Class My.Custom.Task Extends (%SYS.Task.Definition, Ens.BusinessService)
{

Parameter TaskName As STRING = "My Custom Task";

Property Prop1 As %Integer [ InitialExpression = 1 ];

Method OnTask() As %Status
{
    set tSC = $$$OK
    try{
        // Define the Existing Service intended to execute the work
        Set tServiceConfigName = "My.Custom.Service"
        // Create the needed Message Request Parameters 
        set tRequest = ##class(My.Custom.Request.Message).%New()
        set tRequest.Prop1 = ..Prop1
        
        // Send message for processing
        $$$ThrowOnError(##class(Ens.BusinessService).SendRequestAsync(tServiceConfigName, tRequest))
    }catch ex{
        set tSC = ex.AsStatus()
    }
    quit tSC
}

ClassMethod TestTask() As %Status
{
	// Assuming that the task has already been created
	set tTask = ##class(%SYS.Task).OpenId("My Custom Task")
    set tTask.Prop1 = 1    // Must save to update an existing task's properties
    return ##class(%SYS.Task).RunNow(tTask.%Id())
}

}

Class My.Custom.Service Extends Ens.BusinessService
{

Method OnProcessInput() As %Status
{
    set tSC = $$$OK
    try{
        // Perform the needed processing
    }catch ex{
        set tSC = ex.AsStatus()
    }
    quit tSC
}

}

The task, service, and request message may need to be adjusted for your specific use cases. If you want to use SendRequestAsync as part of your solution, you need to include it as part of the class definition.

Documentation:
Scheduling Tasks - https://docs.intersystems.com/healthconnectlatest/csp/docbook/DocBook.UI.Page.cls?KEY=GSA_manage_taskmgr
%SYS.Task::RunNow - https://docs.intersystems.com/healthconnectlatest/csp/documatic/%25CSP.Documatic.cls?LIBRARY=%25SYS&CLASSNAME=%25SYS.TaskSuper#METHOD_RunNow 

%SYS.Task::OpenId - https://docs.intersystems.com/healthconnectlatest/csp/documatic/%25CSP.Documatic.cls?LIBRARY=%25SYS&CLASSNAME=%25SYS.TaskSuper#METHOD_OpenId 

• Note: Different from the %OpenId() call

Business Service Impl - https://docs.intersystems.com/iris20261/csp/docbook/DocBook.UI.Page.cls?KEY=EGDV_busservice#EGDV_busservice_onprocessinput 

Business Service CallInternval - https://docs.intersystems.com/iris20261/csp/docbook/DocBook.UI.Page.cls?KEY=EEMA_settings_inbound#EEMA_CallInterval 

• Depending on the use case, you could consider a CallInterval on the component itself. Though, for visibility purposes, I agree that a Task is likely the preferred approach.