Hi Peter,
I think I have done similar thing before. This flow template may be
useful in your case, too.
https://gist.github.com/ijokarumawak/9e1a4855934f2bb9661f88ca625bd244
Thanks,
Koji
On Tue, Nov 14, 2017 at 12:58 PM, Peter Wicks (pwicks)
wrote:
> Matt,
>
> I played around with your idea. I haven't been able to get it to work.
>
> First flow file comes in, goes out the wait relationship. Now how do we stop
> the next FlowFile from going out the wait relationship and entering the flow?
> Well we'd have to use Notify along with some scheduling on Wait so multiple
> FlowFile's don't come through right away; so I put a Notify processor right
> after Wait. Now the second FlowFile enters, goes out the success relationship
> because there is a signal count, then immediately goes down wait since the
> signal is clear...
>
> If this use case seems common enough, I was thinking that the solution might
> be to have add an option on Wait that lets you choose whether you want to
> "Wait for signal" or "Wait only if signaled". This would restore the
> relationships back to their proper uses. Then you'd use the Notify property
> 'Signal Counter Delta' mode of 0 at the end of the flow. Flow would be
> something like Wait (Wait only if signaled)->Notify (Signal to 1)->...
> Processors ...->Notify (Signal to 0). Or perhaps as part of the feature,
> "Wait only if signaled" mode would do the notify step internally.
>
> Would still like to find a clean/easy way to do this though.
>
> Thanks,
> Peter
>
> -Original Message-
> From: Matt Burgess [mailto:mattyb...@apache.org]
> Sent: Tuesday, November 14, 2017 08:53
> To: users@nifi.apache.org
> Subject: [EXT] Re: Wait only if flagged?
>
> Peter,
>
> I haven't tried this, but my knee-jerk reaction is to switch the roles
> of the "wait" and "success" relationships. Maybe you can send the
> "wait" relationship downstream and route the "success" one back to
> Wait. Then when the flag is "cleared", the flow files will start going
> to the "success" relationship which is routed back to wait.
>
> Regards,
> Matt
>
> On Mon, Nov 13, 2017 at 7:21 PM, Peter Wicks (pwicks)
> wrote:
>> I have a database flow, which is a sequence of 4 processors. For database
>> performance reasons I need to make sure only one file is in this section of
>> the flow at a time. Not just one file per queue/processor, but for the whole
>> section.
>>
>>
>>
>> I feel like I should be able to use Wait/Notify to do this, but Wait/Notify
>> seem to do the opposite. I want to allow a file to go into the flow unless
>> there is a flag. If there is a flag I want the FlowFile to wait until the
>> flag is cleared.
>>
>>
>>
>> Thoughts?
>>
>>
>>
>> Thanks,
>>
>> Peter
