Alternatives to Parse? - <AUTHOR> Parse is shutting down, which sucks. What alternatives are out there at are comparable? <comment><USER2> Parse Server: [http://blog.parse.com/announcements/introducing-parse- server...](http://blog.parse.com/announcements/introducing-parse-server-and- the-database-migration-tool/)

Other than that, I'm looking for something myself.

<comment><AUTHOR> Parse Server doesn't handle Push Notifications.

</comment></comment><comment><USER3> If you are interested in push notifications, I'd recommend you Pushwoosh. Flexible pricing, long trial period for intensive testing, fast support.

</comment><comment><USER4> Still trying to work out if AWS is a viable alternative but seems complex.

</comment><comment><USER5> Firebase

<comment><USER6> Firebase is lacking in terms of ease of use and feature set.</comment></comment>


Spotify vs the US Competition - <AUTHOR> http://blog.like.fm/top-5-music-streaming-services-reviewed

<comment><USER3> Spotify's discovery is better than a 4. Since a playlist can be represented by a URL, sites have emerged to share playlists, which is actually awesome, one of those living in the future moments. Even better, these can be dynamic, like a top 40 list, and also curated by everyone.

That said, Spotify could certainly do much more in this area (a lot of their energies have been focused on getting the US launch, it seems).

<comment><USER4> This.

See spotylist.com, discovery through non-friends playlists beats algorithms as you can understand why songs are grouped together and get a feel for a persons music tastes.

<comment><AUTHOR> I'm not sure if any "social" type of discovery can beat algorithmic in quality. The added benefit of "social" is the socializing bit, not the discovery bit. Algorithms can always match you up with similar people faster and better.

But thanks for the link I'll re-consider the rating.

<comment><USER5> After testing out Turntable.fm for the past few weeks, I have to almost disagree. And this is coming from someone who worked on Grooveshark Radio for a year, which is almost all algorithmic.

<comment><AUTHOR> Turntable is fun with friends. But being a listener in a DJd room is no different than listening to a curated playlist, a curated radio station, and probably worse than personalized algorithmic radio in terms of efficacy of discovery.

You'll discover music on Turntable, but for the same amount of time spent on an algorithmic radio station you'll probably discover more.

<comment><USER5> You might "discover" more in the sense that you'll get far more recommendations of songs you've never heard of, but those recommendations might not be relevant to you. Why? Because your mood changes from song to song and algorithms will never capture human emotion quite like, well, humans.

When I'm in a well-DJ'ed Turntable room, the "radio" feels so much more natural. Songs flow. People are constantly editing their queues to best the song before it and I find myself rarely having to vote on a song. Its already better than Pandora, IMO. It also beats BMAT which has amazing algorithmic recommendations (based on waveform analysis and musical feature decomposition).

The only issue I see right now is that if your tastes are outside of Electronica and Indie, theres not much else for you at the moment.

</comment></comment></comment></comment></comment></comment><comment><USER6> After two days with a free account, on a Mac, I noticed this:

\- If you mute your speakers via OS X while an advertisement is playing, it pauses the ad until you unmute your speakers.

\- If you turn down your speaker volume via OS X too much while an advertisement is playing, the same behavior occurs until you turn the volume back up. This appears to be relative to the volume you were just listening to music at.

Quick fix around this; use headphones. Just take them off to ignore an ad. Or if you have a separate sound system, mute that. Annoying if you have a laptop though. This behavior doesn't occur when music is playing.

<comment><USER7> Does this happen on a PC?

<comment><USER8> Yes, but I if I remember correctly it does not happen if you run the PC version in wine on Linux.

</comment></comment></comment><comment><USER9> Out of interest, does Spotify (the free version) for US have the 5 plays limit on each song? Having limited numbers of hours I can deal with, but after they introduced limited plays on Spotify, I practically never used it again after my premium account ran out.

The 5 plays doesn't appear to renew at the end of the month like the number of hours, and it just means that my playlists have more and more holes in them (as often has happened when artists suddenly change their minds over streaming). Spotify tried to explain that most of their users only use their service to discover new music – maybe I'm too hipster for them, but the new and interesting music I want to listen to isn't generally in their catalogue, and last.fm's discovery features are much better.

When they provided everyone free access for unlimited plays (with ads, granted), most of my friends used it and updated their playlists — which I would subscribe to and we'd drop music on to each other's user icons and share interesting music. Now, even if I were to re-upgrade to premium (which I probably won't, especially when in the UK we appear to be getting a raw deal in cost), it's like a ghost town.

<comment><USER6> They don't seem to mention it anywhere on the U.S. site. It appears in Europe that they have a 5-plays-per-track limit for free accounts, but not paid accounts.

<comment><USER10> It's mentioned on their terms and conditions page in the first paragraph: <http://www.spotify.com/us/legal/end-user-agreement/>

</comment></comment></comment><comment><USER11> Where is Last.FM on this list? It's actually the best (in my opinion) service out there. Their "discovery" feature is the best, and simplest to use - <USER2> choose "Play artist/song/tag XXX radio", and it will play related songs for you. Their catalog seems immense, and I listen to some of the most obscure stuff out there (/hipster joke). And it's completely free.. the only thing it doesn't do is play music "on demand", but nobody else got that right either (for free).

<comment><USER12> > And it's completely free

Am I missing something here? I've got 30 plays on my trial account and after that it asks me to pay for subscription.

<comment><USER13> You're missing living in (or proxying to) the UK, US or Germany, where it's still free.

<http://blog.last.fm/2009/03/24/lastfm-radio-announcement>

</comment></comment></comment><comment><USER14> I have been a huge Rdio fan for awhile and after playing with Spotify I have come to the conclusion that Spotify is great if you don't want to pay, if you want to pay then Rdio is much better because of the method in which it presents new music to you. I get the feeling in 6 months the front page of Spotify will be new albums which compete for attention space on your monitor by how much money is put behind them - pushing them into your view, where as Rdio (because it is paid for) will continue to be a screen full of albums liked by your friends or people you follow. I much prefer the later, however the former isn't a bad option if you don't want to pay for anything.

</comment><comment><USER15> I signed up for Spotify and was pretty disappointed. I have years and years of Data in iTunes, and the only thing Spotify does is pull out tracks. It won't even sync my SmartPlaylists. So it's kind of like starting over. Not something I'm willing to do.

<comment><USER16> I'm a Spotify dev. What sort of data would you find most useful to have extracted from iTunes?

The reason we don't do the smart playlists is that we just take a snapshot (the lists aren't kept in sync) and the very nature of smart playlists is that they are dynamic.

<comment><USER17> Even a snapshot of smart and dumb playlists would be better than nothing. The use case is, users who want to migrate to Spotify from whatever they've been using for years, intend to copy over their playlists to Spotify, and permanently switch to Spotify as their main playlist organizer/generator. But having to recreate all their playlists by hand in Spotify is enough to stymie even the most enthusiastic US/NA Spotify fan.

Same problem on the Android app I just discovered yesterday, all my local playlists are made with a third party app called Playlist Builder, and both PowerAMP and Google Music can use them, but apparently not Spotify. I only have Premium, but it seems Premium is intended to enable local music and playlists just not sharing and streaming...

<comment><USER16> What format is Playlist Builder using, m3u perhaps?

<comment><USER17> .m3u8, all stored in what appears to be /Playlists, though my phone isn't rooted so I'm not sure if that's the highest level of the directory structure.

</comment></comment></comment></comment></comment><comment><USER18> Can we subtract 1-2 points from Grooveshark for their questionable legal tactics?

Awesome comparison, Chris. This should be the go to page used to respond to any question about these services.

<comment><USER5> How are our (I'm a grooveshark employee) legal tactics questionable? We sign deals with new labels all the time and our #1 company-wide goal is to help an artist make over $1M through our service. Here is a list of all our label agreements: <http://www.grooveshark.com/labelslist>. I don't think its updated though since we have a deal with EMI and I can't find it on the list. Yes, a few of the other majors are missing, but that is always an on-going conversation. We also fully comply with the DMCA in the same way YouTube and all other UGC sites work. Case in point: try searching for Beatles.

<comment><USER18> Grooveshark has been playing a lot of copyrighted material without licenses for a very long time. It takes it down; the content reappears. I understand that you're somewhat protected by DMCA, but the entire business was built on the backs of mostly mainstream content. It wasn't until you already had a big audience that you started securing the majority of your most important licenses, and plenty of the music there is still not properly licensed. EMI is a perfect example. Only recently did you get a license from them, and yet their artists have been playing on Grooveshark for ages.

If you really did a good job of making sure the music that was uploaded wasn't copyrighted, you wouldn't have a business because nobody would be looking for that music. The period between illegal mainstream content going up, and that content coming down, is just long enough for Grooveshark to have a competitive cost advantage over companies who properly license their material from day one.

If the tactics aren't at least "questionable", then why has Universal declared "legal jihad" on Grooveshark?

P.S. My band's music is on your site. I didn't put it there and neither did anybody else with proper authority to do so.

<comment><USER5> Its not a black or white issue. Licensing is incredibly complex with ownership sometimes changing between territories, products, people and having the technology in place to enforce specific terms so all parties are happy. I'm not completely knowledgeable about the subject so I won't comment on that further, but its not something we turn a blind eye to. Our content ID system is getting better and better. Ultimately its a question of resources, and when you're a cash-starved startup, you're spread super thin.

My point is that we genuinely do our best to help artists. We're good people. If you want your band's presence taken down, you're entitled to have that done for you. You can also leave your music up so millions of users can discover it and find out more about who you are. We have tens of thousands of individual artists managing their own music and we get tons of fan mail from artists who say that our platform has not only decreased piracy but has actually encouraged fans to buy more of their music and see their shows.

<http://www.digitalmusicnews.com/stories/040811grooveshark>

<comment><USER18> I'm not going to lie, we're competitors, and I have plenty of people tell me they're happy with Grooveshark, and that you provide a lot of value. I also hear the other side, and I hope that Grooveshark gets what it deserves from Universal.

