Table of Contents
This document describes the aggregator sources provided with the GT 4.0. Aggregator sources collect information from or about WS-Resources and feed that information to aggregator sinks (such as the Index Service and Trigger Service). The following graphic describes the basic information flow including the three standard aggregator sources: Query Aggregator Source, Subscription Aggregator Source and Execution Source.
The aggregator sources supplied with the toolkit collect information using resource property queries (query sources), subscription/notification (subscription sources), and execution of external programs (execution sources).
The aggregator sources supplied with the Globus Toolkit are listed in the following table.
![[Note]](../../../../../docbook-images/note.gif) | Note |
|---|---|
All aggregator sources listed in this
table are in the |
Table 1. Standard aggregator sources
| Aggregator Source | Description |
|---|---|
| QueryAggregatorSource | The query source collects information from a registered resource by using WS-Resource Properties polling mechanisms:
Polls are made periodically, with both the period and target Resource Properties specified in the registration message. |
| SubscriptionAggregatorSource | The subscription source collects information from a registered resource using WS-Notification mechanisms. Data is delivered when property values change, rather than periodically. |
| ExecutionAggregatorSource | The execution source collects information about (not necessarily from) a registered resource by execution of a local executable, which is passed as input the identity of the registered resource. Details of the interface between the execution source and local executables are in Configuring the Execution Aggregator Source. |
The following is general configuration information necessary for all aggregator sources (including any custom ones).
To register resources:
- Create a configuration file in XML that specifies registrations. See
$GLOBUS_LOCATION/etc/globus_wsrf_mds_aggregator/example-aggregator-registration.xmlfor 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 2. 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. |
The following links provide information for configuring the three types of aggregator sources provided by the Globus Toolkit: