKER_TASK_LIST by default. This is a special value which indicates that the task list used by the worker, which is performing the registration, should be used.

defaultTaskScheduleToStartTimeoutSeconds

Specifies the defaultTaskScheduleToStartTimeout registered with Amazon SWF for this activity type. This is the maximum time a task of this activity type is allowed to wait before it is assigned to a worker. See the Amazon Simple Workflow Service API Reference for more details.

defaultTaskHeartbeatTimeoutSeconds

Specifies the defaultTaskHeartbeatTimeout registered with Amazon SWF for this activity type. Activity workers must provide heartbeat within this duration; otherwise, the task will be timed out. Set to -1 by default, which is a special value that indicates this timeout should be disabled. See the Amazon Simple Workflow Service API Reference for more details.

defaultTaskStartToCloseTimeoutSecond

Specifies the defaultTaskStartToCloseTimeout registered with Amazon SWF for this activity type. This timeout determines the maximum time a worker can take to process an activity task of this type. See the Amazon Simple Workflow Service API Reference for more details.

defaultTaskScheduleToCloseTimeoutSeconds

Specifies the defaultScheduleToCloseTimeout registered with Amazon SWF for this activity type. This timeout determines the total duration that the task can stay in open state. Set to -1 by default, which is a special value that indicates this timeout should be disabled. See the Amazon Simple Workflow Service API Reference for more details.

@Asynchronous

When used on a method in the workflow coordination logic, indicates that the method should be executed asynchronously. A call to the method will return immediately, but the actual execution will happen asynchronously when all Promise<> parameters passed to the methods become ready. Methods annotated with @Asynchronous must have a return type of Promise<> or void.

daemon

Indicates if the task created for the asynchronous method should be a daemon task. False by default.

@Execute

When used on a method in an interface annotated with the @Workflow annotation, identifies the entry point of the workflow.

Important

Only one method in the interface can be decorated with @Execute.

The following parameters can be specified on this annotation:

name

Specifies the name of the workflow type. If not set, the name defaults to {prefix}{name}, where {prefix} is the name of the workflow interface followed by a '.' and {name} is the name of the @Execute-decorated method in the workflow.

version

Specifies the version of the workflow type.

@ExponentialRetry

When used on an activity or asynchronous method, sets an exponential retry policy if the method throws an unhandled exception. A retry attempt is made after a back-off period, which is calculated by the power of the number of attempts.

The following parameters can be specified on this annotation:

intialRetryIntervalSeconds

Specifies the duration to wait before the first retry attempt. This value should not be greater than maximumRetryIntervalSeconds and retryExpirationSeconds.

maximumRetryIntervalSeconds

Specifies the maximum duration between retry attempts. Once reached, the retry interval is capped to this value. Set to -1 by default, which means unlimited duration.

retryExpirationSeconds

Specifies the duration after which exponential retry will stop. Set to -1 by default, which means there is no expiration.

backoffCoefficient

Specifies the coefficient used to calculate the retry interval. Set to 2 by default. You can set this to 1 to get linear back-off or 0 to get a constant back-off.

maximumAttempts

Specifies the number of attempts after which exponential retry will stop. Set to -1 by default, which means there is no limit on the number of retry attempts.

exceptionsToRetry

Specifies the list of exception types that should trigger a retry. Unhandled exception of these types will not propagate further and the method will be retried after the calculated retry interval. By default, the list contains Throwable.

excludeExceptions

Specifies the list of exception types that should not trigger a retry. Unhandled exceptions of this type will be allowed to propagate. The list is empty by default.

@GetState

When used on a method in an interface annotated with the @Workflow annotation, identifies that the method is used to retrieve the latest workflow execution state. There can be at most one method with this annotation in an interface with the @Workflow annotation. Methods with this annotation must not take any parameters and must have a return type other than void.

@ManualActivityCompletion

This annotation can be used on an activity method to indicate that the activity task should not be completed when the method returns. The activity task will not be automatically completed and would need to be completed manually directly using the Amazon SWF API. This is useful for use cases where the activity task is delegated to some external system that isn't automated or requires human intervention to be completed.

