Researchers have identified 100 mysteriously disappeared stars in the night sky - <AUTHOR> https://www.sciencealert.com/a-look-through-past-star-catalogues-finds-scores-of-stars-that-have-mysteriously-vanished <comment><USER2> My experience with big data analysis immediately leads me to suspect that in a dataset of tens of millions of elements, 100 elements having anomalous behavior can actually be operator error, hardware error, noise, anomalous near-Earth object miscatalogued as a star, &c. The article touches on this possibility: "Another explanation – although very unlikely – is they're all just scratches after all, and never existed to begin with." It's unlikely, but unlikely phenomena become phenomena one expects to see if one "rolls the dice" 10 million times.

But it is still an interesting story and a topic worth exploring, even if subsequent research concludes the team has found 100 smudges on glass.

<comment><USER3> These are comparisons of deep, long exposure time survey images. They aren't imaging one star at an instant time, but entire fields of them over many minutes to hours, so:

> operator error

would effect the entire image. If it were damage to the film/sensor, scratches etc, it wouldn't look like a star point source with a star like point spread function.

> hardware error, noise

Digital sensors do add noise to an image, but it doesn't occur as bright point sources concentrated in a small area. noise can be removed through statistical analysis, dark frame subtraction, lucky imaging, etc. Dust on the lenses or mirrors aren't in the focal plane and don't resolve to points. Dust on film or sensors would block light, not produce it. Many exposures all over the sky quickly characterize the on sensor defects and other instrument specific information that can be removed from the data.

> anomalous near-earth objects

these are long exposures, if they are anomalous objects, they would have to have very slow apparent motion against the stellar background. satellites and planes would leave trails. balloons would drift with the wind. what would stay basically static through the entire long-exposure against the celestial sphere?

I appreciate your skepticism, I'm just taking the other side of the argument. Thoughts?

<comment><USER4> im with you. this is astrophysics: there are other lines of evidence to consider: like the missing stars sharing certain properties (color, velocity), suggesting an astrophysical explanation (remember it's not strange for stars to go away. whats new here is how)

</comment></comment></comment><comment><USER5> [https://en.wikipedia.org/wiki/The_Nine_Billion_Names_of_God](https://en.wikipedia.org/wiki/The_Nine_Billion_Names_of_God)

..they notice that "overhead, without any fuss, the stars were going out."

<comment><USER6> I very much like the 2 part epic space opera "Pandora's Star" and "Judas Unchained" by Peter F Hamilton.

In it, an Astronomer spots a star that disappears. This star is 1,500 light years away. He travels to another star system (Humanity is a multi-system species) and observes the star again, at just the right moment to see the light from its disappearance. It disappears within a couple of seconds, as does a nearby star. But its infrared output is undimmed.

This kicks off an epic, and I really do mean epic, space opera. Peter F Hamilton is really great at such stories, and I love this pair of books so much that I've read them about a dozen times each.

Highly recommended!

<comment><USER7> I'll echo this recommendation. Peter F. Hamilton is firmly my favourite sci-fi author, and that's a hard spot to take.

The Commonwealth Saga (mentioned by the parent) is followed by The Void Trilogy and then The Chronicle of the Fallers, all set in the same Commonwealth universe. It's some of the most evocative writing I've ever heard the pleasure to read, and the stories told are massive in scale but without seeming lacking as a result.

My e-reader says that my most recent read-through was my 9th, so add that to a number done with physical books and it should give some idea of how good I consider these books!

<comment><USER8> I read quite a lot of books thanks to suggestions on HN, so my thanks to all giving suggestions!

</comment></comment></comment></comment><comment><USER9> From the paper: [https://sci-hub.se/10.3847/1538-3881/ab570f](https://sci- hub.se/10.3847/1538-3881/ab570f)

"We show that these objects are redder and have larger proper motions than typical USNO objects." \-- Interesting, not sure what that'd imply.

"A particular focus is given to USNO objects that have several detections before vanishing" \-- implies that these at least some of these objects are not just detector glitches or scratches or similar, although "Visual checks confirm that indeed the most interesting cases, about 100, are mostly one-time detections in the red band."

"In a separate paper by K. Pelckmans et al. (2019, in preparation). we propose a new tool for handling a large number of images using methods of machine learning." (since people were talking about ML in astronomy)

<comment><USER10> > Visual checks confirm that indeed the most interesting cases, about 100, are > mostly one-time detections in the red band.

So that could be fusion torch flashes. Or maybe weapons.

I wonder if they have spectra for any of these suspects.

</comment></comment><comment><USER11> Universe v2432134542235788654 Release Notes

</comment><comment></comment><comment></comment><comment></comment><comment></comment><comment></comment><comment></comment><comment>===

* Removed ~100 stars to fix bug #9533465222. If your star was affected, please reach out to customer support.

<comment><USER12> Customer support, when we applied the latest upstream patch we notice E=MC^2+0.001. Please advice.

<comment><USER13> Please upgrade to premium service to get an answer.

</comment></comment></comment><comment><USER14> I was reminded of a great start of a sci-fi novel:

"The star vanished from the centre of the telescope's image in less time than a single human heartbeat. There was no mistake, Dudley Bose was looking right at it when it happened. He blinked in surprise, drawing back from the eyepiece. "That's not right," he muttered.

He shivered slightly in reaction to the cold air around him, slapping gloved hands against his arms. His wife, Wendy, had insisted he wrap up well against the night, and he'd dutifully left the house in a thick woollen coat and sturdy hiking trousers. But as always when the sun fell below Gralmond's horizon, any warmth contained in the planet's thinner-than-average atmosphere evaporated away almost immediately. With the telescope housing open to the elements at two o'clock in the morning, the temperature had dropped enough to turn his every breath into a streamer of grey mist.

Dudley shook the fatigue from his head, and leaned back in to the eyepiece. The star field pattern was the same, there had been no slippage in the telescope's alignment, but Dyson Alpha was still missing. "It couldn't be that fast," he said.

He'd been observing the Dyson Pair for fourteen months now, searching for the first clues of the envelopment which would so dramatically change the emission spectrum. So far there had been no change to the tiny yellow speck of light one thousand two hundred and forty light-years away from Gralmond which was Dyson Alpha.

He'd known there would be a change; it was the astronomy department at Oxford University back on Earth that had first noticed the anomaly during a routine sky scan back in 2170, two hundred and ten years ago. Since the previous scan twenty years earlier, two stars, a K-type and an M-type three light-years apart, had changed their emission spectrum completely to non-visible infra red. For a few brief months the discovery had caused some excited debate among the remnants of the astronomy fraternity about how they could decay into red giants so quickly, and the extraordinary coincidence of two stellar neighbours doing it simultaneously. Then a newly settled planet fifty light-years farther out from Earth reported that the pair were still visible in their original spectrum. Working back across the distance, checking the spectrum at various distances from Earth allowed astronomers to work out that the change to both stars had actually taken place over a period of approximately seven or eight years and was simultaneous. Given that speed, the nature of the change ceased to become a question of astronomy; stars of that nature took a great deal longer to transform themselves into red giants."

\-- Peter F. Hamilton. Pandora's Star

<comment><USER15> Sorry, Peter F. Hamilton's _ideas_ are awesome but his writing--not so much. He desperately needs an editor to chop out 1/3 to 2/3 of his words.

I'm reminded of an old Bugs Bunny cartoon: Detective: "Okaaaay, start at the beginning." Bugs: "In the beginning, the Earth was without form and void ..." Detective: "You can skip ahead a bit, thanks ..."

<comment><USER16> Maybe he gets paid by the word?

<comment><USER17> That's why I hated Dickens' novels.

<comment><USER15> Ayup. "Tale of Two Cities" is a wonderful book with a sub-par book sandwiched in the middle.

</comment></comment></comment></comment></comment><comment><USER18> Probably the denizens of the next star over noticed that the star in question had inhabited planets, and turned it off against the possibility they might, otherwise, someday become a threat.

This is a candidate for the Great Filter: interstellar civilizations that come into contact destroy one another.

<comment><USER19> Since everything in physics tells us that FTL travel is impossible (as far as I am aware), then when a civilization detects signs from another civilization in another solar system it knows that 1) that civilization was advanced enough to produce signals into space light years ago, and 2) by the time it reaches it at sublight speeds (hundreds, possibly thousands of years) it will be more advanced still. That means your extermination mission might be facing a technologically superior enemy with home field advantage.

<comment><USER20> This may be where intuition and cosmic scale don't align. The Milky Way is very old and is ~100k light years in diameter.

Say you are a few million year old civilization and you detect radio from a civilization 100k light years away takes 500k years for you fleeting arrive. You are still millions of years ahead in technology. If you are a stagnant civilization you probably stay home cause the other side would overtake you, but then again that motivation to get to them as early as possible. In any event presumably as your fleet get closer you would have a better idea of the technology difference and can just do a U turn

<comment><USER18> Civilizations that come into contact will tend to be those that are closer together, particularly if they make any effort to be inconspicuous.

The longer they go without contact, the wider their reach, and the greater their odds of contact.

We might suppose that the technology necessary to obliterate another civilization is arrived at early, and is hard to counter despite long subsequent development. Alternatively, civilizations that succeed in suppressing weaker ones eventually meet their match.

</comment></comment></comment></comment><comment><USER21> This reminds me vaguely of the community science project I contributed to a few years ago trying to investigate why epsilon Aurigae [0] goes dim every ~27 years. It turns out to be a likely dust disk of an orbiting body that dims the main star and happens to be directly along the line of sight with Earth.

I imagine there are a lot of possible ways a line of site occlusion could cause a dim star to appear as not existing at all, and as another commenter mentions, maybe the original measurement was some sort of amplification in the first place.

Space is damn cool.