The fact still remains that Grooveshark as it is wouldn't exist if not for the many years it's had to benefit from free use of mainstream content. That's not what DMCA was created for. It was created to protect people who mostly have UGC and occasionally have their terms violated. If Grooveshark was one of those companies, they would look more like Unsigned.com right now.

The music industry's legal system is complex. We all know that. Other companies are navigating that complexity in much more difficult ways, being much more honest to the spirit of the law. Grooveshark takes advantage of the laws and operates a service that has only one foot in legality. Of course it would be easy to build a business that way and then get the praises of those companies you forge relationships with _after_ your audience and platform is already valuable. But there is more to be said for a company that takes the hard road and does the same. I think Pandora has had a miserable time of it, but at least they did it right.

<comment><USER5> Whichever way you look at it, building a business in the music space is difficult. We're all probably competing with piracy more so than each other. There is no good road. You make it sound like we've had it easy, which is not the case. Every employee has at some time gone without pay for an extended period of time. Mine was 10 months. That's the sort of dedication it takes to bring a product from a thousand users to millions when you're underfunded. And our relationships didn't form suddenly when we had millions of users. They were the result of years of work in the trenches when our userbase was small- going to concerts, promoting artists, branding our site...basically everything we could do to get their songs heard.

<comment><USER18> I think you're straying a little from the topic. Yes, company building is hard. No, that does not make it okay that Grooveshark built it's business by streaming a lot of mainstream music that it didn't, and in many cases still doesn't, have licenses for.

I didn't say you've had it easy. I said you built your company on the backs of artists' content without paying them. So, each employee went a few months without pay. Most of the artists playing on Grooveshark went (and are still going) much longer.

</comment></comment></comment></comment></comment></comment></comment><comment><USER19> I'm in Canada and was disappointed that we were cut out of the stateside Spotify launch, so I went looking and heard a number of recommendations for Rdio.

Out of 18,384 tracks it matched 3,142. Considering my tastes are pretty mainstream and my files have very clean tags, it's hardly impressive.

<comment><AUTHOR> With most of these services you're bound to not be able to find a few songs. What's important is whether or not it fails gracefully into letting you manage those missing music files yourself and Spotify, Rhapsody, and Grooveshark are the only ones that let you do that to some extent.

<comment><USER19> True, but I expected them to have more deals in place. Most artists are missing key tracks, albums, or aren't represented at all. I also don't really think it's a few songs. Knowing my library and how mainstream it is, at least 8,000-10,000 tracks should have been matched. That's my library minus most independents and instrumentals.

</comment></comment></comment><comment><USER20> I just started playing around with spotify and the one major feature missing is something akin to itunes genius. I wonder if anything like this is in the works?

<comment><USER21> Not really. In Europe Spotify does have radio features - both genre and artist-based versions. But to be honest, neither option is very good. My music tastes don't seem to fit in well with the genre options you have on Spotify, and the artist-based radio plays that artist way too much, so you don't get a lot of variety. --Hopefully this is something Spotify will try to do better on. Right now you really have to know what you're looking for.

</comment></comment><comment><USER22> The killer feature in Spotify for me is that it aggregates the music on my HDD and their stuff. I have a library of 14000 songs, so it's nice to have all of this music side by side.

The higher quality MP3s in the premium version is a nice touch too.

</comment><comment><USER23> Unless the US version of Spotify is drastically different from the European version, discovery on Spotify is excellent in my opinion. The Radio feature does exist (although it's not one of Spotify's strongest features) and when you're on an artist page there is a tab to view related artists. There is even an radio tab on the artist's page which will play music from related artists.

<comment><USER24> The radio feature is not available in the US.

"The lack of a radio feature for the time being is a factor of licensing agreements with the rights holders but it will eventually be available." [http://getsatisfaction.com/spotify/topics/radio_mode_missing...](http://getsatisfaction.com/spotify/topics/radio_mode_missing_in_premium_us_account)

<comment><USER23> That's a shame for now, but the fact that related artists are presented very clearly (and you're able to quickly see their most popular songs) doesn't make discovery as bad as the article is claiming. I find myself listening to a lot more different music with Spotify than other discovery services such as Last.fm.

<comment><AUTHOR> Pretty much every service out there has related artists. But the US version of Spotify has _only_ that.

<comment><USER16> There is also friend's playlists, which I find very useful to discover stuff.

<comment><AUTHOR> Amounts to browsing random peoples' music. Compared to MOG's discovery features, MOG's is much better. You might get lucky if a friend just happens to find lots of new music you like though.

<comment><USER16> You can add Spotify-users to your friends list too, you don't need to be Facebook friends.

To add me, go to spotify:user:parbo or <http://open.spotify.com/user/parbo> and click the "Add Pär" button.

</comment></comment></comment></comment></comment></comment></comment><comment><USER25> Spotify should lose a point for having no web based player. Installing the Spotify client on a friend's computer can be kind of intrusive.

All of them should lose a point for having not having an integrated music locker to fill in the holes where they don't have licenses to certain tracks.

<comment><AUTHOR> You can fill in the holes with Spotify, Grooveshark, and Rhapsody.

<comment><USER25> Speaking to just Spotify (and Rhapsody if I remember correctly), only in some scenarios. On your local machine it is easy to fill in the holes. On your phone you have to sync everything over wifi, this is slow and limited by your phones memory.

Comparatively these limits don't exist on Amazon Cloud Player where I can have much more music the my phones memory and after syncing it to their servers I don't have to sync it with each device I have.

</comment></comment></comment><comment><USER26> I was very unimpressed with Spotify when it launched in the US this week. The app (at least on a Mac) seemed very non-native and used a lot of resources when it was inactive. It apparently uses Flash, so that may be it. It can't connect to my speakers, though that's Apple's fault more than Spotify's (AirPlay). I saw some top music lists, but not much else. My iTunes Playlists sort of came over, but not the Smart Playlists which are the only ones I use. Didn't see any recommendations.

tl;dr I closed the app and haven't listened to any music with it.

<comment><USER27> I strongly encourage you to give it another try. Spotify is not iTunes or Pandora, it has very different strengths. At least here in the UK, it streams insanely quickly, streaming starts immediately and the size of their catalogue is simply incredible. You might still find that you don't like it in the end but I wouldn't give up on it after five minutes, really.

Also, just to clarify a few things: it's not based on Flash. It's written in C++. It uses Ogg Vorbis. The user interface closely resembles iTunes so if you're familiar with that (many people are) Spotify shouldn't be too confusing.

</comment></comment><comment><USER28> "…suffers from one same key issue as Rdio: the inability to manage non- catalogue music makes it incapable of being an exclusive music player."

This is simply not true. I am an exclusive Rdio user and despite the opinions of the author, their management system does not render it useless as an exclusive music player.

<comment><AUTHOR> There are many songs not in Rdio's catalog and I have to pull up iTunes to play them. I cannot mix and match non-catalog music with Rdio. I did not say it's useless, just that it cannot be my exclusive music player. Furthermore this becomes even more of a hassle on the go as I would have to pull into a different app on the phone to play non-Rdio music. New releases will not show up instantly in Rdio and there's no way to get them into Rdio's interface. MOG suffers from the same issue.

Of course this has been my experience. I reason it's possible for someone to be completely satisfied by Rdio's catalog but for most people there will be missing music.

</comment></comment><comment><USER29> Is there a reason Slacker is not reviewed?

<comment><USER18> They are a radio service. This is a review of on-demand services where you can access songs whenever you want and build your own playlists.

<comment><USER29> Their premium service is on-demand.

<https://store.slacker.com/store/Subscriptions.do>

<comment><AUTHOR> Ok thanks for the tip. I'll try to review their premium service too.

</comment></comment></comment></comment><comment><USER30> Spotify "discover" 7/10 IMO, I find new music everyday via Spotify + Facebook integration.

Though discovery should not get high ratings in 2011 as there are so much that could be done using social and Music-DNA to discover music - so giving any of these services more than 8 is just a joke.

<comment><AUTHOR> If you only use Spotify and whatever it provides to discover music then you will discover music from what Spotify provides. The rating is relative to what the other services provide, and a service like MOG provides a superior discovery experience.

0/10 means you cannot discover any music, which is almost impossible to achieve. 4/10 means yes it's possible to discover music but the features are not very optimized for it or they dont perform as well as other services.

Discovery isn't weighted very heavily in the overall rating since there are plenty of other places to discover music from.

</comment></comment><comment><USER31> Kept hearing about Spotify this week and after reading this article decided to give it a try...and found like almost everything else involving media, Canada's left out in the cold. Guess I'm sticking with grooveshark for now.

</comment><comment><USER32> The "social" component of these services are worthless if your friends aren't there. Most of my friends and co-workers are on Rdio, so I plan to stick there for the foreseeable future.

<comment><AUTHOR> Even if they are you'll find that it's mostly inconsequential towards your day to day music listening.

</comment></comment><comment><USER33> does anybody know what these apps, such as spotify, are written in, and any hints on resources used? itunes is good at not spiking CPU usage, which means listening to music while running servers, doing dev work etc. is possible, while some fat clients (especially thinking of Adobe AIR here) are just terrible

<comment><AUTHOR> Rdio's desktop app used to be adobe air. Now it's something else, probably native. Spotify is C++. Most of the others are just browser sites. Grooveshark is now mostly HTML5 with the music playback component in flash.

<comment><USER34> Rdio is some native UI, a lot of HTML, and a copy of the Flash runtime (I installed it just last night, and was curious about why it was so large).

</comment></comment></comment><comment><USER35> I can't figure out this rating. What perspective are you taking on usage? Technical user? Casual music consumer?

</comment><comment><USER36> I have no incentive to switch from Grooveshark to Spotify since I'm grandfathered in to Grooveshark's $3.00 a month plan that has no ads and lets me stream to my phone.</comment>


Chrome 79 no longer shows preflight CORS requests - <AUTHOR> https://httptoolkit.tech/blog/chrome-79-doesnt-show-cors-preflight/ <comment><USER2> TL;DR: CORS preflight OPTIONS requests are "going to be completely invisible to you."

