Shulou(Shulou.com)06/03 Report--

This article mainly introduces what the XML namespace is, the article is very detailed, has a certain reference value, interested friends must read it!

XML namespaces represent the scope of use of XML names, and because XML can customize element tags, there is a good chance that XML names are duplicated between different XML applications.

If there is no way to distinguish between names that are not used, it will cause confusion. XML namespaces are designed to solve this problem. Through XML namespaces, we can distinguish between phases from different XML applications

XML namespaces represent the scope of use of XML names, and because XML can customize element tags, there is a good chance that XML names are duplicated between different XML applications. If there is no way to distinguish between names that are not used, it will cause confusion. XML namespaces are designed to solve this problem. Through the XML namespace, we can distinguish between elements and attributes with the same name from different XML applications. Relevant elements and attributes from a single XML application can be grouped together to facilitate software identification and processing.

Namespaces consist of prefixes and local parts, separated by colons. The prefix identifies the namespace of the element or attribute, and the local part identifies an element or attribute in the namespace. The entire name is also known as a qualified name (qualified name). The prefix can be made up of any legal XML name character except XML (any combination of uppercase and lowercase). The prefix in each qualified name must be associated with a unique URI. Names with prefixes associated with the same URI belong to the same namespace.

Example linuxsir...

A prefix is generally defined in the uppermost element that uses the prefix. Different prefixes can also be defined in the lower elements:

Example linuxsir...

By appending an unprefixed xmlns attribute to the root element, you can specify that the unprefixed element and all unprefixed child elements belong to a namespace.

If namespaces are used only to identify elements and attributes from some XML application, rather than to distinguish different elements with the same name, a fixed xmlns attribute can be defined in the elements of the DTD, rather than in the document. The definition is as follows:

When defining a DTD, those that need to use a namespace prefix should also write the prefix to the DTD definition, such as:

Using parameter entity references to define namespace prefixes can facilitate the maintenance, collation and release of DTD documents! Please indicate the source of the reprint, thank you!

Next, use the parameter entity name to define more parameter entity references, such as:

In this way, if you need to change the prefix, you only need to modify one place, not the entire document.

% prefix; and% colon;, cannot be used directly in ATTLIST and ELEMENT declarations because when these parameter entities are used outside another entity, the XML parser adds extra spaces on both sides of the entity replacement text. The above is all the content of the article "what is the XML Namespace?" Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.