Glossary

List of Abbreviations

  • AAI - Authentication and Authorization Interface

  • API - Application Programming Interface

  • DAG - Directed Acyclic Graph

  • DCI - Distributed Computing Infrastructure

  • DDI - Distributed Data Infrastructure

  • FAIR principles - Findable, Accessible, Interoperable, Reusable

  • GPU - Graphics Processing Unit

  • HEAppE - High-End Application Execution Middleware

  • HPC - High-Performance-Computing

  • iRODS - Integrated Rule-Oriented Data System

  • PI - Principal Investigator

  • PIDs - Persistent unique identifiers

  • WCDA - Weather and Climate Data API

HPC Command Application

These applications are defined by the HEAppE command template on clusters. The list of available templates can be viewed in the portal or accessed via the HEAppE API.

HPC Computational Project

An HPC Computational Project is an abstraction of the computing resources allocated to the HPC users by the HPC centres for running their applications. HPC centres usually allocate a given amount of resources represented by core hours (or different units, depending on the centre). HPC Computational Projects have the following characteristics:

  • Requests are submitted by users that want to utilise the resources. HPC centres then grant the resources to the selected requests. Different computing centres can provide different resources (GPU nodes, Cloud etc.) and the request for the resources must contain what resources the user asks for.

  • After the resources are granted, the HPC Computational Project is created. The project itself usually has an ID which is unique within a given centre and has a given timeframe in which the resources have to be depleted.

  • Commonly, a project has one Principal Investigator and possibly additional project members with administrator-like roles (privileged users), depending on the HPC centre and the project. The privileged and normal users within an HPC Computational Project have respective accounts in the HPC centres’ AAI systems.

HPC Container Application

Container applications are executed from APPTAINER images on HPC clusters. The images are staged from data storages, such as LEXIS DDI.

LEXIS Computing Resource

A LEXIS Computing Resource refers to the individual hardware or software component (such as HPC nodes, storage systems, or cloud instances) that is allocated or made available within the LEXIS platform to support the execution of tasks in a LEXIS Computational Project. These resources may include CPU/GPU compute power, memory, storage, and network access, and they are typically provisioned from HPC centres or cloud environments integrated into the LEXIS infrastructure.

LEXIS Computational Project

A LEXIS Computational Project is an abstraction of the computing and storage resources allocated for running LEXIS Workflows. As such, each LEXIS Computational Project can have multiple associated HPC Computational Projects which may be provided by different HPC centres following some dedicated approval process.

LEXIS Dataset Listing

The LEXIS Dataset Listing produces a list of the datasets available via the LEXIS DDI and via the WCDA. In general, this comprises of public datasets, project specific datasets and datasets owned and managed by the user, all hosted on the DDI.

LEXIS Task

A LEXIS Task represents an element of the LEXIS Workflow, and it defines a set of operations to be performed, along with attributes such as the required input data, output data, monitoring information etc. The lifecycle of a LEXIS Task depends on the specific operations it has to perform. However, it is (in any case) restricted to the lifetime of the LEXIS Workflow.

LEXIS Task Execution

A LEXIS Task Execution represents the actual execution of a task within a LEXIS Workflow Execution. The tasks are selected and deployed on the resources dynamically by the orchestrator.

LEXIS User’s Dataset

A LEXIS Dataset represents the input or output set of data that a LEXIS Workflow consumes or produces respectively during its execution. The datasets can be uploaded or downloaded in the LEXIS Portal user interface. User’s dataset is set of files uploaded to LEXIS platform via LEXIS portal, HTTP API or other options. User’s dataset consists of zero or more files structured into directories, and dataset’s metadata inspired by DataCite format. Modifiable level of visibility has three levels: user, project, and public.

LEXIS Workflow

Starting from a LEXIS Workflow template, the corresponding LEXIS Workflow associates the inputs to the LEXIS Tasks and the application of configurations (i.e., setting up of specific input parameters) to each LEXIS Task.

LEXIS Workflow Catalogue

The LEXIS Workflow Catalogue provides the repository of LEXIS Workflow Templates managed by the LEXIS Platform. It contains the set of workflow templates (catalogue) that users can instantiate and execute on the associated computational resources in particular centres (HPC systems, Cloud, etc.). Note that access restrictions apply to the Workflow Catalogue: users can only create LEXIS Workflows based on the LEXIS Workflow Templates available to them.

LEXIS Workflow Execution

A LEXIS Workflow Execution represents the actual deployment of the LEXIS Workflow on the resources selected by the orchestrator. Each LEXIS Task is deployed on the set of computational resources dynamically selected by the orchestrator (according to monitoring data, internal placement policies, user’s specified criteria), along with their required inputs (e.g., LEXIS User’s Dataset). The operations defining the LEXIS Tasks are thus executed. The execution of LEXIS Tasks generates outputs (e.g., output LEXIS User’s Dataset).

LEXIS Workflow Template

The LEXIS Workflow Template is a description of the connections of LEXIS Tasks that must be performed to complete the processing of the input LEXIS User’s Datasets and producing output LEXIS User’s Datasets. As such, LEXIS Tasks inside a LEXIS Workflow Template can be organised to form a DAGs, with ability to access the databases, etc. A LEXIS Workflow Template provides a description of its LEXIS Tasks and the correct sequence of their execution.

Principal Investigator

Each HPC Computational Project must have a Principal Investigator. Principal Investigator is responsible for appropriate use of the project resources. The PI can perform standard administrative operations on the project including adding and removing users, viewing usage of the resources, requesting more resources etc. Note that the LEXIS can support HPC Computational Projects in which the Principal Investigator is not involved in any of the LEXIS Projects (i.e., they are not a LEXIS user).