Index Service queries are performed using resource property requests; consult Java WS Core for details.

The contents of an index are maintained using the aggregator framework programming model, and can receive data from any aggregator source. Information about how to configure existing aggregator sources (such as the aggregator sources distributed with the Globus Toolkit, which include one that polls for resource property information, one that collects resource property information through subscription/notification, and one that collects information by executing an executable program) is found in the Aggregator Sources Reference; information about how to create new aggregator sources can be found in Aggregator Developer's Guide.

The Aggregator Framework builds on the WS-ServiceGroup and WS-ResourceLifetime specifications. Those specifications should be consulted for details on the syntax of each operation.

Each Aggregator Framework is represented as a WS-ServiceGroup (specifically, an AggregatorServiceGroup).

Resources may be registered to an AggregatorServiceGroup using the AggregatorServiceGroup Add operation. Each registration will be represented as a ServiceGroupEntry resource. Resources may be registered to an AggregatorServiceGroup using the service group add operation, which will cause an entry to be added to the service group.

The entry will include configuration parameters for the aggregator source; when the registration is made, the following will happen:

The method of collection by source and processing by the sink is dependent on the particular instantiation of the aggregator framework (see per-source documentation for source information and per-service documentation for sink information - for example the Index Service and the Trigger Service.)

The Aggregator Framework throws standard WS-ServiceGroup, WS-ResourceLifetime, and WS-ResourceProperties faults and does not define any new faults of its own.

Other relevant source files are the:

The index service exposes information via service groups and is accessed using the same command-line tools used to query other WSRF services for information. These tools are part of Java WS Core.

A set of functionally equivalent tools exist written using WS C core. They tend to be faster alternatives to the above java programs.

The mds-servicegroup-add(1) command in the Aggregator Framework is used to configure the Index Service to query information from various sources.

The globus-index-add(1) command line tool is written using WS C and offers similar functionality to mds-servicegroup-add(1) with a few new options.

There is no domain-specific interface specific to the Index Service, however, the ExecutionAggregatorSource, which may be used by the Index Service, does have a domain-specific interface (specifically, the inputs provided to and outputs expected from the executable program).

The syntax of the execution source's domain-specific interface is described in Execution Aggregator Sources Reference.

For a basic installation, the index service itself does not need any configuration changes from default; a default Index Service is available and automatically "registers" with the following GT web services based resources to allow monitoring and discovery: CAS, RFT, and GRAM4 (click the links for information about what data is sent and how to change it).

	Note
	Auto-registration is turned on by default in GT 4.1.2. See the per service links above for information about configuring this capability.

In order for information to appear in the index, the source of that information must be registered to the Index Service. Information sources are registered using tools like mds-servicegroup-add(1). 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 WS MDS Aggregator Framework and can use any Aggregator Sources Reference 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.

The Aggregator Framework does not have its own service side configuration, although services which are based on the framework have their own service side configuration options (such as MDS Index and MDS Trigger") which are documented in the per-service documentation.

Registrations to a working Aggregator Framework are configured for the mds-servicegroup-add(1) tool. This tool takes an XML configuration file listing registrations, and causes those registrations to be made.

In general, configuration of aggregator services involves configuring the service to get information from one or more sources in a Grid. The mechanism for doing this is defined by (inherited from) the Aggregator Framework and described in this section.

<parameter>
   <name>publishAggregatorConfiguration</name>
   <value>false</value>
</parameter>