[0] [https://en.wikipedia.org/wiki/Epsilon_Aurigae](https://en.wikipedia.org/wiki/Epsilon_Aurigae)

</comment><comment><USER22> Could it be gravitational microlensing? Maybe the apparent magnitude of the missing stars was amplified by an intervening massive object just as the older pictures were taken.

<comment><USER23> That seems likely to this amateur.

Lensing could also move the (perceived) location of a star.

</comment></comment><comment><USER24> _" there seem to me too many anomalies to explain all the vanished stars as known natural phenomena. In their current paper, the authors themselves discuss the possibility that they're seeing unknown phenomena, or that the vanished "stars" could be relics of technologically advanced civilizations, particularly the theoretical mega-engineering projects known as Dyson spheres."_

What about the possibility that the inclusion of those stars in those 1950's star catalogs was a result of human error, instrument error, or scientific fraud?

<comment><USER25> This is a comparison of images, not just catalogs of sources in images. If you look at the image in the linked article, you can easily spot one of the stars that has "gone missing".

Looking at the brightness of the source that went missing, it is hard to suggest instrumental error - much fainter stars remain detectable in both epochs.

And fraud, really? Who would bother to fake stars in catalogs and plates in the 1950s, and why?

<comment><USER26> So they could identify who plagiarized their catalogs?

[https://en.wikipedia.org/wiki/Fictitious_entry](https://en.wikipedia.org/wiki/Fictitious_entry)

<comment><USER27> Well you could, but why would you want to? Other than video games which didn't exist in 1950, I can't think of any reason someone would use a star catalogue in a for-profit scenario.

</comment></comment></comment></comment><comment><USER28> Trap stars? [https://en.wikipedia.org/wiki/Fictitious_entry](https://en.wikipedia.org/wiki/Fictitious_entry)

<comment><USER29> Ah, a star catalogue equivalent of non-existent streets in a map that are only drawn there to prove copyright infringers. Somehow I was expecting to read about a stellar equivalent of a D&D mimic.

</comment></comment><comment><USER30> I bet some of them are moving a little faster than we expected them to and are just not where we last saw them. Creepy nonetheless.

<comment><USER31> I don't think that's likely. It takes the closest star 5,000 years to move the distance our moon covers in the night's sky.

Video of ten years worth here: [https://www.facebook.com/watch/?v=10160104518220167](https://www.facebook.com/watch/?v=10160104518220167)

<comment><USER27> I was thinking that, but if these objects are much closer than expected, small physical motion could be a large angular motion. I don't know if that would be _enough_ to explain them away.

</comment></comment></comment><comment><USER32> Obligatory Sci-Fi premise:

[https://www.greaterwrong.com/posts/5wMcKNAwB6X4mp9og/that- al...](https://www.greaterwrong.com/posts/5wMcKNAwB6X4mp9og/that-alien- message)

<comment><USER33> Thank you! I've been searching all afternoon for this one.

</comment></comment><comment><USER34> In case there's any interest, this Archiv page includes a PDF. [https://arxiv.org/abs/1911.05068](https://arxiv.org/abs/1911.05068)

"We visually examine the images for a subset of about 24,000 candidates, superseding the 2016 study with a sample ten times larger. We find about ∼100 point sources visible in only one epoch in the red band of the USNO which may be of interest in searches for strong M dwarf flares, high-redshift supernovae or other catagories of unidentified red transients.

Comments: SETI meets time domain astronomy."

</comment><comment><USER35> The paper:

"The Vanishing and Appearing Sources during a Century of Observations Project. I. USNO Objects Missing in Modern Sky Surveys and Follow-up Observations of a "Missing Star"" Beatriz Villarroel et al 2019 December 12, The Astronomical Journal, Volume 159, Number 1

[https://doi.org/10.3847/1538-3881/ab570f](https://doi.org/10.3847/1538-3881/ab570f)

</comment><comment><USER36> Something in the foreground that was originally misclassified as a star?

<comment><USER37> This is my thought. I suspect these are asteroids. The tell is whether the stars show up on plates, say, a year later. If so, then they're not asteroids.

However, that seems to have been ruled out in the Astronomical Journal article:

"Given the exposure time of 45 minutes of the POSS-I E red image, if our object were an asteroid that quickly moved out of the field, it would have left a stripe (and not be point-like)." (Page 5)

"The exposure time for the red image is about 50 minutes. If the object were an asteroid and was quickly moving through the field of the red image in a few minutes, then it would be elongated on the plate. However, this object is point-like. In addition, the candidate is anomalously red and not seen in the blue band, which further decreases the likelihood that it is an asteroid." (Page 13)

<comment><USER36> That doesn't rule out foreground objects at all. Kuiper belt objects are distinctly red, as we learned from New Horizons, and so far away that they wouldn't noticeably move over 45min.

<comment><USER37> The question is whether such Kuiper objects would show up on the old POSS plates. I don't know enough about that, so I yield to those who do. It certainly seems a more plausible explanation.

</comment></comment></comment></comment><comment><USER38> Could it be that a group of stars was passing by between us and the stars that remained when the first picture was taken?

</comment><comment><USER39> Wellp, my crazy sci-fi thought:

 _There are patches in the sky._

( [https://en.m.wikipedia.org/wiki/Lexx](https://en.m.wikipedia.org/wiki/Lexx) )

</comment><comment><USER40> While an interesting article, I wish people didn't feel the need to try to make things out to be more 'exciting' than they likely are. I think it takes away a lot from the real reasons to be excited. This seems to be common in astronomy journalism.

"Hmm, we've observed something weird. What could be some reasonable explanations? We'll dedicate 3 to 4 sentences on those then spend the rest of the article talking about Dyson Spheres and extraterrestrial star ships."

<comment><USER41> Ok, we've changed the URL from [https://www.airspacemag.com/daily- planet/stellar-mystery-how...](https://www.airspacemag.com/daily- planet/stellar-mystery-how-could-100-stars-just-vanish-180973821/) to a different popular article that seems to dwell on topic somewhat longer before the aliens show up.

</comment></comment><comment><USER42> For those a little sceptical of traditional dyson spheres, like the linked article, there are many more ways to envision such a sphere. My personal favourite is a kind of computonium dust layered loosely around the star, like that found in Charles Stross' Accelerando.

<comment><USER43> True, but Dyson spheres should be easily visible in the infrared, and I know searching for them is set as an undergrad project by at least one IR astronomy professor. So, I'd expect them to be spotted by now if they are widespread.

<comment><USER31> It seems silly for us to make a bunch of rigid conclusions about an unimaginably high technology solar-system scale megastructure.

<comment><USER27> We could make one with known tech, it would only take a few thousand years thanks to exponential population growth and humans being universal constructors.

We'd expect to see Dyson swarms' heat signatures because of the laws of thermodynamics. If super-advanced aliens can avoid or circumvent thermodynamics, all bets are off.

<comment><USER31> The laws of thermodynamics don't forbid radiating heat in a directed manner, right?

<comment><USER27> I think you're only able to do that if you're not in thermal equilibrium.

I'm not a trained physicist, so I'm not 100% certain about this, however the phrase "there is no stealth in space" seems to come up a lot in the stuff I read, and that specifically excludes directing heat away in specific directions.

<comment><USER31> I'd think you could do something like have a deep, V-shaped hole with radiators at the bottom, and really good insulation / conductors throughout the sphere to funnel heat into that radiator. Anything radiating in the wrong direction would just get picked back up and re-directed through the system again.

Point that V into deep intergalactic space and buy yourself a few hundred million years.

</comment></comment></comment></comment></comment></comment></comment><comment><USER44> Has anyone used machine learning to help identify and track stars in the data set they mention? I'd love to contribute to space exploration as a software engineer, and building systems to analyze the data seems like one promising approach.

<comment><USER45> Take a look here:

[https://arxiv.org/search/?query=astronomy+machine+learning&s...](https://arxiv.org/search/?query=astronomy+machine+learning&searchtype=all&source=header)

 _Plenty_ of ML work being applied to astronomy. Much of the code is open source too so you can dive right in and contribute.

Here's a recent survey you might start with: [https://arxiv.org/pdf/1912.02934.pdf](https://arxiv.org/pdf/1912.02934.pdf)

</comment></comment><comment><USER46> Davros and the Reality Bomb[1]?

[1]: [https://en.wikipedia.org/wiki/Journey%27s_End_(Doctor_Who)](https://en.wikipedia.org/wiki/Journey%27s_End_\(Doctor_Who\))

</comment><comment><USER47> Fermi style estimate: 600M stars with live spans from several billions to several millions years, say average - 600 million years, thus 1 star per year got to go. 50 years - 50 stars.

</comment><comment><USER48> Not a single mention of Katamari Damacy in this whole thread? Players of that game all know it was because of the King of All Cosmos and his clumsiness!

</comment><comment><USER49> What do the stars look like in 3d space? Do they form some sort of wavefront?

</comment><comment><USER50> Are the stars vanishing in the _sky_ or just in the _data?_

Are stars also appearing?

<comment><USER37> They are photographic plates, then vs. now. This cannot be dismissed as simple user error. Especially in 1950 where we did not have to contend with this massive population of artificial satellites. Other solutions must be sought.

What is not clear to me is whether one can find these missing stars on other plates taken at a later time. If so, then this lends credence to some sort of stellar phenomenon. The paper rules out asteroids due to the long exposure times of the images, which would have turned any objects moving in our solar system into a smear rather than a point source.

<comment><USER51> What chemistries are we looking at, near-Earth phenomena might be responsible for the appearance of one-time "stars" on a photographic plate. I'm thinking cosmic-rays but I'm sure there are a tonne of potential sources.

Perhaps also different wavelength star sources too? Or are they doing the observations across the whole spectrum (that's probably common nowadays?).

