what is the use of xsi schemaLocation

Question

I see that we have multiple url s as value of this attribute like in spring    lt beans xmlns  http   www springframework org schema beans  xmlns xsi  http   www w3 org 2001 XMLSchema-instance  xmlns aop  http   www springframework org schema aop  xsi schemaLocation  http   www springframework org schema beans http   www springframework org schema beans spring-beans-2 0 xsd http   www springframework org schema aop http   www springframework org schema aop spring-aop-2 0 xsd  gt    Why is it needed and what is it used for  Does Spring goes to the url and validate   what is the difference between xmlns and xsi schemaLocation

User · Answer

According to the spec for locating Schemas

there may or may not be a schema retrievable via the namespace name... User community and/or consumer/provider agreements may establish circumstances in which [trying to retrieve an xsd from the namespace url] is a sensible default strategy

(thanks for being unambiguous, spec!)

and

in case a document author (human or not) created a document with a particular schema in view, and warrants that some or all of the document conforms to that schema, the schemaLocation and noNamespaceSchemaLocation [attributes] are provided.

So basically with specifying just a namespace, your XML "might" be attempted to be validated against an xsd at that location (even if it lacks a schemaLocation attribute), depending on your "community." If you specify a specific schemaLocation, then it basically is implying that the xml document "should" be conformant to said xsd, so "please validate it" (as I read it). My guess is that if you don't do a schemaLocation or noNamespaceSchemaLocation attribute it just "isn't validated" most of the time (based on the other answers, appears java does it this way).

Another wrinkle here is that typically, with xsd validation in java libraries [ex: spring config xml files], if your XML files specifies a particular schemaLocation xsd url in an XML file, like xsi:schemaLocation="http://somewhere http://somewhere/something.xsd" typically within one of your dependency jars it will contain a copy of that xsd file, in its resources section, and spring has a "mapping" capability saying to treat that xsd file as if it maps to the url http://somewhere/something.xsd (so you never end up going to web and downloading the file, it just exists locally). See also https://stackoverflow.com/a/41225329/32453 for slightly more info.

User · Answer

If you go into any of those locations  then you will find what is defined in those schema  For example  it tells you what is the data type of the ini-method key words value

User · Answer

The Java XML parser that spring uses will read the schemaLocation values and try to load them from the internet  in order to validate the XML file  Spring  in turn  intercepts those load requests and serves up versions from inside its own JAR files   If you omit the schemaLocation  then the XML parser won t know where to get the schema in order to validate the config

User · Answer

An xmlns is a unique identifier within the document - it doesn t have to be a URI to the schema      XML namespaces provide a simple method for qualifying element and attribute names used in Extensible Markup Language documents by associating them with namespaces identified by URI references    xsi schemaLocation is supposed to give a hint as to the actual schema location      can be used in a document to provide hints as to the physical location of schema documents which may be used for assessment

[xsd] what is the use of xsi:schemaLocation?

Examples related to xsd