Out of Proc Orchestrator Execution Schema Reference

Out-of-proc orchestrator functions, such as those that run in Node.js, communicate with the Functions host process and the Durable Functions extension by consuming a provided execution history and returning information about the orchestrator execution. If you are developing a library to write orchestrator functions in a language that the Azure Functions host runs out-of-proc (ex. JavaScript/Node.js), an orchestrator execution's return value must conform to this schema.

A library's API should have parity with the DurableOrchestrationContext in .NET. However, not all methods may make sense for the language you are writing the library in. For example, generic overloads such as CallActivityAsync(String, Object) are less at home in a loosely-typed language such as JavaScript.

Also consider the naming conventions of your target language. The -Async suffix is a C# convention to indicate a method that returns an instance of .NET's Task class, but JavaScript does not have this practice. Thus, the JavaScript library's version of CallActivityAsync is callActivity.

This schema will be added to as new features are introduced to Durable Functions.

Sample orchestrator execution result

The following sample JSON shows a sample execution result. All fields are required.

{
  "isDone": false,
  "actions": [
    [
      {
        "actionType": 0,
        "functionName": "E4_SendSmsChallenge",
        "input": "+14562345678"
      }
    ],
    [
      {
        "actionType": 5,
        "fireAt": "2018-04-24T01:12:01.083Z",
        "isCanceled": false
      },
      {
        "actionType": "waitForExternalEvent",
        "externalEventName": "SmsChallengeResponse"
      }
    ]
  ],
  "output": null,
  "customStatus": "Reticulating splines.."
}

The following sections of this article explain each top-level property.

isDone

Specifies whether this is the last execution of this orchestrator instance. When this value is true, the Durable Functions extension will consider the orchestration instance completed and will attempt to return the output value.

{
    "isDone": false
}

actions

An ordered list of async actions the orchestrator function should perform. This list is append-only; it must contain all scheduled async actions up to the latest requested work, even actions that have already been completed.

Actions are grouped by execution. Each subsequent orchestrator execution should add a new array of action objects to the collection.

{
    "actions": [ 
        [
          {
            "actionType": 0,
            "functionName": "E4_SendSmsChallenge",
            "input": "+14562345678"
          }
        ],
        [
          {
            "actionType": 5,
            "fireAt": "2018-04-24T01:12:01.083Z",
            "isCanceled": false
          },
          {
            "actionType": "waitForExternalEvent",
            "externalEventName": "SmsChallengeResponse"
          }
        ]
    ]
}

Property	Description
actionType	The type of action to perform; e.g. CallActivityAsync
externalEventName	The name of the event to wait for.
fireAt	The time at which the timer should expire.
functionName	The name of the orchestrator or activity function to run.
input	The JSON-serializable input to pass to the orchestrator or activity function.
instanceId	A custom instance ID (if any) a sub-orchestrator should be instantiated with.
isCanceled	CreateTimer action only. Whether the timer has been canceled.
retryOptions	The RetryOptions for an orchestrator or activity function call.

Action Types

Action Type	Accepted Values	Required Fields
Call Activity	0, "callActivity"	actionType, functionName, input
Call Activity with Retry	1, "callActivityWithRetry"	actionType, functionName, retryOptions, input
Call Sub-Orchestrator	2, "callSubOrchestrator"	actionType, functionName, instanceId, input
Call Sub-Orchestrator with Retry	3, "callSubOrchestratorWithRetry"	actionType, functionName, retryOptions, input, instanceId
ContinueAsNew	4, "continueAsNew"	actionType, input
Create Timer	5, "createTimer"	actionType, fireAt, isCanceled
Wait for External Event	6, "waitForExternalEvent"	actionType, externalEventName

output

Optional. The JSON-serializable value returned by the orchestrator instance on completing execution.

{
    "output": true    
}

customStatus

Optional. The JSON-serializable value set by a call to DurableOrchestrationContext.SetCustomStatus.

{
    "customStatus": { 
        "splines": "reticulated", 
        "references": "dated"
    }
}

error

Optional. The stack trace of an unhandled exception thrown by the orchestrator.