Task and Call - BlockX Docs

A Task is one unit of work submitted to a Worker. A Call is one invocation of a user function within that task. For block computation, a Call Builder turns source rows into Calls, and a Writer Plugin handles their outputs.

Task input

Part	Purpose
Task identifier	Identify a submission when watching or querying its result
Call Builder configuration	Select explicit arguments, a trigger block, or a historical bundle
Optional Writer Plugin	Select returned values or table writes
Optional timeout	Bound execution on the Worker

The chain and block used for reads belong in the relevant configuration or function arguments. The task identifier carries no chain context. See service API for request fields.

Call

Each Call supplies a function and positional arguments.
Calls have no input-order execution guarantee. Return an input identifier when you need to associate outputs with inputs.
A function can read EVM state or invoke a contract at an explicit block.
An EVM contract call inside a function is not a separate submitted Task.

Outputs

Function return	Table-writing behavior
`dict`	One candidate row, projected onto target columns
`list[dict]`	Multiple candidate rows
`None`	No row

ReturnValueHandler returns the collected outputs as JSON. Without a Writer Plugin, the task does not expose function outputs as returned data. See configuration reference.

Visible states

State	Meaning
`ALLOCATED`	A slot is reserved; the task has not been submitted
`RUNNING`	The task is executing its input, function, or output phase
`SUCCEEDED`	The task completed its result-handling phase successfully
`FAILED`	Execution ended with a failure

Keep a WatchTasks stream attached while the task runs. Querying results does not replace this running connection. See execution semantics.

Summary

Task groups work; Call invokes one function.
Keep chain and block context explicit in configuration and arguments.
A task result and storage readiness answer different questions.

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