Hi Endre,
Thanks for the hint with *GraphStage*. I tried to use the code from
*UnzipWith2* and adjust it to my needs, but the API was not really clear
for me.
*When* should I call *pull* and what effects does it have? I wasn't able to
create a queue inside the GraphStage (e.g. like a Source that gets
flattened into the progress output).
In the end I had the feeling to build a Broadcast stage. E.g.
+---> map to progress +---> progress
sink
|
+
data +----> stage1 +----> broadcast
+
|
+------------------------------------------------> stage2
which only works for 1-progress-output per stage. However I would like to
be able to ouput more then one progress in one stage. Eg.
override def onPush(elem: TrajectoryBoxes, ctx:
Context[RotatedTrajectoryBoxes]): SyncDirective = {
val angle = calculateAngle(elem)
progress(25, "angles calculated")
val rotated = rotate(elem, angle)
progress(100, "boxes rotated")
ctx.push(rotated)
}
Am Montag, 23. November 2015 12:33:28 UTC+1 schrieb Akka Team:
>
> Hi Muki,
>
>
>
> On Sun, Nov 22, 2015 at 4:49 PM, Muki <[email protected] <javascript:>>
> wrote:
>
>> Hi,
>>
>> I have a stream pipeline like this:
>>
>> progress queue +---------> mapping +---------+
>> |
>> ^ ^ ^ |
>> | | | v
>> | | +------------------------+ +-- merge +--->
>> | | | ^
>> | +---------+ | |
>> + + + |
>> data +--------> stage1 +--------> stage2 +----+
>>
>>
>>
>> - *data* is a single source that generates the data to be processed
>> - *progress queue* is a
>> Source.queue[Progress](10, OverflowStrategy.dropHead) where the
>> progress should be emitted
>> - *stage1 *and* stage2* are emitting elements to the next stage and
>> also the the *progress queue*
>>
>>
>> So these are actually two different data pipelines, which are only
>> connected by the *progress queue* and the *merge* in the end.
>> The initial implementation just sent messages to a progress actor, which
>> then send it over a play-websocket. Now I want to do this
>> with akka-http and the websocket describes as a Flow[Message, Message].
>>
>> I read "Accessing the materialized value inside the Graph"
>> <http://doc.akka.io/docs/akka-stream-and-http-experimental/2.0-M1/scala/stream-graphs.html#Accessing_the_materialized_value_inside_the_Graph>,
>>
>> but couldn't figure out how to implement this kind of pattern.
>>
>
> That will not likely to help you, as that let's you access the
> materialized value as a value of a Source. What you will need actually is
> to model your progress emitting stages as GraphStages instead. They will
> let you to expose a second output port for the only purpose of sending
> progress information. Those are available in M1 but not really documented
> unfortunately. Also, that will mean that your stage1 and stage2 will no
> longer be Flows but three-port stages (which means that you would need to
> use the graph DSL to connect them).
>
> -Endre
>
>
>>
>> Thanks in advance,
>> Muki
>>
>> --
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>
>
> --
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>
--
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