5. Task types

Groups

Every task has a type. Types fall into three groups by who performs them:

• Interpreter types control the flow. The engine handles them without calling anything.
• Activity types call something: an API, a model, a tool, a topic. The engine runs them itself.
• The worker type hands the step to your own program.

Interpreter types

Type is the value of the task's type field. Fields lists the properties the task must carry in addition to type and taskReferenceName.

Type	Behaviour	Fields
SWITCH	Picks one branch from a value	on, cases, defaultCase
FORK_JOIN	Runs several branches at once and waits for all	forkTasks
FORK_JOIN_DYNAMIC	Same, with the branch list taken from a previous output	dynamicForkTasksParam
DO_WHILE	Repeats its tasks while a condition holds, up to a bound	loopCondition, loopOver, maxIterations
WAIT	Pauses for a duration or until a time	duration or until
HUMAN	Pauses until a decision is posted. Page 10.
SUB_WORKFLOW	Runs another definition and waits for it	subWorkflowParam.name, .version
SET_VARIABLE	Updates run variables	inputParameters = the new values
TERMINATE	Ends the run with a given status	terminationStatus, workflowOutput
NOOP	Does nothing

Activity types

Input lists the keys of inputParameters; Output lists the keys of the task's output that later tasks can reference.

Type	Behaviour	Input	Output
HTTP	Calls a URL through the gateway	uri, method, headers, body	status, headers, body
JSON_TRANSFORM	Extracts and reshapes JSON with JSONPath	source, expressions	The constructed object
LLM_CHAT	Sends messages to a model	model, messages or instructions + context, tools, maxTokens, temperature, responseSchema	text, toolCalls, usage
LIST_TOOLS	Lists the tools the workflow may use		tools
CALL_TOOL	Calls one tool	tool, arguments	The tool's result
CALL_AGENT	Sends a goal to an agent hosted outside the engine and waits for its result. Page 14.	agent, prompt, context, executionId (resume), timeoutSeconds	executionId, state, text, output
PUBLISH_EVENT	Publishes a message to a topic	topic, payload	messageId
START_WORKFLOW	Starts another run without waiting	name, version, input, correlationId	workflowId
PULL_MESSAGES	Reads messages sent to this run	maxCount	messages

HTTP is also how the engine reaches Logic Apps connectors (for SaaS systems) and Azure AI Document Intelligence (for documents). No special task type is needed.

The worker type

Type	Behaviour
WORKER	Puts the step on the queue for its task type and waits for a worker to post the result. Page 9.

The field name gives the task type name, for example parse_pdf. The queue, the settings, and the worker all use that name.

Excluded types

Not offered	Use instead	Reason
Inline scripts in the definition	A worker, the action service, or a Logic Apps connector	Keeps logic in tested, versioned code. No script engine in the engine.
Direct database tasks	A tool on the action service	All data changes go through one audited path.
Remote agent protocol tasks	Deferred	Added when the first external agent must be called.