"We moved CORS checks out of our renderer process to (among other things) ensure that we're not exposing cross-origin data to Spectre, et al. In the short-term, this is a pain in the ass for developers, and I'm sorry for that. I do hope it's temporary." [https://twitter.com/mikewest/status/1227918108242989056](https://twitter.com/mikewest/status/1227918108242989056)</comment>


An example HTML5 game: killing cockroaches teleported on your slice of pizza - <AUTHOR> http://cockroach.herokuapp.com/

<comment><USER2> Needs some sound, especially a cockroach squash sound when you get one.

<comment><USER3> more important than sound, add a random gut splatter. The most satisfying thing about stepping on cockroaches is trying to send the gut fluids as far as possible. The sound is hardly heard even on the crunchest ones.

</comment></comment><comment><USER4> Pizza vendors are going to hate this...

<comment><AUTHOR> I hope they're not gonna sue cockroaches

</comment></comment><comment><USER3> that is beautiful.

<comment><AUTHOR> thanks

</comment></comment><comment><USER5> wtf

<comment><AUTHOR> what's wrong?</comment></comment>


Khan Academy Triples Unique Users To 3.5 Million - <AUTHOR> http://techcrunch.com/2011/10/19/khan-academy-triples-unique-users-to-3-5-million/ <comment><USER2> Count me as one of those recent sign-ups. I've been doing Khan Academy religiously for the past month, and have gotten up to 800,000 points and 185/211 exercises. The practice board is addicting and fun, and reminds me in ways of role playing games (like Final Fantasy XI's "License Board"), which I've always been a fan of. After I finish, I plan on moving on to the MIT OCW math classes.

I can't imagine how much easier K-12 would have been had Khan Academy been around. I've looked at other math and learning resources, and while they're all solid in ways, there just seems to be something that Khan "gets" that others don't, even if it's just as simple as a good UI and design.

In my opinion, Khan Academy is worth every ounce of hype, and I'm usually someone who is strongly anti-hype.

<comment><USER3> This is gonna sound stupid but I'm serious. Did you learn anything worthwhile from your investment? Any new useful "skill" or all just top level knowledge? Do you consider materials learned from Khan life changing?

<comment><USER4> Why would it have to be life changing in order to be useful?

The trade-off could well be watching soaps vs re-doing your high school or university level math.

<comment><USER3> I meant useful or lifechanging as two seperate questions -- no correlation.

</comment></comment></comment></comment><comment><USER4> I love the Khan academy, it is one of the best things that came out of the internet to date.

But I really wished that they would allow me to sign up with them and them alone without having to use either google or facebook to log in, that's a really bad mistake on their part imo.

<comment><USER5> Why? Things seem to be going well for them (look at the article you're commenting on). There are smart web people building this system up; presumably this is something they thought hard about before implementing.

<comment><USER4>
      - facebook and/or google may not be around forever

      - my account with facebook and/or google could get disabled by them on a whim,
        severing my link with the Khan academy

      - there is no upside to me to log in with a facebook
        and/or google account

      - there is a downside, which is that I have to sign up for a different service, that
        I may have valid reasons for not wanting to join (in the case of fb that does not
        require a whole lot of imagination)

And so on.

Really, when you only allow people to log in to your site by forcing them to become a member of another site first you are creating a barrier that need not exist.

I'm sure there are plenty of valid reasons for them why they do it this way (possibly, for instance because google and facebook do a lot of work to ensure that their accounts are only given out to those that deserve it, thereby cutting out on spam), but for _me_ it does not work.

For sure that is a small minorities, but small minorities are at least still allowed to speak up. Good thing HN does not require a facebook or a google login.

<comment><USER6> This is also a problem for some school boards. My sister is using Khan Academy with her ELL students (they don't speak any English but Khan's working great for them).

Signing a student up to a standalone service is no problem, but as soon as that service includes email or other student communication, the teachers need to get parents' consent.

This is really limiting the adoption across the rest of her school, they don't really want to get everyone a new GMail or Facebook account.

<comment><USER7> We're aware of this, and as @genieyclo said, Google Apps for Education is currently the easiest way for a whole bunch of students to get going. We've been successful using Apps for Education with all of our pilot Khan Academy schools so far.

That being said, we're thinking about becoming our own identity provider as well, primarily for this reason.

Just one of those things that's on the list and has to be weighed against everything else -- the majority of our users are doing just fine w/ Google/Facebook.

<comment><USER4> Super, great to see it's on your radar. Thank you very much for all your hard work.

</comment></comment></comment></comment></comment></comment><comment><USER8> Isn't it required to be at least 13 years old to have a google account? How does this affect the kids who want to use khanacademy? Are they forced to have a facebook account?

EDIT: Actually, facebook also has a minimum age requirement of 13 (<https://www.facebook.com/help/?faq=210644045634222>). Can't see how khanacademy missed that. I think this is a major flaw in their signup system. Should they (khanacademy) really be blocking every kid younger then 13?

EDIT2: It seems like they address it here (<http://www.khanacademy.org/about/getting-started>) but their solution is having the parents create an account for the kids.

I don't really think this is actually acceptable by facebook's terms of service though, not sure about google. See point 4 in <https://www.facebook.com/terms.php>

<comment><USER9> From <http://www.khanacademy.org/about/getting-started>

\</comment></comment><comment></comment><comment></comment><comment>-----

If your students are under 13:

You currently have two options: you can sign your school up for Google Apps for Education, which will help you provide each student with a Google account that can be used with Khan Academy, or you can have your students' parents individually create accounts for each student on either Google or Facebook. We are constantly working to improve this situation, but that's the best we've got at the moment (sorry!).

If you already have Google Apps for Education accounts but aren't able to use them to sign in on the Khan Academy, you might need to upgrade your account.

<comment><USER8> That's only for people with Google Apps for Education (teachers)!! Also, if you are under 13 you can't use the site if you didn't sign up with google/facebook (which have their own weird under 13 rules)

See "1. Eligibility" in (<http://www.khanacademy.org/about/tos>)

EDIT: Also, I found out that youtube actually doesn't let anyone under 13 use their service, so I'm guessing you can't watch the videos either if you're under 13. See "12. Ability to Accept Terms of Service" in ([http://www.youtube.com/static?gl=US&template=terms](http://www.youtube.com/static?gl=US&template=terms))

I just found out the internet is just for people over 13...

</comment></comment><comment><USER10> I hadn't looked at Khan Academy in a year or so, but it looks like they've vastly expanded their offerings since then. In particular, they've added a couple of hundred lessons of Art History stuff, which I'm quite keen to look through.

The mathematics and physics stuff would have been great for me... if it had existed fifteen years ago.

</comment><comment><USER11> I think it would be nice if MIT (and others) would make a deal with the khanacadamy to provide there courses in a khanvideo style and change there exercises in khan-style exercises. Everbody on the World should be able to learn anything from 1+1 to quantum physics on khanacadamy.

OCW kind of stuff is already super awesome but in would be much better in a khan-style. When you watch lectures on OCW you know its not for you, its for the studens in the class. The professor talks about when the exams are and so on. The other thing is that its hard to know when you are ready to take a course, in the khan system you could show what you have to know to do the course.

I see a bright future for education.

<comment><USER12> _change there exercises in khan-style exercises_

It would be a disaster for MIT's education if the legendary MIT problem sets were turned into Khan Academy-style exercises. To explain why I think so, allow me to quote the FAQ I prepare about the distinction between "problems" and "exercises" in mathematics instruction for families of students in the math classes I teach:

PROBLEMS VERSUS EXERCISES

I frequently encounter discussions among parents about repetitive school math lessons, so a few years ago I prepared this Frequently Asked Question (FAQ) document about the distinction between math exercises (good in sufficient but not excessive amount) and math problems (always good in any amount).

Most books about mathematics have what are called "exercises" in them, questions that prompt a learner to practice the concepts discussed in the mathematics book. By reading one mathematics book, and then several more, I learned that some mathematicians draw a distinction between "exercises" and "problems" (which is the terminology generally used by the mathematicians who draw this distinction). I think this distinction is useful for teachers and learners to consider while selecting materials for studying mathematics, so I'll share the quotations from which I learned this distinction here. I first read about the distinction between exercises and problems in a Taiwan reprint of a book by Howard Eves.

"It is perhaps pertinent to make a comment or two here about the problems of the text. There is a distinction between what may be called a PROBLEM and what may be considered an EXERCISE. The latter serves to drill a student in some technique or procedure, and requires little, if any, original thought. Thus, after a student beginning algebra has encountered the quadratic formula, he should undoubtedly be given a set of exercises in the form of specific quadratic equations to be solved by the newly acquired tool. The working of these exercises will help clinch his grasp of the formula and will assure his ability to use the formula. An exercise, then, can always be done with reasonable dispatch and with a minimum of creative thinking. In contrast to an exercise, a problem, if it is a good one for its level, should require thought on the part of the student. The student must devise strategic attacks, some of which may fail, others of which may partially or completely carry him through. He may need to look up some procedure or some associated material in texts, so that he can push his plan through. Having successfully solved a problem, the student should consider it to see if he can devise a different and perhaps better solution. He should look for further deductions, generalizations, applications, and allied results. In short, he should live with the thing for a time, and examine it carefully in all lights. To be suitable, a problem must be such that the student cannot solve it immediately. One does not complain about a problem being too difficult, but rather too easy.

"It is impossible to overstate the importance of problems in mathematics. It is by means of problems that mathematics develops and actually lifts itself by its own bootstraps. Every research article, every doctoral thesis, every new discovery in mathematics, results from an attempt to solve some problem. The posing of appropriate problems, then, appears to be a very suitable way to introduce the student to mathematical research. And it is worth noting, the more problems one plays with, the more problems one may be able to pose on one's own. The ability to propose significant problems is one requirement to be a creative mathematician."

Eves, Howard (1963). A Survey of Geometry volume 1. Boston: Allyn and Bacon, page ix.

