[gmpi] Re: low level API - Abstract Factory summary
- From: "Frederick Umminger" <Frederick_Umminger@xxxxxxxxxxxxxx>
- To: <gmpi@xxxxxxxxxxxxx>
- Date: Wed, 9 Feb 2005 17:15:12 -0800
>suggest they should be exposed to users anyway), but theres no content in
>a GUID, and they cannot be dereferenced, except through a central
>(well-known) resource, and thats far from ideal.
The fact that a GUID cannot be dereferenced is a feature. That means there is
no reference to go stale and invalid. A URI that is designed to be dereferenced
can go bad. Originally it was http://www.supercoolplugins.com/pitchwobbler, but
then I could not afford to keep up the domain so it had to change to
http://users.genericinternetprovider.com/~fumminger/pitchwobbler, but then I
sold the plugin to MegaCorp and it had to change to
http://www.MegaCorp.com/plugins/pitchwobbler. Then they went out of business
and there no longer was any dereferenceable URI. Throughout all of this, the
URIs of plugins in the field kept breaking. Furthermore hosts would try to
instantiate a plugin identified as http://www.MegaCorp.com/plugins/pitchwobbler
and fail, because the hapless user only had the plugin
http://www.supercoolplugins.com/pitchwobbler installed. Wait, they are the same
plugin! Too bad the host had no way of knowing this.
Plugin identifiers should be immutable and in one-to-one relationship with
plugins. URIs are neither.
Adding some kind of version tag into the URI does not fix this.
http://www.supercoolplugins.com/pitchwobbler_VERSION_1.0 goes stale as quickly
as the unversioned tag.
In terms of database theory, the URI solution commits two unfogiveable sins by
conflating the identity of data not only with a location
(www.supercoolplugins.com/pitchwobbler) but also with a method of access
(http:).
Btw, an example of another project that attempts to use meaningful internet
addresses in identifiers is GNU Arch, which uses email address in archive
names. This has generated a lot of bitter complaint from users who need to use
fake email addresses to protect themselves from spammers. See
http://wiki.gnuarch.org/moin.cgi/Why_20not_20Arch. The result is that the
"feature" does not actually work due to fake addresses and a lot of heat is
generated about issues that are entirely extraneous to the problem domain of
Arch, which is source code control.
Sincerely,
Frederick Umminger
-----Original Message-----
From: gmpi-bounce@xxxxxxxxxxxxx [mailto:gmpi-bounce@xxxxxxxxxxxxx]On
Behalf Of Steve Harris
Sent: Wednesday, February 09, 2005 3:37 PM
To: gmpi@xxxxxxxxxxxxx
Subject: [gmpi] Re: low level API - Abstract Factory summary
On Wed, Feb 09, 2005 at 02:51:14 -0800, Frederick Umminger wrote:
>
> I know what a URL is. I do not think the web has ignored localization issues.
Not all URIs are URLs.
It's true that URIs are not localised, but the resource that you retreive
by derefencing the URI /can/ be localised.
They can be versioned, if we specify it, eg. the local name part of the
URI can be speciifed to have a certain parsable form to extract the
version number.
Regardless, these are features that GUIDs dont posses, at all. You can
argue that some people can't read URIs in a human sense (and I dont
suggest they should be exposed to users anyway), but theres no content in
a GUID, and they cannot be dereferenced, except through a central
(well-known) resource, and thats far from ideal.
- Steve
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