Thats my view too:
15:03 < josephg> So, I'm just responding as I read - stenyak: For now,
I want wave to be p2p in the same way that git is p2p.
15:04 < josephg> that is, I want the core algorithms & data structures
to use P2P-capable algorithms, and probably the wave servers will do
p2p between themselves (this is easy because they'll all be both named
and accessable)
15:06 < josephg> as for client-to-client p2p, there's a few options
depending on what kind of use cases we want to support - but I want to
worry about getting the algorithms p2p-capable first. If you're keen
to set up an anonymous, distributed wave system over a DHT - well, I
want to first make that possible
I'm glad some people are thinking about it though - once we have the
OT container working, I'm curious to see what people come up with for
it.
-J
On Fri, Jun 21, 2013 at 7:04 PM, Michael MacFadden
<michael.macfad...@gmail.com> wrote:
> MY humble opinion on the P2P issue is as follows. I think if we develop
> algorithms that can work in a P2P mode, then we can also support a
> client/server architecture as well by just controlling who the peers talk
> to. I think the problem with wave was not the client server architecture,
> but rather the way the servers interacted with each other. The servers
> themselves implemented something like a client/server relationship within
> federation. This meant that even if you were connected to your local wave
> server, if that wave server could not communicate with the wave server
> that initiated the wave, you were out of luck.
>
> I am not against having servers at all. In fact I think that things get
> very complicated if you have no servers what so ever (document storage,
> discovery, users, etc.). But if we need to make sure servers are peers.
> So we need a P2P style OT algorithm. Again do not confuse a P2P network
> topology (DHT, etc) with P2P OT Algorithms. A P2P OT Algorithm can also
> easily be made to behave like a Client/Server OT algorithm, where as the
> reverse is not feasible.
>
> ~Michael
>
> On 6/21/13 5:46 PM, "Sam Nelson" <so...@orcon.net.nz> wrote:
>
>>Wow, that was some heavy reading (:
>>
>>This section raised some questions for me:
>>
>>*4) Routing p2p messages/events in a pure P2P system (5 parts)*
>>How to manage to route all wave-stuff if we want to completely get rid of
>>servers completely, and only use peers.
>>The closest way would be to use a DHT, but huge latency is an unsolved
>>problem, and makes it impossible to use for real-time waving.
>>No other solution has been proposed.
>>
>>My question is simply, perhaps naively: why pure p2p?
>>Originally when I heard of p2p OT I saw it as a way to collaboratively
>>work offline in a LAN environment, and to sync pairs that are almost
>>always offline, by means of a proxy peer that moves between WAN and the
>>offline LAN. The peers would talk in much the same way that two
>>federating servers would, using their offline caches as a datasource
>>instead I'm guessingthis is like the MESH network John refers to.
>>
>>When talking about P2P between peers /over the internet/ - could
>>somebody please explain to be the purpose of and vision for this? Why
>>not just use a server, it seems to simplify things alot? (Firewalls,
>>authentication - can do offline like Windows 8 does with Microsoft
>>Account)
>>
>>Is purep2p just for privacy? Or is it really for alternate uses of the
>>protocol - other than the the documents and conversation use cases we
>>saw in Google Wave?
>>
>>Just an idea, in order to "open the eyes" of those drawn to this mailing
>>list, might it be beneficial to build up a wiki page of accepted use
>>cases so that everyone can read them and take them into account when
>>considering different ideas? That'd facilitate discussions like "well
>>this works for all our use cases except #13.... <discussion ensues about
>>this case>"
>>
>>Sam
>>
>>
>>On 22/06/2013 01:06, John Blossom wrote:
>>> Bruno,
>>>
>>> Thanks, this is an excellent summary. It helps me to get the gist of
>>>things
>>> more clearly.
>>>
>>> On the P2P latency, I don't think that it would be unacceptable to draw
>>>a
>>> line and say that P2P provides limited, non-guaranteed realtime OT or
>>>that
>>> it's not realtime OT and more of a syncing mode than a conversation
>>>mode.
>>> That would probably be sufficient for what needs to be done, especially
>>> since in some instances P2P-enabled Wave sessions may be using MESH
>>> networks for transport - a key factor in how a lot of experimental
>>> communications services are being deployed in developing nations (not
>>>just
>>> the Project Loon concept). In the MESH model, you're likely to have one
>>> node within range of another temporarily, which may sync with it, and
>>>then
>>> pass along data to another node when it comes in range of it. That's the
>>> most probable scenario for P2P in many instances, I would think. The
>>>other
>>> potential scenario: two people in a remote location, for the sake of
>>> argument two movie script-writers who have holed themselves up in a
>>>remote
>>> location to collaborate on a common script. They're on two devices that
>>>are
>>> very proximate to one another, so perhaps the latency issues will not
>>>be so
>>> severe.
>>>
>>> Things to think about, I will look at this more carefully later today.
>>>
>>> All the best,
>>>
>>> John Blossom
>>>
>>> On Fri, Jun 21, 2013 at 8:05 AM, Bruno Gonzalez (aka stenyak) <
>>> sten...@gmail.com> wrote:
>>>
>>>> Following Joseph's "A Very Wavey Plan (P2P!)" thread, a couple of
>>>> discussions have taken place at the irc.freenode.net #wiab channel, all
>>>> related to P2P.
>>>>
>>>> I've taken the liberty to restructure the IRC logs, remove some
>>>>chitchat,
>>>> and divide it into sub-discussions. Feel free to reply to any part of
>>>>this
>>>> email to continue a discussion.
>>>>
>>>>
>>>> *Summary of discussions:*
>>>> *====================*
>>>> *1) Underlying protocol for P2P federation*
>>>> Currently XMPP is used. HTTP and raw TCP are two suggested candidates
>>>>(HTTP
>>>> allowing to much more easily reach restricted networks).
>>>>
>>>> *2) Message/event types needed for P2P federation to work*
>>>> We'd need something similar in concept to certain git operations (git
>>>> clone, git push...). All will be based on hashes (not incremental
>>>> integers).
>>>>
>>>> *3) Routing p2p messages/events in a server-aided network*
>>>> One option is to somehow detect server clusters, send data to one of
>>>>them,
>>>> and let the rest of the cluster servers synchronize to it (locally).
>>>> Alternatively, the originator server can naively send stuff to all
>>>>possible
>>>> destination servers, regardless of the cost.
