Hi, I created an GWT project in eclipse. Now I tried to implement openId with using the openid4java library. I imported the .jar files via properties--java build path: openid4java-0.9.5.jar lib/*.jar In addition I copied the .jar files into the war/WEB-INF/lib directory. The problem at hand comes up when I call the authenticate() method. Then I get a: HTTP ERROR 500 Problem accessing /openid/openid. Reason: access denied (java.lang.RuntimePermission modifyThreadGroup)Caused by:java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup) at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkPermission(DevAppServerFactory.java:166) at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkAccess(DevAppServerFactory.java:191) at java.lang.ThreadGroup.checkAccess(Unknown Source) at java.lang.Thread.init(Unknown Source) at java.lang.Thread.<init>(Unknown Source) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$ReferenceQueueThread.<init>(MultiThreadedHttpConnectionManager.java:1039) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.storeReferenceToConnection(MultiThreadedHttpConnectionManager.java:164) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.access$900(MultiThreadedHttpConnectionManager.java:64) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$ConnectionPool.createConnection(MultiThreadedHttpConnectionManager.java:750) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.doGetConnection(MultiThreadedHttpConnectionManager.java:469) at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager.getConnectionWithTimeout(MultiThreadedHttpConnectionManager.java:394) at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:152) at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:396) at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:324) at org.openid4java.util.HttpCache.head(HttpCache.java:296) at org.openid4java.discovery.yadis.YadisResolver.retrieveXrdsLocation(YadisResolver.java:360) at org.openid4java.discovery.yadis.YadisResolver.discover(YadisResolver.java:229) at org.openid4java.discovery.yadis.YadisResolver.discover(YadisResolver.java:221) at org.openid4java.discovery.yadis.YadisResolver.discover(YadisResolver.java:179) at org.openid4java.discovery.Discovery.discover(Discovery.java:134) at org.openid4java.discovery.Discovery.discover(Discovery.java:114) at org.openid4java.consumer.ConsumerManager.discover(ConsumerManager.java:527) at auth.openid.server.OpenIDServlet.authenticate(OpenIDServlet.java:138) at auth.openid.server.OpenIDServlet.doGet(OpenIDServlet.java:101) at javax.servlet.http.HttpServlet.service(HttpServlet.java:693) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166) at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:51) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:122) at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) at com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:70) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:349) at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:326) at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923) at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:547) at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212) at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409) at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) Here my servlet source: import com.google.gwt.user.client.rpc.RemoteService; import org.openid4java.OpenIDException; import org.openid4java.consumer.ConsumerException; import org.openid4java.consumer.ConsumerManager; import org.openid4java.consumer.VerificationResult; import org.openid4java.discovery.DiscoveryInformation; import org.openid4java.discovery.Identifier; import org.openid4java.message.AuthRequest; import org.openid4java.message.ParameterList; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.text.MessageFormat; import java.util.List; public final class OpenIDServlet extends HttpServlet implements RemoteService { private final ConsumerManager manager; public OpenIDServlet() { try { manager = new ConsumerManager(); } catch (ConsumerException e) { throw new RuntimeException("Error creating consumer manager", e); } } ... private void authenticate(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { final String loginString = request.getParameter(nameParameter); try { // perform discovery on the user-supplied identifier List discoveries = manager.discover(loginString); // attempt to associate with the OpenID provider // and retrieve one service endpoint for authentication DiscoveryInformation discovered = manager.associate(discoveries); // obtain a AuthRequest message to be sent to the OpenID provider AuthRequest authReq = manager.authenticate(discovered, "openid", null); // redirect to OpenID for authentication response.sendRedirect(authReq.getDestinationUrl(true)); } catch (OpenIDException e) { throw new ServletException("Login string probably caused an error. loginString = " + loginString, e); } } My question now is: What could be my fault? Did I make any mistakes in importing the openid4java library? (which?) All other methods in the servlet which do not use the openid4java implementation work fine. Thanks, Andreas