dataflow priorities.

Dear friends,

¿Somebody could to explain me if exists a method to send different data in the same dataflow but with different priority level? At the moment I suppose that the priority is only an port attribute. My question is that perhaps exists an implementations (trick) to use different levels of data on the same data-flow port.

Best regards, Toni

dataflow priorities.

On Mon, Nov 28, 2011 at 05:57:25PM +0100, antonio [dot] castellon [..] ... wrote:
> Dear friends,
>
> ¿Somebody could to explain me if exists a method to send different data in
> the same dataflow but with different priority level? At the moment I suppose
> that the priority is only an port attribute. My question is that perhaps
> exists an implementations (trick) to use different levels of data on the same
> data-flow port.

Priority is an attribute of the Activity that drives your
component. For Dataflow such priorities within one connection are not
supported. However sometimes we use multiple connections to deliver
different priority events. What exactly is your use case?

Markus

enkulator's picture

preemptive queues

Dear Markus,

I'm searching to use something like preeemptive queues, where the messages haves priority levels associated on the same queue.

Toni

preemptive queues

On Tue, 29 Nov 2011, antonio [dot] castellon [..] ... wrote:

> I'm searching to use something like preeemptive queues, where the messages
> haves priority levels associated on the same queue.

Going the way of priorities is opening a can of worms... Priorities do not
scale, nor compose into more complex systems. In addition, the system's
behaviour is only implicitly defined by priorities. Bad idea, overall.

> Toni

Herman

preemptive queues

On Nov 29, 2011, at 01:29 , Herman Bruyninckx wrote:

> On Tue, 29 Nov 2011, antonio [dot] castellon [..] ... wrote:
>
>> I'm searching to use something like preeemptive queues, where the messages
>> haves priority levels associated on the same queue.
>
> Going the way of priorities is opening a can of worms... Priorities do not
> scale, nor compose into more complex systems. In addition, the system's
> behaviour is only implicitly defined by priorities. Bad idea, overall.

Agreed. Find some way to coordinate this more explicitly. Markus indicated one possible solution in a similar question you posted.
S

preemptive queues

On Tue, 29 Nov 2011, S Roderick wrote:

> On Nov 29, 2011, at 01:29 , Herman Bruyninckx wrote:
>
>> On Tue, 29 Nov 2011, antonio [dot] castellon [..] ... wrote:
>>
>>> I'm searching to use something like preeemptive queues, where the messages
>>> haves priority levels associated on the same queue.
>>
>> Going the way of priorities is opening a can of worms... Priorities do not
>> scale, nor compose into more complex systems. In addition, the system's
>> behaviour is only implicitly defined by priorities. Bad idea, overall.
>
> Agreed. Find some way to coordinate this more explicitly. Markus indicated one possible solution in a similar question you posted.

I might contradict myself a little bit: for the sole use case of
_communication_, it might make sense to introduce priorities, because it is
often the case that there is only one single communication medium available
(e.g., the radio link to a satellite). But this kind of prioritization
should then be done inside the communication middleware, and not in your
RTT components.

> S

Herman

enkulator's picture

preemptive queues

It is clear, thanks again for your support.

I began to design a system where my business layer implements the priority
of the messages before to send the correct output dataflow channel of the
component, I asked for any library or supported method that implements it
from orocos framework.

Best regards,
Toni