I have since read about this distinction in several other books.

"Before going any further, let's digress a minute to discuss different levels of problems that might appear in a book about mathematics:

Level 1. Given an explicit object x and an explicit property P(x), prove that P(x) is true. . . .

Level 2. Given an explicit set X and an explicit property P(x), prove that P(x) is true for FOR ALL x [existing in] X. . . .

Level 3. Given an explicit set X and an explicit property P(x), prove OR DISPROVE that P(x) is true for for all x [existing in] X. . . .

Level 4. Given an explicit set X and an explicit property P(x), find a NECESSARY AND SUFFICIENT CONDITION Q(x) that P(x) is true. . . .

Level 5. Given an explicit set X, find an INTERESTING PROPERTY P(x) of its elements. Now we're in the scary domain of pure research, where students might think that total chaos reigns. This is real mathematics. Authors of textbooks rarely dare to pose level 5 problems."

Graham, Ronald, Knuth, Donald, and Patashnik, Oren (1994). Concrete Mathematics Second Edition. Boston: Addison-Wesley, pages 72-73.

This digression becomes the subject of a, um, problem in Exercise 4 of Chapter 3: "The text describes problems at levels 1 through 5. What is a level 0 problem? (This, by the way, is NOT a level 0 problem.)"

"First, what is a PROBLEM? We distinguish between PROBLEMS and EXERCISES. An exercise is a question that you know how to resolve immediately. Whether you get it right or not depends on how expertly you apply specific techniques, but you don't need to puzzle out what techniques to use. In contrast, a problem demands much thought and resourcefulness before the right approach is found. . . .

"A good problem is mysterious and interesting. It is mysterious, because at first you don't know how to solve it. If it is not interesting, you won't think about it much. If it is interesting, though, you will want to put a lot of time and effort into understanding it."

Zeitz, Paul (1999). The Art and Craft of Problem Solving. New York: Wiley, pages 3 and 4.

". . . . As Paul Halmos said, 'Problems are the heart of mathematics,' so we should 'emphasize them more and more in the classroom, in seminars, and in the books and articles we write, to train our students to be better problem-posers and problem-solvers than we are.'

"The problems we have selected are definitely not exercises. Our definition of an exercise is that you look at it and know immediately how to complete it. It is just a question of doing the work, whereas by a problem, we mean a more intricate question for which at first one has probably no clue to how to approach it, but by perseverance and inspired effort one can transform it into a sequence of exercises."

Andreescu, Titu & Gelca, Razvan (2000), Mathematical Olympiad Challenges. Boston: Birkhäuser, page xiii.

"It is easier to advance in one topic by going ahead with the more elementary parts of another topic, where the first one is applied. The brain much prefers to work that way, rather than to concentrate on ugly technical formulas which are obviously unrelated to anything except artificial drilling. Of course, some rote drilling is necessary. The problem is how to strike a balance."

Lang, Serge (1988), Basic Mathematics. New York: Springer-Verlag, p. xi.

"Learn by Solving Problems

"We believe that the best way to learn mathematics is by solving problems. Lots and lots of problems. In fact, we believe the best way to learn mathematics is to try to solve problems that you don't know how to do. When you discover something on your own, you'll understand it much better than if someone just tells it to you.

. . . .

"If you find the problems are too easy, this means you should try harder problems. Nobody learns very much by solving problems that are too easy for them."

Rusczyk, Richard (2007). Introduction to Algebra. Alpine, CA: AoPS Incorporated, p. iii.

</comment></comment><comment><USER13> I'm loving Khan Academy since I saw a post by John Resig about their practice framework. Math is so much more fun and interesting since I started using Khan Academy.

<comment><USER14> Unless you practice your mathematics and physics daily, you will eventually forget most of what you know.

<comment><USER15> Yes, but hopefully KA will get its spaced repetition ( <http://www.gwern.net/Spaced%20repetition> ) efforts going at some point, while most users are still there.

</comment></comment></comment><comment><USER16> I teach the SAT, and I have all of my students do the arithmetic exercises on Khan academy + the exercises for any subjects they have difficulty with.

It works great. Students nowadays tend to do all of their math on a calculator; they're not so great at mental math. It really holds them back on the SAT. The test's format invites calculation errors. The SAT specific videos are great, too.

</comment><comment><USER17> 1\. I wonder what their international user base looks like. (Not counting native English speaking countries like UK & India)

Two weeks ago my mom cut out a lengthy article for me, as she often does when she thinks she's read something relevant to my interests. To my surprise it was on Khan Academy, something I already read about past summer in Wired.

2\. Does anyone know whether KA has received any more international press coverage lately?

<comment><USER18> KA plus One Laptop per Child would be an incredibly powerful combination for third-world schools. OLPC should make it the homepage on the XO.

</comment></comment><comment><USER19> In case anyone is wondering, Khan Academy did not launch today, as CrunchBase seems to think.

</comment><comment><USER20> I'd be much more impressed it these (or at least a part of them) were paying customers.

<comment><USER21> Why? Khan Academy is a non profit organization. They are not looking to make money. They are trying to change the world of education.

I am impressed by these numbers because it means that more people are now aware that there is a quality free resource where they can educate themselves.

<comment><USER20> Why would it be more impressive? Because paying customers vote with their money. Money is a better validation than "you're great!".

<comment><USER21> Yes, money is a validation if your goal is to make money. If I am a for-profit company and I show you millions of visitors for my website but no real revenues, I would agree that it's not impressive.

As the other commentator pointed out, their goal is not to make money. And this is impressive because it's a huge progress towards their stated goal.

</comment></comment></comment></comment><comment><USER22> I found some of Khan's orgo videos helpful review material. In fact, the doctorate-level professor I had didn't do a much better job (if at all better) of explaining the material the first time around.</comment>


Show HN: Tracely - Manage your daily tasks and habits - <AUTHOR> http://trace.ly

<comment><AUTHOR> This is my first application and I wanted to get some feedback from fellow hacker news readers. The application is not feature complete but I wanted to know if this might be useful to someone before I add any more functionality. I and my wife use this for tracking our todos and habits daily. Please let me know what you guys think of this. I would really appreciate your feedback. Thanks.</comment>


Will CoreOS stop supporting flannel too? - <AUTHOR> After there announcement on torusdb, https://news.ycombinator.com/item?id=13678979  will their other projects hit a similar fate? The last commit on the flannel happened 20 days ago.. <comment><USER2> Flannel is actively maintained. But, it is a mature project that doesn't have a ton of active needs.

The most recent release added a major feature: etcd-less mode backed by Kubernetes. [https://github.com/coreos/flannel/releases/tag/v0.7.0](https://github.com/coreos/flannel/releases/tag/v0.7.0)</comment>


Secret History of OpenStack, the Free Cloud Software That's Changing Everything - <AUTHOR> http://www.wired.com/wiredenterprise/2012/04/openstack/ <comment><USER2> A nice read and informative about the background of OpenStack, but doesn't really give the reader any information about what state OpenStack is really in and what trying to use it is like.

I work for a small to medium sized web hosting company and we looked into using OpenStack as a solution for offering a Cloud product, and the problem is that OpenStack is very much in a dough-like state. It's great if you want to bake your own solution. But if what you need is bread to build a sandwich on, you're going to be starting a lot further back in the proces than you maybe want to.

I also fundamentally disagree with the whole direction of playing chase with Amazon. Linux didn't supplant Windows by copying it; it supplanted Windows by offering something that was better. If Linux had merely been free and Windows compatible, I don't think it would be the success it is today. It was not just free and open, but also technically superior.

I think OpenStack had -- and may still have -- an opportunity to provide a much better platform than what Amazon has. EC2 has a lot of design flaws and faults which result not from technical limitation but just bad design choices, and there's no need for OpenStack to follow in them.

The biggest of them in my mind is the flavor issue. In the EC2/OpenStack model, you cannot have customers spool up VMs with arbitrary specs; they must choose from available flavors. So that means if you want to offer a wide variety of options, you have to have many, many flavors on option. Which then leads to the customer having to pick one of them -- or to obfuscate this issue behind an interface which can match up the user's choices with the appropriate flavor. Neither of which is a good solution.

There's no reason a cloud VM platform should have this kind of restriction. Other competing platforms don't. I think OpenStack will eventually be supplanted by something much better. It's just that this is a very new industry, much more like competing computing platforms in the 1970's than the much more mature battle that happened in the 1990's. Where even though Linux was new, it was based on 25+ years of prior work and experience.

<comment><USER3> Linux did not supplant Windows by copying it, but it did supplant proprietary Unix. Most (not all) really successful infrastructure open source projects tend to be implementations of standards (MySQL/SQL, Apache/HTTP, Bind/DNS, etc.) In this case the defacto standard is AWS and there is certainly a lot of value in offering a compatible alternative. For me, the main issue is that most people want to use a cloud, not run one. Obviously your case is different because you are a web hosting company that want to compete with Amazon. My take is that it is going to be incredibly difficult to match Amazon technology and pricing and that existing web hosting companies will get consolidated and disappear. Please note this is not what I wish and I am not arguing this would be good for the ecosystem either, just that what it looks to me it is heading to.

<comment><USER2> A couple of things here, I'd say:

\- EC2/AWS may be the de facto standard but it's not an actual standard the way SQL/HTTP/DNS are so I don't think the comparison is totally accurate. I think there's plenty of room to supplant AWS by offering a better system.

\- There's plenty of room to compete with Amazon. Despite what you might think their prices are actually pretty high with plenty of room for even small hosts to undercut them. There's a reason that it's been so successful for Amazon; they are making a mint on it.

The big problem for smaller hosts wanting to compete with Amazon is that there's currently no ready made cloud solution that's 100% end user ready. Every single solution on the market requires some amount of custom coding in order to bring it up to end user quality. Which is frustrating.

