# Interface Callbacks.BeforeExecuteCallback

Enclosing class:
  `Callbacks`

Functional Interface:
  This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface public static interface Callbacks.BeforeExecuteCallback
Async callback interface for actions to be performed before an execution is started.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `io.reactivex.rxjava3.core.Single<Boolean>`
  `call(io.a2a.server.agentexecution.RequestContext ctx)`
  Callback which will be called before an execution is started.

- ## Method Details

  - ### call

    io.reactivex.rxjava3.core.Single<Boolean> call(io.a2a.server.agentexecution.RequestContext ctx)
    Callback which will be called before an execution is started. It can be used to instrument a context or prevent the execution by returning an error.
    Parameters:
      `ctx` - the request context
    Returns:
      a `Single` that completes with a boolean indicating whether the execution should be prevented