>>>>
>>>> *4) Routing p2p messages/events in a pure P2P system (5 parts)*
>>>> How to manage to route all wave-stuff if we want to completely get rid
>>>>of
>>>> servers completely, and only use peers.
>>>> The closest way would be to use a DHT, but huge latency is an unsolved
>>>> problem, and makes it impossible to use for real-time waving.
>>>> No other solution has been proposed.
>>>>
>>>> *5) Implementing "undo": invertibility, tombstones, edge cases, TP2*
>>>> No server means no canonical order of commits, which means that undo is
>>>> hard to do correctly.
>>>> (uhm... not sure if that's a good summary, some stuff went over my head
>>>> :-D, please read the log instead)
>>>>
>>>> *6) Usability of a pure p2p system in Real Life (tm)*
>>>> Being pragmatic, pure P2P is probably only usable in peers with good
>>>> connectivity. Rest of peers will need to rely on a server/proxy that
>>>>*does*
>>>> have good connectivity.
>>>>
>>>> *7) Comparison with BitTorrent and P2P-TV technologies*
>>>> Both technologies are much less restricted than wave with regards to
>>>> real-time responsiveness. So none are really a good reference for our
>>>> purposes.
>>>>
>>>> *8) Identifying participants (3 parts)*
>>>> Pure p2p means many peers don't have a n...@centralized-server.com user
>>>> handle, so an alternative has to be used.
>>>> However, it's easy to provide a traditional friendly handle, if the
>>>>user
>>>> prefers the tradeoff of having to often rely on a permanent server.
>>>>This
>>>> tradeoff can be mitigated by using a sort of userhandle cache.
>>>>
>>>> *9) P2P anonymity (lurking in a wave) (2 parts)*
>>>> In a pure p2p wave network, anonymous peers may want to read a public
>>>>wave,
>>>> without other peers knowing. A solution could be to make private the
>>>> required wavelets (where the anonymous participants IDs are stored).
>>>>
>>>> *10) Encryption of waves*
>>>> It's been proposed to use an AES key to encrypt all the wave data, and
>>>>only
>>>> allow participants to decrypt it.
>>>>
>>>> *11) Addition and removal of participants, and their ability to read
>>>>past
>>>> and future wave versions/deltas*
>>>> The aforementioned AES key can change over time, allowing a
>>>>finer-grained
>>>> restriction of what deltas new/removed participants can read.
>>>>
>>>>
>>>> *
>>>> *
>>>>
>>>> *Actual conversations:*
>>>> *====================*
>>>> *
>>>> *
>>>> *1) Underlying protocol for P2P federation:*
>>>> [in response to Joseph's email]
>>>> [23:42] <alown> I [...] agree with option 2 (make every root a JSON
>>>>blob)
>>>> [23:43] <alown> You haven't really detailed (at all) how the P2P
>>>>federation
>>>> is actually going to work (beyond 'not like IRC')
>>>> [23:44] <josephg> Personally, I'd love some raw TCP action
>>>> [23:44] <alown> I agree using KISS principle.
>>>> [23:44] <josephg> a few years ago (not long after wave was cancelled)
>>>>there
>>>> was a 'wave summit'
>>>> [23:45] <josephg> - and a few of us chatted about how we could make the
>>>> federation protocol simpler
>>>> [23:45] <josephg> we ended up (somehow) deciding that doing it over
>>>>http
>>>> woul dbe a good idea
>>>> [23:45] <josephg> because then we could sneak it into companies past
>>>>their
>>>> corporate HTTP firewalls, etc
>>>> [23:45] <josephg> but in any case, I'd like to figure out the protocol
>>>>and
>>>> (at least) have a TCP version
>>>> [23:46] <josephg> it should be pretty easy to wrap the same messages in
>>>> websockets if we want
>>>>
>>>>
>>>> *2) **Message/event types needed for P2P federation to work:*
>>>> [23:46] <alown> Do we need anything more complicated than the
>>>> waveletSubmit/Commit messages used currently?
>>>> [23:46] <alown> (Replace wavelet with 'abstract p2p ot container name)
>>>> [23:46] <josephg> um, yeah.
>>>> [23:47] <josephg> we'll also be able to rip out all the code that deals
>>>> with managing the tree of servers per wave
>>>> [23:47] <josephg> but yeah - the protocol will get a bit more
>>>>complicated
>>>> [23:47] <josephg> ... because we'll lose our beautiful integer version
>>>> numbers
>>>> [23:47] <josephg> so we'll need a protocol for syncronizing ops
>>>> [23:48] <josephg> yeah - ops will each have a hash
>>>> [23:48] <josephg> and two servers could each have ops the other server
>>>> doesn't have
>>>> [23:48] <josephg> so we have to be able to deal with that
>>>> [23:47] <alown> What other 'events' are cared about by any particular
>>>> server?
>>>> [23:47] <alown> For a SHA hash?
>>>> [23:48] <josephg> -> we'll need something like git's sync protocol
>>>> [23:48] <alown> So, initial server contact is 'git clone', and then
>>>>some
>>>> form of 'git push' on changes?
>>>> [23:49] <josephg> yep.
>>>> [23:49] <josephg> push on changes is easy - its basically the same
>>>>thing we
>>>> have now
>>>> [23:49] <josephg> just instead of saying "This should be applied at
>>>>version
>>>> 10" we say "This op has parents [abc123, def456]"
>>>>
>>>>
>>>> *3) **Routing **p2p **messages/events in a server-aided network:*
>>>> [23:49] <alown> With P2P do we have to broadcast to all peers? How do
>>>>we
>>>> coordinate that between them?
>>>> [23:50] <josephg> between servers? I dunno.
>>>> [23:50] <alown> How does BT handle this?
>>>> [23:50] <josephg> should we just connect every server to every other
>>>> server? That'd work fine...
>>>> [23:50] <josephg> I guess every server can address every other server
>>>> [23:50] <josephg> beacuse the wave will have al...@a.com and
>>>> josephg@b.comand so on on it
>>>> [23:50] <alown> This feels very inefficent...
>>>> [23:51] <josephg> so if you submit an op to your server, your server
>>>>can go
>>>> "Oh, I need to tell b.com about this too"
>>>> [23:51] <josephg> well, if there's 10 servers, presumably all 10
>>>>servers
>>>> need to find out about ops somehow.
