IMAS – introduction to basic concepts

Key IMAS element: the Data Model

...

• For Integrated Modelling, the Data Model also defines Interface Data Structures (IDS). These are structures within the Data Model that are used as standard interfaces between codes
• Solves the N2 problem (large number of components from various ITER members expected in IMAS)
• The usage of the IDSs makes the coupling of codes straightforward if they are in the same programming language
• The usage of the IDSs + AL allows coupling of codes even if they are not written in the same language
• The usage of the IDSs does NOT constrain your choice of coupling method. Codes can be coupled as:
  • Subroutines within a main program
  • Executables within a script
  • Components within a workflow engine

https://portal.eufus.eu/documentation/ITM/imports/itm/public/imas_data_dictionary/3.23.1/dd_data_dictionary.xml.html

Data Model: Interface Data Structure

...

• Dynamically generated

• Open the documentation by typing: dd_doc

Image Modified

What is in the documentation ?

...

• A Data Entry is a collection of potentially all IDS 
• Multiple occurrences of a given IDS can co-exist, e.g. multiple equilibria calculated by different codes / assumptions
• A Data Entry is defined by:
  
  • IMAS version
  • User name
  • Machine name
  • Pulse number
  • Run number
• The recommended usage for a Simulation is that 
  • The simulation starts by reading data from an Input Data Entry (can be the from of another User)
  • During the simulation, intermediate results are stored in a temporary “work”
  • Entry (another Run number)
  • During or at the end of the run, the results intended to be archived are written to an Output Data Entry (Run number)

Data Dictionary Lifecycle

• An IMAS DD version is defined by 3 levels of revisions named M.N.i (Major.Minor.Micro) : example 3.16.0
• The degree of evolution flexibility depends of the lifecycle status of the considered part of the DD:
  • “Alpha” parts of the DD may freely evolve (through micro revisions)
  • “Active” parts of the DD may only evolve through backward compatible changes (minor revision) – or trigger a major revision
  • “Obsolescent” parts of the DD are kept for temporary backward compatibility of modules but might not exist in the next major revision
• JIRA trackers / GIT pull requests provide an effective way to ask for DD evolutions and public release of a new DD version
• The IMAS installer provides a mechanism to install and work with any private development branch of the DD

Conclusion

• This introduction presented the IMAS basic concepts and some details on the ITER Physics Data Model
• Other training sections will guide you for interfacing codes, generating workflow components, running workflows
• The Physics Data Model User Guide is the technical reference for using IMAS and the Access Layer. You can find it (and many other information) on https://confluence.iter.org/display/IMP

...