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From Sijie Guo <guosi...@gmail.com>
Subject Re: hedwig question
Date Fri, 04 Jan 2013 20:04:25 GMT
Yannick,

Seems a producer/consumer queue model might be more suitable for your user
case, I guessed. It would be quite interesting on adapting a queue in
Hedwig or based on BookKeeper. Would look into it.

-Sijie


On Fri, Jan 4, 2013 at 9:01 AM, Yannick Legros
<yannick.legros59@gmail.com>wrote:

> "for currently, we don't support this semantic in Hedwig. I am doubting
> why not subscribe first before publish. is it difficult in your case?"
>
>     => subscribers and publishers are waiting for external events to begin
> their publish/subscribe. i can't be sure of the order that my "Agents"
> detects the external event. So in some cases the publishers starts before
> the subscribers and i can loose few message :-(.
>
>
> "if to support your semantic, all the messages had to be kept until a
> subscriber arrived. if there is no subscriber, how to deal with those
> published messages? kept them forever?"
>
>     => I know that hedwig is a pub/sub framwork and it is not a treatment
> queue, but keep them during a parametrized time would be great
>
> thanks,
>
> Yannick.
>
>
> 2012/12/29 Sijie Guo <guosijie@gmail.com>
>
>> thanks, yannick. I got your idea.
>>
>> for currently, we don't support this semantic in Hedwig. I am doubting
>> why not subscribe first before publish. is it difficult in your case?
>>
>> if to support your semantic, all the messages had to be kept until a
>> subscriber arrived. if there is no subscriber, how to deal with those
>> published messages? kept them forever?
>>
>> -Sijie
>>
>>
>> On Sat, Dec 29, 2012 at 3:58 AM, Yannick Legros <
>> yannick.legros59@gmail.com> wrote:
>>
>>> thanks for your answer sijie.
>>>
>>> what i need is not exactly
>>>  "subscribers be aware of messages publish before they subscribe"
>>> but
>>>  "be sure that my message be consume by almost one subscriber"
>>>
>>> so if a publisher publish message on topics with no subscribers the
>>> first subscriber who will read the topics will get all published messages
>>> before his subscription.
>>>
>>> hope i was clear.
>>>
>>> Thanks, yannick.
>>>
>>> 2012/12/28 Sijie Guo <guosijie@gmail.com>
>>>
>>>> > does this is the default behaviour of hedwig?
>>>>
>>>> A subscriber would receive all the messages published after its first
>>>> time subscribe until it unsubscribe.
>>>>
>>>> so go back to your example:
>>>>
>>>> 1) if the subscriber subscribe T first time, it would only receive M2.
>>>> 2) if the subscriber already subscribe before M1. so the subscribe
>>>> between M1 and M2 is an attach subscribe, so it would receive M1 and M2
>>>> eventually (if it doesn't receive M1 at its first time subscribe)
>>>>
>>>> > can we configure something (in subscription option for exemple) for
>>>> subscribers be aware of messages publish before they subscribe and not
>>>> consumed yet.
>>>>
>>>> Currently Hedwig doesn't support it. But I am just curious why a
>>>> subscriber need to be aware of messages published before they subscribed?
>>>> Is there any special case you are considering?
>>>>
>>>> -Sijie
>>>>
>>>>
>>>> On Fri, Dec 28, 2012 at 3:23 AM, Yannick Legros <
>>>> yannick.legros59@gmail.com> wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> I have just another question.
>>>>>
>>>>> in this case :
>>>>>
>>>>> publisher post a message M1 on topics T
>>>>> subscriber subscribe to T
>>>>> publisher post a message M2 on topics T
>>>>>
>>>>> when subscriber starts delivery he will get M2 but not M1 because he
>>>>> has subscribed after M1 was publish.
>>>>>
>>>>> does this is the default behaviour of hedwig?
>>>>> can we configure something (in subscription option for exemple) for
>>>>> subscribers be aware of messages publish before they subscribe and not
>>>>> consumed yet.
>>>>>
>>>>> thanks a lot.
>>>>>
>>>>
>>>>
>>>
>>
>

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