transfer of XML file

[John Cowan]

Gang He wrote:

> Suppose I have a xml file on the server side. In it there are some
> elements
> pointing to some external binary entity and external text entity, and
> some XML-LINK elements.

The first thing to understand is that these references are different.
An external text entity is referred to using an entity reference,
of the form "&some-name;" (in other words, syntactically, it is the
same as a reference to an internal entity).

A non-validating XML processor is free to expand external entities
(replacing the reference with the content of the entity) or else
just leave them in place.  (Validators must expand external entities.)

References to external entities, however, look completely different.
They cannot be achieved by an entity reference using "&".
Instead, one must have an attribute attached to some element, and
this attribute must be declared as of type "ENTITY" or "ENTITIES".
The value of the attribute is either a single entity name or
multiple entity names separated by whitespaces, respectively.
This form is not available for referring to internal entities.

> What about the pages pointed by the URL
> in the XML-LINK elements? Is there any way to let the client to specify
> when to retrieve the external entity?

XML-Link elements can specify whether the content is to be inlined
or shown as an explicit link, but this is advisory; the client
may allow the user to override.

> Does http support the transfer of
> xml file? If so, in which way?

HTTP will transfer pages that are in any format: text/html, text/plain,
image/gif, application/xml, or x-unrecognized/confusing.

-- 
John Cowan	http://www.ccil.org/~cowan		cowan at ccil.org
	You tollerday donsk?  N.  You tolkatiff scowegian?  Nn.
	You spigotty anglease?  Nnn.  You phonio saxo?  Nnnn.
		Clear all so!  'Tis a Jute.... (Finnegans Wake 16.5)

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