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Show HN: Crondom (crondom.com)
62 points by mathgladiator on Dec 16, 2010 | hide | past | favorite | 56 comments



This is my first real node.js product that I'm taking into production, and I'm looking for feedback. Thank You.

Please try to break it since it is really fresh. I should have the /etc/init.d stuff and a while true; do bash script set up, so it should come back if it crashes. I would like to have it not crash, but if it does, then things should come back online. It is using https://github.com/mathgladiator/win and https://github.com/mathgladiator/servy


I haven't bothered to register yet, but after looking at the site I don't understand what it does. You say that it's a cron replacement. So is it a software package that you sell? For which platforms? Or is it some kind of SAAS that does something (like doing HTTP requests, or invoke something on my server using some unspecified protocol)?

I honestly don't have any idea what it does. All I know is that it does something in configurable intervals. I guess some additional info on the site would be helpful :)


I think it's a way to schedule a visit from a dominatrix?


It's basically an HTTP crontab replacement that does a bit more than crontab. Crontab is very regular where as crondom can be irregular. For instance, When there is a lot of events to handle, you want polling to be very fast (1 second resolution). However, where there are very few events, you want the polling to be very slow (every 2 minutes). crondom enables this use case by enabling the developer to determine how long to wait until the next hit.

You can also break up a cron job into # of clients. This enables you to process reasonable large # of clients by giving each client a URL to go with rather than doing the work at the moment. For instance, you want to pull 1000 user twitter feed every day. Well, if it takes 1 second, then you have 1000 seconds of work for the script, or 16 minutes. Most developers are forced to live within 30 seconds per request.

In this same scenario, what happens when it fails for user 377? what happens for 378? Handling errors is not always straight forward especially from a business case. Ideally, crondom will enable us to graph for failure cases (coming soon) and isolate which part of the cron task failed.


Why is it called Crondom? It sounds a bit like some form of 'protection' for cron.


It's a perfect name b/c I don't need this tool now, but I probably will later. And I will never, EVER forget the name. Kudos.


It's great to live in a time when developers can build products for other developers.


When was that ever not the case?


The key word was products, i.e. making a living from building tools for other developers.

There are many more developer-run companies today than there were 10 years ago and the number will continue to grow. There have never been more opportunities to do that than right now.


AFAIK, it's actually the opposite — only recently is this a hard thing, with the proliferation of OSS development tools.


OSS is an opportunity. It's not about the software; it's about the services and the ecosystem. There are a lot of people making money from Wordpress plugins, themes, and development.


I got the idea from pingdom.com , and then I put crondom.com together and my mind was utterly juvenile and told me "WOW, this is the best thing EVAR".


I actually didn't even consider that far; I stopped after "why would you name your product something like condom".

To be fair, it's a solid idea that I imagine would do well regardless of the name. To continue being fair, it's hard to picture the name not being a point of friction in at least some scenarios For instance, picking the name out of a list of possible choices. There are unfortunately likely more limiting scenarios than that.


I'll probably launch a better brand-name that's more family safe, but when I thought up this name my gut instinct was a giant "YES, this is so awesome".


You're not selling to families. You're selling to sysadmins and developers. Crondom is a perfect name.


He's selling to sysadmins and developers many (most?) of whom will have to get management approval to purchase. The name can definitely be a limiting factor to sales.


That was also my first thought.


I was thinking an image of a "hot babe" on the landing page would add a little more humor to the domain name.


No, it would merely add sexism. Don't be sexist.


Would be hilarious if the UI was a text box where it said “type a Crontab line.”

Seriously though, sounds easy to use, if perhaps a bit overpriced for something I’d mostly want to use on small or personal projects.


It strikes me as the sort of thing that should be one function of a much larger app. Not a standalone app on its own. If the intention is to make it a paid for service, I simply don't think it's worth paying for. Other people might be willing to pay for it, but I'm not sure exactly who.


Some of the features sound neat. The question in my mind is, how do the jobs on the Crondom server trigger local scripts? Also the name is both cool and terrible: it reads like condom everytime I glance at it.


"10 Things you can do with crondom.com that you can't do with crontab: 1. Run a job every 7 minutes"

I thought you could just do:

  */7 * * * * whatever...


I don't know. It feels like with this line, the job will be run at 7, 14, 21, 28, 35, 42, 49, 56, thus, between 56 and the next 7, you will have 11 minutes interval. Not that familiar with crontab, I may be wrong here.


Correct


I am ignorant on specific time requirements on running crontabs but I always do either 6min or 10min or something which is divisible.

Are there any specific app requirements in running 7min or 17sec?


Another problem with 17 seconds is that normal cron has resolution of one minute :)


screen -dmS 17secondjob perl -e 'while(1){`run the command`;sleep 17}'


Or, simpler, use watch:

watch -n 17 -p command

Make a wrapper to run command in the background (&) if the process runtime is greater than your interval.


This will not run the `command` in 17 seconds intervals. You need to take into account the amount of time that it takes to run it.


Ok. Whilst we're being anal:

screen -dmS 17secondjob perl -Mthreads -e 'while(1){threads->create(sub{`run the command`})->detach();sleep 17}'


Or just use watch.


Cool. I was unfamiliar with this command. Looks useful.


Look for `watch -p'.


How else would you divide 60 by 7?


I think the idea is that instead of:

    7, 14, 21, 28, 35, 42, 49, 56,(11 min gap), 7, 14, etc
Crondom would run:

    7, 14, 21, 28, 35, 42, 49, 56, 3, 10, 17, 24, ..., n+7
OP correct me if I'm wrong with the intention of that bullet point.


If it's that important that a job runs at exactly 7 minute intervals, you don't want to be relying on a remote service.


You don't. You divide 60*7 by 7.


You want me to run it every hour?


You misunderstand what he's saying. Because 60 doesn't divide into 7, don't use one 60 minute cron job. Use 7 cron jobs. You could get this magical 7 minute experience over a 24 hour period by creating the following 7 jobs:

0-56/7 0-21/7 * * * Command

3-59/7 1-22/7 * * * Command

6-55/7 2-23/7 * * * Command

2-58/7 3-17/7 * * * Command

5-54/7 4-18/7 * * * Command

1-57/7 5-19/7 * * * Command

4-53/7 6-20/7 * * * Command

Of course, the last job would finish at 23:55, and the next start at 00:00 which is bad. So you'd need to do it on a per day basis. Luckily there are 7 days in the week. So you would just need to write those 7 jobs above on a per day basis. You'd end up with 49 jobs all looking similar to this:

0-56/7 0-21/7 * * Wed Command


Well, you could put multiple cron lines in. e.g. for every 8 minutes:

  0,8,16,24,32,40,48,56 0,2,4,6,8,10,12,14,16,18,20,22 * * * cmd
  4,12,20,28,36,44,52 1,3,5,7,9,11,13,15,17,19,21,23 * * * cmd
This starts to get a bit silly when the interval isn't a factor of 24 though.


I wrote a simple script to generate cron tab specs for "every X minute", and while I enjoyed using gcd and lcm in a real application; something wasn't right. 7 is a very canonical and crazy case because it takes 7 days to cycle. but even then, it doesn't work with months except for February for non leap years.


*/7, but ya.

That is a Linuxism. I found out the hard way setting up some Solaris 9 scripts last summer.


it's a vixie cron'ism. vixie cron is in all the bsds, linuxes, and mac os.


It is in OS X cron too.


Hey, just a small thing but when trying to sign up it's saying my me@robotmo.de email address is invalid.


Side note: Registration rejects paton@bu.edu as an invalid email.


Site seems to be down. Would love to check it out, though.


I'm learning a lot about production node.js and what happens when things go very wrong... Will blog about it.


Adding a bit of info about what I'd need to implement on my end would be useful. I'm assuming that this will fetch a HTTP URL once per "hit"?


I'll make that generally accessible from the landing page, and It's available within the site.

http://crondom.com/documentation

(very hastily written)


Awesome name. The site is down though. Edit: back up now.


Can it do: Twit Goodbye when I die. ?


No, but that does sound like an interesting service. ObitWatch


why not put an openID login. I find a lot of new review my app's but every app I find points me to register as a new user. Why doesn't it use some thing like openID where I can easily login to test it for my needs.


I plan to add that to the standard win user system ( https://github.com/mathgladiator/win/blob/master/pages/std.w... ).




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