I built Notifyr couple months ago. I actually got off my ass and did it in order to learn Ruby on Rails, and at the same opportunity scratch a little itch (no pun please) I had about sharing Flickr photos.
I was travelling a bit at the time and was getting tired of emailing friends & family whenever I returned and uploaded new trip photos to my Flickr page. RSS could have solved this, but almost no one (that’s among people with a life) uses RSS. I considered RSS to email gateways, like RssFwd, but these usually send an email for every new item – 20 new photos from my last trip would mean 20 emails to each contact.
So, I wrote a simple app which monitors a Flickr page’s RSS once a day and, if new images were published, sends one email per contact: “I got new photos in my Flickr page”.
Next was the registration issue. I really dislike having to register to use sites – there’s probably no way around this for email services or banks, but for tiny apps like Notifyr it’s absurd to have to register, wait for confirmation mail, remember a password etc. My solution was basically adapted (read “lifted”) straight from RssFwd – no registration at all, every email sent contains an easily-filterable sender address and an unsubscribe link with a unique string.
No one can find out what pages you’re monitoring without breaking into your email account (or into notifyr.com), or subscribe you to something you don’t want without being easily deleted, nor unsubscribe you without figuring out the hash string. I believe this is good-enough-security: obviously it can be compromised, just like your bank’s website can. I believe the Evil Genius Cracker would rather concentrate her powers on the latter first.
An added bonus of having no registration is solving the “Grandma Case”: I wanted people to be able to send a link to their non-geek contacts that will subscribe them to their Flickr page, or even subscribe them without sending a link so that, for example, you could have your grandmother get an email whenever new family pictures are uploaded. You enter her email and your photo page URL, and it starts working. She never has to register or even visit notifyr.com at all.
Building these links is quite easy – the examples show you how to build URLs (or “Access Via REST API” if you like that sort of stuff) by yourself. I’m work on the assumption here that, while Notifyr users may not be computer geeks, they can figure how to alter a URL by themselves. Happily, it seems to have worked out well so far, and indeed people have been creating their own Notifyr links on their blogs or Flickr profiles etc.
Finally, you might wonder about spammers using Notifyr. This is simply handled by making it a lousy tool for spamming. Emails get sent at most once a day. Emails don’t contain the actual photos are other content (text etc) that can be influenced by the photo page’s owner. Emails do contain an unsubscribe link. A spammer would have to publish his content as Flickr images – and be vulnerable to Flickr’s own content editing. So, rather than make it hard for spammer, I just made it useless for them. If this is not Zen I do not know what is.
Well, that’s Notifyr. Hope you might find it useful. There’s probably more text here than in the actual code already, but that’s how it goes – us lazy people know that talking a lot about what we’ve done keeps us from having to do more of it.