Heliophysics Integrated Observatory

HELIO Glossary

This document gives outline details s of the Services developed by HELIO and well as definition of other common terms.

Community Interaction Service (CIS)

While most HELIO services can be used without user authentication, there are advantages if the system knows who the user is – they are able to save preferences and return to long-running processes.

The CIS allows the user to authenticate and for the services that require user authorisation – the HPS and HSS – it passes the necessary tokens to the service

Context Service (CXS)

The CXS generates plots that are needed by different user interfaces within HELIO including the HELIO Front End (HFE) and the IDL/SolarSoft access code.

Coordinate Transformation Service (CTS)

While we try to condition pointing information as it is ingested into the HEC, not all data that must be used by HELIO is in the correct coordinate system. The purpose of the CTS is to do the necessary translation between different coordinate systems.

This service has still to be implemented.

Data Evaluation Service (DES)

The DES is designed to provide the user with the capability of examining time-series data and defining functions that can be used to identify events. A set of functions has been defined; the values of parameters that should be used are supplied as part of the call, as well as the time interval and instrument.

Data Provider Access Service (DPAS)

The DPAS is used to retrieve the required data sets. The Service know how the data are stored and how to access them – this id defined in the Provider Access Table (PAT).

Heliophysics Event Catalogue (HEC)

The HEC contains event lists from various sources and domains; so far more than 40 different events lists have been added including numerous flare and CME catalogues.

Heliophysics Feature Catalogue (HFC)

The HFC contains lists that describe features detected in images at various wavelengths. The features currently included are Sunspots, Active Regions, Filaments, Coronal Holes and Type II and III events; generally the coverage is from 1996 to the current date.

HELIO Monitoring Service (HMS)

The monitoring service continuously checks on the status of the services listed in the HRS. Is purpose is to provide the Registry with information of which services are currently available.

HELIO Registry Service (HRS)

The Registry should be the first point of call for external services, it contains information about all the Services that have been created by HELIO or that HELIO knows about.

HELIO Processing Service (HPS)

The HPS provides access to high-performance processing capabilities in IDL, Java, etc. Currently only pre-canned routines can be run but eventually the user will be able to upload their own code.

In order to use this service the user must be authenticated and authorised.

HELIO Storage Service (HSS)

The HSS provides storage for data and results and for use in conjunction with the HPS.

In order to use this service the user must be authenticated and authorised.

Instrument Capabilities Service (ICS)

The ICS is a relational database that describes the capabilities of all the instruments that could be included in HELIO. This is at a very basic level, sufficient to allow searches based on type of observation, observing domains, common terms, etc.

Instrument Location Service (ILS)

The ILS is a relational database that holds information about the location of the planets and major heliospheric missions. We are currently in the process of adding details of selected missions that are in close planetary environments.


HELIO provides access to observations from several related but separate domains; considerable effort has been expended within the project to try to ensure the services can handle differences in the way that data are described and managed by the different communities.

Interoperability is key to providing seamless access to these data. Within HELIO various techniques are used to standardise and semantically map the metadata based on standards developed by the IVOA.

International Virtual Observatory Alliance (IVOA)

The International Virtual Observatory Alliance is an organisation that debates and agrees the technical standards that are needed to make the virtual observatory (VO) possible. It also acts as a focus for VO aspirations, a framework for discussing and sharing VO ideas and technology, and body for promoting and publicising the VO.

Provider Access Table (PAT)

The PAT is used by the DPAS to determine how to fulfil a data request made to HELIO. The PAT defines where data from an observatory and instrument can be found and how they should be accessed. There can be multiple records in the PAT for an instrument if there are multiple sources of that particular data set; the protocol used for access may differ.

Semantic Mapping Service (SMS)

The SMS is an experimental service that is exploring how to map between the semantic description of observations from the different domains that are supported by HELIO.

Service Interfaces

The HELIO Services have interfaces that are based on IVOA standards.
  • The HELIO Query Interface (HQI) is used for most of the services; it supports both SOAP and REST protocols.
  • The Univeral Worker Service (UWS) pattern is used for the more complex interface of the Context Service.
Also see Web Service.

Service Oriented Architecture

A service-oriented architecture (SOA) is an architectural pattern in computer software design in which application components provide services to other components via a communications protocol, typically over a network.

HELIO is based around this type of architecture with the various tools needed to identify, locate, retrieve and process interesting observations being provided as a set of services. Currently defined services include:

  • Identify interesting events and features — HEC, HFC, DES
  • Determine if instruments to provide the desired observations are suitable located — ICS, ILS, CXS
  • Locate and retrieve the data — DPAS, UOC
  • Process the observations and modelling — HPS, HSS, CXS
The HELIO Services are described here.

Unified Observing Catalogue (UOC)

The UOC serves two purposes within the HELIO infrastructure:
  • It contains information related to instruments that are difficult to access for one reason or another. Currently this type of record includes i) planetary data from NASA's Planetary Data System (PDS) and ESA's Planetary Science Archive (PSA) and ii) h-alpha data in the Global H-Alpha Network (GHAN).
  • It contains records giving details of the modes of the pointed remote-sensing solar instruments – i.e. those with a limited field-of-view.

Virtual Observatory (VO)

A Virtual observatory (VO) is a collection of interoperating data archives and software tools that utilise the Internet to form a scientific research environment in which astronomical research programs can be conducted.

VOTable Format

The preferred output format for most if the HELIO Services is VOTable, a format define by the International Virtual Observatory Alliance (IVOA). This format has the advantage that the parameters can be unambiguously defined in the field definition statements using UCDs and utypes making is easier for other projects to use HELIO data products.

For more information see "VOTable Format Specification" in the IVOA Document Store.

Web Service

A Web service is a software system designed to support interoperable machine-to-machine interaction over a network (W3C Glossary).

Web services interfaces are generally of two types:

  • SOAP (Simple Object Access Protocol) messaging, an XML-based Web service protocol described by a WSDL (Web Services Description Language) file
  • The simpler REST (REpresentational State Transfer) protocol that resembles normal HTML used in Web URLs

Last updated: 12th March 2016