This document is a technical deliverable describing the SKA Regional Centres (SRCs) Network (SRCNet) software architecture. The document describes modules and their interrelation in an  abstract way, so there is no decision of the software stack, or implementation details that could vary from one SRC to another.

This description covers the use cases to be implemented on the SRCNet, the common modules needed for the SRC blueprint implementation, the interfaces between these modules and other SRCNet nodes and the constraints on the implementation. That involves

• Classification of use case types and actors.
• Logical view of the modules and decomposition in submodules of the SRCNet.
• UML diagrams including class diagrams.
• Dynamic aspects of the system, explains the system processes and how they communicate and focuses on the run-time behaviour of the system. The process view addresses concurrency, distribution, integrator, performance, scalability, etc.
• UML diagrams to represent the process view include the sequence diagram, communication diagram and activity diagram.

After the scope and context sections, we compile the architectural principles that the architecture should follow, in line with the requirements that have been compiled in a previous process.

Then, a description of a basic SRCNet node is provided, including the different modules that should be implemented at all the nodes of the network. These modules are expected to have a default implementation that could be shared between the different SRCs. Also, other versions of the modules could be provided (e.g. using different software stacks or programming languages) in case SRCs could require them. These other versions should be compatible from the interfaces point of view.

Finally, we present some process views showing how these modules are working together. Some of the examples provided include data ingestion, data access, Authentication/Authorisation, Collaborative Environments, Federated Execution and Distributed software.

This document presents a top-level roadmap of the development phases of the SRCNet, in line with the requirements coming from external activities to the SRCNet context (e.g. SKA construction milestones or scientific events). An estimation of the resources required at every stage is also presented, both at the level of personnel and hardware resources. 

First, general SKA project milestones and the impact on the SRCNet are analysed. From these milestones, different versions of the SRCNet development are identified, defining the expected functionality of every version and the foreseen time for the release. These versions, as defined relative to the general SKA project milestones, could change if general milestones (or scope) change.

Depending on the complexity and implementation expected for every version, the number of FTEs and expertise needed is estimated. Also, engineering and scientific support for the operations are estimated for every expected deployed version.

Finally, this document proposes a platform deployment plan (in terms of storage and computing resources) until the first totally public deployment and proposes a division of the provision of pledged resources in line with the national share to the SKA construction plan. This proposal could be evolved to align local national budgets or to incorporate new partners.

This document describes the SRC vision for the first iteration of the Science Analysis Platform intended to be delivered across the SRCNet. This platform will be consistent across the nodes and provide an interface between Square Kilometre Array (SKA) users and their data, and a powerful and intuitive environment for carrying out reproducible data analysis, collaboration, and other essential research tasks, while offering enough flexibility for individuals to customise the platform to meet their own needs.

Within this vision document we describe a science platform appropriate to the needs of the SRCNet in broad terms. It is not a set of detailed requirements or specifications, nor is it a design document. Rather, it sketches a high-level view of the necessary platform functionality and identifies key interfaces with other SRCNet technologies and areas of development. The vision outlined here is sufficiently broad as to allow the proposed platform to be moulded to the use-case requirements at a later stage of development.

The purpose of this document is to provide a high-level overview of tasks an astronomer as well as SKAO/SRC Staff would be likely to perform within the SRCNet. This includes interfacing with the data archive, exploring the data using visualisation tools, running scripts for further data processing, and managing computing resources. The SRCNet Operational Use Cases are presented in Section 2 and the SRCNet Scientific Use Cases in Section 3. The presented use cases are intended to provide a reference for the kinds of activities that users are expecting to conduct within the SRCNet, in order to inform thinking and provide guidance to the SRC ART. This broad set of use cases incorporates several efforts in a similar vein, in an effort to define one extensive set of use cases. In particular, nearly all the SRCNet User Stories [RD1; associated user stories are given in square brackets throughout the document] stemming from a survey of the Science Working Groups (SWGs) conducted by the SRC Steering Committee (SRCSC) WG6, as well as work done by the SRC ART teams (e.g. Orange and Coral), have been folded into this set.

This document provides a set of use cases that are intended to be representative of the kinds of activities users might want to conduct on the SRCNet. 

It does not:

• Attempt to address how the use cases will be implemented, e.g. the choice of software, computational requirements; or
• Describe proposal preparation and submission activities as these will not be a service provided by the SRCNet.

This document provides the vision and operating principles for the collaborative network of SKA Regional Centres (SRCs). The Vision statement and the Principles presented in this document are to inform and guide the development work leading towards the first prototype SRC Network, as well as the operations of that Network.

 Principles are classified into:

• ​​Operational Principles
• Sustainability and Environmental Principles
• Security Principles
• Fairness, Equity and Inclusion
• User-facing Principles
• Compute Principles
• Data Storage and Archive
• Data Processing

This document aims to define what is required from an infrastructure provider to support SRCNet v0.1 [AD2]. This is expected to be an iterative process. Where possible, we are informing our initial choices based on work done. The basic use cases to be covered for this version are:

• Ingestion of relevant data products ingested into the SRCNet nodes, which would include a significant amount of data from precursors, synthetic data from SKA, etc.
• Data available for discovery and access from all the nodes
• Data and services discovery from a simple user interface
• Client command line libraries to allow data access, data discovery and data analysis, e.g. through notebook environments and support for a limited set of science workflows
• Visualisation of certain formats of imaging data from remote locations
• Common Authentication/Authorisation system