Is Dedicated Hosting for Critical DTDs Necessary?

pcause asks: "Recently there was a glitch, when someone at Netscape took down a page that had an important DTD (for RSS), used by many applications and services. This got me thinking that many or all of the important DTDs that software and commerce depend on are hosted at various commercial entities. Is this a sane way to build an XML based Internet infrastructure? Companies come and go all of the time; this means that the storage and availability of those DTDs is in constant jeopardy. It strikes me that we need an infrastructure akin to the root server structure to hold the key DTDs that are used throughout the industry. What organization would be the likely custodian of such data, and what would be the best way to insure such an infrastructure stays funded?"

Re:DTD?

[x_MeRLiN_x]

Document Type Definition

Re:Centralization

[Bogtha]

There needs to be a way to refer to decentralized internet resources in a unique fashion. We need the equivalent of the URL for a file that is hosted simultaneously in many places.

This is known as a URN [wikipedia.org]. URLs and URNs are together known as URIs.

Don't know what a DTD is?

[ryanisflyboy]

This can help:
http://en.wikipedia.org/wiki/Document_Type_Definit ion [wikipedia.org]

Re:Centralization

[kwark]

You meant something like magnet URIs?
http://en.wikipedia.org/wiki/Magnet:_URI_scheme [wikipedia.org]

Not again

[dedazo]

This has been covered before here and elsewhere... anyone who is using a DTD as a URL rather than a URI needs to be taken out and shot. I say bring them all down and let all the apps that rely on them die or be fixed.

XML catalog files let your app use local copies...

[KarmaRundi]

You can map public and system identifiers to local resources. Use them for dtds, schemas, stylesheets, etc. Here's the spec [oasis-open.org]. Google for more information.

Re:Don't use them

[Skreems]

Exactly. The only point of having a URL associated with a DTD is to assure a unique identifier for each one. It wasn't worth starting a group specifically to regulate DTD identifiers, so they hooked it to a system that's already regulated. Yeah, it's nice to have the DTD live at that location, so if you get a file with a reference to an unfamiliar DTD you can pull it down on the spot, but it shouldn't be required.

Re:I know!

[Anonymous Coward]

ICANN!
Mhahahahaha. Yeah. I know, I crack myself up.

You laugh, but ICANN's Internet Assigned Numbers Authority (IANA) has a track record of running countless protocol registries. i.e. port numbers, SNMP private enterprise numbers, MIME types etc. It seems to make sense to me.

Re:Centralization

[frisket]

The defects of the URN/URI/URL mechanism were well known at the time this was discussed in the working groups and SIGs while XML was gestating.

The correct solution would have been to fix the outstanding problems with FPIs and use a combination of local catalog and DNS-style resolution, but this was turned down. Perhaps it's time to wake it up.

In the 1990s I did try to devise a resolution server for FPIs, in the hope that someone like the (then) GCA (now IdeAlliance) -- who were the ISO 9070 Registration Authority and theoretically still are -- would pick up the idea.

I still have the large collection of SGML DTDs used at the time, now largely redundant, but replacing it with current XML is not the problem. This is something that should probably be discussed at the Markup conference in Montreal this summer.