<comment><USER3> A de facto standard is still a standard. Windows was the de facto standard in desktop OS in the 90s and there was plenty of room for technical improvements. But because it became standard and the network effects kicked in, there was little incentive and a lot of cost for ISVs, system integrators, etc. to support alternative platforms. The problem for smaller hosts is not that they don't have a ready made cloud solution, it is that they are never, ever, going to be able to match Amazon in terms of scale or efficiency. ISVs are going to support the platform that allows them to reach more users, users are going to choose the platform that has the apps/functionality they want. People are going to need customized cloud solutions, but my take is that they will be provided by third parties on top of Amazon, not as an alternative to it.

</comment></comment></comment></comment><comment><USER4> "Whenever I would talk in Washington about this cloud technology enabling data centers to run without people, this was interpreted as jobs going away," Kemp says. "There was a serious political challenge to the project…and I was called before the NASA administrator — of the whole agency — to explain it."

This is disturbing to say the least.

<comment><USER5> Anecdotal counterpoint: I worked much of my graduate assistantship in C.S. at Shelby Hall, named for the senator cited in the article as leading the charge against OpenStack.

[http://www.bama.ua.edu/~chem/facilities/buildings/shelby.htm...](http://www.bama.ua.edu/~chem/facilities/buildings/shelby.html)

<comment><USER6> How is that a counterpoint?

<comment><USER5> My graduate STEM education and paid job was partially funded by the guy. He's not entirely out to stifle innovation.

</comment></comment></comment></comment><comment><USER7> Interesting, but a big risk is that generic interfaces/software will limit functionality and lead to suboptimal performance. Amazon can roll out a new kind of hyper-advanced SSD-based database with some awkard custom interface any day of the week because they control the hardware, software, and API. You just cannot do that if your software runs in hundreds of different environments you cannot control.

</comment><comment><USER8> Well written piece, as accurate as anything that has been published to date. The title is a bit sensationalist (though I suppose that is what gets readers) -- none of this has been kept secret, it just hasn't been told on a stage the size of Wired before.

<comment><USER9> I do wish you'd gotten props, Bret, for your work in creating the openstack case at Rackspace that we took to the board, and for your work in building the ecosystem! We couldn't have done it without you, no doubt about it.

<comment><USER10> As an OpenStack user with several PB in production, thank you!

</comment></comment></comment><comment><USER11> We recently moved our app from AWS to Rackspace because of OpenStack. If we are successful, we know we want to run on our own hardware, but to get a sense of the market is too expensive using dedicated hardware. Rackspace and OpenStack gives us a way to test the waters using a cloud provider, then take ownership of the whole ball of wax later, without massive disruption to the software development effort.

<comment><USER3> You can do the same with Eucalyptus <http://www.eucalyptus.com>

</comment></comment><comment><USER12> Anyone have more info about these communal software houses? They sound pretty interesting.

</comment><comment><USER13> Can anyone comment on the main difference between this and Cloud Foundry?</comment>


Easy Concurrency in Python - <AUTHOR> http://pljung.de/posts/easy-concurrency-in-python/ <comment><USER2> One thing to remember about ProcessPoolExecutor is that parameters and return values are pickled (serialized/deserialized) in order to communicate with other Python processes. Subinterpreters (PEP 554) aims to alleviate this.

[https://www.python.org/dev/peps/pep-0554/](https://www.python.org/dev/peps/pep-0554/)

<comment><USER3> How can I determine whether a function can be pickled? A few months ago, I developed a concurrent system using ProcessPoolExecutor. In that case, the function made use of numpy, scipy, and some instaces of classes. I worked as expected, but I am not sure if that function was pickable.

</comment></comment><comment><USER4> just like the author said in the end, this is literally the simplest case of concurrent programming where it's very easy to break your works down into independent pieces and no synchronization is required.

</comment><comment><USER5> This is all great and exactly how I approached basic async stuff in Python 2.7 but I'm surprised there's literally no mention of async/await syntax or the AsyncEventLoop.</comment>


Why you should not invest in bitcoins yet - <AUTHOR> http://forum.bitcoin.org/index.php?topic=14065.0

<comment><USER2> yeah, why?

<comment><AUTHOR> bitcoins can apparently disappear, even when you do everything right</comment></comment>


Facebook Has Failed Artists and Music Fans Alike - <AUTHOR> https://medium.com/@ronanmason/facebook-has-failed-artists-and-music-fans-alike-2eee559f8839#.j9b9rbtsw <comment><USER2> This has happened with pretty much every site that has gotten big. Look at Twitter: They gave developers access to their data, allowed them to build companies around it, and then removed access abruptly.

In some cases, they offered these companies the same data at an exorbitant cost. Most of the time, it's not even factored into the business model of the company and they are forced to find another source of data or quit.

This is why you shouldn't base your entire company or idea on one source of data.

</comment><comment><USER3> You will never own your data on a 3rd party platform so there was always this risk. Music industry was blind to it.

As silly as it sounds, email is still a great way to own the comms with your customers. OK it's not what it was, but at least you have control!</comment>


Show HN: Quickly find royalty-free images directly from Slack - <AUTHOR> https://imagez.app <comment><AUTHOR> Hi,

I've started working on this Slack app about a month ago.

The app is called Imagez and it's listed officially in the Slack app directory (it's 100% free).

It basically lets you search for royalty-free images directly from within Slack, and helps you get feedback from your teammates in order to choose the best photo when you need one.

Initially, I thought that this app might be useful for digital marketers who write content frequently and need photos for their content, or even for designers who need photos for their work. However, after a few weeks of trying to acquire users in order to get some feedback, I'm not sure it solves any problem at all.

Looking forward to hearing your feedback, both about the use-case and the user experience.</comment>


Abusing Open Records to Attack Academic Freedom - <AUTHOR> http://scholarcitizen.williamcronon.net/2011/03/24/open-records-attack-on-academic-freedom/

<comment><USER2> Bollocks. You joined the political fray, now you reap the results. Academic freedom is not condition-free; the tradition that demands "academic freedom" also says academics should stay out of what they ought to consider "mere politics". I read the original op-ed, and while this is selective quoting it is selective to prove my point: "Mr. Walker's assault on collective bargaining rights... Mr. Walker's conduct has provoked a level of divisiveness and bitter partisan hostility the likes of which have not been seen in this state since at least the Vietnam War... Scott Walker is not Joe McCarthy. Their political convictions and the two moments in history are quite different. But [McCarthy comparisons made anyhow]..."

This is a very partisan piece. I could probably rewrite it without much work to be a much more neutral-POV historical piece with the same basic content, but as it stands now it is not neutral-POV. (In fact I agree with the underlying premise that the Republican party's priorities have shifted over time, but consider it uninteresting. All political parties shift over time; the further back in time you go, the less related to a modern party it is. Abraham Lincoln was a Republican, but... so what? It doesn't count as credit to the modern party, because they're only related via historical continuity, not by methods, persons, or platform. Democrats have shifted too, or should we pretend they are violating their core principles by not vigorously fighting for southern segregation?)

Academic freedom is the freedom to be free of mere politics in the pursuit of your academic studies. It is not a blank check to participate in political discourse from a privileged position above all others, with a unique defense not available to the rest of us. You have chosen to step out of your academic shield and function as a citizen.

That said, this is certainly a major overreaction from the Republican party. I don't see what they think they are going to get out of this. But this whole "I'm a noble academic under attack" is just BS, you simply _do not_ get to run into a room, start lobbing "McCarthyite!", "Radical!", and a laundry list of other thinly-veiled plausibly-deniable political attacks worthy of any modern political speech writer around in a still-current political debate, and expect there to be no reaction from the political world. You jumped in with both feet. Stop whining.

(And yes, I know the entire linked piece is itself just the next level of political game, and that, itself, is shameful. This is not how academics should behave.)

<comment><USER3> Actually, it wasn't the op-ed that occasioned the response, the Republicans launched their request prior to the publication of the op-ed.

It was in respones to this blog post: <http://scholarcitizen.williamcronon.net/2011/03/15/alec/> about the The American Legislative Exchange Council.

<comment><USER2> OK, that's even more nakedly partisan. Still an overreaction from the Republicans, but less of one.</comment></comment></comment>


Yahoo has entered the live video streaming space; YouTube will follow. - <AUTHOR> http://www.informationweek.com/news/showArticle.jhtml?articleID=206901113

<comment><USER2> I don't believe this matters much free broadcasting over the web of video is a commodity (or will be) but what is not a commodity is the technology that justin.tv has built itself.

One good idea would be to partner with a a company that builds Satellite trucks and start making the infrastructure to use video over IP instead of video direct to Satellite. The goal being to become the protocal of broadcasting video over ip for television newsrooms.

</comment><comment><USER3> See <http://news.ycombinator.com/item?id=126382></comment>


Trello: How A Proven Founder Launches A Startup – with Joel Spolsky - <AUTHOR> http://mixergy.com/trello-joel-spolsky-interview/ <comment><USER2> My biggest takeaway from Trello so far: make it easy to get started, understand, and share your product with others. With Trello, they've nailed this. Good things to study and copy.</comment>


Amaya Gaming In Deal To Buy PokerStars For $4.9 Billion - <AUTHOR> http://www.forbes.com/sites/nathanvardi/2014/06/12/amaya-gaming-in-deal-to-buy-pokerstars-for-4-9-billion/

<comment><AUTHOR> And the founder still can't set a foot inside the U.S.</comment>


Opportunities and Challenges of Emerging Technologies for Refugees (2019) [pdf] - <AUTHOR> https://www.worldrefugeecouncil.org/sites/default/files/documents/WRC%20Research%20Paper%20No.11_3.pdf <comment><USER2> > Projects such as the Online Hate Index have helped social and political > scientists identify patterns between people's online and offline social and > political behaviour. They have the potential to assist governments and > intergovernmental agencies to predict civil unrest and find better policies > and solution to address its root causes from the very early stages.

This sounds like the Western version of China's Social Credit System.

<comment><USER3> So it turns out independent of whether governments / social scientists / political scientists would find such a thing useful, the Social Credit System reflects an underlying thing that people actually want, especially in this modern era of anonymous behavior and online personae disjoint from a person's IRL persona: the ability to estimate a stranger's reputation based on past behavior. It's something that we had as small villages where "everyone knew everyone" that we've lost in the modern era, and people want it back.

