At the end of October 2018 the SKA SDP Consortium submitted its Critical Design Review (CDR) documentation pack. Contained in this were the formal deliverables of the design consortium covering all aspects of the SDP architecture, system engineering and programmatics (the documents are available here). The documents were received by the CDR reviewers (consisting of 3 external members and 15 internal to SKAO) who proceeded to generate clarification questions, requests and notes in the form of observations (called OARs after the Observation Action Register approach commonly used for them). Where possible these were addressed via communication exchanges in JIRA OAR tickets.
From 15th to 19th January 2019 members of the SDP Consortium then visited the SKAO HQ at Jodrell Bank (see figure 1), where direct discussions took place in the new SKAO Council Chamber (see figure 2), to further explore the architecture and identify risks as part of an SEI Architecture Tradeoff Analysis Method (ATAM).
At the end of October the SDP Consortium submitted its full document set for Critical Design Review. (These can be found at http://ska-sdp.org/publications/sdp-cdr-documentation) together with a large number of supporting memos (http://ska-sdp.org/publications/released-sdp-memos-i and http://ska-sdp.org/publications/released-sdp-memos-ii). Table 1 below shows the documents in three main categories: those associated with software and hardware architecture; those explaining the supporting prototyping work that has been undertaken in support of the architecture, and finally those associated with system engineering (SE) and programmatics aspects (e.g. specifications for how SDP interfaces with the wider telescope systems and how components will be constructed). The documents will receive observations from a panel of reviewers up until the end of December. Responses to the observations and scenarios to ‘test’ the architecture will then be discussed at a review meeting from 15th to 18th January 2019 at Jodrell Bank.
After many years of effort, on 31st October 2018, the SDP Consortium submitted its design documentation for Critical Design Review (CDR). The SDP element already went through a pre-CDR review in June which included an Architecture Tradeoff Anaysis Method (ATAM) to identify risks and gaps with the architecture and examined the readiness of the System Engineering artefacts.
Since the last eNews submission in April 2018, the SDP Consortium successfully submitted a documentation pack of roughly 30 documents for its Pre-CDR, M20, milestone to the SKAO. The documentation pack included key Systems Engineering documents, Interface Control Documents (ICDs) and an updated snapshot of the latest SDP Architecture views since the M19 submission and review in November 2017.
In late June, a two-step review process was undertaken between SDP Consortium representatives and the SKAO M20 review panel. The first step was a documentation review process where the objective was to understand and assess the suitability and risks associated with the SDP design before entering the CDR review process. The second step was a face to face meeting which first analysed the suitability of SDP software architecture to meet the needs of its stakeholders, conducted using the SEI ATAM (Architecture Trade-Off Analysis Method) process and based on scenarios generated previously and then discussed observations made against the documentation pack in the first step.
Since the last eNews submission the SDP has successfully submitted and certified its last milestone, M19, and now is busy preparing for the next milestone, M20, Pre-CDR. The M20 Release Readiness Notice (RRN) was submitted in early March and contains 19 documents within the submission pack. This list includes Systems Engineering documents, Interface documentation (ICDs) and an updated snapshot of the latest SDP Architecture views since the M19 submission.
This pre-CDR milestone is a stepping stone to a successful CDR delivery in October. An incremental submission allows valuable key stakeholder feedback to be gained in particular on the architectural design to ensure continuous improvement and alignment of architectural priorities.
In addition to the finalisation of deliverables for Pre-CDR submission, other areas of focus for the Consortium are - further iterations of the SDP software architecture, advances in the SEI views of the high-level SDP architecture, continued understanding of the SDP interfaces, progress on the SDP functional model using the Algorithmic Reference Library (ARL), progress on the SDP prototyping testbed (P3) in Cambridge, progress on the SDP Integration Prototype (SIP) including end-to-end testing, consolidation of data models work, monitoring of the hardware costs evolution and updates to the corresponding predicted cost to name a few!
The sections below expand in further detail the recent work efforts and progress in the areas of platform and systems integration prototyping (P3, SIP) as well as the ARL. This work reduces risk and provides the rationale for design choices ahead of System CDR.
The next significant milestone for the SDP Consortium is M19 on the 30th November. M19 is a lightweight review of the current state of the SDP software architecture and forms a checkpoint with the SKAO to present the current state of the architecture and progress towards Critical Design Review (CDR).
All relevant SDP SEI style views and other supporting documentation for functionally close blocks of architecture will be reviewed. The goal is to present the information in sufficient detail to facilitate immediate use by a knowledgeable audience member.
In preparation for this review, a Stakeholders Overview will take place. The required participants will include key members of the SDP architectural design team and knowledgeable stakeholders from SKAO. This review is to ensure that the high-level architecture documentation, for the purposes of providing an introductory, high-level explanation of the design, is sufficiently complete. In preparation for this overview, key members of the SDP Architecture design team recently selected a collection of views for review and this information has been distributed to the SKAO.
Comments and or suggestions made during the Stakeholder Overview and the official M19 review will guide further architectural priorities ahead of M20 (Element pre-CDR).
Members of the SKA Organisation and SDP Consortium are in Denver this week attending the annual SuperCompuing conference. This year the conference keynote "Life, the Universe and Computing: The Story of the SKA Telescope" was given by the SKA Director General Phil Diamond, and the SKA Regional Centre Project Scientist Rosie Bolton. The talk gives an excellent introduction to the background of radio astronomy and how and why the SKA project is moving forwards. You can replay it here.
Along with other SKA consortia, SDP is working towards implementing Software Engineering Institute (SEI) approaches to its software architecture documentation. This style is useful for promoting architecture decision processes based on concrete "quality attribute" scenarios. These methods will help us with addressing the many architectural trade-offs that SDP faces - balancing scientific accuracy with long-term modifiability and performance.
The SDP proceeds apace, implementing the management changes we outlined in our last SKA eNews contribution.
We planned our work for the October-November time period so that we could support the ongoing SKA engineering activities, and so that we could continue our work on the SDP Execution Framework, as well as work on the key algorithms that we will use to do all the processing within the SDP. We've also been conducting engineering workshops to make sure that we fully understand what makes designing the SDP such a challenge.