From a7e9d3f37d5e9fba4b9acaa43e7c12b6d9a669ae Mon Sep 17 00:00:00 2001 From: Mike Hommey Date: Thu, 8 Jun 2006 10:59:26 +0200 Subject: Load /tmp/libxml2-2.6.26 into libxml2/branches/upstream/current. --- doc/namespaces.html | 70 ++++++++++++++++++++++++++--------------------------- 1 file changed, 35 insertions(+), 35 deletions(-) (limited to 'doc/namespaces.html') diff --git a/doc/namespaces.html b/doc/namespaces.html index 32c7787..a4d6ace 100644 --- a/doc/namespaces.html +++ b/doc/namespaces.html @@ -7,44 +7,44 @@ H1 {font-family: Verdana,Arial,Helvetica} H2 {font-family: Verdana,Arial,Helvetica} H3 {font-family: Verdana,Arial,Helvetica} A:link, A:visited, A:active { text-decoration: underline } -Namespaces
Action against software patentsGnome2 LogoW3C LogoRed Hat Logo
Made with Libxml2 Logo

The XML C parser and toolkit of Gnome

Namespaces

Main Menu
Related links

The libxml2 library implements XML namespaces support by -recognizing namespace constructs in the input, and does namespace lookup -automatically when building the DOM tree. A namespace declaration is -associated with an in-memory structure and all elements or attributes within -that namespace point to it. Hence testing the namespace is a simple and fast -equality operation at the user level.

I suggest that people using libxml2 use a namespace, and declare it in the -root element of their document as the default namespace. Then they don't need -to use the prefix in the content but we will have a basis for future semantic -refinement and merging of data from different sources. This doesn't increase -the size of the XML output significantly, but significantly increases its -value in the long-term. Example:

<mydoc xmlns="http://mydoc.example.org/schemas/">
+Namespaces
Action against software patentsGnome2 LogoW3C LogoRed Hat Logo
Made with Libxml2 Logo
The XML C parser and toolkit of Gnome
Namespaces
Main Menu
Related links
The libxml2 library implements XML
+namespacessupportbyrecognizing namespace constructs in the input, and
+does namespacelookupautomatically when building the DOM tree. A namespace
+declarationisassociated with an in-memory structure and all elements or
+attributeswithinthat namespace point to it. Hence testing the namespace is a
+simple andfastequality operation at the user level.
I suggest that people using libxml2 use a namespace, and declare it
+intheroot element of their document as the default namespace. Then they
+don'tneedto use the prefix in the content but we will have a basis for
+futuresemanticrefinement and  merging of data from different sources. This
+doesn'tincreasethe size of the XML output significantly, but significantly
+increasesitsvalue in the long-term. Example:
<mydoc xmlns="http://mydoc.example.org/schemas/">
    <elem1>...</elem1>
    <elem2>...</elem2>
-</mydoc>
The namespace value has to be an absolute URL, but the URL doesn't have to
-point to any existing resource on the Web. It will bind all the element and
-attributes with that URL. I suggest to use an URL within a domain you
-control, and that the URL should contain some kind of version information if
-possible. For example, "http://www.gnome.org/gnumeric/1.0/" is a
-good namespace scheme.
Then when you load a file, make sure that a namespace carrying the
-version-independent prefix is installed on the root element of your document,
-and if the version information don't match something you know, warn the user
-and be liberal in what you accept as the input. Also do *not* try to base
-namespace checking on the prefix value. <foo:text> may be exactly the
-same as <bar:text> in another document. What really matters is the URI
-associated with the element or the attribute, not the prefix string (which is
-just a shortcut for the full URI). In libxml, element and attributes have an
-ns field pointing to an xmlNs structure detailing the namespace
-prefix and its URI.
@@Interfaces@@
xmlNodePtr node;
+</mydoc>
The namespace value has to be an absolute URL, but the URL doesn't
+havetopoint to any existing resource on the Web. It will bind all the
+elementandattributes with that URL. I suggest to use an URL within a
+domainyoucontrol, and that the URL should contain some kind of version
+informationifpossible. For example,
+"http://www.gnome.org/gnumeric/1.0/"isagood namespace scheme.
Then when you load a file, make sure that a namespace
+carryingtheversion-independent prefix is installed on the root element of
+yourdocument,and if the version information don't match something you know,
+warnthe userand be liberal in what you accept as the input. Also do *not* try
+tobasenamespace checking on the prefix value. <foo:text> may be
+exactlythesame as <bar:text> in another document. What really matters
+is theURIassociated with the element or the attribute, not the prefix string
+(whichisjust a shortcut for the full URI). In libxml, element and attributes
+haveannsfield pointing to an xmlNs structure detailing
+thenamespaceprefix and its URI.
@@Interfaces@@
xmlNodePtr node;
 if(!strncmp(node->name,"mytag",5)
   && node->ns
   && !strcmp(node->ns->href,"http://www.mysite.com/myns/1.0")) {
   ...
-}
Usually people object to using namespaces together with validity checking.
-I will try to make sure that using namespaces won't break validity checking,
-so even if you plan to use or currently are using validation I strongly
-suggest adding namespaces to your document. A default namespace scheme
-xmlns="http://...." should not break validity even on less
-flexible parsers. Using namespaces to mix and differentiate content coming
-from multiple DTDs will certainly break current validation schemes. To check
-such documents one needs to use schema-validation, which is supported in
-libxml2 as well. See relagx-ng and w3c-schema.
Daniel Veillard

+}

Usually people object to using namespaces together with validitychecking.I +will try to make sure that using namespaces won't break validitychecking,so +even if you plan to use or currently are using validation Istronglysuggest +adding namespaces to your document. A default +namespaceschemexmlns="http://...."should not break validity even +onlessflexible parsers. Using namespaces to mix and differentiate +contentcomingfrom multiple DTDs will certainly break current validation +schemes. Tochecksuch documents one needs to use schema-validation, which is +supportedinlibxml2 as well. See relagx-ngand w3c-schema.

Daniel Veillard

-- cgit v1.2.3