>>>> [23:51] <josephg> - assuming we stick with the current model of having
>>>> servers store all your operations
>>>> [23:51] <josephg> .. and documents for all the users at their domain
>>>> [23:51] <alown> But server 'b' and 'c' might both be part of a wave,
>>>>but
>>>> also know each other, and know that they are 'closer' to each other
>>>>than
>>>> 'a' is. So, we would want a->b/c then b<->c
>>>> [23:52] <josephg> so actually, having the server which originates an
>>>> operation send it to all the other servers on that wave is actually
>>>>close
>>>> to ideal.
>>>> [23:52] <josephg> yeah maybe.
>>>>
>>>>
>>>> *4) **Routing **p2p **messages/events in a pure P2P system (part 1):*
>>>> [23:54] <alown> BT uses DHT for its P2P stuff...
>>>> [23:54] <josephg> ...I guess we could use a DHT storing all the ops,
>>>>but
>>>> thats pretty slow
>>>> [23:55] <josephg> and you still need to notify all servers with users
>>>>on
>>>> the wave that the wave was updated.
>>>> [23:55] <alown> Maybe, or perhaps only notify those within a certain
>>>> 'distance', with each server doing that. (Though could mean some
>>>>servers
>>>> are never updated)
>>>> [23:58] <alown> Perhaps we could make the network setup 'SuperWaves'
>>>>which
>>>> broadcast to all peers, and carry all information, but normal wave
>>>>servers
>>>> do not reach this status?
>>>> [23:58] <alown> By having it decide itself based on how 'connected' a
>>>> server is, this could find the most efficent ways to route it.
>>>> [00:01] <josephg> Do you think it'll really be a problem?
>>>> [00:01] <josephg> I mean, thinking about it - how many servers will be
>>>>on a
>>>> given wave?
>>>> [00:01] <alown> Depends.
>>>> [00:01] <alown> No idea.
>>>> [00:01] <josephg> If it were a public wave, I can imagine clients just
>>>> connecting to one (or more) centralized servers
>>>> [00:01] * josephg nods
>>>> [00:02] <josephg> ... But say if we were having a conversation on
>>>> wave-dev@apache, there's like, at most 20 people in a discussion from
>>>>5 or
>>>> so domains
>>>> [00:03] <josephg> ... I think we can deal with that kind of load.
>>>> [00:04] <josephg> but if the protocol lets any server tell any other
>>>>server
>>>> about an operation, then it should be pretty easy to set up something
>>>>like
>>>> that.
>>>> [00:04] <josephg> maybe.
>>>> [00:04] * josephg thinks
>>>> [00:05] <josephg> hm - you're right. I think I've just gotten used to
>>>>the
>>>> crappy state of doing routing for broadcasting messages to a network
>>>> [00:05] <josephg> if you can find / think of a better solution, I'm in.
>>>> [00:12] <alown> Heh, anyway replacing the network layer code SHOULD be
>>>> easy, since it SHOULD be cleanly seperated.
>>>> [00:13] <alown> Getting an initial implementation up using broadcast is
>>>> fine.
>>>> [00:13] <alown> (I was thinking of Wave's use in other apps as a
>>>>reason you
>>>> could have a lot of different participant domains)
>>>> *...4) Routing **p2p **messages/events in a pure P2P system (part 2):*
>>>> [08:53] <stenyak> as for the "how to *really* do p2p", i see two
>>>>options:
>>>> a) use a dht-like algorithm and/or b) use a helper server to route
>>>>stuff
>>>> for you
>>>> [08:54] <stenyak> a) can be pretty slow if you want all OPs to reach
>>>>all
>>>> peers (if I'm not mistaken)
>>>> [08:54] <stenyak> and b) is essentially makes it not-p2p
>>>> [08:55] <stenyak> additionally, using p2p, how are we going to deal
>>>>with
>>>> routing problems (such as firewalls on both sides, etc)?
>>>> [08:56] <stenyak> in my mind, the only universal solution is to have a
>>>> third party server available to go through if we want speed or if we
>>>>want
>>>> to work on all edge cases
>>>> [08:56] <stenyak> and wave being advertised as realtime, i don't see
>>>>how
>>>> something like dht can ever fly
>>>> [11:20] <alown> stenyak: This is why I was wondering about a DHT system
>>>> with 'Superwave' servers (to act as a first point of contact).
>>>> [11:59] <stenyak> that would be like skype dynamic supernode list?
>>>> [11:59] <alown> The original system, yes.
>>>> [12:02] <stenyak> so we would devise a method to identify candidates to
>>>> being a supernode, in order to prevent cellphone wave peers from
>>>>becoming
>>>> one, and in order to promot certain other nodes (like major peers that
>>>>have
>>>> 99% uptime, e.g. wave.google.com or whatever) to become one
>>>> [12:03] <stenyak> bandwidth, latency, open ports, uptime...
>>>> [12:04] <alown> Once a network has been bootstrapped using something,
>>>>it is
>>>> relatively easy to identify the hosts which are most densely connected
>>>>(and
>>>> would be good supernode candidates)
>>>> [12:05] <stenyak> what do you mean with "using something"?
>>>> [12:06] <alown> Somehow the network has to initially be able to make
>>>> contact with other nodes (before it knows anything about them)
>>>> [12:07] <alown> For a LAN you could get away with a broadcast
>>>>'announce',
>>>> but it is a bit less clear on an internet-sized scale.
>>>> [12:08] <stenyak> bittorrent sync uses a broadcast for LAN. for
>>>>internet it
>>>> uses a tracker server for fast discovery of peers, or you can disable
>>>>that
>>>> and force to use DHT (with the long wait that means)
>>>> [12:09] <stenyak> the tracker can also act as a meeting-point for
>>>> firewalled peer pairs (which in my experience is a lot of them)
>>>> [12:09] <alown> Precisely the problem, because we don't really want
>>>>long
>>>> waits or trackers.
>>>> *...4) Routing **p2p **messages/events in a pure P2P system (part 3):*
>>>> [12:42] <stenyak> hmmm... i'm not sure how a peer gets a list of waves
>>>>in
>>>> which he's a participant of
>>>> [12:43] <alown> Having a canonical source makes it all so much easier.
