3.1 Creating a model

In this step, you will discover which files are needed to create a model, and learn where to put these files and how to name them.

Every uncompiled model consists of a minimum of one files: modelname.java. This file is created by the Model Wizard and can then be compiled into .class files. It is essential that all model files are stored under a directory structure of org/jelsim - the default directory is the org directory underneath the eSim Builder installation directory, but it is recommended that you create another jelsim directory elsewhere on in which to store your own models.

Note: if you create a model using the Model Wizard that model will automatically be available within the Interface Builder running on the same machine. If you create a model without using the wizard you will have to import the model into the Interface Builder.

Create a sub-directory in your jelsim folder, and call it training - this is where you'll store your new model.

Start up the Model Wizard from the start menu.

You will see the introduction screen. Select Next>.

In the following screen you will be asked to define the name of the package and class you are going to create.

The package name is always org.jelsim. followed by the name of the folder in which your model is going to be stored (in this case, training). The destination directory is the full path of the root folder that contains the jelsim directory, and the class name is the name of the model file created (e.g. if your class name is 'cat', then the final files created will be cat.java.

Complete the package and class definition, using the class name 'ohmsLaw'.

The Wizard will look something like this:

Go to the next page when you've finished. In this page you can set which class your model class is going to inherit from; if, and how often, the class is going to automatically check for updates to its properties; and where output properties or custom data are to be saved. How to use these options is beyond the scope of this tutorial, so select Next> to move straight on, keeping the settings as they are. More information on these settings can be found in the Programmer's Guide.

You can now start adding properties to the model. This is covered in the next step.