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Re: Interplatform (interprocess, interlanguage) communication

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On 2/12/2012 7:27 AM, Arne Vajhøj wrote:
> On 2/12/2012 1:03 AM, BGB wrote:
>> On 2/11/2012 1:18 PM, Arne Vajhøj wrote:
>>> On 2/11/2012 3:06 PM, Lew wrote:
>>>> XML is just fine for just about every purpose to which it's put.
>>>> That's why it's popular now. People who cavil about "bandwidth" and
>>>> "10 Hz network messages" are tossing us red-herring sashimi. You
>>>> aren't going to get 10+ Hz message exchanges over the WAN. For
>>>> realistic message rates, XML suits beautifully. I speak from
>>>> experience with many, many projects that used every conceivable
>>>> message format from binary to CSV to custom to XML to protocol buffers
>>>> to JSON, and XML has distinct advantages. Its purported disadvantages
>>>> of bulk and bandwidth turn out to be non-issues in practice. Really.
>>>> That's real.
>>>
>>> ????
>>>
>>> The industry standard for smartphone apps and AJAX web apps
>>> are JSON because the bandwidth actually matters.
>>
>> yeah.
>
> But please note that you do not invent your own JSON parser
> either - you use something already done. In Java there are json.org,
> gson etc..
>

in Java, yes, one may use the libraries.

on the C end, one may choose to throw one together, or use a JavaScript 
VM if one is available, ...

it all depends.


>> and, in fact 10Hz asynchronous throughput is possible... (this is
>> typically how most online gaming works).
>>
>> one can't reasonably get 10Hz synchronous (IOW: request/response), due
>> to ping times, but this is a different matter.
>>
>> I am not claiming one can do request/response at 10Hz, as this probably
>> would be impossible over a WAN (at reasonable ping times).
>>
>> online gaming generally isn't based on request/response though, so the
>> problems of not being able to get responses at this rate don't really
>> matter too much (the user may still notice the results of bad ping
>> times, namely stuff being out of place or seemingly teleporting around
>> or similar, but this is a different issue).
>>
>> TCP has a throughput limit due to ping, where assuming unlimited
>> bandwidth but a 200ms ping, one will still be limited to somewhere
>> around 320kB/s or so (assuming a 64kB window).
>>
>> however, as is, there are typically bandwidth constraints as well (but,
>> they are a little more subject to fudging).
>>
>> the main goal is mostly to send everything at a bandwidth low enough
>> that the connection doesn't risk getting backlogged (depends on internet
>> connection, but 16-32 kB/s seems reasonably safe, as internet radio
>> often tends to operate in this range, say, 192kbps is 24kB/s).
>>
>> stalls are also a potential risk as well.
>
> I can not follow you way of thinking. With multiple interactions
> in parallel there are no strict correlation between latency and
> throughput.
>

there is a rough correlation though.


for the part about TCP, this was related to how TCP worked (in its 
traditional form), namely the existence of a 64kB maximum window size.

apparently, this is out of date, as there is a feature known as 
RFC-1323, which is enabled by default on Windows Vista and newer, which 
allows a larger TCP window.

http://tools.ietf.org/html/rfc1323


for the part about moderating kB/s, this has a lot more to do with a 
users' internet connection.

say, hypothetically, a user has dial-up.

now, what if the data being sent does not fit over dial-up (one is 
trying to send 10kB/s, but a 56k modem can only handle ~6.5kB/s or so)? 
well, then, the connection will backlog (the connection will send at the 
rate it can send, and anything else will have to wait).

similar limits may exist over the internet, but in a less direct form:
consider, the internet is prone to occasionally drop a packet here or there.

so, stream is going over the internet, and a (single) packet drops, what 
happens:
well, all the data up to the dropped packet reaches the other end, the 
other end may send a packet back indicating the point recieved;
the sender will start resending data from that point;
the reciever will start transmitting again.

this results in essentially a ping-time delay in which no data can be sent.

