Plug-and-play modularity using
submodels

"Plug-and-play" modularity means the ability to replace one module in a
model with another, without having to specify how the module's inputs and
outputs link up with the rest of the model. This requires that the modules
to be swapped share the same interface to the rest of the model.

In Simile, a module is a submodel. There
is a mechanism for replacing one submodel with another: simply open a
separate window for the submodel, and use the File: Open command to load a
new submodel. However, this by itself does not automatically remake all
the links between variables in the submodel and those in the rest of the
model.

In order to have plug-and-play modularity, we need to specify the
interface between a submodel and the rest of the model. This means stating
which variable in the submodel is linked to which variable in the main
model, and the nature (dimensions, units) of the two variables. This
specification is saved in a separate interface specification file, and can
be loaded when we create a new submodel, in order to re-make all the
linkages.

Demonstration of plug-and-play modularity

• Step 1: Build a model with submodels
• Step 2: Save one of the submodels as a
  separate model
• Step 3: Save the interface
  specification
• Step 4: Clear the submodel
• Step 5: Load an alternative version of the
  submodel
• Step 6: Load the interface specification
  file

In: Contents >> Working with submodels