From 35a201cc8ef0c3f5b2df88d2e528aabee1048348 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Fri, 30 Apr 2021 18:47:09 +0200 Subject: Initial/Final commit --- libxml2-2.9.10/doc/namespaces.html | 50 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 libxml2-2.9.10/doc/namespaces.html (limited to 'libxml2-2.9.10/doc/namespaces.html') diff --git a/libxml2-2.9.10/doc/namespaces.html b/libxml2-2.9.10/doc/namespaces.html new file mode 100644 index 0000000..995587b --- /dev/null +++ b/libxml2-2.9.10/doc/namespaces.html @@ -0,0 +1,50 @@ + + +Namespaces

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/">
+   <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;
+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

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