In the West, it's likely not going to be tracked by governments but is _absolutely_ going to be offered by private institutions (for credit, it already is by several credit reporting agencies; social reputation is on the near-term horizon as well, with the ease of consolidating a person's Facebook, Twitter, LinkedIn profiles using modern techniques).

<comment><USER4> It's nothing like the reputation of a small village. Reputation in a village is relatively peer to peer. The system here is technocratic and top down. It is by its natural purely totalitarian.

<comment><USER3> I don't disagree, and yet I think it will be built and people will use it anyway outside of China.

I wonder if multiple competing reputation schema will have any impact on the totalitarian aspect of it, or if we'll just have our choice of despotic masters.</comment></comment></comment></comment>


Ethereum's Not-so-Smart Contracts - <AUTHOR> https://steemit.com/ethereum/@dantheman/ethereums-not-so-smart-contracts <comment><AUTHOR> >It is time we stopped pretending these platforms are trust free, and instead recognize that we will always end up trusting someone with the power to fix bugs. The power to fix bugs is the power to destroy.

I was talking about this with my dad. It feels like there is no way to escape the Greek classics on political philosophy. Whenever decision making and ressources are involved, we have to deal with politics and governance. In the case of blockchain technology, the devs are the legislators, the "smart" contracts the legislations, etc.

Blockchain forces us to reconsider the way we come to consensus but to this day, we haven't been able to find an alternative to what was brought forward thousands of years ago.</comment>


Ask HN: Software with tiered dependencies – A reliant on B reliant on C - <AUTHOR> I want to keep this is as abstract as possible. I have a project where a high-level component "C" relies directly on "B". In turn, "B" relies directly on "A" so "C" indirectly relies on "A" too.
Therefore, the hierarchy is C->B->A.
Currently, all of these components are in active development and are having major changes made. Changing anything in A is requiring adapting of code in B which in turn requires adapting of code in C. Changing B requires modification of A.
My question is if anybody has advice on how to avoid this and to some degree mitigate the issue to make development of "B" and "A" easier without breaking upstream components.
In my specific situation, the actual components are "C" = an object/model handling class, "B" = an abstract version of that class with common functions for all the models, "A" = a database handler. So I hope you see how changing A or B requires rewrites of C and/or B. <comment><USER2> This would suggest to me that you have a Coupling mistake or an Abstraction problem of some sort. I can't quite offer specific fixes based on the specifics here, but abstractly my gut reaction is that it sounds likely that B is too tightly coupled to A and is likely something that either should be part of A or C more directly (possibly merged together; or at the very least versioned together).

Certainly I don't often feel like an abstract class is a separate enough concern to be its own module (an abstract class without any available implementation is useless on its own), and that seems a flag that maybe should reconsider your architecture, but without too many specifics I'm not sure I can tell you exactly what is wrong with your abstract class.

Hope that helps maybe lead you in the right direction at least.

</comment><comment><USER3> What exactly is changing? Are these completely separate pieces as in can they be separately deployed services? Or are you talking about a View layer, middle/business layer, db layer in the same app? If they can be separate apps, then create APIs with agreed upon interfaces. Then do not change those interface contracts. Version them if they need to change then the other components can still use the old version while upgrading to the newer version of the interface contract if needed

</comment><comment><USER4> Call everybody together in a big meeting, have A and B set api contracts, and shout at people when they try to break them.</comment>


1.7 petabytes and 850M files lost, and how we survived it - <AUTHOR> https://csc.fi/web/blog/post/-/blogs/the-largest-unplanned-outage-in-years-and-how-we-survived-it <comment><USER2> "The directory is intended for temporary storage of results before staging them into a more permanent location [...] During the three years that the filesystem has been in operation, it has accumulated 1.7 Petabytes of data in 850 million objects."

There needs to be some law about how temporary directories always end up containing vitally important data.

<comment><USER3> What was interesting to me about this was that they had decided _not_ to enforce a deletion policy on /wrk, because they had so much space and the filesystem hadn't ever failed. But a rolling deletion policy would have gone a long way to containing the damage by encouraging the users to move their data to a filesystem optimized for reliability instead of availability. Still, I appreciate the heroics involved in restoring the data.

<comment><USER4> Author here. We have had an automated deletion policy on our previous filesystems but opted out this time: There are users that have temporary files that they want to persist on the /wrk and we have plenty of capacity. We definitely learned our lesson, though. :)

<comment><USER5> Better solution for the future: client side scripts that push those files back after every purge.

</comment></comment></comment></comment><comment><USER6> Lots of fun; while backing up the filesystem prior to wiping and rebuilding it, they ran out of IOPS to do it in a reasonable time frame, so after considering other options:

 _One obvious solution would be to use a ramdisk, a virtual disk that actually resides in the memory of a node. The problem was that even our biggest system had 1.5TB of memory while we needed at least 3TB.

As a workaround we created ramdisks on a number of Taito cluster compute nodes, mounted them via iSCSI over the high-speed InfiniBand network to a server and pooled them together to make a sufficiently large filesystem for our needs._

A hack they weren't at all sure would work, but it did nicely.

<comment><USER7> Couldn't they add 1.5TB of swap to their 1.5TB of memory system and run a ramdisk on that? I'm curious what performance would look like, but given 2-3k IOPS for the on-disk solution, and 20k IOPS for the in-memory I would naively expect at least 11k IOPS for random access, which should have been fast enough without the headache of clustering?

<comment><USER4> Author here: We considered that but as the access pattern was likely pretty much random, the performance would have been terrible. Due to the break we had nearly a 1000 clustered servers sitting idle so it was reasonably quick to do the ramdisk trick.

<comment><USER8> I'm sorry but I don't understand something. What did you put on that big ramdisk ? The metadata ?

<comment><USER4> We copied the raw image file of the corrupted metadata filesystem (MDT in Lustre lingo) to the ramdisk.

Then we mounted it via loopback and copied the files to tarballs. The bit that was really slow on the spinning disk was reading the millions of files from the metadata FS.

The basic process of the file-level backup is documented here: [https://build.hpdd.intel.com/job/lustre- manual/lastSuccessfu...](https://build.hpdd.intel.com/job/lustre- manual/lastSuccessfulBuild/artifact/lustre_manual.xhtml#dbdoclet.50438207_21638)

<comment><USER9> For those still not quite getting it:

The first copy to RAM was a sequential image copy, thus not bottlenecked on seeks despite spinning platters.

The second copy from RAM was a file copy with a lot of random I/O, but not bottlenecked on seeks because it was reading from RAM.

Bulk writes tend to be more efficient. They might have made temporary configuration changes to make that end faster, or not if they lacked the appetite for the extra risk.

</comment></comment></comment></comment></comment></comment><comment><USER10> Current HN Title: 1.7 petabytes and 850M files lost, and how we survived it.

Article title: The largest unplanned outage in years and how we survived it

Article overview: A month ago CSC's high-performance computing services suffered the largest unplanned outage in years. In total approximately 1.7 petabytes and 850 million files were recovered.

Although technically correct, the HN title is misleading.

<comment><USER11> _1.7 petabytes and 850M files lost_ \--- _1.7 petabytes and 850 million files were recovered_

Given that the latter statement is from the article, how is the former "technically correct"?

<comment><USER12> Imagine an article "One web server lost and how we survived it" simply said "Our load balancer automatically removed that server from the pool and we let the other 15 web servers pick up the load. We didn't have to do anything." This is different from "Oh crap, we only had one web server and we absolutely had to do a lengthy recovery process to get it back online."

</comment></comment></comment><comment><USER13> It should be noted that this is about a Lustre filesystem hosted on DDN hardware. It's unclear whether the failed controller contributed to the file system corruption, but Lustre is quite capable of accelerating local entropy all by itself. It was designed/spec-ed at LLNL as huge file, high performance, short term scratch/swap and even after 15 years isn't especially reliable or fit for use outside that domain.

</comment><comment><USER14> I'm surprised that the copying bottleneck seems to have been entirely at the target rather than the source. Is that because there were multiple copies of the source?

I've had to employ the horrible hack of iscsi from compute nodes, raided and re-exported, but it's not what I'd have tried to use first. The article doesn't mention the possibility of just spinning up a parallel filesystem on compute node local disks (assuming they have disks); I wonder if that was ruled out. I don't have a good feeling for the numbers, but I'd have tried OrangeFS on a good number of nodes initially.

By the way, it's been pointed out that RAM disk is relatively slow, if in the context of data rates rather than metadata <[http://mvapich.cse.ohio- state.edu/static/media/publications/...](http://mvapich.cse.ohio- state.edu/static/media/publications/slide/rajachan-hpdc13.pdf>).

<comment><USER4> The reading of the metadata required quite a lot of random acces. We were fairly sure that if a high-end array and controller with fast disks is struggling with it, then a traditional clustered solution with slower node local disks would not fare much better. Thus we tried to find the solution which yields the highest possible IOPS.

<comment><USER14> I misunderstood the bottleneck, not having had to do that. (Distributed metadata for the parallel filesystem could actually be tuned to be memory resident.)

</comment></comment></comment><comment><USER15> Out of curiosity, why weren't they running the metadata drive in a mirroring raid? If you have PB of data, wouldn't it make sense to spend the ~$100 for a second 3TB drive to mirror your metadata?

Or was the inode problem not a local disk problem but a problem in the Luster fs? I couldn't quite tell from the article.

<comment><USER13> It's almost a certainty that the MDS (metadata server) was situated on a mirrored RAID (prob RAID10). I'm guessing that the RAID system itself (software MDRAID or some HW array, DDN or something like a NetApp E-Series) corrupted the data under the FS that the MDS used, which I'm also assuming was XFS.

Lustre, for those who don't know it, is a cluster meta-filesystem, with separate metadata and object servers, each sitting on top of host file systems/RAID/storage.

