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

Table of Contents

1. Introduction
2. Registering
3. Configuration file: parameters for the subscription aggregator source

1. Introduction

The SubscriptionAggregatorSource gathers resource property values from the registered resource using WS-Notification subscriptions.

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 blockThe 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.
defaultRegistrantEPRThe 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.
defaultSecurityDescriptorFileSimply the path to the security descriptor file.
ServiceGroupRegistrationParametersEach ServiceGroupRegistrationParameters block specifies the parameters used to register a resource to a service group. The parameters specified in this block are:
ServiceGroupEPRThe 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.
RegistrantEPRThe 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.
InitialTerminationTimeThe 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.
RefreshIntervalSecsThe 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.
ContentAggregator-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 subscription aggregator source

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>

where:

TopicExpression

This is the only required parameter; it specifies the topic expression to use in the subscription request.

[TODO: link to core notification/subscription docs ].