GT 3.9.5 WS MDS Index Service: System Administrator's Guide

Introduction

This guide contains advanced configuration information for system administrators working with the WS MDS Index Service. It provides references to information on procedures typically performed by system administrators, including installation, configuring, deploying, and testing the installation.

This information is in addition to the basic installation instructions in the GT 3.9.5 System Administrator's Guide.

Building and Installing

The Index Service is built and installed as part of a default GT 3.9.5 installation. For basic installation instructions, see the GT 3.9.5 System Administrator's Guide. No extra installation steps are required for this component.

Configuring

Configuration overview

For a basic installation, the index service itself does not need any configuration changes from default.

In order for information to appear in the index, the source of that information must be registered to the information service. Information sources are registered using tools like mds-servicegroup-add. Each registration has a limited lifetime; mds-servicegroup-add should be left running in the background so that it can continue to refresh registrations. Depending on administration preference, it may be run on the same host as the index, on the same host as a member resource, or on any other host(s).

The Index service is built on the WS MDS Aggregator Framework and can use any aggregator source to collect information. In the most common case, the index service uses the QueryAggregatorSource to gather resource property values from the registered resource using one of the three WS-Resource Properties operations to poll for information; the polling method used depends on the configuration element supplied in the registration content.

Two other aggregator sources are supplied with the distribution: the SubscriptionAggregatorSource, which gathers resource property values through subscription/notification, and the ExecutionAggregatorSource, which executes an external program to gather information.

Syntax of the interface

Specifying the Aggregator Source

The aggregation source used to collect data can be changed from default by editing the aggregatorSource parameter in the index configuration in $GLOBUS_LOCATION/etc/globus_wsrf_mds_index/jndi-config.xml: 

  <resource name="configuration"
               type="org.globus.mds.index.impl.IndexConfiguration">
    <resourceParams>
      <parameter>
        <name> factory</name>
        <value>org.globus.wsrf.jndi.BeanFactory</value>
      </parameter>
      <parameter>
        <name>aggregatorSource</name>
        <value>org.globus.mds.aggregator.impl.QueryAggregatorSource</value>
      </parameter>
    </resourceParams>

This parameter specifies a java class that will be used to collect data for the index. By default it is set to the QueryAggregatorSource. It can be changed to one of the other sources supplied with the toolkit, or to one installed later. Details of the supplied sources are in the Aggregator Framework Developers Guide.

Configuring the Aggregator Source

Configuration options are specified by creating a configuration file and running mds-servicegroup-add to perform the registrations specified in that configuration file. The syntax of that file is: 
<?xml version="1.0" encoding="UTF-8" ?>
<ServiceGroupRegistrations
  xmlns="http://mds.globus.org/servicegroup/client" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xmlns:agg="http://mds.globus.org/aggregator/types">

   <defaultServiceGroupEPR>
      Default service group EPR
   </defaultServiceGroupEPR>

   <defaultRegistrantEPR>
      Default registrant EPR
   </defaultRegistrantEPR>

   <defaultSecurityDescriptorFile>
      Path name of security descriptor file
   </defaultSecurityDescriptorFile>

   One or more of the following:
   <ServiceGroupRegistrationParameters>
      <ServiceGroupEPR>
         EPR of the service group to register to
      </ServiceGroupEPR>
      <RegistrantEPR>
         EPR of the entity to be monitored.
      </RegistrantEPR>
      <InitialTerminationTime>
         Initial termination time
      </InitialTerminationTime>
      <RefreshIntervalSecs>
         Refresh interval, in seconds
      </RefreshIntervalSecs>
      <Content>
         Aggregator-source-specific configuration parameters
      </Content>
   </ServiceGroupRegistrationParameters>

</ServiceGroupRegistrations>
Each ServiceGroupRegistrationParameters block specifies the parameters used to register a resource to a service group. The parameters specified in this block are:
ServiceGroupEPR The EPR of the service group to register to. This parameter may be omitted if a defaultServiceGroupEPR block is specified; in this case, the value of defaultServiceGroupEPR will be used instead.
RegistrantEPR The EPR of the resource to register. This parameter may be omitted if a defaultRegistrantEPR block is specified; in this case, the value of defaultRegistrantEPR will be used instead.
InitialTerminationTime The initial termination time of this registration (this may be omitted).
RefreshIntervalSecs The refresh interval, in seconds.
Content Aggregator-source-specific registration parameters. The content blocks for the various aggregator sources are described in detail in the following sections.

The defaultServiceGroupEPR block provides a convenient way to register a number of resources to a single service group -- for example, if you wish to register several resources to your default VO index, you can specify that index as the default service group and omit the ServiceGroupEPR blocks from each ServiceGroupRegistrationParameters block.

The defaultRegistrantEPR block provides a convenient way to register a single resource to several service groups -- for example, if you wish to register your local GRAM server to several index servers, you can specify your GRAM server as the default registrant and omit the RegistrantEPR blocks from each ServiceGroupRegistrationParameters block.