>>>>:P
>>>> [12:44] <stenyak> for pure p2p peers to "receive" new waves, either the
>>>> FROM or the TO peer (or both) would need to try to find their way to
>>>>the
>>>> other
>>>> [12:44] <stenyak> and we're assumign here that each person only runs
>>>>one
>>>> peer
>>>> [12:45] <stenyak> e.g. my privatekey may be used by 5 wave peers at the
>>>> same time, and we must make sure the new wave reaches all of them
>>>> [12:46] <alown> Looks like we may need to have mulitple DHTs then (one
>>>>for
>>>> ops, one for waves)
>>>> [12:46] <stenyak> in BT, it's the receiver end who actively looks for
>>>>peers
>>>> to receive from. in wave, it's not like that..
>>>> [12:46] <alown> Or could we have a pubkey->wave mapping in one?
>>>> [12:46] <stenyak> and in BT, you can assume *many* people has the data
>>>>you
>>>> want
>>>> [12:46] <stenyak> in wave, its possible and probably that only one
>>>>other
>>>> peer in the universe has the wave
>>>> [12:46] <stenyak> (because it's a personal wave sent to you)
>>>> [12:47] <alown> I would expect any long-running supernodes to be
>>>>implicitly
>>>> part of all waves they know about.
>>>> [12:47] <alown> Though on second thought, this seems like it would add
>>>>its
>>>> own problems to authentication, storage, promotion of supernodes etc.
>>>> *...4) Routing **p2p **messages/events in a pure P2P system (part 4):*
>>>> [12:51] <alown> Does it make sense for a peer to have your privkey,
>>>>since
>>>> you could be logged in anywhere, so it would be down to the place you
>>>>are
>>>> logged in, to 'subscribe' to that wave on the network, and attempt to
>>>> retrieve all data from it...
>>>> [12:55] <alown> I was expecting the network as a whole to act like a
>>>> WaveBus pubsub system, whereby once 'logged in' at some server (which
>>>>means
>>>> it gets your privkey from the authentication system), that server then
>>>> 'subscribes' to your waves on the 'network'. If somebody else at some
>>>>other
>>>> server changes it, then that server would be announcing to the network
>>>>of a
>>>> change (doesn't necesserily have to be a broadcast), which your server
>>>> would 'hear'.
>>>> [12:56] <alown> You could do this from any server where you logged in
>>>> (hence the concept of a domain is lost).
>>>> [12:57] <stenyak> by "server" you mean supernodes?
>>>> [12:57] <alown> Not necessarily.
>>>> [12:59] <stenyak> this pubsub network must be aware of nodes that are
>>>>in
>>>> it, in order to directly route wave updates to them, correct?
>>>> [12:59] <stenyak> and also, this network wouldn't be very volatile, but
>>>> would rather ideally be long-lived peers?
>>>> [13:00] <alown> It has no reason to have to directly route updates,
>>>>(though
>>>> it would hopefully be able to identify the best routes automatically).
>>>> [13:00] <alown> Yes it would require a few long-lived peers (which
>>>>would be
>>>> part of the requirement to be a supernode).
>>>> [13:01] <stenyak> so let's say i connect my laptop wave peer to the
>>>> "server" in the living room, at my firewalled home. this "server"
>>>>would be
>>>> already subscribed to the pubsub network, and in this specific case it
>>>> would route all wave updates to me
>>>> [13:02] <stenyak> in other cases (let's say, ipv6-enabled nodes
>>>>everywhere,
>>>> no firewall at home), the living room server could simply notify the
>>>> original "FROM" peer to send stuff to my laptop ipv6 ip, right?
>>>> [13:03] <alown> That sounds right. Supernodes are really only needed
>>>>for
>>>> getting the routing right.
>>>> [13:05] <stenyak> ok. in both these theoretical cases, the "server"
>>>>hasn't
>>>> necessarily been a wave node per se (nor a supernode either), but
>>>>rather a
>>>> second type of wave node that helps get stuff quickly wherever it's
>>>>needed
>>>> [13:05] <alown> Yes.
>>>> [13:05] <alown> I am not even sure where OT should be happening in this
>>>> picture...
>>>> [13:05] <stenyak> if OT happens, the "server" is a blind proxy i think
>>>> [13:06] <stenyak> so does not need the privkey to work
>>>> [13:07] <stenyak> unless we're also using OT in the wavebus pubusb
>>>>network
>>>> for some reason?
>>>> [13:07] <alown> Supernodes can be blind (though they might also just be
>>>> normal well-connected wave servers). I would expect normal servers to
>>>>still
>>>> be doing OT. The question is whether the 'client' (whatever that means)
>>>> should be doing it also.
>>>> [13:08] <alown> The network shouldn't need OT. (Algorithms exist that
>>>>allow
>>>> the incoming ops to be arbitarily queued and only processed when
>>>>needed).
>>>> [...]
>>>> [21:21] <josephg> alown: the client always needs to do OT because
>>>>otherwise
>>>> they can't both edit a document live and receive operations from
>>>>people who
>>>> didn't have their ops.
>>>> [21:22] <josephg> the server doesn't need to do OT, although if it
>>>>doesn't
>>>> do OT, it'll punt the OT work to its clients - which will result in a
>>>> higher CPU utilization on mobile devices.
>>>> [...]
>>>> [13:08] <stenyak> i pictured this "server" as being an optional item
>>>>that
>>>> shortcuts the long waits of DHT, rather than something necessary for
>>>> "clients"?
>>>> [13:08] <alown> Hmm.
>>>> [13:08] <alown> I suppose we should define what a 'client' is then...
>>>> [13:09] <alown> We have at least 2 layers of stuff going on here: 1)
>>>>Wave
>>>> OT/operation layer 2) Network routing/P2P layer
>>>> [13:13] <alown> But it is quite plausible something might be doing
>>>>both of
>>>> those
>>>> [13:10] <stenyak> with your pubsub net suggestion, i was picturing 2
>>>>kinds:
>>>> a regular pure p2p peer, and a helper kind of node to route stuff
>>>>quickly
>>>> when a peer is connected to it
>>>> [13:13] <stenyak> so with that picture in mind, layer 1 stuff could go
>>>> directly from peer to peer (if connectivity/firewalls allows), or
>>>>through
>>>> the "helper node" if available
>>>> [...]
>>>> [13:20] <stenyak> [...] all this discussion looks very similar to
>>>> discussing how to design internet+dns, i think the problems are the
>>>>same
>>>> really
>>>> [13:20] <stenyak> or at least we could take some inspiration from it
>>>>maybe
>>>> [13:20] <alown> This was my conclusion last night with josephg. ('The
>>>> problmes should already be solved (see The Internet)')
>>>> [14:09] <stenyak> and The Internets solved the problem how? By having a
>>>> large set of supernodes (dns servers), that may take a whole day to
>>>> propagate updates. The alternative being having the actual IP address
>>>>in
>>>> the first place, or to centralize stuff
>>>> [14:10] <stenyak> (aka use servers everywhere)
>>>> [14:22] <alown> Maybe, but the internet's design is X (where X > 20)
>>>>years
>>>> old, so may not represent the most modern thinking of how to make
>>>> distributed networks.
>>>> [14:59] <alown> (Don't forget that our aim for Wave is at the
>>>>cutting-edge
>>>> of academic research also).
>>>> [...]
>>>> [14:50] <stenyak> i just threw the question at some friends who should
>>>>be
>>>> more up-to-date with networking technologies than me... hopefully they
>>>> comeback with some revolutionary dns-2 design or something that we can
>>>>copy
>>>> [15:18] <stenyak> could give as some ideas: http://openpeer.org/
>>>> [15:18] <stenyak> (it's not a solution, but maybe they did the same
>>>> reasoning we're going through)
>>>> [15:46] <stenyak> another response i got goes along the lines of...
>>>>hard as
>>>> fuck, but if you manage to do it, you are a hero
>>>> [...]
>>>> [15:02] <stenyak> looking at it from a wider perspective, what we want
>>>>is
>>>> similar to having each peer shout at the whole world "here i am,
>>>>anything
>>>> got something for meeee?" in some way that doesn't clog the internet
>>>>tubes,
>>>> and that is so fast as shouting would be. i start to think it's not
>>>> physically possible to do that...
>>>> [15:03] <stenyak> if publickeys were handed to people based on the
>>>> location, then we could have routing tables similar to how internet
>>>> currently works
>>>> [15:03] <stenyak> but pubkeys are... well, random. so that kind of
>>>>routing
>>>> that allows anyone to connect to an arbitrary IP in a matter of
>>>> milliseconds is impossible, i believe
>>>> [15:04] <alown> So, we end up with DNS for public keys?
>>>> [15:04] <stenyak> something like dns, but much faster [wrt. propagation
>>>> times]
>>>> [15:05] <stenyak> so in essence, a tree of servers or whatever (which
>>>>is
>>>> similar to how wave currently works, right?)
>>>> [15:05] <alown> Heh. But the whole point was to avoid the tree system
>>>> currently (since it is susceptible to netsplits)
>>>> [...]
>>>> [15:56] <stenyak> maybe the real question could be: how do we make DHT
>>>>much
>>>> faster?
>>>> [16:14] <stenyak> once the initial discovery process is finished, the
>>>> transmission of data will not have the lag associated with DHT, so
>>>>even if
>>>> DHT takes 10 seconds, that could be acceptable
>>>> [16:15] <stenyak> i.e. a new peer takes 10 seconds to be discovered by
>>>>the
>>>> rest of participants collaborating in a wave
>>>> [16:16] <stenyak> (or viceversa.. the new peer takes 10 seconds to
>>>>discover
>>>> the participants)
>>>> [...]
>>>> [16:25] <stenyak> this could shed some light:
>>>>
>>>>
>>>>http://en.wikipedia.org/wiki/Distributed_hash_table#Algorithms_for_overl
>>>>ay_networks
>>>> [19:06] <stenyak> http://dsn.tm.kit.edu/english/2936.php
>>>> *...4) Routing **p2p **messages/events in a pure P2P system (part 5):*
>>>> [21:03] <josephg> [...] For now, I want wave to be p2p in the same way
>>>>that
>>>> git is p2p.
>>>> [21:04] <josephg> that is, I want the core algorithms & data
>>>>structures to
>>>> use P2P-capable algorithms, and probably the wave servers will do p2p
>>>> between themselves (this is easy because they'll all be both named and
>>>> accessable)
>>>> [21:06] <josephg> as for client-to-client p2p, there's a few options
>>>> depending on what kind of use cases we want to support - but I want to
>>>> worry about getting the algorithms p2p-capable first. If you're keen
>>>>to set
>>>> up an anonymous, distributed wave system over a DHT - well, I want to
>>>>first
>>>> make that possible
>>>> [21:15] <josephg> .... and as for ipv6, network admins _love_ NAT now
>>>>that
>>>> we have it
>>>>
>>>>
>>>> *5) Implementing "undo": invertibility, tombstones, edge cases, TP2:*
>>>> [00:17] <alown> I am not sure how an 'undo stack' is going to work (at
>>>>all)
>>>> with federation...
>>>> [00:18] <josephg> well, you just do undo at the application level
>>>> [00:19] <josephg> "submit op which inserts text" ... later "submit op
>>>>which
>>>> removes text"
>>>> [00:19] <josephg> you don't need OT for that.
>>>> [00:20] <josephg> I imagine like, a semantic undo. In the client you
>>>>can
>>>> imagine making an undo op (which might not necessarily rollback an
>>>> operation (because of tombstones and all that))
>>>> [00:20] <josephg> ... but would seem that way as far as the user is
>>>> concerned
>>>> [00:21] <josephg> then if the user hits ctrl+z, you can transform that
>>>> operation up to the current version and apply it
>>>> [00:21] <josephg> - the fact that its an undo isn't really relevant.
>>>> [00:21] <josephg> the bad thing about losing invertability is doing
>>>> playback
>>>> [00:21] <josephg> - because you can't scrub back through time
>>>> [00:21] <alown> But you have all the operations since the start, so
>>>>you can
>>>> play forward at least?
>>>> [00:23] <josephg> yeah exactly.
>>>> [00:23] <josephg> ... and make like, keyframes of the document
>>>> [00:23] <josephg> - and play forward from them or something.
>>>> [00:23] <alown> Hmm, so you can do the step-back without recalculating
>>>>the
>>>> entire document?
>>>> [00:24] <alown> I don't really like the idea of then having another
>>>> datastructure to have to pass around...
>>>> [00:24] <josephg> right - if you have a snapshot at version 1000, and
>>>>the
>>>> user is looking at 1010 and they try to step back to 1009, you can just
>>>> replay ops 1001-1009 on that version 1000 snapshot
>>>> [00:24] <alown> What was the problem with invertible operations (I
>>>>don't
>>>> understand OT enough yet to be able to properly comment on that side).
>>>> [00:25] <alown> (Other than it confuses people?)