<comment><USER4> The metadata target (MDT) in the MDS is actually "ldiskfs" which is an enhanced version of ext4. One possibility may be to use ZFS in the future as the support in Lustre seems to be quite stable now.

It seems pretty impossible to find out the exact root cause in retrospect as the system was running for a long time without apparent issue. Any ideas are welcome though.

</comment></comment></comment><comment><USER16> I bookmarked this for whenever I think I'm having a really bad day...

<comment><USER4> Hehe.. In retrospect the whole team was in fairly good spirit although the situation was stressful. A lot of this was due to the top management giving the time and space for the specialists to do their thing and the very understanding response from the customers once we explained the situation.</comment></comment>


Ask HN: How many hours of interview "homework" is appropriate? - <AUTHOR> I just had a first interview with a company.  They have given me a coding assignment and bug bash assignment that would take a rockstar coder a minimum of 4 hours and for someone like me would take about 6-8 hours.  Is that absurd?  Should I be offended? <comment><USER2> It's up to you. That doesn't feel absolutely absurd to me. If you work with them, you're going to spend much more than 8 hours working... 8 hours is very small to judge people, but it will give them an idea of how clean and careful you can be. Companies like Automattic would start with a 4-8 hours assignment, then if you do well, they would ask you to work part-time for them for 2 weeks. Some companies won't ask you anything except to code for one hour over the phone...

</comment><comment><USER3> I was a strong proponent of the "write some code for us" interview approach for years. We used a variation, slightly unusual - we would pay interviewees for some hours of work so they did not feel we were trying to get them to work for free as an interview.

But looking back at the results over a period of years, some hires never reached the level of quality/productivity they had shown in the interview homework. I don't know why this is, one possibility is that some interviewees "cheat" by getting someone else to do the project for them. I don't know if that happened to us, but whatever did happen, the net result is that the interview homework approach is not ultimately all that great.

Now we do something different. As part of the interview process, the interviewee sets and codes with a couple of our developers for a couple of hours. This has its own downsides (some otherwise excellent people have trouble with the stress of being "in the hot seat"), but so far we're much happier with it.

Also, spend a few hours trying to write code with someone, and you have a pretty good sense of the oh-so-desired "cultural fit" without having to ever actually look for such a vague thing.

</comment><comment><USER4> It's not absurd, you shouldn't be offended, and only you can decide if you want to invest 8 hours proving your fitness to this company.</comment>


What are the new big ideas in tech? - <AUTHOR>

Deep learning? Massive adoption of mobile and Internet? Big data? Software eating the world? <comment><USER2> IMO, advanced biotech and nanotechnology in general, it's coming eventually.

I personally think that we are at a point that we can make some significant advances in miniature engineered things that interact with the human body (and everything really).

Miniature robots in our bodies (or just blood, I don't know that much about the subject) that we can program or have upgrades for, or just monitor. They could clean cholesterol, monitor numerous levels/vitals, prevent clots, and anything really. They could be especially useful for preventing overdose or sudden onset diseases. I can imagine a text in the future to people, "Warning, your Blood Pressure is abnormally high, here are some tips to help you lower it." or "Blood Alcohol Content is currently at .10, you are not legally allowed to drive."

Yes, it's dangerous. Yes it will probably be possible to easily engineer something that will kill all of humanity, but those are problems we will have to make safeguards for.

</comment><comment><USER3> I didn't see this, so maybe it's hopeless. BBC Horizon - "Tomorrow's World" - (<http://www.bbc.co.uk/programmes/b01rwgt6>). Not on iPlayer, but probably available via other means.

The clip is stomach churning. Don't watch it if you're eating.

</comment><comment><USER4> I believe ubiquitous wireless internet attached to an abundance of sensors will change life on earth in ways we are just starting to understand.

<comment><USER5> I can imagine having wireless internet everywhere. No need to worry about dead zones. Imagine being lost in the middle of nowhere but having some wireless internet to call for help or guide you out. It would be pretty neat.

</comment></comment><comment><USER6> The mentioned would be pretty mainstream by now.

I'd go for quantum computing

</comment><comment><USER7> I would go vote for real time Natural Language Processing and translation.

<comment><USER2> That's been the goal of many research groups for 50+ years. I can see Google releasing a service (API) for it within the next few years.

What would be the applications for real-time NLP and translation? I can't think of anything beyond being able to have the words appear on the screen faster or actions being preformed half of a second faster.

<comment><USER5> I think talking to someone on the phone in English to someone who doesn't speak English, but gets the message in his native tongue in real time would be super awesome (English speaker speaking to someone who hears Japanese and the Japanese speaker speaking back in Japanese but the English speaker hears English).

<comment><USER8> star trek's universal translator :)</comment></comment></comment></comment>


Why the Flash Crash Really Matters - <AUTHOR> http://nautil.us/issue/23/dominoes/why-the-flash-crash-really-matters

<comment><USER2> Ok, I read that twice, is the summary "The market is a complex tightly coupled system." ?

I get that, and I get such systems can be subject to anomalous events (early fly by wire systems for dynamically unstable aircraft was a good test case to study). But such systems can also be 'calmed' by damping. Isn't the SEC in charge of adding such damping to our financial trading systems?

<comment><USER3> One of the authors here. I think that's a pretty good summary. And, yes, I agree that there are ways to introduce damping into many such systems and some has been added since the Crash, as another comment points out.

I think it would be great if the SEC believed that that was their mandate. Unfortunately, I think that is predicated on much more sophisticated and nuanced understand of the dynamics of the markets than regulators typically have.

The claim in the recent CFTC's Complaint that alleged market manipulator Navinder Sarao directly contributed to the crash is only one example of this. If one guy can cause a Flash Crash, there is a bigger problem with the structure of the markets.

<comment><USER4> I'm curious whether you have seen this speech from last year given by Gregg Berman who was, until recently, an associate director in the division of Trading and Markets at the SEC.

[http://www.sec.gov/News/Speech/Detail/Speech/1370541505819](http://www.sec.gov/News/Speech/Detail/Speech/1370541505819)

I think it shows that the regulators (at least some of them) do want to have a better understanding of the dynamics of the US equity market, and that they are trying to build the tooling that will give them the right sorts of insights. Berman's suggestion that policy changes ought to be driven by data are, I think, something that most technologists would agree with. For whatever it's worth, Berman also has a physics Ph.D. from Princeton. So if your insinuation is just that the regulators are more lawyer than scientist I don't think that's completely true.

edit: Also wanted to add that there has been a lot written about the flash crash and I think this article is definitely one of the better ones.

<comment><USER3> I have heard Gregg Berman speak, though I hadn't read this speech until skimming it just now. I do think that there is, generally speaking, a heartfelt desire to develop the tools and data needed to gain insights that Berman is talking about.

I think there are two challenges to unpack. One, though I wasn't insinuating it, I could have been. I do believe that regulators are more lawyers than physicists. Berman is the exception rather than the rule.

Two, Berman, in particular, makes a fundamental error that I think is very easy to make. There's a difference between "complex" in the sense that something has a lot of parts, and interactively complex in the sense that parts of a system are fundamentally unknowable and it can experience wild and unexpected dynamics. I think Berman doesn't distinguish between those two types of systems (repeated analogies to cell phones give some indication of his thinking), and more generally, regulators don't understand the aggregate cost of complexity.

In my view, things like Midas are orthogonal to some deeper issues facing the markets. Regulators have created a quasi-competitive market that breeds this sort of interactive complexity. Then, when something goes wrong, they rely on punishment and enforcement actions [1] to target individual firms that have made "mistakes." This not only does not address root causes, it creates a culture of silence around technology risk issues within firms and across the industry. I've written more about this here: [http://harvardkennedyschoolreview.com/preventing-crashes- les...](http://harvardkennedyschoolreview.com/preventing-crashes-lessons-for- the-sec-from-the-airline-industry/)

[1] See, e.g., [http://www.sec.gov/litigation/admin/2013/34-70694.pdf](http://www.sec.gov/litigation/admin/2013/34-70694.pdf) and [http://www.sec.gov/litigation/admin/2013/34-69655.pdf](http://www.sec.gov/litigation/admin/2013/34-69655.pdf)

</comment></comment></comment></comment><comment><USER5> When events are happening at the microsecond scale, its not really a 'market' anymore, its more like a casino. Its just some game with arbitrary rules that various actors are trying to win via different strategies. The link to any real world concept of 'investing in companies' is very weak when positions are only held for the very short term.

<comment><USER6> Why do you assume the markets are about investing in companies? They are in fact very much not about investing in companies. Even the closest analog a single share, doesn't represent an investment in the company. The company got it's investment many many transactions ago, when it offered the shares originally.

<comment><USER7> Well, they're (usually) about taking over someone else's investment. In theory, each share should be priced at the present value of future dividends, all the way forward to the company's eventual liquidation -- if market price is below your estimate of this, you should be buying; if above, you should be selling.

<comment><USER6> Right, but what you are now talking about risk and liquidity. Most market transactions have nothing to do with investment in companies, they have to do with pricing risk. That it makes it easier for companies to find investments in some cases is a beneficial impact of this, not it's main focus.

It is a particularly HN bias to think of the market as a place to go fund a company, but that is largely a by product for most people. For most people (including everyone with an index fund/etf) its a place for managing risk. That doesn't even take into account, that a big component of this story was about S&P _futures_. Which are all about risk.

So it is uninteresting (even if it were true, which i doubt) that microsecond time scales make the markets less about investing in companies, they already aren't about that.

</comment></comment></comment></comment><comment><USER8> Aren't markets expected to figure out the true price of things and do other similar stuff? And doesn't that imply that the state of the market should always be close to the global optimum and market force should drive it even further into this direction? Sounds very much like a stable system to me, so how can it run away unless the current state is just a local optimum and a correction to the global optimum - or a better local optimum - happens?

<comment><USER9> The vast majority of the time, this is true. Notice that after the Flash Crash, most prices came back to basically where they started within a few minutes.

