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IMAS – introduction to basic concepts
Key IMAS element: the Data Model
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- 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
Data Model: Interface Data Structure
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Dynamically generated
Open the documentation by typing: dd_doc
What is in the documentation ?
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- 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
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