BATCH-1456: add dummy 2.0 schema and a detector for the wrong schema declaration.

spring-batch-core/src/main/java/org/springframework/batch/core/configuration/xml/CoreNamespaceHandler.java

@@ -37,4 +37,5 @@ public class CoreNamespaceHandler extends NamespaceHandlerSupport {
 		this.registerBeanDefinitionParser("job-listener", new TopLevelJobListenerParser());
 		this.registerBeanDefinitionParser("step-listener", new TopLevelStepListenerParser());
 	}
+
 }

spring-batch-core/src/main/java/org/springframework/batch/core/configuration/xml/JobParser.java

@@ -58,6 +58,14 @@ public class JobParser extends AbstractSingleBeanDefinitionParser {
 	@Override
 	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
 
+		if (!namespaceMatchesVersion(element)
+				|| !namespaceMatchesVersion(element.getOwnerDocument().getDocumentElement())) {
+			parserContext.getReaderContext().error(
+					"You cannot use spring-batch-2.0.xsd with Spring Batch 2.1.  Please upgrade your schema declarations "
+							+ "(or use the spring-batch.xsd alias if you are feeling lucky).", element);
+			return;
+		}
+
 		CoreNamespaceUtils.autoregisterBeansForNamespace(parserContext, parserContext.extractSource(element));
 
 		String jobName = element.getAttribute("id");
@@ -107,7 +115,7 @@ public class JobParser extends AbstractSingleBeanDefinitionParser {
 		}
 
 		Element description = DomUtils.getChildElementByTagName(element, "description");
-		if (description!=null) {
+		if (description != null) {
 			builder.getBeanDefinition().setDescription(description.getTextContent());
 		}
 
@@ -134,4 +142,21 @@ public class JobParser extends AbstractSingleBeanDefinitionParser {
 
 	}
 
+	/**
+	 * Check that the schema location declared in the source file being parsed
+	 * matches the Spring Batch version. (The old 2.0 schema is not 100%
+	 * compatible with the new parser, so it is an error to explicitly define
+	 * 2.0. It might be an error to declare spring-batch.xsd as an alias, but
+	 * you are only going to find that out when one of the sub parses breaks.)
+	 * 
+	 * @param element the element that is to be parsed next
+	 * @return true if we find a schema declaration that matches
+	 */
+	private boolean namespaceMatchesVersion(Element element) {
+		String schemaLocation = element.getAttributeNS("http://www.w3.org/2001/XMLSchema-instance", "schemaLocation");
+		return schemaLocation.matches("(?m).*spring-batch-2.1.xsd.*")
+				|| schemaLocation.matches("(?m).*spring-batch.xsd.*")
+				|| !schemaLocation.matches("(?m).*spring-batch.*");
+	}
+
 }

spring-batch-core/src/main/resources/META-INF/spring.schemas

@@ -1,2 +1,3 @@
 http\://www.springframework.org/schema/batch/spring-batch.xsd=/org/springframework/batch/core/configuration/xml/spring-batch-2.1.xsd
-http\://www.springframework.org/schema/batch/spring-batch-2.1.xsd=/org/springframework/batch/core/configuration/xml/spring-batch-2.1.xsd
+http\://www.springframework.org/schema/batch/spring-batch-2.1.xsd=/org/springframework/batch/core/configuration/xml/spring-batch-2.1.xsd
+http\://www.springframework.org/schema/batch/spring-batch-2.0.xsd=/org/springframework/batch/core/configuration/xml/spring-batch-2.0-error.xsd

spring-batch-core/src/main/resources/org/springframework/batch/core/configuration/xml/spring-batch-2.0-error.xsd

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xsd:schema xmlns="http://www.springframework.org/schema/batch"
+	xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	targetNamespace="http://www.springframework.org/schema/batch"
+	elementFormDefault="qualified" attributeFormDefault="unqualified"
+	version="2.0-error">
+	<xsd:annotation>
+		<xsd:documentation><![CDATA[
+	It is an error to load this file.  That will happen if you use Spring Batch 2.1 and declare the namespace schema
+	location as http://www.springframework.org/schema/batch/spring-batch-2.0.xsd.  If you see errors mentioning this 
+	URL or this file, just change your schema declarations to 2.1, or to the alias spring-batch.xsd.  This file is
+	included in the 2.1 jar file to make sure the error is fail fast: otherwise you might get the parser going out
+	to the internet looking for the old 2.0 XSD.
+		]]></xsd:documentation>
+	</xsd:annotation>
+</xsd:schema>

spring-batch-core/src/test/java/org/springframework/batch/core/configuration/xml/JobParserExceptionTests.java

@@ -5,6 +5,7 @@ import static org.junit.Assert.fail;
 
 import org.junit.Test;
 import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.parsing.BeanDefinitionParsingException;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 
@@ -48,4 +49,20 @@ public class JobParserExceptionTests {
 		}
 	}
 
+	@Test
+	public void testWrongSchemaInRoot() {
+		try {
+			new ClassPathXmlApplicationContext(
+					"org/springframework/batch/core/configuration/xml/JobParserWrongSchemaInRootTests-context.xml");
+			fail("Error expected");
+		}
+		catch (BeanDefinitionParsingException e) {
+			String message = e.getMessage();
+			assertTrue("Wrong message: "+message, message.matches("(?s).*You cannot use spring-batch-2.0.xsd.*"));
+		} catch (BeanDefinitionStoreException e) {
+			// Probably the internet is not available and the schema validation failed.
+			// We don't want an automated build to fail if that happens.
+		}
+	}
+
 }

spring-batch-core/src/test/resources/org/springframework/batch/core/configuration/xml/JobParserWrongSchemaInRootTests-context.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/batch"
+	xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch-2.0.xsd
+	http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">
+
+	<beans:import resource="common-context.xml" />
+
+	<job id="job1">
+		<step id="s1">
+			<tasklet ref="dummyTasklet" />
+		</step>
+	</job>
+
+
+</beans:beans>