Online Simulation Technologies

OESjs

...is a JavaScript framework for Object Event Simulation that allows building web-based simulations.

OESjs core simulator code is available under the permissive Open Source license MIT License. It can be used as a starting point for building Discrete Event simulators, which may be run as a frontend app in the browser, with NodeJS or in a cloud environment like Firebase, where a simulator can be executed as one or more Firebase Functions.

OESjs Core 0: ...implements a minimal architecture for Object Event Simulation (OES), supporting models with (global) model variables and functions, object types, event types, and simple simulation experiments.
OESjs Core 1: ...implements an architecture for OES that extends the OESjs Core 0 simulator by adding fixed-increment time progression, a seedable random number generator, a set of probability distributions (uniform, triangular, normal, exponential, etc.), parameter variation experiments, as well as persistent storage and export of experiment results.
OESjs Core 2: ...implements an architecture for OES that extends the OESjs Core 1 simulator by adding support for resource-constrained activities.
OESjs Core 3: ...implements an architecture for OES that extends the OESjs Core 2 simulator by adding support for Processing Networks.
OESjs Core 4: ...implements an architecture for OES that extends the OESjs Core 3 simulator by adding support for Agents.

Research and development of simulation concepts and technologies already started in the 1960'ies, using historical programming languages like Fortran and C. Today, simulation technologies more and more move to the Web. Especially for educational simulations, it is mandatory that they are accessible on the Web.

Important examples of web-based simulation tools are:

AnyLogic Cloud
Insight Maker: a heavy-weight JavaScript-based open-source front-end simulation framework for making System Dynamics and agent/object-based models.
NetLogo Web: a heavy-weight free-to-use front-end simulation framework (based on the NetLogo desktop simulation app) for making agent/object-based models.
OESjs: a light-weight JavaScript-based open-source front-end simulation framework for making event-based, activity-based and agent-based Discrete Event Simulation models.
SimScript: a light-weight TypeScript-based open-source front-end simulation framework for making Discrete Event Simulation models based on the simulation language GPSS (with support for 2D and 3D animations).

These tools differ with respect to several aspects. The following table identifies the licensing and architecture characteristics of these tools. The distinction of three architecture types ("Front-End", "Back-End" and "Hybrid") refers to the distribution of the simulation engine and the user interface. The table also shows a preliminary performance evaluation with respect to the loading aspects (i.e. data download and memory consumption) of an epidemiology model implemented in these tools.

Comparison of web-based simulation tools.
Tool	Licensing	Architecture	Download (MB)	Memory (MB)
AnyLogic Cloud	Commercial	Hybrid	0.68	2.80
Inside Maker	Free	Front-End	1.50	22.50
NetLogo Web	Free	Front-End	1.20	34.10
OESjs	Free	Front-End	0.16	2.90

One important feature to consider when running a web-based simulation model is the amount of communication resources (i.e., Download) necessary to run the model. OESjs (0.16 MB) has the smallest footprint to run a model and it does not consume any additional data communication during the simulation run. Although AnyLogic Cloud (0.68 MB) has a smaller footprint than NetLogo Web (1.2 MB) and Insight Maker (1.5 MB), AnyLogic runs the simulation remotely, which requires the simulation results to be transmitted to the client machine, thus increasing the download considerably at the end of a simulation run.