Embedding structure

Organization, responsibilities, authorities and policies related to Embedding

Due to the increasing demand of the STAR collaboration, associated to the need for redundancy and more cohesion in the embedding activity, the embedding structure will move toward a distributed (computing) model paradigm with a structured set of responsibilities.


The embedding activity is a cross between the Simulation and Reconstruction activities and an important part of our data mining and data analysis process. Hence, the Embedding structure described below is an activity part of the Software & Computing (S&C) project structure.
The embedding activity will be led by the Embedding Coordinator (EC) helped by Embedding Deputies (ED) whose responsibilities and authorities are described below. It is understood that each Physics Working Group (PWG) may assign a contact person to help running an embedding series, or an Embedding Helper (EH). EC, ED and EH constitute the embedding team and core structure.
Embedding tasks will be created consistent with Appendix A “Initiating Embedding requests”.


The EC

The primary mission of the EC is to organize the work and the set of QA results related to each of the embedding series and communicate to the collaboration the progress and difficulties encountered in the data production process. The EC is the interface to many areas in STAR and to efficiently achieve the goals prescribed by the function, his/her responsibilities and authorities are described below:

The EC responsibilities are:

  • The EC will work in close relation to the S&C Leader, Physics Analysis Coordinator (PAC) and the PWG Convener (PWGC) to define and facilitate the processing of the embedding requests needed by the collaboration to carry its scientific goals
  • The EC will work with the PWG EH and gather keep up-to-date a set of macros and code aimed to provide appropriate QA for the PWG of interest
  • The EC is responsible for the communication with the PWGC whenever embedding requests clarifications are needed (Physics process and/or intent unclear). This communication should happen only when the PWG EH  feels it is best to properly relefct the matters at hand. Communications to/from the PWG are expected to flow through the EH.
  • The EC will communicate and feedback to the S&C leader any issues related to resources needed to accomplish the mission.
    • This may include discussions involving tasks lists and priorities, assignment of additional workforce, addition of computational resources allocations or difficulties encountered during the embedding process.
    • The discussions may be substantiated by summary of resource needed in the form of a written document (and provided by the EC) as requested.
  • The EC is responsible for regularly bringing to the collaboration, via weekly S&C meeting venue, summaries of the tasks at hand and presenting the priorities or priority reshape as applies. All modified embedding requests are expected be announced at “a” S&C meeting as a summary and in addition of the communication with the PWGC. The frequency of such intervention is at the discretion of the EC and should not be below once a month
  • The EC will be responsible for communicating with the ED and organize the work and tasks with the ED forming the core force of the embedding
  • The EC is expected to handle and resolve with the ED issues (technical, resource) which may be raised by the EH and help toward a reolution and understanding


The EC authorities are

  • Assign tasks as applies to the ED

  • Request highly prioritized resource allocation to perform tasks
  • Contact and discuss directly issues related to embedding requests with PWGC, PAC and S&C leader as applies
  • Authoritative decisions are granted to the EC on the following area:
    • Declare an embedding request as improper and re-direct to the simulation leader
    • Re-prioritize or close embedding tasks and requests upon PWGC feedback or lack thereof.
    • Similarly, close an incomplete request upon PWGC lack of feedback
    • Re-assign priorities to a low priority shall precisions on an embedding request not be provided
    • Has authoritative leverage to declare an embedding series as 'good or not', based upon quantitative arguments and backed by proper embedding related QA.
  • May request discussions and/or arbitration ruling to the PAC and S&C leader shall a contention arise with PWG(C) of interest

Conflict resolution

  • In the event an embedding request is re-directed, re-prioritized, closed, declared 'bad' and shall the decision be contested by the  PWGC, the following applies:
    • The responsibility to present a case and burden of proof is on the PWGC
    • Explicit discussion and approval of both S&C leader and Physics Analysis Coordinator (PAC) is necessary for re-considering the EC decision


The ED

The Embedding deputies' role and responsibilities are the one previously expected of the PDSF Tier1 center in 2005 and as defined in wording in 2007. An Embedding Deputy is intimately tight to a site's resources or a specific well-defined tasks (such as performing the base QA).