</comment></comment></comment><comment><USER52> It's not aliens.

<comment><USER53> It's always not aliens until the day it is.

</comment></comment><comment><USER54> Somebody is building Dyson Spheres, obviously.

</comment><comment><USER55> Flip burn?

</comment><comment><USER56> The simulation is shutting down.

<comment><USER57> Or maybe some memory got corrupted by a passing cosmic ray (out in the realverse).

</comment></comment><comment> ur-whale Dyson spheres completed baby !

</comment><comment><USER58> Something out there low on power and needs recharging

</comment><comment><USER59> Jim Carrey almost got hit by a spot. Someone to change the light bulbs quickly!

</comment><comment><USER60> No... it was indeed not a dream. We really did it. The King of All Cosmos really has done it. A sky full of stars... We broke it. Yes, We were naughty. Completely naughty. So, so very sorry. But just between you and Us, it felt quite good

</comment><comment><USER61> Dust on the optics or on the film during development.

<comment><USER62> Please don't post comments without reading the article first. It just wastes everyone's time.

 _That short list was visually inspected, excluding around 18,000 images that were messed up by flaws or artefacts. Lastly, the team removed images where the missing star was towards the edge of the field, just to reduce risk of any false positives.

One final sweep using yet another method for comparisons removed other possible flaws in data collection, or unclear results. That left 100 dark shadows where a star once shone._

</comment></comment><comment><USER63> I'm guessing this is related to rising co2 and climate change. Dampens out what we can see.

</comment><comment><USER64> What if these aren't stars that are disappearing but instead the appearances and disappearances of wormholes that are either allowing us to see to another place in space where that star is or perhaps a wormhole blocking where that star previously was for us and we are now looking into another section of space where a star is not?

<comment><USER65> While fun to think about, I think it is hard to go anywhere, scientifically, from such a proposition. How would you disprove it?

<comment><USER64> Hmm haven't thought of how to disprove it but there is a theory about measuring the red shift[0] around the "object" in this example the wormhole

[0] [https://www.livescience.com/64033-shape-of-a- wormhole.html](https://www.livescience.com/64033-shape-of-a-wormhole.html)

</comment></comment></comment><comment><USER66> "Once you eliminate the impossible, whatever remains, however improbable, must be the Truth" -Sherlock Holmes

It seems like now might be the perfect time, for the price of a single space telescope, to build an exa-scale computer capable of simulating _every_ extreme astrophysical event.

Technosignature "clues", and all probable causes could be instantly classified. It's now also possible to add gravity waves and neutrinos to the simulation ;)

<comment><USER67> >"Once you eliminate the impossible, whatever remains, however improbable, must be the Truth" -Sherlock Holmes

This axiom works in the fictional universe of Sherlock Holmes, where it's guaranteed that the protagonist will know all of the variables with perfect unbiased clarity and can, therefore, eliminate all unnecessary possibilities and solve the case.

But in the real universe, one often cannot "eliminate the impossible," because one cannot always know everything that is possible, or where ones assumptions are wrong.

>It seems like now might be the perfect time, for the price of a single space telescope, to build an exa-scale computer capable of simulating every extreme astrophysical event.

This is a good example of what I mean. We don't know what the set of all extreme astrophysical events contains, or what their nature is (ex: dark matter and dark energy) and we're constantly discovering new events and phenomena. If we _could_ perfectly simulate the universe in this manner, we wouldn't _need_ to.

And this is why, despite many fields of science already spending far more than 'the price of a single space telescope' to simulate everything from the Big Bang to biology and neurons to particle collisions, "instant classification of everything" isn't possible.

That's just not a thing that computers can do outside of science fiction.

<comment><USER66> But "possible / impossible" seems in itself to be a really useful classifier!

Perhaps not worthy of exa-scale computing resource allocation. When it could be put to better use in say, nuclear fusion instability prediction. And with the qualifier "possible" conditioned on "known astrophysics by humans in the early 21st Century". But still an interesting tool for likelihood candidate detection.

And it still seems constrained to me at least (not a professional astronomer) by the scale of astrophysical phenomena which would be detectable here across the vast expanse of space. It could be an infinite set, certainly.

But so far we have cataloged only a handful of significant sources of, in the case of gravitational wave interferometry, bursts: black holes, quasars, pulsars, neutron stars...

[https://www.ligo.caltech.edu/page/gw- sources](https://www.ligo.caltech.edu/page/gw-sources)</comment></comment></comment>


Heisenbug - <AUTHOR> http://en.m.wikipedia.org/wiki/Heisenbug

<comment><USER2> I love the other kind of bug, where the code works until you read the source, you realize the code can't work, and then your pre-existing binaries all break.</comment>


Apple: "Quit running those Laptop Hunters ads." Microsoft: (Maniacal laughter) - <AUTHOR> http://www.crunchgear.com/2009/07/15/apple-quit-running-those-laptop-hunters-ads-microsoft-maniacal-laughter/ <comment><USER2> I'm a Mac and I'm a PC....

hypocrisy much? although the mac ads were at least good</comment>


7 heinous lies "American Sniper" is telling America - <AUTHOR> http://www.salon.com/2015/01/23/7_enormous_lies_american_sniper_is_telling_america_partner/

<comment><USER2> I was shocked at how little value was presented in this article.

Points 1,2,3, could be relabeled... "Hollywood doesn't stick to the facts, but invents a storyline that helps audiences relate". HARDLY NEWSWORTHY???

Most entertaining was point #4 "lies in.."American Sniper". They even said "the claim doesn't appear in the film".

For those who have seen it, did 4,5,6,7 even appear in the movie?

</comment><comment><USER3> as for claim #2 -- it is worth nothing (see here for reference: [http://www.longwarjournal.org/archives/2007/01/iran_and_alqa...](http://www.longwarjournal.org/archives/2007/01/iran_and_alqaeda_in.php)) that iran (whom some allege to have supported the shi'a insurgency) has been known to also support sunni insurgents (often 'al qaeda' or some variant thereof)...

<comment><USER4> Just like the CIA has been known to support them, as well. Your point?</comment></comment>


Live Tracker for Amazon Prime Day Sales - <AUTHOR> http://zentail.com/primeday <comment><AUTHOR> Hey everyone, Zentail (YC S12) is an all-in-one SaaS platform for ecommerce sellers, it's our mission to make ecommerce simple. Our customers are online merchants who sell on a variety of sales channels including Amazon (their third party merchants, think "Shipped and sold by ..").

Amazon has created a great buying holiday in the middle of the summer and we wanted to provide insight into what we are seeing to anyone who might be curious about how much business actually happens on prime day. Happy to answer any questions about our model or company!

</comment><comment><USER2> What exactly is this supposed to be tracking? Feels like just an opportunity to get the affiliate click-through.

<comment><AUTHOR> Removing the affiliate link. The main goal of this is to provide insight into the buying holiday for people that are interested. We added the affiliate link so we can track how effective we are at pushing people over there, but we just want to draw attention to Prime Day as it's great for our customers (third party amazon sellers)

</comment></comment><comment><USER3> > Check out this up-to-the-minute prediction of Prime Day GMV Sales to find > out. This prediction is based on a sophisticated data model taking in last > year's estimated $2.3 billion total sales, and our unique view of Amazon > sales trend data

So not a live tracker at all?

<comment><AUTHOR> Great question! It is based on live data as well as historic data. We only have access to a % of total Amazon sales through our SaaS platform for 3rd party sellers. We have confidence in our model to hit within 10% of the total Prime Day Sales.

</comment></comment><comment><USER4> How do we know this is not anything more than a gimmick to get a 'zentail-20' affiliate tag on the way to shopping on one of Amazon's busiest day so they can get their referral commissions?</comment>


New feature? Google Image Search... Image Search? - <AUTHOR> http://www.zaccohn.com/2012/07/google-image-search-image-search/

<comment><USER2> not even close to a new feature. Google has had reverse image search for probably about a year now.

<comment><USER3> Yup.

Search by text, voice, or image - Google Inside Search Blog - July 14th, 2011 [http://insidesearch.blogspot.ca/2011/06/search-by-text- voice...](http://insidesearch.blogspot.ca/2011/06/search-by-text-voice-or- image.html)

<comment><USER4> Previous discussion on HN: <http://news.ycombinator.com/item?id=2653870>

</comment></comment></comment><comment><USER5> It's been around for a while.

If you click the camera icon in the search bar, you can enter an image URL instead of uploading one.

</comment><comment><USER6> Wow, this is old news, guess you guys don't even know about voice search on the desktop : <http://goo.gl/muLG1> Google is like the mythical hydra, only it's real!

</comment><comment><USER7> Won't this kill off services such as TinEye? From what I gather, this feature pretty much is exactly the service they provide; it's not unreasonable to think Google can pull it off better with their resources.

</comment><comment><USER8> This is a fantastic feature, especially to discover in what place a photo has been taken etc.

Now you can get funny results when putting face pictures.</comment>


Ask HN: OpenGateway for recurring billing instead of Chargify/Recurly/Spreedly? - <AUTHOR>

I ran across http://opengateway.net/ , which is a $99 installable framework for recurring billing. In light of the recent Chargify pricing changes, it seems an attractive alternative since it's a one-time upfront cost and no monthly charges - in other words, the pricing is a known quantity.
Apparently it doesn't store credit card info locally, which was my biggest concern.
Has anyone tried it? If so, what did you think? <comment><USER2> Hmm this looks like a great alternative to <http://amember.com> which I have been using for a long time (and am not particularly fond of - old code, ugly UI).

I basically use Amember to manage member subscriptions e.g. what plan they are on, sending them transactional emails, and handling the callback from the payment gateway (in my case PayPal) - and providing the API hook to build into my app.

