Friday, April 28, 2017

Command line versus web application

The development of the web application for the circuit simulator is under way and can be found on my GitHub account:

For a while, both command line and the web app will be available simultaneously for those who would prefer command line. The main disadvantage of the web application is the need to have Django installed. Though not a significant task, for someone who doesn't want a server running on their computer, it may not be the best option. I am still thinking of ways to automate the setup of the Django server so that maybe a single script could have everything up and going.

The first few steps in this direction seem promising. For example, so far, I have been able to replace the circuit_inputs.csv file. When a new simulation is created, the first form is the one that contains the fields similar to circuit_inputs.csv. Django provides features where error messages can be automatically generated when the user enters wrong data. For example, the user needs to specify the working directory that will contain the circuit schematic spreadsheets and other files. This working directory will be used also to write the output data file and therefore needs to have write permission to it. Since this Django app should be preferably run as user rather than root or Administrator, the working directory chosen should be writable by a user. This check is performed at the model level where a validation method has been written. This validation method writes a dummy file just to check if the app can write into the directory and failure to do so results in an error which shows up in the form. So the user can't submit a form without choosing an appropriate directory.

The user interface is divided into several segments. The first form above will only ask for basic parameters like time duration, time step, data storage interval, working directory etc. Once done, these parameters will appear as a table and the next form will ask for the user to choose the circuit spreadsheets from a file browser form. The user can still go back and edit the simulation parameters with an Edit parameter option. The file browser button makes life easier in choosing files rather than write them in circuit_inputs.csv. It would also be possible to check if the files are .csv files an also if they actually exist in the working directory.

The same goes for control files. They will have similar file browser buttons that can allow the user to choose Python control code.

As compared to the command line, the major advantage is that errors are pointed out right away and in a little more friendlier manner. The command line does provide error messages and I will try to bring it close to the web app in terms of how immediately the errors are pointed out. This might save the user progressing to the last stage and then seeing the simulator point out an error in the schematic which should have been picked up right away after the circuit_inputs.csv file was provided.

In the web app, errors in the circuit file and also errors in parameters can be generated by processing all these files. The same checks could be imposed - paired jump labels, closed branches etc. Since, a circuit can only really be checked after all circuit spreadsheets have been read and processed, this error generation will need to take place at a higher level.

What will be challenging is to generate parameters for all the circuit spreadsheets. The simplest way to do this will be create models for every component and add them to the circuit files as ManyToMany objects. This also allows a ModelForm to be created to every component model and further to connect each component to the circuit spreadsheet. Eventually, the parameters obtained from the ModelForms will need to be returned to the classes in circuit_elements. Which means the read_parameter methods of every class will need to be changed or overloaded for an interface to the web app.

Django seems to provide a fairly convenient and hierarchical structure.

Simulation Case  ---> Circuit files ---> Component objects
                            ---> Control files ---> Control objects

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