Those responsibilities include

  • Respond to the EC requests for assigned tasks or work unit and provide estimate on time need to complete the tasks and feasibility of accomplishing he goals
  • Prepare the embedding jobs and ensures the full workflow is working for achieving the asssigned tasks. Run a sample and help validate the production chain
  • Help resolve technical details as appears and file/track trouble tickets as applies
  • Keep the EC informed of progress, issues and difficulties encountered during the setup of the embedding process including resource allocation difficulties if any as well as technical difficulties
  • Maintain the embedding framework consistent with a distributed model and provide feedback on improvements / fixes suitable for all sites
  • Keep the embedding related documentation up-to-date
  • Work closely with the EH as applies to accomplish task at hand


The authorities of the ED include

  • Manage global assigned local resources as necessary to perform tasks
  • Reshuffle and assign portion of resources to EH as see fit to perform task (tasks passed to the EH could include running a portion of the jobs and managing batch related to the relevant to the PWG's EH)
  • Request EC intervention whenever necessary
  • Directly communicate with the EH issues related to geometry tag, magnetic fields and other parameters wherever applies (see appendix B) while keeping summarizing the outcome to the EC
  • Request feedback from the PWG EH on the adequacy of the samples provided to the PWG's requests. It is expected that the EH will communicate with the PWG (PWG specifc QA may be performed) and provide an explicit answer to the ED, accompagnied of material putting into evidence inadequacy of the sample or documenting adequacy as applies.


The EH

The Embedding Helpers are individuals recruited from within the PWG and hence, are STAR collaborators helping with the running of the embedding and carry some of its burden as a general service. The EH is part of a workforce supplement provided by the PWG and the expectation is for a EH to serve for a minimal time of two years during which, knowledge build-up and stability in our procedure and communication can be achieved. PWG may or may not provide EH, understanding however that the lack of EH may result in delays in delivery of results.

The EH responsibilities is to carry the communicating of all issues to/from the PWG and the Embedding team and seek that the requests made by the PWG are carried to their end. TO this end, rhe EH are expected to work closely with the ED and EC to perform the embedding tasks related to their respective PWG and consistent with the principles stated above. Examples of duties:

  • Help clarifying embedding requests and communcate with the PWG in case of questions of lack of clarity
  • Whenever an embedding request is determine valid by the EC and assigned to an ED, the EH will work within guidance and supervision of the assigned ED. The EH is then expected to carry the tasks assigned (or delegated) by the ED and possibly carry production related work to complete the requests on behalf of their related PWG. It is understood that resource managements and allocation remian the prime responsibility and call of the ED.
  • Communicate pro-actively with the PWG and work internally to the PWG structure to carry QA testing on samples provided for satisfying the PWG requests.
  • Provide a clear and documented response to the ED on the adequacy (or lack thereoff) of the produced sample for the request.


Appendix A – Initiating Embedding requests

Embedding requests and need will be initiated and discussed within either PWG or R&D working group with respectively the supervision of the PWGC of interest or R&D simulation coordinator. The following caveats apply.

Pure embedding will be asked by PA of a pending publication / paper or whenever the accuracy needs to be as-close as possible to the real data. All other cases will be reviewed by the EC and may be transformed into a enriched sample simulation (“injection” simulation) wherever it applies and re-directed to the simulation leader consistent with the EC authorities.

After discussions within the PWG, embedding requests will be recorded by one of the PWGC via a provided interface which purpose will be to keep track of all requests and allow for priorities and overview of status and progress. The PWGC may designate an embedding point of contact as PWGC representative for embedding. In such case, the communication will be carried through the Embedding Point of contact.

No embedding requests outside of the provided framework and interface shall be satisfied and no “pending discussions” without an actual requests will be considered. It is also understood that a ill-defined requests may be closed by the EC consistent with the feedback gathering policy described in the EC responsibilities and authorities section. In such event, the request slot is not re-usable by the PWG.

Unless specified otherwise and priorities assigned explicitly by the PAC, EC or S&C leader, the requests will be considered as per a first in first done basis and upon availability of resources.

Appendix B – ED responsibilities and authorities regarding geometry tag and field settings

Upon request from the PWGC, the embedding team will ensure that the proper information is obtained as per the production series the embedding requests relate to. For a given production, the field setting and geometry tag used will be checked for consistency. Consistency must arise between simulation, real data and intended study. The geometry tag will be acquired from the production options page maintained by the production coordinator [currently Real Data production option].
The ED will be responsible for carrying those checks and will pass on functional macros to the EH assigned to assist them. If a setting is inaccurate (field or geometry tag), the EH shall immediately inform the PWG and the EC and request explicit confirmation. An embedding series shall not be started nor be run without the acknowledgment of the related field or geometry tag adequacy as chosen by the PWGC or PWG Point of Contact.

Jérôme Lauret, STAR Software & computing Leader 07/05/16

Jérôme Lauret, STAR Software & computing Leader 09/10/20, revised for expanding and clarifying the EH role