ServiceGroupRegistration Content Blocks for QueryAggregatorSource

The QueryAggregatorSource can use one of the following three configuration blocks.
GetResourcePropertyPollType
If a GetResourcePropertyPollType block is used, QueryAggregatorSource will request a single resource property. The block has this form: 
   <Content xsi:type="agg:AggregatorContent"
      xmlns:agg="http://mds.globus.org/aggregator/types">
      <agg:AggregatorConfig xsi:type="agg:AggregatorConfig">
         <agg:GetResourcePropertyPollType>
            <agg:PollIntervalMillis>interval_in_ms</agg:PollIntervalMillis>
            <agg:ResourcePropertyName>rp_namespace:rp_localname</agg:ResourcePropertyName>
         </agg:GetResourcePropertyPollType>
      </agg:AggregatorConfig>
      <agg:AggregatorData/>
   </Content>
The PollIntervalMillis parameter is the poll refresh period in milliseconds; the ResourcePropertyName parameter is the QName of the resource property to poll for.
GetMultipleResourcePropertiesPollType
If a GetMultipleResourcePropertiesPollType block is used, QueryAggregatorSource will request one or more resource properties. The block has this form: 
   <Content
        xmlns:agg="http://mds.globus.org/aggregator/types"
        xsi:type="agg:AggregatorContent">
      <agg:AggregatorConfig xsi:type="agg:AggregatorConfig">
         <agg:GetMultipleResourcePropertiesPollType>
            <agg:PollIntervalMillis>interval_in_ms</agg:PollIntervalMillis>
            <agg:ResourcePropertyNames>rp1_namespace:rp1_localname</agg:ResourcePropertyNames>
            <agg:ResourcePropertyNames>rp2_namespace:rp3_localname</agg:ResourcePropertyNames>
            <agg:ResourcePropertyNames>rp3_namespace:rp3_localname</agg:ResourcePropertyNames>
         </agg:GetMultipleResourcePropertiesPollType>
      </agg:AggregatorConfig>
      <agg:AggregatorData/>
   </Content>
The PollIntervalMillis parameter is the poll refresh period in milliseconds; the ResourcePropertyNames parameters are the QNames of the resource properties to poll for. There is no limit on the number of ResourcePropertyNames that may be specified.
QueryResourcePropertiesPollType
If a QueryResourcePropertiesPollType block is used, QueryAggregatorSource will request that a query be executed against the Resource Property Set of the remote resource. In the GT 3.9.5 implementation of core, the only query language that is supported is XPath. The block has this form: 
   <Content
        xmlns:agg="http://mds.globus.org/aggregator/types"
        xsi:type="agg:AggregatorContent">
      <agg:AggregatorConfig xsi:type="agg:AggregatorConfig">
         <agg:QueryResourcePropertiesPollType>
            <agg:PollIntervalMillis>interval_in_ms</agg:PollIntervalMillis>
            <agg:QueryExpression Dialect="dialect">
               Query Expression
            </agg:QueryExpression>
         </agg:QueryResourcePropertiesPollType>
      </agg:AggregatorConfig>
      <agg:AggregatorData/>
   </Content>
The PollIntervalMillis parameter is the poll refresh period in milliseconds. The QueryExpression is an xsd:any element; the Dialect attribute specifies the dialect of the query expression.

ServiceGroupRegistration Content Blocks for SubscriptionAggregatorSource

The SubscriptionAggregatorSource gathers resource property values from the registered resource using WS-Notification subscriptions. The configuration block for SubscriptionAggregatorSource looks like this: 

   <Content
        xmlns:agg="http://mds.globus.org/aggregator/types"
        xsi:type="agg:AggregatorContent">
      <agg:AggregatorConfig xsi:type="agg:AggregatorConfig">
         <agg:AggregatorSubscriptionType>
             <TopicExpression Dialect="dialect">
                Topic Expression
             </TopicExpression>
             <Precondition Dialect="dialect">
                Precondition
             </Precondition>
             <Selector Dialect="dialect">
                Selector
             </Selector>
             <SubscriptionPolicy>
                Subscription Policy
             </SubscriptionPolicy>
             <InitialTerminationTime>time</InitialTerminationTime>
         </agg:AggregatorSubscriptionType>
      </agg:AggregatorConfig>
      <agg:AggregatorData/>
   </Content>
The only required parameter is the TopicExpression, which specifies the topic expression to use in the subscription request. [TODO: link to generic notification/subscription docs].

ServiceGroupRegistration Content Blocks for ExecutionAggregatorSource

The ExecutionAggregatorSource gathers arbitrary XML information about a registered resource by executing an external script and passing registration as parameters. The configuration block for ExecutionAggregatorSource looks like this: 
   <Content xsi:type="agg:AggregatorContent"
      xmlns:agg="http://mds.globus.org/aggregator/types">
      <agg:AggregatorConfig xsi:type="agg:AggregatorConfig">
         <agg:ExecutionPollType>
            <agg:PollIntervalMillis>interval_in_ms</agg:PollIntervalMillis>
            <agg:ProbeName>dummy_namespace:filename</agg:ProbeName>
         </agg:ExecutionPollType>
      </agg:AggregatorConfig>
      <agg:AggregatorData/>
   </Content>
The PollIntervalMillis parameter is the poll refresh period in milliseconds. The ProbeName parameter specifies the path name to the executable file, relative to the $GLOBUS_LOCATION/libexec/aggrexec directory. The path name should be specified as the local name part of this QName; the namespace part is ignored.

The aggregation source used to collect data can be changed from default, as detailed in the public interface guide

Deploying

The Index service is deployed into the Globus container by default during the standard toolkit installation.

Testing

The entire content of the default index service in a deployment can be seen by executing the following command, which will dump the entire RP set of the service:

wsrf-query -a -z none -s https://127.0.0.1:8443/wsrf/services/DefaultIndexService /

Security Considerations

The security considerations for the Aggregator Framework also apply to the Index Service

Troubleshooting

If an index entry has AggregatorConfig data but an empty AggregatorData entry, there is probably something wrong with the registration. For example, a registration that uses QueryAggregatorSource aggregator source may have incorrect values for the resource's hostname or port number or a misspelled resource property name, or the remote resource may impose security restrictions that prevent the queries from the index from working. You can use the standard toolkit resource property query tools (such as wsrf-get-properties) to verify that the remote resource is responding.