HELIO - Service Capabilities

HELIO is being implemented with a service-oriented architecture – this basically means that the required capabilities of HELIO are split into a number of separate services. In principle, the services can be grouped into two areas: search for interesting events and phenomena; and identify, locate and retrieve observations.

The first of these is quite difficult to quantify – what information is required and how it will be used depends on the science problem being addressed. HELIO is therefore creating a set of services that we believe will provide the types of capability that might be needed; these can be combined together using the workflow tool deployed by HELIO – Taverna.

The Heliophysics Event Catalogue and Heliophysics Feature Catalogue facilitate searches on events and features throughout the heliosphere; the catalogues contain the metadata that has been generated by semi-automated techniques. Because some occurrences are quite subtle and cannot easily be detected, the Metadata Evaluation Service allows the user to manipulate time series data and search for events; a similar capability will be provided for image data.

In order to understand the temporal and spatial relationship between phenomena and events observed in different parts of the Solar System, the ability to run models is provided; this is just one of a number of processing capabilities that can be provided. Quick-look information, combining inputs from several sources, will be generated by the Context Service and present them as a means of helping the user to decide which events are most interesting and worth pursuing.

In comparison to looking for interesting events, once the times, locations and types of observation required have been determined the task of matching these to data is relatively straightforward. The Instrument Capabilities Service and Instrument Location Service, together with Observation Coverage Service allow the user to know whether suitable observations were made at the required location at the desired time. The Data Provider Access Service is then used to find the required data, wherever and however they are stored and accessed in archive around the world.

As part of the process of determining whether it is worth pursuing a particular event, a user may be interested in data coverage and the quality of observations available; also, they may have already made decisions about what they need based on their own criteria.

The split between the tasks should therefore not be considered as rigid and the design of HELIO makes it possible to use services in the order that is required and if necessary jump into workflows at any point.

A Semantic Mapping Service is used to manage differences in the ways that the communities describe their data. Storage and Processing services are also available; authorization to use these services is managed by another service. All services are described in a the HELIO Registry Service.

Table of HELIO Services

Service Name Purpose

   Search Metadata

Heliophysics Event Catalogue (HEC) Maintain and provide access to existing event data from all domains

Heliophysics Feature Catalogue (HFC) Maintain and provide access to existing feature data from all domains

MetaData Evaluation Service (MDES) Allows the user to create an auxiliary event list based on a newly-derived parameter, etc.

Context Service
(CXS) Provide context information to help the user make a selection

   Review suitable observations

Instrument Capabilities Service (ICS) Match required observation type to one or more instruments (each part of an observatory)

Instrument Location Service (ILS) Determine the location of an instrument (part of an observatory) at a specified time

Observation Coverage Service (OCS) Provide information on whether an instrument was making suitable observations at a specified time

   Locate and Retrieve the Data

Data Provider Access Service (DPAS) Provide integrated access to data archives in all domains no matter how the data are stored or accessed

   Enabling Services

HELIO Registry Service
(HRS) Maintain and provide access to a registry that describes all the services available to HELIO

Community Interaction Service (CIS) Manages interactions with the community, including authentication and usage statistics

Processing Service Support processing on demand

Storage Service Provide storage for user information

Ancillary Information Service (AIS) Provide integrated access to external resources that do not conform to HELIO interface standards

Coordinate Transformation Service (CTS) Translated between the different coordinate systems used by the communities

Semantic Mapping Service
(SMS) Maps terms used in the metadata from the different communities

HELIO Monitoring Service
(HMS) Keeps track of the status and performance of the services that the HRS knows about

Resource Usage Service
(RUS) Keeps track of usage of HELIO so that the project can provide statistics to users, providers, etc.