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Data Mgt
MDS4
Execution Mgt
In addition to the services described above, MDS4 includes several additional software components, including an Aggregator Framework, which provides a unified mechanism used by the Index and Trigger services to collect data.
The Aggregator Framework is a software framework used to build services that collect and aggregate data. Services (such as the Index and Trigger services) built on the Aggregator Framework are sometimes called aggregator services, and have the following in common:
- They collect information via Aggregator Sources. An Aggregator Source is a Java class that implements an interface (defined as part of the Aggregator Framework) to collect XML-formatted data.
- They use a common configuration mechanism to maintain information about which Aggregator Source to use and its associated parameters (which generally specify what data to get, and from where). The Aggregator Framework WSDL defines an [aggregating service group entry type] that holds both configuration information and data. Administrative client programs use standard [WSRF Service Group registration mechanisms] to register these service group entries to the aggregator service.
- They are self-cleaning – each registration has a lifetime; if a registration expires without being refreshed, it and its associated data are removed from the server.
MDS4 includes the following three Aggregator Sources:
- the Query Aggregator Source, which polls a WSRF service for resource property information,
- the Subscription Aggregator Source, which collect data from a WSRF service via WSRF subscription/notification,
- the Execution Aggregator Source, which executes an administrator-supplied program to collect information.
Depending on the implementation, an Aggregator Source may use an external software component (for example, the Execution Aggregator Source uses an executable program), or a WSRF service may use an external component to create and update its resource properties (which may then be registered to an Index or other aggregator service, using the Query or Subscription Aggregator Source). We refer to this set of components as Information Providers.
Currently, MDS4 includes the following sources of information:
Hawkeye Information Provider: An Information Provider that gathers Hawkeye data about Condor pool resources using the XML mapping of the GLUE schema and reports it to a GRAM4 service, which publishes it as resource properties. This information includes:
- basic host data (name, ID)
- processor information
- memory size
- OS name and version
- file system data
- processor load data
- other basic Condor host data.
Ganglia Information Provider: An Information Provider that gathers cluster data from resources running Ganglia using the XML mapping of the GLUE schema and reports it to a GRAM4 service, which publishes it as resource properties. This information includes:
- basic host data (name, ID)
- memory size
- OS name and version
- file system data
- processor load data
- other basic cluster data.
GRAM4: The job submission service component of GT4. This WSRF service publishes information about the local scheduler, including:
- queue information
- number of CPUs available and free
- job count information
- some memory statistics.
Reliable File Transfer Service (RFT): The file transfer service component of GT4. This WSRF service publishes:
- status data of the server
- transfer status for a file or set of files
- number of active transfers
- some status information about the resource running the service.
- Community Authorization Service (CAS) This WSRF services publishes information identifying the VO that it serves.
- Any other WSRF service that publishes resource properties. Note: In addition to any other resource properties, GT4 services publish a basic
ServiceMetaDataInfoelement that includes start time, version, and service type name.
WebMDS is a web-based interface to WSRF resource property information that is available as a user-friendly front-end to the Index Service. WebMDS uses standard resource property requests to query resource property data and displays the results in various formats.