If OpenGateway can replace all of that, it's a done deal. I'm switching!

</comment><comment><USER3> Looks like a good solution; we have to make a decision re: billing soon so we would also be interested in others' experiences with this.

<comment><USER4> I just emailed them to come post a thread at HN. If they're smart, you'll hear from them tomorrow.

</comment></comment><comment><AUTHOR> Clickable link: <http://www.opengateway.net/>

<comment><USER5> How to insert clickable links here? Or bold, italic, underline text?

</comment></comment><comment><USER6> Does it handle dunning?

<comment><AUTHOR> Doesn't mention dunning specifically but does say "automatic emails which are sent during specific events such as a new charge, new recurring charge, expiration, cancellation, upcoming expiration, upcoming charge, etc." .

<comment><USER6> Nice. That might do the job.</comment></comment></comment>


Any VMware experts out there? - <AUTHOR> http://blogs.law.harvard.edu/philg/2008/07/08/any-vmware-experts-reading-this-blog/

<comment><USER2> I think his broader point is spot on: virtualization is currently being used to solve a bunch of problems that existing time sharing systems (!!) have been handling well for decades. Running a few different development servers on a single box is trivial with any modern unix, and really isn't a call for virtualization.

That said, the specifics of his problems sounds alot more to me like bad administration than they do issues with virtualization per se. Done sanely, virtualization isn't that bad. But it has to be done by someone who understands the problem. A typical IT team might not be up to the challenge.</comment>


Sir Clive Sinclair: "I don't use a computer at all" - <AUTHOR> http://www.guardian.co.uk/technology/2010/feb/28/clive-sinclair-interview-simon-garfield

<comment><USER2> I bought a Sinclair ZX80 30 years ago - I thought about writing a commercial game app for it but I got busy on other things. Compared to the Apple II (I had serial number 71 of the original Apple II model line), the ZX80 was a big disappointment.

<comment><AUTHOR> I have been looking into the Apple II and IIe recently, for various reasons, and I get the impression that these computers were way ahead of their time, at least compared to the other "home computers" back then. They sure seem more powerful than the (very successful) Commodore 64; better BASIC, powerful other programming languages available, extension cards, disk operating system with subdirectories (unusual for the time), etc.</comment></comment>


Object-Oriented Programming – The Trillion Dollar Disaster  - <AUTHOR> https://medium.com/@ilyasz/object-oriented-programming-the-trillion-dollar-disaster-%EF%B8%8F-92a4b666c7c7 <comment><USER2> This is.... quite strikingly poorly written - no research even by self admission on most of this: "The complexity graph is not based on any research, it simply reflects my own experience working with Object-Oriented, Procedural and Functional Programming."

We all can say negative things about any paradigm or pattern - but this is quite a hit piece. Proposing "functional programming" as a replacement is quite ignorant of many (vast majority?) of platforms and realities of programming different kinds of software (especially event driven).

Functional Programming is notoriously hard to ramp engineers onto, or for folks that join a team with a codebase written as such it can be extremely difficult.

Maybe I should write one; "Medium - the Trillion Dollar Mistake"

<comment><USER3> I agree. Not to mention that functional programming has been around for decades. The reason why it's not popular is simple: because most people hate it and it's even more complex than OOP.

One doesn't need to look for conspiracy theories about functional programming when there is none.

</comment></comment><comment><USER4> It's difficult to take an article seriously when it has an emoji at the end of every sentence.... It was so distracting I could not read past the first paragraph.

<comment><USER5> I was just about to comment the same thing.

Opened it up, saw a bunch of emoji's and subsequently decided this was not serious enough to warrant my time.

It'd be cool to have something automated to de-mojify articles and such, I've encountered this style of emoji-heavy writing before.

<comment><USER6> On the one hand, maybe it would be nice. On the other hand, this style of writing is essentially a subtitle in all-caps saying "I don't know how to write properly and this isn't worth your time", which has its own use in, well, saving me time.

</comment></comment></comment><comment><USER7> Does the poor quality of this article have something to tell us about Medium and pieces published there? What about it could cause it to attract particularly poorly constructed and sourced arguments?

Or is this just Sturgeon's Law at work?

<comment><USER2> Both?</comment></comment>


How to defend against zombie attack - <AUTHOR> http://news.bbc.co.uk/1/hi/sci/tech/8206280.stm

<comment><USER2> <http://news.ycombinator.com/item?id=770121></comment>


Startup Idea - <AUTHOR>

I've just found a new job but got interviewed at two different places. However, I've just realized that I had a friend inside the company at both of those places.
They helped me to get inside (i.e. accelerating the process, talking of me in good term, etc.)
So:
1- For the one who actually work for a company: When you search searching your job, did you knew someone inside? Or what they you use?
2- If you own a company, how did your employees known about you?
I say that because when you're good, it's easy to find a job. However, it might not be easy to find your perfect job since you don't know about all the company.
And now, finally, for the startup idea:
A simple "friendsjob" where you log on with facebook, and you see job opportunities posted by your friend.
Does it already exist? Would someone be interested in creating that website? :) <comment><USER2> _friendsjob_

Not sure if it exists but I work in IT recruitment and am curently toying with more inovative ideas for jobseekers online and to be honest, if this doesn't already exist then I will legitimately consider creating something similar.

The fact is, there are so many companies trying to avoid using external agencies for recruitment due to cost/economic climate that they are turning to employee referrals more than they ever have in the past so a user-friendly forum that offers a degree of discretion for people to post vacancies that have yet to be advertised is a great idea in my opinion.

I'll draft some ideas and let you know how I get on. You never know, there might be a job in it for you!

<comment><AUTHOR> To be honest with you, I don't really know linkin (>_< I know). But I really was thinking of something simpler. Nothing clever or trying to be too smart.. Simply a job posting but only available to personal contacts and friends. Maybe with a few filter, but you get the idea.

</comment></comment><comment><USER3> Every job I have gotten was through someone I knew. This goes all the way back to my very first job as bus boy. To me this greatly reduces the risk at working at a crappy place and helps smooth out the hiring process.

When I've been in the position to hire people, the first thing I do is ask the current employees to recommend one of their friends or former coworkers. If I like and respect the current employee, odds are the person they bring in will be of similar caliber.

Linked-in might be the closest fit to what you have described. Right now I'm guessing its mostly word of mouth. So there might be a market for it, but the trick is to get enough job postings.

</comment><comment><USER4> _it might not be easy to find your perfect job since you don't know about all the company_

www.glassdoor.com has anonymous reviews of companies. People post salaries, reviews, interview questions, etc. It helps you get an idea of the company before you accept. They have recently introduced photo uploads for offices, and a referral feature.

Imagine applying for a job and going in knowing what questions they ask in the interview, what salary range they offer, and even what the office looks like.

</comment><comment><USER5> LinkedIn? Social network and you can post jobs there. Works pretty much how you've described it.</comment>


Ask HN: What's still missing in Netflix, Hulu, Amazon video? - <AUTHOR>

What do you think are the needs that they didn't have filled yet?
Are you always been satisfied by Hulu + Netflix?
How are they if compared with the tv scheduling? <comment><USER2> Content availability is the main problem. Hulu is really annoying because I pay for it yet still have to endure commercials, and their have strange restrictions on how you can consume the content. 30 Rock, for example, cannot be streamed through my Apple TV's Hulu. I could stream it to my laptop, however. Instead I wound up paying Apple for it, so I'm in the seemingly absurd situation of paying Apple $20, Hulu $8/month and Netflix $8/month, and I still don't get all the TV I want to watch--or even all of broadcast TV. I can't get Seinfeld without Crackle, and Crackle is about the worst.

These services are all partially overlapping solutions. Here's what I want:

\- All TV shows, current season as it airs and all past seasons

\- No commercials

\- No time pressure to watch before "expiration"

I'm willing to pay substantially for this. I'm talking $40-60/month, and I don't care about HBO or Showtime either. Instead I have two services that charge me $8/month and have the selection of a small-town Blockbuster. If any of these services were actually trying to compete with cable, they could charge more and provide access to the rest of the content. Instead they seem happy to play the annoying long-tail game with off-brand crap, and it's deeply dissatisfying.

The real problem here is absolutely not technical. It's contractual with the companies that own the content. I doubt you could do better than they have without offering more money, but I think there could be a real niche there if you're willing to charge customers actual money to provide actual service.

<comment><USER3> +1 I totally agree. I want to watch any show or available movie whenever I want with no commercials and I am willing to pay a fair amount of money for this.

After about 18 months, I just cancelled Hulu+ because the commercials are too long. Otherwise a nice service and I wanted to support them, but...

Netflix is pretty good. Both my wife and I pay them $8/month and like the content, the recommendations, etc. Good value.

I think that Directv is way too expensive because we don't actually watch much content through Directv. I want to cancel but there there is some resistance from my family.

<comment><USER2> The commercials are too long, and they have the same problem Crackle does of showing the same commercials back-to-back-to-back-to-back... It actually really makes me angry when they say "This episode of X presented with limited commercial interruption by Y" because there's nothing limited about it! Especially if it's new. They seem to have some kind of back-off algorithm so it doesn't show as many commercials for old stuff. But old stuff has a way of vanishing randomly.

I'm thinking seriously of getting an old-school DVR and a massive antenna. Problem is, I live out in the sticks where I'll need a huge antenna just to get about half the broadcast TV.

<comment><USER4> The commercial breaks on Hulu+ range from 15 seconds to 1 min 45 seconds (I've found they're heavily on the shorter side for me). That's significantly shorter than commercial breaks on broadcast television or cable in my experience .

Was it really that bad for you? (Genuinely curious).

<comment><USER2> When there are six of them it doesn't matter how long they are.

<comment><USER4> There are at least as many on broadcast and cable. I still fail to see how the commercials on Hulu+ aren't the lesser of the two evils...

<comment><USER2> So we went from "genuinely curious" to "I'm going to debate you until you decide to feel things differently."

Like I said, where I live broadcast isn't an option without an expensive antenna. I have a cheap ($25) antenna and I get exactly one of three channels depending on how I orient it. The other options are cable without internet, which chafes badly, and satellite. The lesser evil I lived with for years was no TV at all. I prefer Hulu to nothing, but not to the other two options, and the question I was responding to above is "how can we do better than Hulu and Netflix?" not "how can I convince strangers to man-up and love shitty options?"

<comment><USER4> Wow. Didn't realize this was such a touchy subject for ya. Forget I ever asked. :)

<comment><USER2> It's not a touchy subject. I'm just sick of everybody trying to turn every conversation into some kind of fact-war, especially when opinions are explicitly asked for. What do you think you're going to win?

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER5> I mostly watch Netflix streaming on a DVD player, so I'm not sure if there's a way to do this on other alternate interfaces or not, but it'd be nice if you could tag particular episodes of programs. Mark your favorites, or even type in keywords perhaps.

The ability to build playlists might be useful as well.

More of a blue sky wish would involve deeper searchability, like, find all episodes of "Star Trek" across all series with an appearance of the character Sarek, as an example.

</comment><comment><USER6> Sports. I would cancel my cable subscription in a heartbeat if we could either subscribe to our favorite sports (NCAA Football, NASCAR - my wife's) or pay per game to stream (I'd even take it with commercials). Also, there is a major lack of current season shows, except for Hulu, and they're missing some critical producers (CBS, many cable networks) and shows seem to expire randomly. But sports is the only thing that refuses to let me cut the cord. Oh, and Hulu+ is a joke with 90% of content being "Web Only".

</comment><comment><USER7> Recommendation engines are broken. Once you get past rating 1600 movies on Netflix the recommendations go to basically zero and you see the same thing over and over again :(

for that reason I'm starting to like the mash-ups people are making like <http://abetterqueue.com/>

</comment><comment><USER8> Channel surfing. Someone should make a system that creates a channel guide with various "channels" playing different streaming content available. That way you can surf channels and find something without actually seeking out individual films/shows yourself. Replicate the cable experience.

<comment><USER9> This! I am currently using Amazon prime and Netflix for my television/movie consumption. I lack any sort of cable service. It is incredibly difficult to laze on the couch and watch TV because unless I'm watching a television series, I have to make a conscious decision about what to watch next.

</comment></comment><comment><USER10> International support.

</comment><comment><USER11> Discoverability is a massive issue for me still. I use a Netflix for most of my content in the UK (I have no TV) but I struggle to find content that is of interest - although after effort it does exist.

I am not sure it is as simple as just better recommendations.

</comment><comment><USER12> How about the DVD extras... I don't think outside of DVDs there is anywhere one can watch the DVD extras: be it the commentary or the making of.

</comment><comment><USER13> I'm in Europe. No, not satisfied by either of them.

<comment><USER14> Yes. The ability to use them where I live is a major feature missing in most services.

</comment></comment><comment><USER15> Here's a really simple one. Sometimes I just want to watch a random episode of a show, or even a random movie based on my preferences.</comment>


12 Steps to Short-Circuit the Fundraising Marathon - <AUTHOR> http://gigaom.com/2008/10/12/12-steps-to-short-circuit-the-fundraising-marathon/ <comment><USER2> the best way to get a good VC to take you seriously is through a trusted referral, and then to have something promising to show -- a great prototype or great traction.

blasting emails is a waste of your time and theirs (hi, i'd like you to give me $15mm, but can't take the time to email you personally or find a trusted intro) and it smacks of desperation.

</comment><comment><USER3> I heard an interesting talk at Startup Rockstars last week (an event hosted by Viget labs in Arlington, VA) given by Jonathan Aberman of Amplifier Venture Partners.

Speaking about how the current economic "dip" will affect startup funding, he said that the current situation is a result of people investing in completely un-transparent things, and then not being able to untangle the mess.

He went on to say that funding for entrepreneurs will not dry up because people are searching for transparency in their investments, and what is more transparent than one or two guys working on an idea in a garage?

On the other hand, he said that bigger funding will be harder to get.

Finally, he echoed Sequoia in that the goal now is to become profitable and to make your company last, and let economics drive your competition out of business.

It seemed like a reasonable analysis to me. Any thoughts?

</comment><comment><USER4> That is an excellent process to follow. Now I just wish we had someone on the team with 29 startup ventures under their belt.

Does anyone know where/how he built the financial model? It looks like it could come in handy.</comment>


Ask HN: Project-based resource on python application development - <AUTHOR>

can anyone recommend a resource (book,tutorial,etc.) that focuses on application development in python? something similar to Practical Django Projects, but for stand alone applications instead of web apps (for now).<p>i'm in a bit of a funny place, i have a decent/good grasp of python syntax and my logic isn't bad, but i have no clue on how to assemble an application, i seem to be stuck on writing scripts. <comment><USER2> Why not contribute to an existing application ?

<comment><AUTHOR> i've looked at the source of a few projects but the flow is way over my head, i understand the syntax but not the logic, which is why i'm looking for a project-cenetered learning resource, instead of a reference or language- feature resource. also, it seems that a lot of app programming is 90% gui bindings, with very little actual code, or am i totally way off mark?

i recently picked up the django practical projects book, and in a few days i re-wrote a website i did with django. i feel it was the book's project-centric approach that made this possible.</comment></comment>


Ask HN: What Products/Segments need an open source Alternative? - <AUTHOR> Looking for areas where an open source alternative is feasible and required.If possible, explain Feasibility in terms of implementation and profitability. <comment><USER2> I believe almost everything in the public education "stack" should be open. That would go a long way toward equalizing the opportunities available to students and staff in public schools. There is plenty of funding available for education-related products, but most of that is steered toward private companies. The quality of these products is often abysmal, particularly in the UI/ UX area and interoperability.

</comment><comment><USER3> A free software implementation of SystemVerilog for hardware guys. Hardware development is rapidly growing and the ways to over come its complexity in verification all requires proprietary software tools.

</comment><comment><USER4> Most of the things I can think of are firmware, like for tractors, thermostats, hearing aids, etc. Things that are generally so proprietary that it's hurting the industries.</comment>


Petition The White House For Hyperloop - <AUTHOR> https://petitions.whitehouse.gov/petition/fund-musk-san-francisco-la-hyperloop/z9qrqz4x

<comment><USER2> Wow, PT Barnum was right.</comment>


Ask HN: Why COBOL is not hip anymore? - <AUTHOR> So I've been looking into various modern languages and have been working in few of them. While new kids like Golang, Rust, Kotlin, Crystal, and Elixir are getting great traction in today's world of writing business oriented web applications, something that was designed to be expressive is not getting enough traction. There are no mainstream languages that are inspiring their syntax from COBOL (like Elixir or Crystal did). There are no popular frameworks, no famous community or a famous company (exclude legacy) that is promoting COBOL. Looking at sample code listings I can see a huge potential where businesses can write really expressive code. Yet I don't see somebody like say Salesforce, or IBM pushing it. Why? <comment><USER2> [https://medium.com/@donhopkins/cobol- forever-1a49f7d28a39](https://medium.com/@donhopkins/cobol- forever-1a49f7d28a39)

There was a really great COBOL programmer back in the 1990's who was making piles of money hand over fist. But she was terribly overworked, and getting really tired of slaving away on Y2K fixes.

From all her experience fixing mission critical code, she was becoming increasingly worried that civilization was going to collapse due to Y2K bugs.

After all that hard work, she never wanted to look at another line of COBOL ever again, she was just so sick and tired of it.

So she signed up with Alcor, and had herself cryonically frozen in 1999, leaving behind explicit instructions that she was to be revived after civilization had finally put itself back together again.

Time passed by, Y2K came and went, but to her, it was only the dreamless flickering of an instant.

Finally she woke up, in a clean futuristic hospital room, surrounded by inscrutable machines that go "ping" and strangely dressed doctors with funny accents and weird hairdos.

She was just so happy to be alive that she proclaimed "Thank you so much for bringing me back to life! I am eternally grateful, and in your debt! Is there anything I can do to repay you? And by the way, what year is it?"

Then one of the doctors smiled at her cheerfully and said, "Yes, actually! It's the year 9999, and the records indicate that you're a COBOL programmer..."

</comment><comment><USER3> COBOL is usually asociated with the tuple [ Old, Mainframe ].

In tech you can get a job easily learning a new technology that's getting traction and hope demand is bigger that offer. This is a classic first job / career reboot case.

For old techonologies usually demand is lower than the offer. I don't know the exact case about COBOL; but I guess since boomers are retiring now, COBOL demand out there might unexpectedly grow.

And for the Mainframe stuff... Everybody says they're expensive, even without having seen an actual Mainframe bill, so it can be wrong (and might be a competitive advantage for some).

Bit since the 90s everybody has been trying to grab that Mainframe dollars, and that's too much time. Some succeeded with Client/Server, others with Java, Linux, Virtualization...

So, COBOL land looks unsexy. When it is already stablished it gets the job done; so don't expect headlines about COBOL except when something weird shows like Y2K.

</comment><comment><USER4> You can write expressive code in any language and you can write non-expressive code in those same languages. Real world COBOL (which would be COBOL 85 and earlier) is not going to be nearly as nice to write as many of the langauges that you provided as examples. You lack things like generics (which AFAIK are still not in the language) and collections (which show up in COBOL 2014). Until 2002 there wasn't free form COBOL either. Now, it is entirely possible for COBOL to make a comeback and become "hip", but it is going to require a lot of tooling and other development that just isn't happening now.

</comment><comment><USER5> It never was hip I believe - the perceived userbase of COBOL were "men in suits and black leather shoes", i.e. non-tech, business/MBA staff.

</comment><comment><USER6> COBOL was never "hip". It existed to do work, not to excite or entertain. It's the parcel van of languages -- not a Tesla, nor even an SUV.

But for a lot of needs over the past 50 years(!), that parcel van does a reliable job.

</comment><comment><USER7> This short video provides a good explanation: [https://www.youtube.com/watch?v=f3WVa2zyyGE](https://www.youtube.com/watch?v=f3WVa2zyyGE)

</comment><comment><USER8> Can you provide an example of a cobol script for doing a basic CRUD etc task that you find inspiring/simple/makes the point?

<comment><AUTHOR> Taking a look at this article [https://opensource.com/article/17/8/what-about- cobol](https://opensource.com/article/17/8/what-about-cobol) for example.

<comment><USER8> Thx

</comment></comment></comment><comment><USER9> COBOL existed to turn your army of clerks into programmers. Those people no longer exist.

The modern equivalent is Java.</comment>


A conversation with the Go team - <AUTHOR> http://blog.golang.org/a-conversation-with-the-go-team

<comment><USER3> "What surprises me is that almost nobody complains about the lack of generics."

Strange. Lack of generics is probably the single most common thing I read/hear people complain about.

(Btw, I like and use Go)

<comment><USER4> Sorry what's a generic? Can you explain it in Delphi 6 terms? er actually Python terms would be even better.

<comment><USER5> Generics are used to defer type setting from compile time to run time, allowing for flexible, yet type-safe constructs.

The classic example is a list (in a strongly-typed language) - <USER2> generics you would create specialised strongly-typed list classes - you could have a StringList (only strings), an IntList (only ints), etc.

Using generics you can define a single list class of type <T>, where <T> is any type. Then at runtime you would create a List<String> or a List<Int>. Same outcome, less code, easier to maintain.

MSDN has a good intro to C# generics - [http://msdn.microsoft.com/en- us/library/ms379564(v=vs.80).as...](http://msdn.microsoft.com/en- us/library/ms379564\(v=vs.80\).aspx)

They are less appropriate in dynamic languages, as type-safety isn't a compile time concern.

<comment><USER6> Runtime? Huh?

Whether it's static or dynamic is language-dependent. Example: Java in particular does erasure on parameterized types, so generics are _only_ compile-time.

</comment></comment></comment></comment><comment><USER7> It was so disappointing when I realized it was not referred to the band

<comment><USER8> Yep, but at least it's a good reminder to listen to them.</comment></comment>


Copyright Doesn't Mean Unlimited Control - <AUTHOR> https://www.eff.org/deeplinks/2016/05/copyright-doesnt-mean-unlimited-control <comment><USER2> I can't help but think that in this matter EFF (which I generally support) is far off the mark - at least re what the FCC is actually doing. Here's a quote from FCC Chairman Tom Wheeler:

"There is nothing in here that allows third parties to disaggregate cable content or sell advertising around it... It takes the same system that goes to the cable box today with the same structures and moves it through a different box requiring the same structures. As a result, existing copyrights and programming agreements are unaffected, consumer privacy is protected, emergency alerts are passed through and child protection laws are unaffected. Nothing in this proposal slows down or stops cable innovation."

In other words, the current copyright aggreements don't insist on a particular box, so the FCC is able to step in to insist on more competition in that regard - thus preventing cable companies from leveraging someone else's legitimate monopoly into a different unsanctioned monopoly of their own.

But could copyrightholders could be that specific? Could they insist on a particular means of reproduction (as they could with a printer.) Maybe.

However note that long established law finds that after you broadcast a copyrighted work, this narrows your rights. For example, see this perhaps extreme view of a recent EU decision: [https://falkvinge.net/2015/05/05/a-year-ago-the-european- sup...](https://falkvinge.net/2015/05/05/a-year-ago-the-european-supreme- court-appears-to-have-ruled-the-whole-web-is-in-the-public-domain-and-nobody- noticed/)

<comment><USER3> I am not sure I understand your issue with the EFF's position.

The EFF is _supporting_ the FCC's right to require set-top-box compatibility; their article says "copyright law prohibits copying, not 'doing anything with it' so we think that as a matter of law, the cable companies telling you not to use this regulation are simply wrong".

Do you disagree with this? When you say:

> Could they insist on a particular means of reproduction (as they could with > a printer.) Maybe.

are you suggesting that you think the copyright holders have a legal right to restrict what your set-top-box can do? If so, do you think that they ALSO have a legal right to restrict what your television set can do?

</comment></comment><comment><USER4> > _A television set is worthless without video programming to view, and a home > audio system has little purpose without music. One could argue that the > commercial value of these devices derives from the copyrighted works they > touch._

It's said that this sort of argumentation is still needed: it is home video tape recorders all over again.

</comment><comment><USER5> Of course the cable companies don't want this, because they charge exhorbitant monthly fees for the use of their hideous set-top boxes. It's just a pure cash cow for them.</comment>


We made an app that notifies you to send streaks - <AUTHOR> https://itunes.apple.com/us/app/streaktime/id1315631068?mt=8 <comment><USER2> What makes this more useful than the alarm clock or calendar features built into any phone?</comment>


The worlds first "Balsamic Subscription" - <AUTHOR> http://www.balsamicsauce.com/collections/frontpage/products/balsamic-sauce

<comment><AUTHOR> We do a lot of repeat business, so when I came across Recurhub.com... I immediately realized we needed to create a subscription balsamic option!

Note: just pushed this live about 5 minutes ago. Would appreciate any flaws or breaks that are found. Thank you HN!</comment>


Curiosity Depends on What You Already Know - <AUTHOR> http://nautil.us/issue/33/attraction/curiosity-depends-on-what-you-already-know <comment><USER2> Parallel ideas:

      -The thing you know the most define the things you laugh about
      -Arguments can be won on an abuse of dragging the topic to an area of your knowledge

And last but not least:

      "I know that I know nothing"[0]

Therefore you have curiosity.

[0] [https://en.wikipedia.org/wiki/I_know_that_I_know_nothing](https://en.wikipedia.org/wiki/I_know_that_I_know_nothing)

</comment><comment><USER3> Curiosity does increase the likelihood of survival by expanding the information an organism has or simply have it wander into a more effective or new way of living.

<comment><USER4> Curiosity can also decrease likelihood of survival. See: saying about curiosity and cats. But as a species you might be correct.

<comment><USER5> I believe he is absolutely correct when it comes to curiosity increasing the likelihood of survival of a species (ignoring the species problem [https://en.wikipedia.org/wiki/Species_problem](https://en.wikipedia.org/wiki/Species_problem)). Because others learn from the curiosity of others as well as the one that is curious. Even if the occasional damage is dealt to a species through curiosity, the other members will likely learn and benefit from the mistakes previous beings have made.

<comment><USER6> Curiosity is good for the group, but perhaps not for the individual?

<comment><USER3> In evolutionary terms, this is all that matters. For individuals it's definitely a crapshoot.

</comment></comment></comment></comment></comment><comment><USER7> I wonder how related this is to the mechanics behind confirmation bias. We all have a tendency to seek out get evidence that matches our "predictions" so to say. Maybe what we define as curiosity is actually just searching for the little hit of dopamine you get when you're right.

</comment><comment><USER8> People who are right-brained tend to be creative, curious and intuitive, while those ruled by the left are logical, strategic and rational

<comment><USER9> You can't seriously be saying logical people aren't very curious? :(</comment></comment>


Russian Journalist Charged for 'Controlling Minds' with '1984' Reference - <AUTHOR> https://www.themoscowtimes.com/2019/07/09/russian-journalist-charged-for-controlling-minds-with-1984-reference-a66336 <comment><USER2> Holy shit! Thought police are officially realized! (Ironic, right?)</comment>


Elevating Mechanisms of the Ancient Greeks - <AUTHOR> http://kotsanas.com/gb/cat.php?category=08 <comment><USER2> [http://www.lowtechmagazine.com/2010/03/history-of-human- powe...](http://www.lowtechmagazine.com/2010/03/history-of-human-powered- cranes.html)

</comment><comment><USER3> For a second I was excited to discover the secrets to the ancient Greek philosophers' enlightenment, but hey, cranes are cool too!

<comment><USER4> the secret is that if you're the first inquirer in a new field you get to make the proportionally highest number of discoveries!

</comment></comment><comment><USER5> See wally walington for contemporary usage of very Old tech.

<comment><USER6> If interested in "hard" masonry problems that had to be solved in ancient times, there's also Coral Castle [1].

1: [https://www.youtube.com/watch?v=nOoCuDnmtyM](https://www.youtube.com/watch?v=nOoCuDnmtyM)</comment></comment>


UDP vs TCP - <AUTHOR> http://gafferongames.com/networking-for-game-programmers/udp-vs-tcp/ <comment><USER2> The main difference between TCP and UDP, as this programmer discovered, relates to quality of realtime service.

Times to use UDP over TCP

      * When you need the lowest latency
      * When LATE data is worse than GAPS (loss of) in data.
      * When you want to implement your own form of error correction to handle late/missing/mangled data.

TCP is best when

      * You need all of the data to arrive, period.
      * You want to automatically make a rough best estimate use of the available connection for /rate/ of transfer.

For a videogame, having a general control channel to the co-ordination server in TCP is fine. Having interactive asset downloads (level setup) over TCP is fine. Interactive player movements /probably/ should be UDP. Very likely with a mix of forward error correction and major snapshot syncs for critical data (moving entity absolute location, etc).

