GT 4.0 WS MDS Aggregator Framework: Configuring the Query Aggregator Source

Home -> Toolkit -> Docs -> 4.0 -> Info -> Aggregator	Website Email Lists Search:

Table of Contents

3. Configuration file: parameters for the query aggregator source

3.1. GetResourcePropertyPollType
3.2. GetMultipleResourcePropertiesPollType
3.3. QueryResourcePropertiesPollType

1. Introduction

The QueryAggregatorSource collects information from a registered resource by using WS-Resource Properties polling mechanisms.

2. Registering

To register resources:

Create a configuration file in XML that specifies registrations. See $GLOBUS_LOCATION/etc/globus_wsrf_mds_aggregator/example-aggregator-registration.xml for several specific examples.
Run mds-servicegroup-add to perform the registrations specified in that configuration file.

The file consists of an optional defaultServiceGroupEPR, an optional defaultRegistrantEPR, and then one or more ServiceGroupRegistrationParameters blocks, each of which represents one registration.

The general syntax of the configuration file is:


<?xml version="1.0" encoding="UTF-8" ?>
<ServiceGroupRegistrations
  xmlns="http://mds.globus.org/servicegroup/client">

  // An optional default service group EPR.
  <defaultServiceGroupEPR>
    // Default service group EPR
  </defaultServiceGroupEPR>

  // An optional default registrant EPR.
  <defaultRegistrantEPR>
    // Default registrant EPR
  </defaultRegistrantEPR>

  // An optional default security descriptor file.
  <defaultSecurityDescriptorFile>
    // Path name of default security descriptor file
  </defaultSecurityDescriptorFile>

  // One or more service group registration blocks:

  <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 type="agg:AggregatorContent">
      // Aggregator-source-specific configuration parameters
    </Content>
  </ServiceGroupRegistrationParameters>

</ServiceGroupRegistrations>

The following table describes the different blocks of the file and any parameters:

Table 1. Aggregator configuration parameters

`defaultServiceGroupEPR` block	The 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.
`defaultRegistrantEPR`	The 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.
`defaultSecurityDescriptorFile`	Simply the path to the security descriptor file.
`ServiceGroupRegistrationParameters`	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). If the initial termination time is omitted, then the mds-servicegroup-add sets the initial termination time to the current wall time plus 2 times that of the specified `RefreshIntervalSecs` parameter.
`RefreshIntervalSecs`	The refresh interval of the registration, in seconds. The mds-servicegroup-add will attempt to refresh the registration according to this interval, by default incrementing the termination time of the registration by 2 times this interval for every successful refresh. If at any point the termination time for the registration expires the registration will be subject to removal within a maximum of 5 minutes.
`Content`	Aggregator-source-specific registration parameters. The content blocks for the various aggregator sources are described in detail in the following sections.

3. Configuration file: parameters for the query aggregator source

The QueryAggregatorSource can use one of the following three configuration blocks in the Content block: GetResourcePropertyPollType, GetMultipleResourcePropertiesPollType and QueryResourcePropertiesPollType.

3.1. 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>

where:

PollIntervalMillis: This parameter is the poll refresh period in milliseconds; the ResourcePropertyName parameter is the QName of the resource property to poll for.

3.2. 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>

where:

PollIntervalMillis: This 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.

3.3. 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 GT4 implementation of WSRF 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:QueryExpressionDialect="dialect">
        Query Expression
      </agg:QueryExpression>
     </agg:QueryResourcePropertiesPollType>
   </agg:AggregatorConfig>
  <agg:AggregatorData/>
</Content>

where:

PollIntervalMillis: This parameter is the poll refresh period in milliseconds.
QueryExpression: An xsd:any element; the Dialect attribute specifies the dialect of the query expression.