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

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

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

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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

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

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

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