<comment><USER3> I always wondered why nobody used UDP for bulk data transfer: Ship all the chunks over with a sequential number identifying each, then when you've reached the end, have the client request any lost packets, then repeat the cycle until all are transferred. After all, the client doesn't need everything in sequential order if it knows the size, and it can deal with holes as long as they're eventually repaired.

This gives you (in theory, I've never tried it) better throughout, and you get the equivalent of TCP's retransmission without the window semantics, since you move all the retransmissions to the end. On the other hand, it's probably bad for everyone else, since there's no congestion control.

<comment><USER4> NFS on Linux defaulted to UDP for what seems like a really long time. There were perf issues with TCP (can't remember what they were).

<comment><USER5> NFS used to default to UDP for the same reasons that games still would use UDP, it just needed the data as quickly as possible since it was blocking IO. Now a days, we don't need UDP for NFS because networks are a lot faster and the advantages of TCP start to over rule UDP.

<comment><USER6> The original reason was that using UDP was much faster CPU-wise back in the 80's. There was a requirement to go fast because it was used for transferring data in bulk, not events like games.

When Linux came around it just followed suit. TCP support came to NFS only later with other bells and whistles in later NFS versions, and Linux stuck with basic NFSv2 for a good while.

NFS was designed for local-area networks, so it didn't need to worry about working over the Internet.

In addition to the network being much faster relative to CPUs back then, the TCP stacks hadn't seen the tuning they have now. Making TCP fast came later.

</comment></comment></comment></comment></comment><comment><USER7> Do you want to hear a joke about UDP?

You might not get it, but I don't really care.

<comment><USER8> Here's a joke about TCP.

Here's a joke about TCP.

Here's a joke about TCP.

Here's a joke about TCP.

Here's a joke about TCP.

> ACK

</comment></comment><comment><USER9> The recommendation to avoid TCP altogether is surprising to me. Having encountered a number of video-conferencing systems which are in a similar space, it seems pretty standard to have separate real-time and control sockets on UDP and TCP respectively. I skimmed the linked paper and didn't find it conclusive; can someone summarize how it is that having a TCP socket can affect UDP traffic on the same interface?

All that said, I certainly see the argument for an all-UDP protocol in terms of defining your own retransmission approach, or attempting to avoid it altogether with forward error correction or whatever.

<comment><USER10> I too was wondering how TCP and UDP can affect one another on the same interface and the explanation I read is that at the lowest level both UDP and TCP segment data into packets and place them onto the same network adapter's queue which can affect they way they are transmitted under congestion depending on the device/drivers.

<comment><USER11> This makes no sense.

UDP will drop data if there is congestion. Basically, if you care about congestion and data loss, you should not use UDP.

\---

If you do UDP and TCP. The UDP transfer will loose data during congestion, while the TCP transfer will slow down and try harder.

This has some usage. For instance, videoconferences software will do TCP and UDP. The TCP is used for control data -low volume data that needs to work- (authentication/joining room/leaving/adjusting quality), the UDP is used for audio/video (some pieces may be lost during congestion, it's okay).

If you use UDP for everything, you'll randomly loose control AND audio/video. It's the worst of both worlds.

Not to be dismissive but I think the guy who gave you the advise doesn't really understand networking (or doesn't explain very well or was talking about some weird usage we don't know about).

<comment><USER10> Error checking can easily be added to udp for control data. Infact in IPv6 it's mandatory. At one moment you say udp will lose out, but we know tcp will back off on its reattempts exponentially based on the congestion window. Thus udp would win out. The argument wasn't that it was a significant impact, the argument is that they can cause interference.

<comment><USER11> > the argument is that they can cause interference.

UDP ignores everything else and always expect resources to be available for itself.

We could say that UDP interferes with everything, we could say that everything interferes with UDP, it's both ways.

<comment><USER10> Who chooses when a UDP packet is dropped? The freaking network adapter device driver which is what I said in the first place!

<comment><USER11> There is a lot more in the transmission chain than just _that_ driver.

<comment><USER10> But it's the driver of the NIC that manages its network packet queue! Then it uses a an interrupt to signal the OS that data is available or that the window is open for transmit. I'm totally aware there's a lot more to it, I do socket programming everyday.

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER12> The entire article makes me shudder in disbelief.

It's aimed at people who don't know the difference between UDP and TCP (and possibly wet string). Yet he recommends they implement their own reliably protocol over UDP, and they avoid TCP because it's better to implement your own QoS?

Why not add obtaining PhD in quantum mechanics just to round it out? It wouldn't alter the odds of pulling it off overly.

<comment><USER11> Agree.

For people who are not familiar with TCP and UDP, the answer should be to ALWAYS use TCP.

The only exception is some subset of games (FPS, RTS), that this article is exclusively intended for.

Even there, for the average user who just wanna make a test game project, TCP may be easier to use and program around. For simple games (e.g. Connect 4), TCP is a better option either way.

<comment><USER13> In the article he clearly states this is for things like syncing physics in BF4 or halo.

</comment></comment></comment><comment><USER14> I appreciate the first user comment on this article:

"I didn't care for this article 7 months ago. I regret it. My whole game is useless now. I should have go with udp."

</comment><comment><USER15> What are some alternative protocols?

It's been a while since my networking class, but if I remember correctly with UDP you have some serious issues where you can end up clobbering your network, filling up buffers in the middle and dropping tons of packets. The lack of congestion control is a huge no-no.

For instance in the example he gives, sure you can tolerate dropped packets for player-position data, but how do you know if you can tolerate sending at 10Hz 100Hz 1000Hz? Even with TCP you can't (I think....) programmatically adapt to the size of your pipe. That's kinda abstracted away for you so that you just say "send file A to B" and it does it for you

Are you supposed to write your own congestion control in userland???? Seems like this should be a solved problem

<comment><USER16> DCCP and SCTP are the two main alternative transport protocols on top of IP

      - UDP: unordered unreliable datagrams
      - DCCP: unordered unreliable datagrams with congestion control
      - SCTP: optionally-ordered reliable datagrams with congestion control
      - TCP: ordered reliable stream with congestion control

SCTP is the most widely used after TCP and UDP: it's often the transport used in phone networks (very popular with Ericsson); but also now with WebRTC (which uses SCTP over DTLS over UDP). The main issue being that consumer firewalls usually only support NAT for TCP, and limitedly for UDP (this is one of the 'other' reasons to look forward to IPv6)

</comment></comment><comment><USER17> > they may arrive out of order, be duplicated, or not arrive at all!

This is first time what I read that datagram can be duplicated. Is it true? It's duplicated by network or does it mean that peer send it again?

<comment><USER18> Packets can be duplicated by faulty routers and loops in the topology. Happens all the time to me when I'm lost with iptables.

<comment><USER19> Observed this recently with a bug in Cisco's VSS. Some packets were being duplicated, which destroyed TCP throughput.

</comment></comment></comment><comment><USER20> Anyone here knows what protocol should be used for mobile multiplayer games , provided they are real time and not turn by turn ? (think people playing on a decent 3g connexion).

I think you can't send a udp paquet to a phone because the carrier will block it, but i'm not sure.

<comment><USER21> Yes an update on this topic for the mobile world would be very interesting.

</comment></comment><comment><USER22> I tried to build an UDP library once in C# with different methods (BeginReceiveFrom, ReceiveFromAsync, ReceiveFrom). You learn a ton and it's quite interesting. My goal was to recreate something similar to .NET remoting based on UDP.

But be aware that it's a daunting task, because there are so many things you need to handle all together: lost packets, reordered packets, duplicate packets, connection handshakes, session handling, reliable/unreliable channels, packet resends, random disconnects, reconnects, network congestion, spoofing, protocol hacking attempts, dos-attacks, banning, encryption, etc...

If you're writing an UDP library, you also need to think of performance, object pooling, connection buffers, threading/async issues and on top of that you also want to provide a nice API to the outside world for the client and server... Well, it gets messy...

If you're into this thing, I can advice you to look at haxe libraries. Learned a lot of them. There are very simple, idiomatic server/client-side implementations which are easy to follow, even if you don't know haxe [1][2].

[1]: [https://github.com/svn2github/haxe/blob/master/std/neko/net/...](https://github.com/svn2github/haxe/blob/master/std/neko/net/ServerLoop.hx)

[2]: [https://github.com/svn2github/haxe/blob/master/std/neko/net/...](https://github.com/svn2github/haxe/blob/master/std/neko/net/ThreadServer.hx)

</comment><comment><USER23> Ah I love Glen's articles. Ive learned so much from them: game physics, integrators, game loops, game networking,..

<comment><USER24> Yes! His writeups on networked physics were extremely lucid and easy to follow. The way that he focuses on minimizing the bandwidth with bitpacking and goes from something absurdly large to equally absurdly small was a mesmerizing read for me as a programmer just getting started because of an interest in games.

</comment></comment><comment><USER25> Does anyone know if SCTP is suitable / in use by any games? It supports streams to work around the head-of-the-line blocking problem TCP runs into and it also supports opt-in unreliable delivery for game data. On the surface seems ideal for games, though I don't know if its getting much actual use.

<comment><USER26> Nobody who's in it for the money wants to be the first one to prove that SCTP can be deployed at scale. Application developers don't want to have to sort out getting a working SCTP implementation installed and configured on the proprietary operating systems they target, and past the firewalls of all the bottom of the barrel consumer routers.

<comment><USER6> You wouldn't use SCTP on top of IP, you would use on top of UDP and implemented in userspace. Browsers do it this way (in WebRTC data channels).

</comment></comment></comment><comment><USER27> "TCP has an option you can set that fixes this behavior called TCP_NODELAY"

That fixes nothing. Now you are sending too many small packets using too many syscalls. Just like UDP, buffer in user space, send in one go. If you do that, TCP_NODELAY makes no difference. (The exception is user input, if you want to send those as they happen, use TCP_NODELAY, but think about the why ... it has little to do with what this article is talking about.)

