GT 4.2.1 WS MDS WebMDS: User's Guide

The WebMDS GUI is a web-based interface for browsing formatted XML data, such as the results of resource property queries on a grid service.

WebMDS can be accessed using any web browser. In a default WebMDS installation, the URL http://hostname:port/webmds corresponds to the top-level WebMDS web page. This page includes a link to a WebMDS invocation that provides summary information (with links to detailed information) about a locally-running MDS Index server. It also contains a link to a page of sample web forms demonstrating other uses of WebMDS.

The WebMDS servlet is located at http://your-tomcat-host:your-tomcat-port/webmds/webmds. It takes the following arguments:

Error conditions (such as typographical errors in resource property names) are presented as stack traces, rather than user-friendly error messages.

Error handling in WebMDS is currently done by throwing exceptions, which are displayed by Tomcat as stack traces.

Table 3.1. WS MDS Trigger Service Error Messages

Error Code	Definition	Possible Solutions
java.net.ConnectException: Connection refused	If you attempt to use WebMDS to collect information from a service that is not running, you will see a stack trace that begins with: org.globus.mds.webmds.xmlSources.resourceProperties.ResourcePropertySourceException: ; nested exception is: java.net.ConnectException: Connection refused	Make sure the service you are trying to collect information from is running.
faultString: org.globus.common.ChainedIOException: Authentication failed [Caused by: Failure unspecified at GSS-API level [Caused by: Unknown CA]]	When WebMDS sends resource property queries to a secure WSRF service instance (such as an WS MDS Index Server), the WebMDS server must trust the certificate authority that issued the certificate used by the WSRF service instance. If the WebMDS server does not trust the CA used by the remote service, then WebMDS queries will produce a stack trace that includes this message.	This can be solved by configuring the Tomcat server that hosts WebMDS to trust the appropriate CA, by either: placing the CA certificate in /etc/grid-security/certificates, or placing the CA certificate somewhere else, and setting the Tomcat process's X509_CERT_DIR system parameter to the directory in which the CA certificate was installed. One way to do this is to set the CATALINA_OPTS environment variable and then restart Tomcat: export CATALINA_OPTS=-DX509_CERT_DIR=/path/to/cert/dir $CATALINA_HOME/bin/shutdown.sh $CATALINA_HOME/bin/startup.sh
WebMDS connections to secure Index Servers (or other secure WSRF servers) just hang	If the JVM used by Tomcat is configured to use a blocking random-number source, WebMDS connections to secure Index Servers (or other secure WSRF servers) can hang. This is the default configuration for many installations.	One solution is to set the CATALINA_OPTS environment variable to ensure that Tomcat's JVM will use a non-blocking random-number source: export CATALINA_OPTS=-Djava.security.egd=/dev/urandom $CATALINA_HOME/bin/shutdown.sh $CATALINA_HOME/bin/startup.sh Note f you encounter this problem with WebMDS, you may also encounter a similar problem with the Globus container on the same system.