[Cosmo-dev] Allowable Characters in Cosmo Usernames

[Todd Agulnick]

On 5/18/2006 7:11 PM, John Townsend wrote:
> I would add @ so that people can use email addresses. So if you add @, 
> +1 from me.
>
>

Trouble-maker! Recall that usernames play a dual role as both account 
identifier and URL component. '@' is one of the several characters in 
the list of reserved characters in URL's (full list is ";" | "/" | "?" | 
":" | "@" | "&" | "=" | "+" | "$" | ",") which means that if you allow 
'@' in usernames you have to ensure that you escape it in any place that 
you generate a URL, and users who enter the URL into a browser without 
escaping it themselves may find the URL doesn't work. Usernames w/@ in 
them will also break any clients (like Foxmarks) that use the form:

    http://username:password@cosmo-demo.osafoundation.org/path/resource.txt

to incorporate authentication information into the URL.

And finally, there's the concern I'd have on the usability front as 
people register accounts with account names that happen to look like 
email addresses (which they can't change, and to which Cosmo will never 
send password reminders, etc.) alongside an recognized email address 
(that they can change, and that Cosmo *will* use for communication with 
the user).

So, for the reasons cited above, I'd recommend against doing this.

-Todd