Games likely send data only around 25 times per second, and ping is likely < 50ms. Waiting on a dropped packet and the delay it causes is unnoticeable. Added that clients will need some kind of latency compensation and prediction, independent of the TCP/UDP choice. Delays and then bursts of 100ms or such are doable.

The problem starts when the connection stalls for more than 100ms, especially in high bandwidth games. During the stall both behave the same. After the stall, TCP will be playing catchup and wasting more time receiving outdated data, and handing it to user space in order. UDP just passes on what is received, with a lot less catching up, and maybe some dropping of packets.

But gameplay has been degraded in both cases. UDP just has a higher chance of masking and shortening degradation more.

Anything more than that is basically cargo-culting, like this article.

<comment><USER28> I will preface this with the fact that the author worked on at least one such FPS game (Titanfall 2) and probably know what he is talking about.

He offered one solution to fix one behavior of TCP, the behavior being that if the data written to the buffer is not big enough, TCP might hold it. Setting TCP_NODELAY forces the protocol to avoid holding data. But this is only written as a note to coders who might think TCP_NODELAY will fix TCP for action games, but it doesn't actually, because the protocol has other characteristics that are undesirable in that type of games.

Moreover, you write this: waiting on a dropped packet and the delay it causes is unnoticeable. Unless you have a FPS game with TCP as its network protocol to validate this claim, I call bull. Many network programmers recommend against TCP. This is probably not simple cargo-culting.

<comment><USER27> "TCP_NODELAY forces the protocol to avoid holding data"

That is the misunderstanding. It will send one non full packet, and only then "hold on to data" until the next packet is a full packet. But that condition will reset when all data has been acknowledged. If you buffer in userspace and write data in one go, at 25 network fps, you basically never trigger the condition where TCP_NODELAY makes a difference.

It is not nagle's algorithm, but a variant of minshall-nagle, what modern systems use.

There is a reason why FPS games use UDP, but that discussion should not start with TCP_NODELAY. That one is misused enough ... often when it fixes anything, it is because it masks a real underlying problem, had you fixed that problem, your system would react much better under stress or bad networks.

</comment></comment></comment><comment><USER29> This feels like a nice introduction.

Anyone here have any experience using QUIC in any application of their own?

The custom congestion control makes me wonder if it only works alongside TCP traffic - once everything goes QUIC, then what happens? I looked for a bit about the story in ancient history of some blazing fast server OS TCP implementation that broke the rules so it fell over when more than one server was on the network, but couldn't find it.

<comment><USER30> QUIC seems like it'd be kind of neat for videogame networking. Does anyone know whether one can get a QUIC channel to deliver datagram-style, as in unreliable and no retransmitting? It'd be really cool if you could set up one QUIC connection that could work across IP address changes and then use it for N reliable TCP-like streams and M datagram-style game update packet channels. If you could set up that sort of thing from JavaScript in a web browser, that'd be straight up amazing.

</comment></comment><comment><USER31> reminds me of this old article we had as assigned reading during a networking class in school.

The Internet Sucks: Or, What I Learned Coding X-Wing vs. TIE Fighter ([http://www.gamasutra.com/view/feature/131781/the_internet_su...](http://www.gamasutra.com/view/feature/131781/the_internet_sucks_or_what_i_.php?print=1)).

</comment><comment><USER32> In short, TCP will work hard to deliver 100% of the packets. So when a packet is lost, TCP asks to re-send the packet. This is fine to display a webpage or send a file, but it can't be tolerated in games where time continuity matters. I think it's the same issue in VOIP and video conferencing too.

</comment><comment><USER33> The reality is that these days there generally isn't any packet loss, so UDP vs TCP isn't such an issue as it might have been in the past. In fact TCP has a number of advantages these days such as easier firewall traversal, WebSockets, etc.

<comment><USER19> >The reality is that these days there generally isn't any packet loss

Do you have any sources/data on that? Genuinely interested where you drew that conclusion from. From my vantage point (anecdotal), ISPs and carriers routinely under-provision, congest peerings, and don't find a problem well until after a number of customers complain.

<comment><USER26> Bufferbloat means that at many potential bottlenecks, you don't get any packet loss until well after the point at which your latency-sensitive application (be it TCP or UDP) has given up hope. Major peering points are pretty much the only place where you _won 't_ see >1second queues when congested, simply because they can't afford buffers that deep for the rates they operate at. But for ordinary everyday occurrences, your congestion will be somewhere around the last mile, where you cannot expect packets to be dropped within a reasonable timeframe.

<comment><USER34> [https://www.bufferbloat.net/projects/bloat/wiki/Introduction](https://www.bufferbloat.net/projects/bloat/wiki/Introduction)

Introduction

Bufferbloat is the undesirable latency that comes from a router or other network equipment buffering too much data. It is a huge drag on Internet performance created, ironically, by previous attempts to make it work better. The one-sentence summary is "Bloated buffers lead to network-crippling latency spikes."

The bad news is that bufferbloat is everywhere, in more devices and programs than you can shake a stick at. The good news is, bufferbloat is now, after 4 years of research, development and deployment, relatively easy to fix. See: fq_codel: wiki. The even better news is that fixing it may solve a lot of the service problems now addressed by bandwidth caps and metering, making the Internet faster and less expensive for both users and providers.

The introduction below to the problem is extremely old, and we recommend learning about bufferbloat via van jacobson's fountain model instead. Although the traffic analogy is close to what actually happens… in the real world, you can't evaporate the excessive cars on the road, which is what we actually do with systems like fq_codel wiki.

Still, onward to the blow.

[...]

</comment></comment></comment></comment><comment><USER35> If you want to get familiar with TCP/UDP and are not gun-shy with C I would suggest the Pocket Socket Guide (now Practical Guide to TCP sockets)[1]. I have a really old edition, but it ages extremely well, and its one of the books I always use to refresh myself on network programming basics.

[1]: [https://www.amazon.com/gp/product/0123745403/ref=ox_sc_act_t...](https://www.amazon.com/gp/product/0123745403/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER)

</comment><comment><USER36> A huge problem with TCP wrt gaming is the default ACK frequency on Windows which is set to 2. This effectively almost doubles the latency of game connections (sending/receiving a lot of time-sensitive small packets).

It can be changed with a registry setting (TcpAckFrequency) but you can't expect even a significant fraction of your users to do that. Why this isn't a per-connection option sort of like TCP_NODELAY is beyond me.

</comment><comment><USER37> I thought that it was somebody who has recently discovered the existence of UDP protocol and brags about that to the world, but from skimming the article, it actually has some non-trivial remarks about UDP and TCP.

BTW, the article's view angle is multiplayer game programming.

<comment><USER38> This guy (Glenn Gaffer) has been writing network protocols for games for years and shipped popular titles.

On his site you can also find an irate rant about people with no experience dismissing his claims as "reimplementing TCP". It has good points but it's a frustrated rant (reader beware). But it addresses a lot of the commonly believed fallacies.

His latest project is an open source library for game networking over UDP: [https://github.com/networkprotocol/libyojimbo](https://github.com/networkprotocol/libyojimbo)

And he is correct, for "real time" games you must use UDP or you will be in trouble in real world networking conditions. When everything runs smoothly, TCP and UDP work almost identically but when packet loss occurs, TCP will make things _worse_.

<comment><USER39> Glenn _Fiedler_ - Gaffer is his online name / handle.

Worked with Glenn on Freedom Force and Tribes. He knows his stuff!

</comment></comment></comment><comment><USER40> There was a similar discussion in Hackernews earlier - [https://news.ycombinator.com/item?id=7507377](https://news.ycombinator.com/item?id=7507377)

</comment><comment><USER41> What about UDT? I never tried it but always wondered about it's benefits/disadvantages.

</comment><comment><USER42> Another important difference: UDP can't be used in the browser =(

<comment><USER43> WebRTC is UDP. It's not easy, but it's there!

<comment><USER44> nitpick: It can be either

<comment><USER45> It is possible to use only one or the other.

</comment></comment></comment></comment><comment><USER46> That's a pretty obnoxious 'donate' button. They can't make it even larger?

<comment><USER47> The guy is providing valuable information for free, he can make his donate button as large as he wants.

<comment><USER48> Yeah, sure. He can put the Donate button all over the screen if he wants but then no-one would donate. I also think it's obnoxious.

</comment></comment></comment><comment><USER49> I think tcp have an unfair reputation. Our networks are better now then 30 years ago ... Worst case latency for tcp is like 3 seconds, compared to the packet never arriving. The trick is to hide the lag with animations. I think google, facebook, and world of warcraft use tcp for their real time apps !?

<comment><USER50> Sad to see you being downvoted when you're absolutely right. Yes, UDP is better for a twitch game, at the expense of a lot more work. No, unless you're building a AAA mouse-and-keyboard shooter, you probably don't need more than a TCP connection sending data packets back and forth using a somewhat well- thought-out protocol.

<comment><USER49> I think the biggest mistake is _only testing the app on localhost_. While real world users can experience up to 150ms latency and fluctuations. It doesn't matter if you use TCP or UDP you still need a strategy for handling different levels of latency. For testing I use netem to add delay ...

The second biggest mistake is _trusting the client_. People never cheat in online games, right !? _smile_ Network latency is often less then it takes to render, so naive solutions with simple broadcast servers work well until you need to deal with rouge clients using teleport hacks etc.

There are no set rules when making real time distributed and scalable applications like MMO Games. In my experience it's best to start with a naive demo/prototype to see where the bottlenecks are. I would suggest starting with TCP and then only switching to UDP, or more likely making your own protocol (TCP ontop of UDP _smile_ ), when you know the requirements.</comment></comment></comment>