Is there a way to create a schema for this simple XML?

Question

Hi! A simple question. Suppose we have a XML that looks like that (simplified)
<documents>
  <total>2</total>
  <doc_1>
    <name>My document</name>
    <code>1234</code>
  </doc_1>
  <doc_2>
    <name>Another document</name>
    <code>5678</code>
  </doc_2>
</documents>In this simple example, if the tag <total> had a numer of three, there would be a <doc_3> tag.
Is it posible to create a XSD to this XML? And is it posible for JAXB to process that XSD?
Thank you in advance

Answer 1

There are some tools around to generate XML Schemas from instance documents, but I don't know if they are too smart. For example, XMLSPY created the following Schema from your sample:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
     <xs:element name="code">
          <xs:simpleType>
               <xs:restriction base="xs:string">
                    <xs:enumeration value="1234"/>
                    <xs:enumeration value="5678"/>
               </xs:restriction>
          </xs:simpleType>
     </xs:element>
     <xs:element name="doc_1">
          <xs:complexType>
               <xs:sequence>
                    <xs:element ref="name"/>
                    <xs:element ref="code"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
     <xs:element name="doc_2">
          <xs:complexType>
               <xs:sequence>
                    <xs:element ref="name"/>
                    <xs:element ref="code"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
     <xs:element name="documents">
          <xs:complexType>
               <xs:sequence>
                    <xs:element ref="total"/>
                    <xs:element ref="doc_1"/>
                    <xs:element ref="doc_2"/>
               </xs:sequence>
          </xs:complexType>
     </xs:element>
     <xs:element name="name">
          <xs:simpleType>
               <xs:restriction base="xs:string">
                    <xs:enumeration value="Another document"/>
                    <xs:enumeration value="My document"/>
               </xs:restriction>
          </xs:simpleType>
     </xs:element>
     <xs:element name="total">
          <xs:simpleType>
               <xs:restriction base="xs:byte">
                    <xs:enumeration value="2"/>
               </xs:restriction>
          </xs:simpleType>
     </xs:element>
</xs:schema>XMLSPY has done its best but this Schema could certainly be cleaned up and made more efficient. If your instance documents aren't going to be too complex, it's probably best to have a tool like XMLSPY start you off, then you can go in by hand.
But, once you have the Schema in hand, you're ready to get started with JAXB.