GT 4.2.1 Component Guide to Public Interfaces: WS MDS WebMDS

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.

WebMDS can be configured to get information from any of various sources and to filter it through any XSL transform. WebMDS uses configuration files to specify the location of (and to name) sources of information and xsl and web form arguments to select among these configured information sources and xsl transforms.

By default, WebMDS comes configured to report information about an index server using transaction-level security on the default port (8443) on the local system. If you are running the Globus Toolkit in this default configuration, then you can use WebMDS to query your local Index Service without any configuration changes.

If you wish to monitor a different Index Service, you will need to edit the file $GLOBUS_LOCATION/lib/webmds/conf/indexinfo to change the URL in the line:

    <value>https://127.0.0.1:8443/wsrf/services/DefaultIndexService</value>

to match the URL of your default index service. Changes to WebMDS configuration files take effect the next time that Tomcat is restarted.

For other configuration changes (e.g., monitoring different kinds of services), see the detailed configuration information below.

Each configuration file in $GLOBUS_LOCATION/lib/webmds/conf defines a source of XML, which can be used in an HTML form to specify sources of information and XSL transforms. The distribution contains some standard configuration files in this directory, including:

Each configuration file defines a WebmdsConfig object. A WebmdsConfig object consists of:

For example, this is $GLOBUS_LOCATION/lib/webmds/conf/servicegroupxsl, which defines the servicegroupxsl XML source:

    <WebmdsConfig>
      <description>
         XSL file to show service group summary information
      </description>
      <className>org.globus.mds.webmds.xmlSources.file.FileXmlSource</className>
      <parameter>
        <name>file</name>
        <value>xslfiles/servicegrouptable.xsl</value>
      </parameter>
    </WebmdsConfig>

This file tells WebMDS to use the org.globus.mds.webmds.xmlSources.file.FileXmlSource Java class (a class which reads XML from a local file) to collect XML data and to pass a file parameter (which that Java class interprets as the name of the file to open, relative to the WebMDS base directory).

Tomcat must be restarted (or one of the more advanced Tomcat administrative mechanisms must be used) for changes to these configuration files to take effect.

The command-line tool webmds-create-context-file is used to create Tomcat configuration files needed to deploy WebMDS.

webmds-create-context-file [-f] tomcat_context_file

The tomcat_context_file argument is the location of the Tomcat configuration file defining the WebMDS context; in a default Tomcat installation, the location of this file will be $CATALINA_HOME/conf/Catalina/localhost.

By default, webmds-create-context-file will not overwrite an existing context file; the -f option is used to force webmds-create-context-file to overwrite an existing file.

Note: webmds-create-context-file is found in $GLOBUS_LOCATION/lib/webmds/bin

    $GLOBUS_LOCATION/lib/webmds/bin/webmds-create-context-file -f \
         $CATALINA_HOME/conf/Catalina/localhost

Changes to the Tomcat context do not take effect until Tomcat is restarted or reloaded.

There is no "client" API for accessing WebMDS; WebMDS is a servlet that is accessed via web forms.

WebMDS uses a WebMDS plugin (a Java class that implements the WebmdsXmlSource interface) to acquire XML documents (which can be used either as raw information sources or as XSL transformations). WebMDS comes with two WebMDS plugins: FileXmlSource, which reads XML from a file (and is primarily used to acquire XSL transformations), and NodeXmlSource. NodeXmlSource in turn calls a node source plugin (a Java class that implements the WebmdsNodeSource interface) to acquire an XML DOM document. acquires XML information using a WebMDS XML source, a Java class that implements the WebmdsXmlSource interface. To summarize: