> On 23. May 2020, at 18:57, Miles Fidelman <mfidel...@meetinghouse.net> wrote:
>
> On 5/23/20 12:29 PM, Jan Lehnardt wrote:
>
>>
>>> On 23. May 2020, at 16:28, Miles Fidelman <mfidel...@meetinghouse.net>
>>> wrote:
>>>
>>>
>>> On 5/22/20 11:13 AM, Jan Lehnardt wrote:
>>>
>>>>> On 22. May 2020, at 15:06, Miles Fidelman <mfidel...@meetinghouse.net>
>>>>> wrote:
>>>>>
>>>>> Hi Jan,
>>>>>
>>>>> On 5/22/20 6:17 AM, Jan Lehnardt wrote:
>>>>>> Hi Miles,
>>>>>>
>>>>>> I wanted to reply for a while, but struggled to find a good angle. I
>>>>>> think I finally figured out what I missed. I’m not sure I understand
>>>>>> your deployment scenario.
>>>>>>
>>>>>> When I think conference app, I think folks having that on their mobile
>>>>>> phones, or tablets. Given that, you’d be using PouchDB (for web apps) or
>>>>>> one of Cloudant mobile sync libraries (if it is a native app). Either
>>>>>> way, to get the data to the devices, it’d have to come from somewhere,
>>>>>> but then you say there is no central server. Where does the data come
>>>>>> from?
>>>>> I was using that as an example - but I'm really thinking more the case of
>>>>> "smart documents." Think of a plan (business, mission) or briefing
>>>>> package - and the whole notion of "living documents.
>>>> not sure what these are and how they compare to CouchDB documents.
>>> "Living Document" as in writerspeak - a binder full of documentation that
>>> is continually being kept up to date, the latest version of a proposal, a
>>> book draft, a theatrical script that's being marked up with commentary
>>> during rehearsal, etc.
>>>
>>> Or think of marrying a wiki to a DCVS.
>>>
>>>>>> It sounds like you imagine the devices talking to each other in a
>>>>>> replication mesh kind of way. While technically possible from a CouchDB
>>>>>> replication protocol point of view, this approach isn’t very practical.
>>>>>> For one, you won’t be able to guarantee that all devices can talk to
>>>>>> each other, especially when you don’t control the wifi.
>>>>>>
>>>>>> What’s more likely is that you’d have central CouchDB server that is
>>>>>> connected to the wifi network, either on site, or in a datacenter
>>>>>> somewhere that all devices connect to.
>>>>>>
>>>>>> Having that many devices talk to a central database to get all the
>>>>>> relatively static data of the conference (schedule, info, etc), doesn’t
>>>>>> sound like much of a problem. Group interaction is a little more
>>>>>> interesting. You could model this a 1-db-per-group, and it would work
>>>>>> okay, but there are some devil-in-the-details-details to work out with
>>>>>> access control and joining and leaving a group, etc.
>>>>>>
>>>>>> So overall:
>>>>>>
>>>>>> - what architecture do you envision?
>>>>>> - I think this can be made to work.
>>>>>> - CouchDB definitely can handle 5000 intermittent clients. Depending on
>>>>>> your use-case, you may need more or less computing resources for this,
>>>>>> but there aren’t any fundamental blockers in CouchDB’s design that would
>>>>>> prevent this from being a success.
>>>>> I keep coming back to the model of replicated copies, stored in something
>>>>> like a distributed version control system, linked by a publish-subscribe
>>>>> network. (Not that much different than the way large-scale modeling &
>>>>> sims are done - local "world models" linked by a protocol like DIS or
>>>>> HLA.)
>>>>>
>>>>> I've been wondering if Couch/Pouch might make a good platform - coupled
>>>>> with something like NNTP for epidemic style distribution of changes.
>>>> If you squint a little, CouchDB fits your buzzword bill here, but without
>>>> more concrete descriptions of what you need (rather than less), we can’t
>>>> help much.
>>>>
>>>> And you didn’t address the network connectivity issue. If you plan to have
>>>> device-to-device communication, and you are not Apple or Google making
>>>> those devices and/or mobile operating systems, you won’t be having much
>>>> luck, especially on the web platform.
>>> I'm thinking tactical environments & mesh networks, with intermittent
>>> connectivity. Updates propagate slowly, but with either automatic
>>> fork/merge, or with eventual consistency.
>> Right, so far the theory, which the CouchDB replication protocol supports.