At the micro level, the problem is uncertainty. The "true" or "fair" price of a security isn't something you can just calculate: it's uncertain and subject to change when new information is introduced into the system. So theoretically, when the price gets very far from the fair value, market makers should become more and more eager to trade, since they'll make a large profit when the price comes back. But in practice, they never know whether the person on the other side of the trade is just panic-selling and moving the price farther from equilibrium, or if they know something the market maker doesn't and are moving the price closer to a new equilibrium. As the price gets farther from its previous stable value, the probability that the counterparty is informed grows, and eventually no market maker is willing to trade and the market dissolves.

This failure mode is related to the "Market for Lemons" problem: asymmetric information causing a market breakdown ([http://en.wikipedia.org/wiki/The_Market_for_Lemons](http://en.wikipedia.org/wiki/The_Market_for_Lemons)).</comment></comment>


The Daily Stormer was back online for a quick second - <AUTHOR> https://techcrunch.com/2017/08/20/the-daily-stormer-was-back-online-for-a-quick-second/ <comment><AUTHOR> The whole matter feels like a witch hunt to me at this point. It is both unnecessary and dumb of the people and businesses repeatedly pulling their plugs. I never knew about The Daily Stormer until GoDaddy decided to cut service. There is no bad publicity after all. Also all those DNS providers dropping a website because they don't support TDS views and content really make me more excited for ENS and a whole uncensored web in Ethereum.

<comment><USER2> "There is no bad publicity after all."

All of those Benghazi congressional trials which came up empty, and hours upon hours of "but what about the emails?", the continued false accusations about selling 20% of the US uranium in exchange for $145 million, etc. ... did nothing?

What an interesting world you live in.

<comment><AUTHOR> My point was that even if TDS is now publicly attacked in the media only one thing will happen: Traffic surge for TDS. Most people would never have heard about that site without these actions. And for the Alt-Right Troll Mob this whole thing is only more fuel.

<comment><USER2> You wrote "There is no bad publicity". Do you agree with your statement or not?

If you really believe that, then you believe Clinton had no negative impact from all of the bad publicity she got, all evidence to the contrary.

If you don't really believe that, then your argument is incoherent, because it means that some bad publicity _can_ be effective.

So which is it?</comment></comment></comment></comment>


Experimenting with CoreOS, CloudFormation, confd, etcd, and fleet - <AUTHOR> http://marceldegraaf.net/2014/04/24/experimenting-with-coreos-confd-etcd-fleet-and-cloudformation.html <comment><AUTHOR> Author of the article here; ping me if you have any questions or comments :-).

<comment><USER2> I am wondering why you have a 1:1 mapping between Docker containers and processes? I have not used Docker but my impression of it was a good way to group a few inter-related processes together while separating them from unrelated processes. Our thought was basically 1 container per role/service in our platform (app servers, workers, DB, logging, etc). If you have 1 process per container, isn't it just a bit stronger form of sandboxing a process?

<comment><USER3> You can do it in several different ways, and it really depends on what you're trying to accomplish.

If you were trying to build wordpress-as-a-service, for example, you might create a Docker instance which includes nginx, php-fpm, memcached, and maybe even mysql (which makes it easy to make snapshots of the entire state of the system).

That said, fleet has a really interesting way of making interconnected systems, so you can create a memcached instance, an nginx instance, and a php- fpm-running-wordpress instance, and you can manage them separately. This makes it easy to upgrade memcached without touching nginx or php-fpm, or to change the nginx config without having to affect the running application server (and risk flushing the APC cache), etc.

It also allows you to make everything pluggable in your design. You might want to add varnish in front of your nginx instance, for example, but sometimes you might not. That sort of flexibility is really useful in some circumstances.

In our infrastructure at work, the design I would use would probably be similar to this; we have front-end services (nginx), internal services that they proxy to, internal services that those services access, asynchronous processing services, dispatch services, activemq, redis, memcached, mysql, etc. Having the flexibility to add more of any one of those things without having to scale any of the rest is really important.

For other circumstances, it makes a lot more sense to bundle everything into a faux-VM. Run supervisord to launch ssh, nginx, php-fpm, memcached, and whatever else needs running. Share volumes to local filesystems so that configs, local changes, etc. can be taken care of, and you're good to go.

So in the end, the real question is what do you want out of your containers? Flexibility or simplicity?

</comment></comment></comment><comment><USER4> I saw a demo of CoreOS yesterday, and was super impressed. I'd heard of it before, but never really understood the power until I saw the demo.

CoreOS is basically an OS with the fundamentals to force you to "do cloud right".

If I were building a company right now on AWS (or any other cloud) I'd seriously be considering basing my infrastructure on CoreOS.

<comment><USER5> > CoreOS is basically an OS with the fundamentals to force you to "do cloud > right".

So what are some of those?

<comment><USER6> one of the better summaries (came out of Heroku, I believe): [http://12factor.net/](http://12factor.net/)

the hardest part is always shedding the baked-in habits.

<comment><USER7> I love the 12 Factor App! I recommend that link all the time to people. It's kind of like functional programming, in that once you grok the fundamentals, it changes your attitude completely.

</comment></comment></comment></comment><comment><USER8> While all this sounds cool it is a tiny bit frustrating that do not have an ISO to boot. I found at least one other person looking at it, but I could not figure out why that was not an option.

It almost sounded like this is an OS but not one you install? Or somehow the OS is only in memory? Like tinycore maybe?

<comment><USER9> I don't think it's quite at the point of being stable enough to provide an ISO yet.

Also, while it is possible to run on bare mettle, it would not be most productive to do so in most cases. One of the strengths of CoreOS is the ability to quickly add new machines to a cluster and manage applications not on the individual server level, but as collections of services running via Docker. This means, unless you have quite a few computers ready to scale, it would work best on something like AWS or Google Cloud Platform.

<comment><USER10> For small to medium clusters cloud providers work great. As deployments of CoreOS get larger, PXE booting will probably become the most popular way to add capacity. Plug in 10/100/1000 servers, turn them on and instant capacity added. The upper end of the target scale for CoreOS consists of companies that own their own datacenters or have many points of presence.

<comment><USER9> True, but they still would not be using ISOs.</comment></comment></comment></comment>


Show HN: weekend project, Hawt Cakes - <AUTHOR> http://hawtcakes.com/ <comment><AUTHOR> I'm the co-founder of a startup called Minno (<https://www.minno.co>), which is a new take on micropayments. We were inspired by Sahil's work on Gumroad last weekend (<http://news.ycombinator.com/item?id=2406614>), so this weekend, we decided to whip together a little link/file sharing service of our own.

You can check out the finished (alpha) version of the product here: <http://hawtcakes.com/>

My co-founder and I worked on it from 10am to 3am on Saturday, 1pm to 3am on Sunday, and a little more this morning. It doesn't look quite as nice as Gumroad, but we can pretty it up later :)

Here's an example of a file you can buy/download with Hawt Cakes: <http://hawtcakes.com/rfPFsN4q9>

What do you thinks think? We're particularly interested in your thoughts on the payment experience :)

</comment><comment><USER2> The nice thing about this, from what I understand, is that unlike Gumroad, it lets you sell things for < 99 cents. Obviously, that's a huge potential market.

I would guess the $10 minimum is a way to "hide" or "bundle" these tiny transactions that you can't efficiently handle through the existing credit card/banking system.

More generally, I guess the whole Minno business model/insight is to aggregate these kinds of small transactions that can't efficiently be handled by the existing financial system. (Minno is the payment service underlying Hawt Cakes.) This is literally speculation; I imagine the founders will correct me if I'm wrong.

<comment><AUTHOR> That's exactly the right analysis.

More generally, there seems to be an entire class of apps out there that could be really useful, but which are really hard to monetize with subscriptions and/or ads revenue alone. Think about an advanced file converter, or maybe a one-off fax service. There are also the more traditional use cases, such as purchasing a single article from an online journal, or streaming a single movie online.

Minno provides an effective alternative to monetize these services, and it does so with much more ease than with traditional payment systems.

</comment></comment><comment><USER3> I like the idea but I do have one immediate question:

 _We give you a unique link for each item you want to sell. You then can tweet, post, or share your link however you want. And as soon as your sales reach $10, we'll send over your earnings._

So if a user sells something and never reaches $10, is that essentially held in escrow forever? Is there any way for users to "cash out", so to speak, after a certain period of time?

<comment><AUTHOR> We'll definitely let users with <$10 "cash out" their earnings eventually, but we're still working out the details. After all, we just built this over the weekend =P

But your right--we could make this more clear on the site. We'll also be sure to keep HN Posted as we add more features to the product!

</comment></comment><comment><USER4> Super landing page. Maybe you could compile a little badge/icon for each listing, so that if the person does some promotion on their own, in a blog say, they can drop the icon in at the end and it will link them to the hawtcakes page. Basically instead of just a plain link, a nice button.</comment>


Should We Be Having Kids in the Age of Climate Change? - <AUTHOR> http://www.npr.org/2016/08/18/479349760/should-we-be-having-kids-in-the-age-of-climate-change <comment><USER2> It may sound a bit brash, but ultimately this is navel gazing. I accept your desire to take yourself out of the gene pool (yet don't really understand it), but this pseudo-scientific and pseudo-moralistic nonsense must be some form of apoptosis within a senescent society experiencing an existential crisis. The real question you should be asking is why you think your society, culture, nation or state should dig itself a grave.

<comment><USER3> It is masochism masquerading as righteousness.

It is not news that people can be sadists in groups, but collective masochism is insufferable.

</comment></comment><comment><USER4> This is why it's important to draw a clear line between science and ideologies.

</comment><comment><USER5> We've been told we need to change our personal behaviour to avoid climate change for years now but that clearly hasn't worked.

It's time we moved on from trying to shame individuals to making some concrete policy decisions such as taxing carbon.

</comment><comment><USER6> No need to make it more complicated than it it:

The problem can be simple modeled as the prisoner's dilemma or more commonly known as the "Tragedy of the Commons".

Its quite unfair to ask Europeans and Americans to cut back on having kids when we are not setting some limits to the Pakistanis, Nigerians, Indians .. etc.</comment>