SAXException - Failed to resolve: arg0=-//GetAhead Limited//DTD Direct Web Remoting *.0//EN

In my previous article I have shown you a simple hello world DWR example however while trying to implement it in an application I faced below exception.


SEVERE: DwrServlet.init() failed
org.xml.sax.SAXException: Failed to resolve: arg0=-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN arg1=http://directwebremoting.org/schema/dwr30.dtd
at org.directwebremoting.impl.DTDEntityResolver.resolveEntity(DTDEntityResolver.java:59)
at com.sun.org.apache.xerces.internal.util.EntityResolverWrapper.resolveEntity(EntityResolverWrapper.java:107)
at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.resolveEntityAsPerStax(XMLEntityManager.java:1018)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1190)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1089)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:1002)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:124)
at org.directwebremoting.impl.DwrXmlConfigurator.setInputStream(DwrXmlConfigurator.java:132)
at org.directwebremoting.impl.DwrXmlConfigurator.setServletResourceName(DwrXmlConfigurator.java:87)
at org.directwebremoting.impl.ContainerUtil.configureFromDefaultDwrXml(ContainerUtil.java:263)
at org.directwebremoting.impl.ContainerUtil.configureContainerFully(ContainerUtil.java:421)
at org.directwebremoting.servlet.DwrServlet.init(DwrServlet.java:79)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1139)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:791)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:127)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:619)
Jan 16, 2013 2:05:46 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet dwr-invoker
org.xml.sax.SAXException: Failed to resolve: arg0=-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN arg1=http://directwebremoting.org/schema/dwr30.dtd
at org.directwebremoting.impl.DTDEntityResolver.resolveEntity(DTDEntityResolver.java:59)
at com.sun.org.apache.xerces.internal.util.EntityResolverWrapper.resolveEntity(EntityResolverWrapper.java:107)
at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.resolveEntityAsPerStax(XMLEntityManager.java:1018)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1190)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1089)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:1002)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:648)
at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:807)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:737)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:107)
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:225)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:283)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:124)
at org.directwebremoting.impl.DwrXmlConfigurator.setInputStream(DwrXmlConfigurator.java:132)
at org.directwebremoting.impl.DwrXmlConfigurator.setServletResourceName(DwrXmlConfigurator.java:87)
at org.directwebremoting.impl.ContainerUtil.configureFromDefaultDwrXml(ContainerUtil.java:263)
at org.directwebremoting.impl.ContainerUtil.configureContainerFully(ContainerUtil.java:421)
at org.directwebremoting.servlet.DwrServlet.init(DwrServlet.java:79)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1139)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:791)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:127)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:619)
Jan 16, 2013 2:09:33 AM org.apache.catalina.startup.HostConfig checkResources



To resolve above error, you need to correct DOCTYPE in dwr.xml file. Check which version of dwr you have implemented. You can check it with the help of JAR dwr.jar file. And accordingly update the below DOCTYPE type.


<!DOCTYPE dwr PUBLIC
    "-//GetAhead Limited//DTD Direct Web Remoting 2.0//EN"
    "http://directwebremoting.org/schema/dwr20.dtd">

<!DOCTYPE dwr PUBLIC
    "-//GetAhead Limited//DTD Direct Web Remoting 3.0//EN"
    "http://getahead.org/dwr/dwr30.dtd">

<!DOCTYPE dwr PUBLIC
    "-//GetAhead Limited//DTD Direct Web Remoting 4.0//EN"
    "http://getahead.org/dwr/dwr30.dtd">