>> Now in practice, say you are using PouchDB, how do you make one device’s
>> browser talk to another device’s browser?
>
> Well... I would see this as a case of mesh networking. An instance of
> PouchDB, on a phone, might sync to one (or more) instances of CouchDB -
> running on a laptop, or a server. The basic model would be that of NNTP.
> Updates would ripple through a mesh of instances. My assumption is, that any
> particular instance of Couch of Pouch needs to know one or more other
> instances to connect to - and from there, stuff moves around.
that is more concrete and we can talk about it now, thanks for clarifying.
> Which comes back to... how well does this scale? What's the largest mesh
> network of Pouch/Couch instances that anybody has run in practice?
since the setup is very non-standard, there isn’t a lot of existing setups to
look for.
I know of a PouchDB-running-inside-node.js on IoT devices scenario covering a
large geographic area with mesh wifi, collecting data and replicating sensory
data through the mesh up to one point that has an internet uplink, which then
sends the whole bunch up to the cloud. At the time I was involved, the target
for this was 1000s of devices, but I know little about the amount of documents
flowing through the mesh.
Again, the replication model fully support this, but given enough data, the
sensory data option might eventually be limited by data size / storage space
available on the devices, to hold, potentially, all data from all devices.
For your use-case, you have a lot less data coming in, so I wouldn’t see much
of an issue, overall.
Best
Jan
—
>
> Miles
>
>
>
>
>>
>> Best
>> Jan
>> —
>>
>>> Cheers,
>>>
>>> Miles
>>>
>>>
>>>> Best
>>>> Jan
>>>> —
>>>>
>>>>> Miles
>>>>>
>>>>>
>>>>>> Best
>>>>>> Jan
>>>>>> —
>>>>>>
>>>>>>> On 20. May 2020, at 14:23, Miles Fidelman <mfidel...@meetinghouse.net>
>>>>>>> wrote:
>>>>>>>
>>>>>>> Hi Folks,
>>>>>>>
>>>>>>> I'm thinking of using Couch (or Couch plus Pouch) as the platform for a
>>>>>>> conference program app - everyone gets their copy of the program, plus
>>>>>>> handouts/proceedings, with the added capabilities to set up one's
>>>>>>> personal schedule, hold side conversations with various groups,
>>>>>>> schedule BOF meetings, etc.
>>>>>>>
>>>>>>> Which leads me to wonder what experience folks have had with scaling -
>>>>>>> particularly without using a central server. Can, say, 5000 instances,
>>>>>>> linked intermittently, stay reasonably consistent?
>>>>>>>
>>>>>>> What's the largest collection of Couch instances anybody has played
>>>>>>> with?
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Miles Fidelman
>>>>>>>
>>>>>>> -- In theory, there is no difference between theory and practice.
>>>>>>> In practice, there is. .... Yogi Berra
>>>>>>>
>>>>>>> Theory is when you know everything but nothing works.
>>>>>>> Practice is when everything works but no one knows why.
>>>>>>> In our lab, theory and practice are combined:
>>>>>>> nothing works and no one knows why. ... unknown
>>>>>>>
>>>>> -- In theory, there is no difference between theory and practice.
>>>>> In practice, there is. .... Yogi Berra
>>>>>
>>>>> Theory is when you know everything but nothing works.
>>>>> Practice is when everything works but no one knows why.
>>>>> In our lab, theory and practice are combined:
>>>>> nothing works and no one knows why. ... unknown
>>> --
>>> In theory, there is no difference between theory and practice.
>>> In practice, there is. .... Yogi Berra
>>>
>>> Theory is when you know everything but nothing works.
>>> Practice is when everything works but no one knows why.
>>> In our lab, theory and practice are combined:
>>> nothing works and no one knows why. ... unknown
>>>
>>> --
>>> In theory, there is no difference between theory and practice.
>>> In practice, there is. .... Yogi Berra
>>>
>>> Theory is when you know everything but nothing works.
>>> Practice is when everything works but no one knows why.
>>> In our lab, theory and practice are combined:
>>> nothing works and no one knows why. ... unknown
>>>
> --
> In theory, there is no difference between theory and practice.
> In practice, there is. .... Yogi Berra
>
> Theory is when you know everything but nothing works.
> Practice is when everything works but no one knows why.
> In our lab, theory and practice are combined:
> nothing works and no one knows why. ... unknown
