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Service ActivitiesHELIO is based on a Service-Oriented Architecture and will establish a number of services handling metadata, data provider access, processing and storage. The services can be used individually or combined through a workflow capability based on Taverna.Work PackagesWPS1 – Infrastructure ManagementThis WP is dedicated to the management and monitoring of the infrastructure as a whole. The first action of the project will be "kick start" the infrastructure. A particular use case to implement will be defined by the Network Activity WPN4 ("Define New Capabilities") and will be based on services provided by EGSO, VSO, and at CESR.The initial infrastructure will be gradually extended as new capabilities prepared in the metadata and data work packages (WPS2 and WPS3) are brought on-line. These additional capabilities will iteratively increase the range of scientific questions the infrastructure can address. WPS2 – Metadata ServicesThe metadata servers will provide access to metadata and derived products used to search for interesting observations. Given the diverse nature of the metadata, it is anticipated that in many cases it will be necessary for HELIO to ingest the metadata in order to condition it to match its data model; improving the interoperability between coordinate systems being one core requirement. We will also look closely at the contents and quality of some of the metadata and if necessary try to improve these by regenerating certain lists in collaboration with the providers.
WPS3 – Data, Processing and Storage ServicesHELIO will not ingest any data; instead the data provider access services will present a unified style of access to the wide variety of data archive interfaces worldwide. This service can be used to determine where observations that match the time interval and location of interest can be found; it will then allow the user to retrieve the selected observations. For archive with intelligent interfaces, the service will let the provider do most of the work; for those with limited resources, the service will establish the mapping into the archive in order to satisfy the request.The processing services will support the production of quick-look products that are required by the user when searching for interesting observations; they will execute the propagation model used to provide the 4D link between observations. Once observations have been selected, it will be possible to used capabilities of the processing services to extract and calibrate a subset of the data and return the results in any desired format. The storage services will be available to store the results of searches and processing activities for a limited interval, for those user known to the system.
WPS4 – WorkflowWorkflows are the glue to put the work done in WPS1, WPS2 and WPS3 together. This WP provides the ways and means to define, store, and execute such workflows, where the output of one service can be connected to the input of other services. Shims will be developed to integrate external services in workflows; they will wrap the interface of the external service to the need of the workflow.A set of workflows will also be developed to provide advanced search capabilities. The workflows will be based on Research Activity WPR2 ("Tools for the 4D heliosphere") and will orchestrate access to metadata, data, and processing services to solve advanced search requests. WPS5 – Access InterfacesThis WP will guarantee the appropriate means to access the HELIO infrastructure. Several levels of access are necessary. On the lower level, individual services, including the workflow, will be made accessible by a Java API wrapped by a Web Service layer. This will allow access to the infrastructure from third-party software such as other VxOs.Specific tasks of this WP will address the provision of the Web client, the standalone client and the IDL client.
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