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From Lakmal Warusawithana <>
Subject Re: proposed architectural changes to Stratos
Date Fri, 11 Oct 2013 07:51:54 GMT
On Fri, Oct 11, 2013 at 11:27 AM, Sanjiva Weerawarana <>wrote:

> On Fri, Oct 11, 2013 at 10:23 AM, Nirmal Fernando <>wrote:
>> +1 for the new design.
>> A question:
>> How can we handle multiple load balancer scenario where one load balancer
>> would not interested in all the clusters but a set of selected ones? I
>> suggest we go for a hierarchical topic concept, instead of one single
>> topology topic.
> Are you suggesting some topic hierarchy which recognizes the actual LB
> type? I don't like that because that couples the CC to LB types. My
> preference is a model where all LBs get all updates and they decide what
> they care about and do something about those.

Yeah, I also think, no need to have hierarchical typology topics (even
hierarchical topology messages), single topic can do the stuff. Maybe we
need to have topology topic for publish full topology (it will used by LBs,
Autoscalar..etc to come current state when it restart or new comers ) and
topology-event topic for sync with the events like add/remove cluster
members. I will draw some sequence and sample topology messages, which
explain it further. These topology topics will utilize by LBs and
autoscalar for there functionalists.

>>>    - Traffic comes in thru any load balancer (e.g. HAProxy for non-HTTP
>>>    traffic and our LB for HTTP traffic). LB routes based on its configuration
>>>    which is periodically updated by the Cloud Controller via topology update
>>>    messages.
>>> IMO we should send topology messages periodically (even there's no
>> change), so that LB can get the current status of the system, even after a
>> restart.
> Yeah to handle fresh LBs we either need to have a periodic update going
> out or have a way for the LB to contact the CC and get the latest config. I
> prefer the latter because that's a bit like ADC being used to config a
> fresh instance. In fact, going forward we could even auto scale LBs .. but
> that's a bit far fetched as it requires possibly doing DNS updates too. But
> its not that hard.

> Sanjiva.
> --
> Sanjiva Weerawarana, Ph.D.
> Founder, Chairman & CEO; WSO2, Inc.;
> email:; phone: +94 11 763 9614; cell: +94 77 787 6880 | +1
> 650 265 8311
> blog:
> Lean . Enterprise . Middleware

Lakmal Warusawithana
Software Architect; WSO2 Inc.
Mobile : +94714289692
Blog :

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