>>>> [00:25] <josephg> hahaha actually people seem to love invertability
>>>> [00:25] <josephg> I don't know why.
>>>> [00:25] <josephg> I've been trying to remove it from sharejs, and
>>>>everyone
>>>> gets sad.
>>>> [00:26] <josephg> the problem is that if I make an op which deletes the
>>>> whole document (version 100, say) then I undo that operation
>>>> [00:26] <josephg> and you insert in the middle of the document at
>>>>version
>>>> 100, then your op gets transformed to do that insert at the start of
>>>>the
>>>> document instead at version 101 (because the content has disappeared)
>>>> [00:26] <josephg> and it never goes back to the middle of the document.
>>>> [00:27] <josephg> so, with tombstones you can get around that by
>>>>having a
>>>> 'resurrect' operation
>>>> [00:27] <josephg> (so deleting the whole document turns the whole
>>>>document
>>>> into tombstones, then we can resurrect them all again in the inverse)
>>>> [00:28] <josephg> but you can't invert an insert - because deleting
>>>>leaves
>>>> the tombstone there
>>>> [00:28] <josephg> and if you have a 'real delete' operation, then yeah,
>>>> you're back in the hole
>>>> [00:28] <josephg> also, with wave in particular, inverting is really
>>>> complicated
>>>> [00:29] <josephg> - see, if the wave says "<annotation bold:true>blah
>>>> blah<annotation bold:false> not bolded"
>>>> [00:29] <josephg> then if you insert at the end of the "blah blah",
>>>>it'll
>>>> automatically get bolded.
>>>> [00:30] <josephg> ... so if the text isn't bolded, and then you bold it
>>>> while I insert at the end of the text, you need to make sure my text
>>>> _isn't_ bolded or something
>>>> [00:31] <josephg> .... and yeah, I can't remember - but there's these
>>>> horror cases that I remember kept me from sleeping when I tried to
>>>> reimplement wave's OT code in C
>>>> [00:31] <alown> hmm
>>>> [00:31] <josephg> and it would have been fine if it wasn't invertible.
>>>> Well, at least it would have been tollerable.
>>>> [00:33] <josephg> So yeah. Conclusion: You can make invertability
>>>>work, but
>>>> its kind of a bitch, and you can't make it work for TP2
>>>> [00:33] <josephg> which means it won't work if we're federating
>>>> [00:33] <alown> How are we hacking around that currently then?
>>>> [00:33] <josephg> well, we don't do TP2
>>>> [00:34] <josephg> remember, federation just uses a bad version of the
>>>> current client-server protocol
>>>> [00:34] <josephg> - arranged in a tree of servers
>>>> [00:34] * alown goes and looks up which one TP2 was again
>>>> [00:35] <josephg> ... its the one that says you don't need a canonical
>>>> ordering of operations
>>>> [00:35] <josephg> sharejs and wave both use the server to pick the
>>>>order of
>>>> operations (based on which order they reach the server)
>>>> [00:35] <josephg> and then they use incrementing version numbers based
>>>>on
>>>> that order
>>>> [00:35] <alown> ah yep.
>>>> [00:35] <josephg> -> for p2p, that doesn't work because you don't have
>>>>a
>>>> centralized server, and anyone can send messages to anyone
>>>> [00:36] <josephg> and yeah, you need TP2 for that (which sort of says
>>>>you
>>>> can apply ops from 3 different sites in any order and it still works)
>>>> [00:37] <josephg> - and apparently someone proved that if you make it
>>>>work
>>>> for 3 sites, it works for any number of sites
>>>> [00:43] <alown> Anyhow, I can see leaving inversion out for
>>>>simplicity, but
>>>> don't yet understand why it can't be made to work with TP2.
>>>> [00:59] <alown> Hmm. Seen 'A Sequence Transformation Algorithm for
>>>> Supporting Cooperative work on Mobile Devices'?
>>>> [01:02] <josephg>
>>>>
>>>>
>>>>http://research.microsoft.com/en-us/um/redmond/groups/connect/cscw_10/do
>>>>cs/p159.pdf
>>>> ?
>>>> [01:15] <alown> The main feature is its use of storing local/remote
>>>> operations and processing them much later than receipt time.
>>>> [01:17] <alown> ABT satisfies TP1+2, so looks like this should(?)
>>>> [01:19] <josephg> need to read it
>>>> [01:19] <josephg> ... I'll go through it later
>>>>
>>>>
>>>> *6) Usability of a pure p2p system in Real Life (tm):*
>>>> [12:13] <alown> We also don't know if storing ops in a DHT is efficent
>>>> enough for our use case...
>>>> [12:14] <stenyak> in any case, let's say i fire up my wavep2p android
>>>> client and want to check for any new waves
>>>> [12:14] <stenyak> i definitely won't put up with a wait of 30 seconds
>>>>when
>>>> i have "this damn fast 4g connection!" in my cellphone
>>>> [12:14] <stenyak> i mean, that's the point of view of six pack joe
>>>> [12:14] <stenyak> and joe is definitely right..
>>>> [12:15] * alown thinks of the hours it took to download the bitcoin
>>>> blockchain from the p2p system
>>>> [12:15] <stenyak> or browse through freenet, or whatever... its painly
>>>>slow
>>>> [12:16] <stenyak> in the end, i think that most users won't be running
>>>>a
>>>> full blown peer, but will be relying on an external server instead
>>>> [12:16] <stenyak> i.e. nobody runs their own email servers nowadays
>>>> [12:16] <stenyak> and the same can happen with wave
>>>> [12:16] <alown> Should a mobile client be doing the full p2p
>>>>federation, or
>>>> simply talking to a server which does it...
>>>> [12:16] <stenyak> the few who decide to run a full-blown wave peer,
>>>>should
>>>> be aware of the problems
>>>> [12:17] <alown> So, this should be less of a problem since the only
>>>>nodes
>>>> doing p2p will be proper full-time connected servers?
>>>> [12:17] <stenyak> the thing is, we can assume most people wont fire up
>>>> their own xmpp server, but go for jabber.org account
>>>> [12:17] <stenyak> and the same thing will presumably happen for wave,
>>>> simply because it's easier to do
>>>> [12:18] <stenyak> which doesn't pervent me from running my own
>>>>full-blown
>>>> wave server
>>>> [12:18] <stenyak> but that's a use case in which the user knows the
>>>> limitations
>>>> [12:19] <stenyak> [...] you and i will run several full-blown wave
>>>>peers at
>>>> home, at our parent's house, or whatever, but we'll know and accept the
>>>> problems
>>>> [12:19] <stenyak> i think that's the way to think about the problem
>>>> [12:19] <stenyak> heck, most people use github for permanent [git]
>>>> connectivity ;-)
>>>> [12:19] <stenyak> instead of opening ports to their laptop in their lan
>>>> [12:19] <stenyak> and those are the tech-savvy people...
