[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: SAX: New Idea for Entity Resolution
> Alex Milowski writes: > > > In effect, although the above interface is useful, it reduces > > interchange in that I can make a document with broken system > > identifiers work on my system. Essentially, I can make an > > *invalid* document valid! > > You can do this in any case, though -- you can intercept URIs in the > system libraries (Java, for example, lets you register your own > schemes), or you can redirect them with a proxy server. > > With URLs, file:// will almost always break on exchange, as will http: > system identifiers that refer to hostnames visible only within a > private network. Yes, but then if you do this, don't expect it to work elsewhere. ;-) Why would you use absolute URLs? Bad author, bad! Ok, maybe you would use them for a standard DTD. ;-) (This is where I beat the URN drum) <SGMLRANT type='mild'> In the SGML world, I could come up with a scheme that made location orthogonal to my documents. I *never* put a system identifier in my documents. In XML, this is much harder. </SGMLRANT> <URNRANT> Now, if URN support was *standard*, I could at least put a URN in the place of every system identifier I needed and then my document is quite portable. The key phrase here is *standard*. </URNRANT> Of course, we could also fix public identifiers and forget about the URN stuff. ...but, then we would have to come up with yet-another-resolution-mechanism... which sounds too much like URNs. > Your other points (which I omitted above) are well taken -- public > identifiers are a bit of a muddle right now, but since they're in XML > 1.0, it makes sense to support them. The interface is not only for > public identifiers, however -- users can also remote URIs to > local/secure equivalents, and they can even screen out certain URIs if > necessary. I'd better copyright "XML-Nanny" before someone else > thinks of it. Well, a further point I was making off-line is that this kind of mapping could be lead people down the wrong road. I have run into so many SGML users over the years that didn't know how to or *couldn't* use public identifiers without system identifiers. In an SGML world, I see this as bad practice. Likewise, I see mapping system identifiers in XML as bad practice. Two general rules I can recommend: 1. Use an internal resolution system inside your production systems. Locations will change even inside your own system. 2. Use a fairly static naming system (URN/Public identifier) when you exchange documents. One thing XML has over SGML is that it is tied more closely to a location mechanism. If you add in URN ability, there is no issue of "configuring" you local system to know about mappings--you just do a URN lookup. (Obviously, URNs can be miss-configured or not available. Ever had problems on the Internet with DNS names? Same idea, same problem, same frustration when it is wrong!) ============================================================================== R. Alexander Milowski http://www.copsol.com/ alex@c... Copernican Solutions Incorporated (612) 379 - 3608 xml-dev: A list for W3C XML Developers. To post, mailto:xml-dev@i... Archived as: http://www.lists.ic.ac.uk/hypermail/xml-dev/ To (un)subscribe, mailto:majordomo@i... the following message; (un)subscribe xml-dev To subscribe to the digests, mailto:majordomo@i... the following message; subscribe xml-dev-digest List coordinator, Henry Rzepa (mailto:rzepa@i...)
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