4 ms·

An algorithmically reversible personal URL shortener

15 points by donohoe 16y ago

nitrogen 16y ago
I like the algorithmic reversibility, but this seems to depend on a specific site layout. Would something like this be possible for abitrary URLs without actually making them longer? Simply converting to base 60 or 64 wouldn't work, but since most URLs have characters that are close to each other, what about storing the differences between characters and/or using Huffman coding (or something similar) to give shorter symbols to the most common characters/differences? Maybe a preshared dictionary of common URL components?
chacha102 16y ago
I think the author got a little too caught up in flickr's cleverness of making an ID based on different information. For instance, the first letter is the post type, then a group of letters is date, and then there is the post number for that day. The fact is, not many people are going to go devise their own URL shortening algorithm and implement it. While it is a good idea, I just don't think many people will put in that kind of effort. What might work is a more general algorithm. An algorithm that can reliably shrink and unshrink any URL. I'm not sure, but this might not be possible considering that many people have invented compression algorithms, and the general rule is that if you compress data, you are going to loose data. (I'd like to hear someone's opinion on that considering I haven't dove deep into compression) Edit: By 'possible' I mean 'meaningfully possible'. Taking a URL around 50-80 characters and making it around 20-30.
- tel 16y ago
  I am not an expert, but for lossless compression I believe the idea is that if there's a mismatch between the size of an encoded symbol and it's information content (novelty) -- then you've got some room for lossless compression. Is that the case with URLs? Probably not directly. Certain atoms (.com, www) might be encodable to save space, but it'll not necessarily be a big gain.
  - nitrogen 16y ago
    It might be enough to shorten only the most common sites and platforms' URL forms.
davnola 16y ago
Yes, but two major difficulties mitigate against its adoption. First, only a tiny number of people will actually devise, implement, and install their own shortener. Perhaps the major blogging platforms would adopt it, but that still leaves a large number of sites uncovered. Second, consumers of URL shorteners actually want unique short URLs so they can track clickthru. So even if a site self-hosts reversible personal short URLs, consumers will not adopt it. I have no alternative positive suggestion. It would be nice if URL shorteners called a webhook on the shortened domain.
wzdd 16y ago
His argument doesn't make sense to me. Consider the uses he gives for the shortened URL: * Presentations * Email * IM and Twitter Given these use cases, what, exactly, is the utility of retaining the longer URL? If every time you reference the location it's through the short URL, then the advantages of the longer URL (comprehensibility, mainly) are lost -- because nobody will ever look at it! It seems like the only reason to do this is to maintain compatibility with systems which impose a particular URL scheme. The post is a good argument for making shorter URLs in general, not a good argument for a personal and application-specific URL shortener.
kuahyeow 16y ago
http://tantek.pbworks.com/NewBase60#AdditionalImplementations http://tantek.pbworks.com/NewBase60#AdditionalImplementation... I can't find any actual code for the shortener. But the base60 should allow you to come up with your own shortening scheme

15 points by donohoe 16y ago

I like the algorithmic reversibility, but this seems to depend on a specific site layout. Would something like this be possible for abitrary URLs without actually making them longer? Simply converting to base 60 or 64 wouldn't work, but since most URLs have characters that are close to each other, what about storing the differences between characters and/or using Huffman coding (or something similar) to give shorter symbols to the most common characters/differences? Maybe a preshared dictionary of common URL components?

chacha102 16y ago

I think the author got a little too caught up in flickr's cleverness of making an ID based on different information. For instance, the first letter is the post type, then a group of letters is date, and then there is the post number for that day. The fact is, not many people are going to go devise their own URL shortening algorithm and implement it. While it is a good idea, I just don't think many people will put in that kind of effort. What might work is a more general algorithm. An algorithm that can reliably shrink and unshrink any URL. I'm not sure, but this might not be possible considering that many people have invented compression algorithms, and the general rule is that if you compress data, you are going to loose data. (I'd like to hear someone's opinion on that considering I haven't dove deep into compression) Edit: By 'possible' I mean 'meaningfully possible'. Taking a URL around 50-80 characters and making it around 20-30.

tel 16y ago
I am not an expert, but for lossless compression I believe the idea is that if there's a mismatch between the size of an encoded symbol and it's information content (novelty) -- then you've got some room for lossless compression. Is that the case with URLs? Probably not directly. Certain atoms (.com, www) might be encodable to save space, but it'll not necessarily be a big gain.
- nitrogen 16y ago
  It might be enough to shorten only the most common sites and platforms' URL forms.

davnola 16y ago

Yes, but two major difficulties mitigate against its adoption. First, only a tiny number of people will actually devise, implement, and install their own shortener. Perhaps the major blogging platforms would adopt it, but that still leaves a large number of sites uncovered. Second, consumers of URL shorteners actually want unique short URLs so they can track clickthru. So even if a site self-hosts reversible personal short URLs, consumers will not adopt it. I have no alternative positive suggestion. It would be nice if URL shorteners called a webhook on the shortened domain.

wzdd 16y ago

His argument doesn't make sense to me. Consider the uses he gives for the shortened URL: * Presentations * Email * IM and Twitter Given these use cases, what, exactly, is the utility of retaining the longer URL? If every time you reference the location it's through the short URL, then the advantages of the longer URL (comprehensibility, mainly) are lost -- because nobody will ever look at it! It seems like the only reason to do this is to maintain compatibility with systems which impose a particular URL scheme. The post is a good argument for making shorter URLs in general, not a good argument for a personal and application-specific URL shortener.

kuahyeow 16y ago

http://tantek.pbworks.com/NewBase60#AdditionalImplementations http://tantek.pbworks.com/NewBase60#AdditionalImplementation... I can't find any actual code for the shortener. But the base60 should allow you to come up with your own shortening scheme