>>>> [12:20] <alown> So, we have a p2p system between wave servers and
>>>>superwave
>>>> servers, with clients connecting to the server rather than doing the
>>>>p2p
>>>> itself...
>>>> [12:20] <stenyak> i'm not saying it's the way we should do it. i'm
>>>>saying
>>>> that's the way it most probably will pan out, because it's already
>>>> hapennign in 100% of the existing p2p protocols i know of
>>>> [12:20] <alown> Hmm...
>>>> [12:21] <stenyak> so we should plan for that instead of a theoretical
>>>>pure
>>>> p2p world
>>>> [12:21] <stenyak> if we assume there's servers like github, bitbucket
>>>>and
>>>> sourceforge, then suddently most of the problems go away, while still
>>>>not
>>>> preventing from people to run fully p2p if they want
>>>>
>>>>
>>>> *7) Comparison with BitTorrent and P2P-TV technologies:*
>>>> [12:21] <alown> BT doesn't have huge servers (and with magnet has
>>>>actually
>>>> move in the opposite direction).
>>>> [12:21] <stenyak> BT has no real-time needs
>>>> [12:22] <stenyak> that's why they can afford DHT
>>>> [12:22] <stenyak> dht could be used for simulating a forum-like
>>>>discussion
>>>> in wave. but we can't force that restriction from the server
>>>> [12:22] <stenyak> (i say forum-like, because people don't expect
>>>>reaction
>>>> within seconds there)
>>>> [12:23] <alown> How did iplayer do its live p2p broadcastinºg?
>>>> [12:23] * stenyak googles what iplayer is
>>>> [12:23] <alown> Sorry, BBC iPlayer is their TV-over-the-internet
>>>>system.
>>>> [12:24] <alown> Originally it used a p2p system, but got lots of
>>>>negative
>>>> press (because of assosciation with BT since it used p2p), so it now
>>>>uses a
>>>> centralized system instead. (And their bandwidth costs are much
>>>>higher).
>>>> [...]
>>>> [12:25] <stenyak> i seem to recall other [p2p] tv clients
>>>> [12:25] <stenyak>
>>>>
>>>>
>>>>http://wiki.xbmc.org/index.php?title=HOW-TO:Play_free_P2P_(peer-to-peer)
>>>>_online_streaming_TV
>>>> [...]
>>>> [12:26] <alown> Found a paper titled "RT-P2P: A Scalable Real-Time
>>>> Peer-to-Peer System with Probabilistic Timing Assurances" (google for
>>>>it)
>>>> [12:28] <alown> Lookt at the paper I mentioned. It relies on 'super
>>>>nodes'
>>>> to enable it to keep low latencies...
>>>> [...]
>>>> [12:27] <stenyak> but i'd be wary of using this (p2p tv) as an
>>>>inspiration.
>>>> i know there's delay of 10-30 seconds from my TV Formula1 image to the
>>>> telemetry that comes through HTTP from formula1.com website. this is
>>>> regular TV, and they don't care about 30 seconds of lag
>>>> [12:27] <stenyak> the only real problem of p2p tv is avoiding much
>>>>jitter
>>>> [12:27] <stenyak> as long as the stream arrives and is viewable, a
>>>>delay of
>>>> a minute doesn't matter that much
>>>> [12:28] <alown> True.
>>>>
>>>>
>>>> *8) Identifying participants (part 1):*
>>>> [12:09] <alown> I am also no longer sure what an 'account' should look
>>>> like, since it has no reason to be stuck to a domain...
>>>> [12:10] <stenyak> current wave discovery works by using the domain
>>>>name of
>>>> the email-address-like list of participants
>>>> [12:10] <stenyak> but here we're talking about hashes, public keys or
>>>> whatever
>>>> [12:10] <stenyak> which do not (necessarily) point to an particular
>>>>IP:PORT
>>>> or whatever
>>>> [12:10] <alown> Exactly the problem...
>>>> *...8) Identifying participants (part 2):*
>>>> [12:33] <stenyak> would it make sense that, while some participants are
>>>> identified by a pubkey (or whatever), many of them could be identified
>>>>by a
>>>> user@domain address, with which any peer can quickly locate supernodes?
>>>> [12:33] <stenyak> i mean some kind of dual "pubkey and optional domain
>>>> email-like addr" for the participants list
>>>> [12:34] <stenyak> the optional part being essential in the broader
>>>>internet
>>>> [12:34] <alown> Isn't that exactly what using Mozilla Persona would do
>>>>(map
>>>> user@domain to some public-key we can use)
>>>> [12:34] <alown> Removing the need for us to have to roll yet-another
>>>> authentication system.
>>>> [...]
>>>> [12:38] <stenyak> the idea would be that, for a person to be a
>>>>participant
>>>> in a wave, you *require* his pubkey. optionally, you may have acquired
>>>>ths
>>>> pubkey by asking "wave.google.com" about the user "joe", getting his
>>>> pubkey
>>>> as a result.
>>>> [12:39] <stenyak> and now that you have the pubkey and one of many
>>>>possible
>>>> email-like addresses (in this case j...@wave.google.com), then you can
>>>>use
>>>> the email-like address for displaying in the UI
>>>> [12:39] <stenyak> this means that, whoever wants to run pure p2p peers,
>>>> will have to give his pubkey
>>>> [12:39] <stenyak> and whoever uses the more traditional style, can
>>>>simply
>>>> give his email-like addr
>>>> [12:39] <stenyak> and the participants list will show a simple
>>>>email-like
>>>> address most of the time
>>>> [12:40] <alown> Do we then allow anyone to 'log in' to any wave server
>>>> running at any domain, since it should no-longer make any difference
>>>>where
>>>> they are in the network...
>>>> [12:41] <stenyak> yes, that's needed for world-wide-public waves,
>>>>which is
>>>> equivalent to a read-only forum on the net
>>>> [12:41] <stenyak> then there could be server-public waves, which is
>>>> equivalent to requiring sign-in to view a forum (and coincidentally the
>>>> current implementation of public waves in WiaB, right?)
