HELIO ServicesThe HELIO Infrastructure has been implemented with a Service-Oriented Architecture – this basically means that the required capabilities are split into a number tasks that have been implemented as separate services. The services can be used independently or in combination, through GUIs or Web Service interfaces – see the service Interfaces and Orchestration pages for more information. The user will be most aware of the primary services – these are the ones they are likely to interact with – but behind the scenes there are also a number of enabling services.
Primary ServicesThe primary services can be grouped into two areas:
- Services used to search for and track interesting events, features and phenomena
- Services used to review the availability of suitable observations and locate and retrieve the data
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 Data 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, an ability to run a simple propagation model 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.
Enabling ServicesThere are also a number of Enabling Services.
A Semantic Mapping Service is used to manage differences in the ways that the communities describe their data while the Coordinate Transformation Service translates between the different coordinates systems used by the communities. Storage and Processing services are also available; authorisation to use these services is managed by another service.
All services are described in the HELIO Registry Service. There are several instances of many of the services which ensures that the system is very resilient – the Registry is used to allow the orchestrating capabilities to switch between instances.
List of ServicesBelow is a list of the HELIO services. They have been designed with interoperability in mind and are compliant with standards developed by bodies such as the IVOA. There are multiple instances of most of the services; this ensures that the system is extremely resilient and contributes to the sustainability of the HELIO infrastructure.
|Identify Interesting Events, Features and Phenomena|
|Heliophysics Event Catalogue (HEC)||Maintains and provides access to existing event data from all domains|
|Heliophysics Feature Catalogue (HFC)||Maintains and provides access to existing feature data from all domains|
|Data Evaluation Service (DES)||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)||Determines the location of an instrument (part of an observatory) at a specified time|
|Unified Observing Catalogue (UOC)||Provides information on whether specific instruments were making suitable observations at a specified time; mainly used to handle complex access issues.|
|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|
|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 (HPS)||Support processing on demand|
|Storage Service (HSS)||Provide storage for user information|
|Coordinate Transformation Service (CTS)||Translates between the coordinate systems used by the different 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|
Last updated: 3rd April 2016