Validity of a QR Code

I have a QR Code that leads to a link. This link, I suppose, will be on the air until 2015. Of course, when the link does not exist, this QR Code will not lead anywhere.

• is basically that. Probably it goes to a 404 or to a server not found.

My question is: Is this code valid?

• the code will be read at any time, since the information contained in it does not depend on anything external.

Someone there in the Transylvania can generate a QR Code identical to mine?

• For sure. The content of the QR Code is only a stream of bytes, which has as output a string. Just someone use the same string, and here is the QR with identical value. And the coolest thing, you don't even have to be in Transylvania for that.

  Inclusive, if the person uses the same compression and encoding criteria, the image will be identical.

I ask that, then, I intend to store them.

• Do you want to store the image or link? (remembering that it's not just links that can be stored in a QR Code. Any string can be stored for a variety of purposes)

  The most common purposes are links, wi-fi connection data and electronic business cards. But there are still codes for internal use, such as packaging identification, or anything else you can imagine that replaces barcodes conventional.

  If you are storing the images, you are probably storing more information than necessary, unless you had a very special use for the encoding characteristics used(which is unlikely).

Suggestion for those who want to create their own codes:

Do not use short third-party links. Create your system of short links, and store the data in your own DB, preferably under a domain of internet that you can keep for as long as you want.

See the main reasons:

• You prevent the link from "expiring", or ceasing to exist if the provider of the short link has problems or term.

• You can fix a wrong link. I've seen a case where a large-scale magazine had to enter into a deal with a famous link shortener, thanks to a link that was published wrong on the cover of the magazine. If you manage your own links, just swap the wrong one for the correct one in the DB, and the problem is solved.

• You can point A QR from an old link to a friendly message warning that the link has expired, instead of simply breaking access, creating a better pro user experience, and who knows directing you to something else interesting, not missing the visit.

Note: I say short links, because the less information, the better the readability of a QR Code. Remember that when it is the in this case, you can use almost 7KB in a single code, but in practice, only with a professional scanner you will be sure to read a QR with so much information.

By the way, I humbly dare to say that the people who normalized the receipt of NFC-e - which began to be used in some states in place of the tax coupon-made a big mess by putting a lot of unnecessary information in the QR Code, making the same "inescanable" by many devices. And look that one of the premises it was the merchant's save on the printer used. In practice, the printer has to be good, and so does the reader. If they had done it more sensibly, even a matrix printer would solve it.