@Signal

When used on a method in an interface annotated with the @Workflow annotation, identifies a signal that can be received by executions of the workflow type declared by the interface. Use of this annotation is required to define a signal method.

The following parameters can be specified on this annotation:

name

Specifies the name portion of the signal name. If not set, the name of the method is used.

@SkipRegistration

When used on an interface annotated with the @Workflow annotation, indicates that the workflow type should not be registered with Amazon SWF. One of @WorkflowRegistrationOptions and @SkipRegistrationOptions annotations must be used on an interface annotated with @Workflow, but not both.

@Wait and @NoWait

These annotations can be used on a parameter of type Promise<> to indicate whether the AWS Flow Framework for Java should wait for it to become ready before executing the method. By default, Promise<> parameters passed into @Asynchronous methods must become ready before method execution occurs. In certain scenarios, it is necessary to override this default behavior. Promise<> parameters passed into @Asynchronous methods and annotated with @NoWait are not waited for.

Collections parameters (or subclasses of) that contain promises, such as List<Promise<Int>>, must be annotated with @Wait annotation. By default, the framework doesn't wait for the members of a collection.

@Workflow

This annotation is used on an interface to declare a workflow type. An interface decorated with this annotation should contain exactly one method that is decorated with the @Execute annotation to declare an entry point for your workflow.

Note

An interface can't have both @Workflow and @Activities annotations declared at once; they are mutually exclusive.

The following parameters can be specified on this annotation:

dataConverter

Specifies which DataConverter to use when sending requests to, and receiving results from, workflow executions of this workflow type.

The default is NullDataConverter which, in turn, falls back to JsonDataConverter to process all request and response data as JavaScript Object Notation (JSON).

Example

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import com.amazonaws.services.simpleworkflow.flow.annotations.Execute; import com.amazonaws.services.simpleworkflow.flow.annotations.Workflow; import com.amazonaws.services.simpleworkflow.flow.annotations.WorkflowRegistrationOptions; @Workflow @WorkflowRegistrationOptions(defaultExecutionStartToCloseTimeoutSeconds = 3600) public interface GreeterWorkflow { @Execute(version = "1.0") public void greet(); }

@WorkflowRegistrationOptions

When used on an interface annotated with @Workflow, provides default settings used by Amazon SWF when registering the workflow type.

Note

Either @WorkflowRegistrationOptions or @SkipRegistrationOptions must be used on an interface annotated with @Workflow, but you can't specify both.

The following parameters can be specified on this annotation:

Description

An optional text description of the workflow type.

defaultExecutionStartToCloseTimeoutSeconds

Specifies the defaultExecutionStartToCloseTimeout registered with Amazon SWF for the workflow type. This is the total time that a workflow execution of this type can take to complete.

For more information about workflow timeouts, see Amazon SWF Timeout Types .

defaultTaskStartToCloseTimeoutSeconds

Specifies the defaultTaskStartToCloseTimeout registered with Amazon SWF for the workflow type. This specifies the time a single decision task for a workflow execution of this type can take to complete.

If you don't specify defaultTaskStartToCloseTimeout, it will default to 30 seconds.

For more information about workflow timeouts, see Amazon SWF Timeout Types .

defaultTaskList

The default task list used for decision tasks for executions of this workflow type. The default set here can be overridden by using StartWorkflowOptions when starting a workflow execution.

If you don't specify defaultTaskList, it will be set to USE_WORKER_TASK_LIST by default. This indicates that the task list used by the worker that is performing the workflow registration should be used.

defaultChildPolicy

Specifies the policy to use for child workflows if an execution of this type is terminated. The default value is ABANDON. The possible values are:

  • ABANDON – Allow the child workflow executions to keep running

  • TERMINATE – Terminate child workflow executions

  • REQUEST_CANCEL – Request cancellation of the child workflow executions