Fetch and Lock External Tasks

Fetches and locks a specific number of external tasks for execution by a worker. Query can be restricted to specific task topics and for each task topic an individual lock time can be provided.

Method

POST /external-task/fetchAndLock

Parameters

Request Body

A JSON object with the following properties:

Name Description
workerId Mandatory. The id of the worker on which behalf tasks are fetched. The returned tasks are locked for that worker and can only be completed when providing the same worker id.
maxTasks Mandatory. The maximum number of tasks to return.
usePriority A boolean value, which indicates whether the task should be fetched based on its priority or arbitrarily.
topics

A JSON array of topic objects for which external tasks should be fetched. The returned tasks may be arbitrarily distributed among these topics. Each topic object has the following properties:

Name Description
topicName Mandatory. The topic's name.
lockDuration Mandatory. The duration to lock the external tasks for in milliseconds.
variables A JSON array of String values that represent variable names. For each result task belonging to this topic, the given variables are returned as well if they are accessible from the external task's execution.

Result

A JSON array of locked external task objects. Each locked external task object has the following properties:

Name Value Description
activityId String The id of the activity that this external task belongs to.
activityInstanceId String The id of the activity instance that the external task belongs to.
errorMessage String The error message that was supplied when the last failure of this task was reported.
executionId String The id of the execution that the external task belongs to.
id String The external task's id.
lockExpirationTime String The date that the task's most recent lock expires or has expired.
processDefinitionId String The id of the process definition the external task is defined in.
processDefinitionKey String The key of the process definition the external task is defined in.
processInstanceId String The id of the process instance the external task belongs to.
tenantId String The id of the tenant the external task belongs to.
retries Number The number of retries the task currently has left.
workerId String The id of the worker that posesses or posessed the most recent lock.
priority Number The priority of the external task.
topicName String The external task's topic name.
variables Object

A JSON object containing a property for each of the requested variables. The key is the variable name, the value is a JSON object of serialized variable values with the following properties:

Name Value Description
value String / Number / Boolean / Object The variable's value.
type String The value type of the variable.
valueInfo Object A JSON object containing additional, value-type-dependent properties.

For variables of type Object, the following properties are returned:

  • objectTypeName: A string representation of the object's type name.
  • serializationDataFormat: The serialization format used to store the variable.

Response Codes

Code Media type Description
200 application/json Request successful.
500 application/json Returned if fetching is not successful, for example due to missing parameters. See the Introduction for the error response format.

Example

Request

POST /external-task/fetchAndLock

Request Body:

{
  "workerId":"aWorkerId",
  "maxTasks":2,
  "usePriority":true,
  "topics":
      [{"topicName": "createOrder",
      "lockDuration": 10000,
      "variables": ["orderId"]
      }]
}

Response

Status 200.

[{
  "activityId": "anActivityId",
  "activityInstanceId": "anActivityInstanceId",
  "errorMessage": "anErrorMessage",
  "executionId": "anExecutionId",
  "id": "anExternalTaskId",
  "lockExpirationTime": "2015-10-06T16:34:42",
  "processDefinitionId": "aProcessDefinitionId",
  "processDefinitionKey": "aProcessDefinitionKey",
  "processInstanceId": "aProcessInstanceId",
  "tenantId": null,
  "retries": 3,
  "workerId": "aWorkerId",
  "priority": 4,
  "topicName": "createOrder",
  "variables": {
    "orderId": {
      "type": "String",
      "value": "1234",
      "valueInfo": {}
    }
  }
},
{
  "activityId": "anActivityId",
  "activityInstanceId": "anActivityInstanceId",
  "errorMessage": "anErrorMessage",
  "executionId": "anExecutionId",
  "id": "anExternalTaskId",
  "lockExpirationTime": "2015-10-06T16:34:42",
  "processDefinitionId": "aProcessDefinitionId",
  "processDefinitionKey": "aProcessDefinitionKey",
  "processInstanceId": "aProcessInstanceId",
  "tenantId": null,
  "retries": 3,
  "workerId": "aWorkerId",
  "priority": 0,
  "topicName": "createOrder",
  "variables": {
    "orderId": {
      "type": "String",
      "value": "3456",
      "valueInfo": {}
    }
  }
}]

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