Package	com.esri.bacore.client
Class	public class BatchTaskParameters
Inheritance	BatchTaskParameters Object

The BatchTaskParameters class provides parameters for a Community Analyst batch task.

Task Providers

The taskProviders array contains task provider objects. Three types of objects are allowed in this array—an object implementing the IBATaskParameters interface, an instance of the BACommand class, or a function. In the last case, the calling function should have the following signature:

taskProvider(parameters:BatchTaskParameters, ...args):Object;

Additional parameters passed to the task provider depend on the batch task (see concrete batch tasks for detail). The result of this function should be either an object implementing the IBATaskParameters interface or an instance of the BACommand class or null.

The task provider function receives on input the current context of parameters, prepares parameters of the task to be executed, and returns them or a BACommand wrapper or another task provider function. If it returns null, the batch task processor executes the task provided with the next task provider object.

If a task provider function throws an error or execution of any task in the batch task fails, the batch task stops execution, and notifies its responder and listeners on the fault event.

Other Batch Task Parameters

The currentStep property specifies a zero-based index of the step currently executed. Since a task provider function has an access to the parameters of the batch task, it can change a step to be executed next by setting the currentStep value to a zero-based index of the step before the next one. For example, if you want to go from the step 3 to 5, set the currentStep value to 4 at the end of the step 3.

The sharedData object is intended for sharing data between steps of the batch task. It can be populated with some initial data before executing the batch task and its contents can be updated in a task provider method executed at the current step.

Batch task execution results are collected in the results array as instances of the BatchTaskResult type. When a task is successfully completed, its result is pushed to the end of this array and becomes available via lastResult property.

Batch Task Director

A special batch task director function, onStepComplete, can be specified in the constructor of this class. It has the following signature:

onStepComplete(parameters : BatchTaskParameters, completedStep : int) : void;

When this function is called, the completedStep parameter specifies a zero-based index of the step completed; the parameters.currentStep value specifies a zero-based index of the step to be executed next; and the parameters.lastResult value contains the result of completion of the last step. This function can perform validation of the last result, logging the execution process, store results in shared data, change a step to be executed next, and so on. In order to complete the whole task after execution a step, set parameters.currentStep=parameters.tokenProviders.length in the scope of this function.

The onStepComplete function can throw an error to prevent execution of the next step. In this case, the execution of the batch task immediately stops and the task responder and listeners are notified on the fault event.

See also

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