The OpenMI 2.0 standard has been released, supporting a more flexible way of linking models and related components for data exchange at run-time. The standard and the preliminary SDK allow the generation of hard-coded compositions (component networks). The final SDK and the GUI for interactive running of compositions will be released in Spring 2011.
New features in OpenMI 2.0 are described here.
More flexibility
The static linking mechanism in OpenMI 1.4 has been replaced by a direct, flexible connection between output and input items (the data-providing and data-accepting components).
If the values of an output are not available in the required form, you can "adapt" an output; this is done by inserting a special kind of (adapted) output that performs the necessary operations, such as interpolation in space or unit conversion. A series connection of adapted outputs offers a piping and filtering mechanism. The user can explicitly define the order in which such adapting operations are carried out, thus optimising performance.
Base interfaces and extensions
OpenMI 2.0 has become more versatile and offers a set of base interfaces, which can easily be extended, e.g. with the extension for time and space dependent components. This implies that an OpenMI 2.0 compliant component has to comply with the base interfaces, but it can also comply with one or more of the extension interfaces. The classical 1.4 compliant components would have to implement the base interfaces as well as the extension for time and space dependent components in order to run successfully under OpenMI 2.0. The current version includes this extension. Future extensions could:
• support compliance with the standards of the Open Geospatial Consortium (OGC),
• express the exchange items and their values in terms of ontologies or
• support parallel computing and much more.
Getting and setting values
In OpenMI 2.0, the concept of the link has been removed. The data definition is now passed in the GetValues() call. For the classical time and space dependent components this call contains the requested timestamps or time spans, element set and value type. If one argument is obsolete, e.g. the timestamp for GIS data, it can be omitted, making the use more intuitive. Furthermore, it is possible to set values before running a component, thus allowing the use of the OpenMI in calibration, optimisation, data assimilation and decision support systems.
Data definitions
Beneath the proved quantitative values, OpenMI 2.0 adds support for qualitative information, e.g. land use types or indications such as "dry" and "wet". The stored values can be objects of any type, e.g. double-precision real (the most common type), integer, boolean or a user-defined type.
The element set definition has been expanded to become more suitable for the standards of the Open Geospatial Consortium (OGC). Its spatial reference is now defined by an OGC-compliant well-known text (WKT) string.
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