>>>> [12:43] * alown has never tested what happens with public waves in the
>>>> current federation system
>>>> *...8) Identifying participants (part 3):
>>>> *
>>>> [21:35] <josephg> - Who is a user? If a user is sten...@example.com,
>>>>then
>>>> we can put a server at example.com and it can hold operations for you
>>>> [21:36] <josephg> ie, if I add you to a wave, my computer (or my wave
>>>> server or something) can send a message to example.com to say "Yo,
>>>>here's
>>>> some ops you should know about"
>>>> [21:36] <josephg> that would be similar to a mailbox
>>>> [21:37] <josephg> ... and it would work pretty well. Bear in mind that
>>>> there's no reason operations have to go through the wave server at
>>>> example.com - if we're both on a LAN together, we could discover one
>>>> another through DNS service discovery and send ops directly
>>>> [21:37] <josephg> .. without going through our respective wave servers
>>>> [21:38] <josephg> However - if our identities aren't tied to a domain
>>>>(eg
>>>> bitcoin), then we'll need to use a dht or something.
>>>> [21:42] <stenyak> the conclussion i've arrived at is that "users"
>>>> ultimately are a publickey (for which they have the privatekey). this
>>>>is
>>>> inconvenient for people to "add you to a wave", so a possibility would
>>>>be
>>>> to have a friendlyname=>pubkey server converter. this way people can
>>>>add "
>>>> sten...@example.com", by first finding out what the pubkey for
>>>> sten...@example.com really is
>>>> [21:43] <stenyak> the friendlyname would be optional, and in LAN
>>>> environments you could directly use the pubkey (instead of the friendly
>>>> name)
>>>> [21:43] <josephg> I think people will be more than happy to use a
>>>>frienly
>>>> name in a lan environment too
>>>> [21:43] <stenyak> discovery in a local network could be done with
>>>>bonjour
>>>> or something too (not just dns)
>>>> [21:44] <josephg> I <3 dns-sd
>>>> [21:44] <stenyak> [...] maybe they already have a contact list (read,
>>>>list
>>>> of friendlyname<>pubkey equivalences) they can use in the UI (even if
>>>>the
>>>> underlying system will use pubkeys anyway)
>>>> [21:44] <stenyak> and by contact list, i really mean a cache of some
>>>>sort
>>>> [21:45] <stenyak> (not some specific, complex roster system)
>>>> [21:45] <josephg> and you can do friendlyname -> pubkey really easily
>>>>by
>>>> just storing the pubkey on the user's domain
>>>> [21:45] <josephg> so, have the example.com webserver host
>>>> https://example.com/.wellknown/stenyak
>>>> [21:46] <josephg> = your public key.
>>>>
>>>>
>>>> *9) P2P anonymity (peers that want to anonymously lurk in a wave) (part
>>>> 1):*
>>>> [12:48] <stenyak> by the way, what about non-participants that simply
>>>>want
>>>> to lurk a wave?
>>>> [12:49] <stenyak> e.g. i'm given a wave uri
>>>> (wave://look_at_these_kittens_wave), and want to view it
>>>> [12:49] <alown> Whilst a wave is public, as soon as they 'read' the
>>>>wave,
>>>> they would have a metadata wavelet created, so would become a
>>>>participant
>>>> (if read-only).
>>>> [12:50] <stenyak> and from then on, whenever the wave changes, someone
>>>>will
>>>> try to make the change reach the peers with my privkey
>>>> [12:50] <stenyak> supposedly..
>>>> *...9) P2P anonymity (peers that want to anonymously lurk in a wave)
>>>>(part
>>>> 2):*
>>>> [21:18] <josephg> stenyak: interesting point about people who want to
>>>>not
>>>> participate but follow a wave anyway - its really bad if other people
>>>>can
>>>> tell that they're there (assuming the wave is public).
>>>> [21:18] <josephg> I guess we just need to make sure that the metadata
>>>>wave
>>>> is invisible, and then its ok..
>>>> [21:21] <stenyak> invisible.. to what peer/s? surely those that are
>>>> transmitting deltas to the lurkers will need to know they exist?
>>>> [21:21] <stenyak> (maybe some of the algorithms behind freenet can help
>>>> with this)
>>>> [21:21] <stenyak> (or even TOR)
>>>>
>>>>
>>>> *10) Encryption of waves:*
>>>> [21:47] <josephg> for waves themselves, I'm imagining giving each wave
>>>>an
>>>> AES key
>>>> [21:47] <josephg> then storing an encrypted version of the key for each
>>>> participant on the wave
>>>> [21:48] <josephg> .... anyway, that way anyone who has the AES key can
>>>>read
>>>> all ops on the wave
>>>> [21:48] <josephg> and can participate (because they can encrypt ops
>>>>for the
>>>> wave)
>>>>
>>>>
>>>> *11) Addition and removal of participants, and their ability to read
>>>>past
>>>> and future wave versions/deltas:*
>>>> [21:48] <stenyak> what about removing a user from a wave?
>>>> [21:49] <josephg> worst case, we can just make a new key and re-add
>>>> everyone using the new key
>>>> [21:49] <josephg> and keep around the old key too
>>>> [21:49] <josephg> so people can still read the old ops as well
>>>> [21:49] <stenyak> the user can access their browser cache for all we
>>>>care..
>>>> if you ever read it, there will be ways to do it. "download now
>>>>wave-spy to
>>>> read waves you were removed from!"
>>>> [21:49] <stenyak> so providing an official way sounds better
>>>> [21:50] <stenyak> the AES key could change at any point in time, e.g.
>>>> whenever a new users is added (to prevent them accessing the history),
>>>>or
>>>> deleting them (to prevent them from reading future history)
>>>> [22:32] <josephg> um - in wave, we let new users see the whole history
>>>> [22:40] <stenyak> but that use case could be desirable, right? and if
>>>>we
>>>> support modification/versioning of the AES key, we might as well allow
>>>>that
>>>> too? the equivalent in email world would be to forward an email,
>>>>removing
>>>> the existing quotes
>>>> [23:17] <josephg> Yep definitely.
>>>>
>>>>
>>>> --
>>>> Saludos,
>>>> Bruno González
>>>>
>>>> _______________________________________________
>>>> Jabber: stenyak AT gmail.com
>>>> http://www.stenyak.com
>>>>
>>
>
>