if the sender is sending messages at a fixed rate, what happens?
well then, the messages will pile up, waiting to be sent;
after transmission resumes, several updates worth of data need to be sent;
if all of the updates fit within the bandwidth of the connection 
(end-to-end), then there is may be no obvious stall (updates can all be 
sent at full speed);
if the enough data back-logs so as to exceed the bandwidth available, 
then it has to wait to be sent, and if the sender just keeps naively 
sending updates, then essentially one gets a stall (and the data being 
received by the receiver will start becoming progressively more 
out-of-date).


these properties can be observed with things like internet radio and 
video streaming (if the connection is fast enough, playback happens in 
real-time without obvious stalls or re-buffering, even though the rate 
at which the data comes over the internet is often very irregular).

similar also applies to internet telephony as well.


if one tries to operate within a fixed-bandwidth window, similar to 
internet radio, most minor stalls can be glossed over (this limit being 
a bit lower than the end-to-end transfer rate of the connection). going 
lower is better, since the lower one goes, the more room there for error 
there is.

the main issue is, namely, that the data being sent has to be able to 
fit within these bandwidth limits (hence, why data compression is highly 
desirable in this case).


an online game basically amounts to a bidirectional stream between the 
client and server, with the server sending out a stream of updates 
(typically, everything going on in the immediate view of the client), 
and the client sends a stream of their attempted actions (in response to 
what they see on screen).

if everything is working well, then the delays and irregularities of 
their internet connection is mostly hidden, and to them it all seems 
like they are interacting with the world in real-time (usually there is 
a lot of trickery here as well, mostly based around linear extrapolation 
and so on).

side note: each end may transmit time-stamps as part of their updates, 
and the other end may transmit the last-received timestamps, partly so 
that the timing delays can be estimated and partially compensated for.


another (similar concept) for players playing games is the concept of 
"leading", where a person will take aim at a moving enemy, estimate the 
speed of the projectile and where the enemy will be at the time, and aim 
and fire at that location instead (then the enemy will essentially "run 
into" the traveling projectile). note that if a player always aims at 
where the enemy is "right now", very often they will miss (as by the 
time the projectile reaches the destination, the enemy has already moved 
out of the way).

so, the game does similar in an attempt to hide the "travel time" that 
is the internet.


or such...

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Re: Interplatform (interprocess, interlanguage) communication jebblue <n@n.nnn> - 2012-02-07 12:11 -0600
  Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-07 16:38 -0700
    Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-07 20:26 -0400
      Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 01:41 -0700
        Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-08 07:19 -0400
          Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 12:07 -0700
            Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-08 21:16 -0500
              Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 19:50 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-09 06:24 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 09:15 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-09 18:58 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 16:15 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:50 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 21:40 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:47 -0500
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 12:06 -0800
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 15:18 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 23:03 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:27 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 13:33 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 15:50 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 14:34 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:48 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 21:46 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 08:51 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 10:43 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 13:15 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 14:50 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-10 14:32 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 17:10 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-10 22:08 -0400
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 00:49 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-02-11 14:04 -0400
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:55 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:52 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 20:06 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 22:41 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 00:46 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:29 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:31 -0500
                Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-12 16:02 +0000
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 11:16 -0500
                Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-12 22:46 +0000
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 11:33 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 20:18 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 01:36 -0700
                Re: Interplatform (interprocess, interlanguage) communication Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-02-12 13:52 -0600
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 14:43 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:49 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:46 -0500
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:45 -0500
        Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-08 14:02 -0800
          Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 18:49 -0700
            Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-08 21:14 -0500
              Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-08 20:07 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 23:29 -0700
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-09 09:40 -0800
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-09 17:02 -0700
              Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 21:10 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-09 18:54 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-10 10:25 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 14:45 -0500
                Re: Interplatform (interprocess, interlanguage) communication Lew <lewbloch@gmail.com> - 2012-02-11 12:14 -0800
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-11 15:20 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-11 22:20 -0700
                Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-12 09:23 -0500
                Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-12 12:13 -0700
    Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-07 20:24 -0500
    Re: Interplatform (interprocess, interlanguage) communication Martin Gregorie <martin@address-in-sig.invalid> - 2012-02-08 01:31 +0000
      Re: Interplatform (interprocess, interlanguage) communication BGB <cr88192@hotmail.com> - 2012-02-08 00:55 -0700

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