Re: handler function

[Yuri Pryadkin <yuri@who.isi.edu>]

"Janssen, S.A." <S.A.Janssen@research.kpn.com> writes:

> Hi, 
> 
> can someone explain the following to me:
> 
> Some objects have a handler() and a recv() method. To me it seems that if
> object A wants to schedule an event at object B,
> 
> -  it calls schedule and the handle() method at object B is invoked. (Y/N)? 

Y

> -  When the handle() method at object B doesn't exist, it's recv() method is
> invoked. (Y/N)

Y, assuming that the object derives from NsObject

> - When bypassing the scheduler, object A uses target_->recv(p,h) and object
> B's recv() function is invoked directly by object A (Y/N)?

Y

> 
> - So what's the function of the handler exactly?

Most often it's used to schedule a future event.  Handler, in fact, is
a container for a callback function.  And an event is not necessarily
a packet, it may be e.g. a wake-up call for a queue.

> - Why should you use the bypass instead of always the scheduler (because you
> want to avoid the handler??)

For example, if you want to transfer a packet from one object to
another and you don't need any delay in between, you can directly call
recv method on this object.  If you do need a delay however, you use
schedule().

 -Yuri