Activities: EJSApp

Maintained by Picture of Ruben Heradio Ruben Heradio, Picture of Luis de la Torre Luis de la Torre
This plugin lets you add any Java or Javascript application (typically virtual and/or remote experiments) created with Easy Java(script) Simulations (EJS) to your Moodle course.
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Virtual and Remote Laboratories



It is commonly accepted that digital media (such as simulations, videos, interactive screen experiments or web labs) can positively impact student knowledge, skills and attitudes. Consequently, tools such as Moodle and web-based labs have become widespread in distance education in the last decade. Moodle supports the administration, documentation, tracking, and reporting of training programs, classroom and online events. Web-based labs make possible to illustrate scientific phenomena that require costly or difficult-to-assemble equipment.


There are two complementary approaches for web-based labs:


  1. Virtual Labs or Experiments provide computer based simulations which offer similar views and ways of work to their traditional counterparts. Nowadays, simulations have evolved into interactive graphical user interfaces where students can manipulate the experiment parameters and explore its evolution.
  2. Remote Labs or Experiments use real plants and physical devices which are teleoperated in real time.



Easy Java(script) Simulations (EJS, is a tool designed for the creation of discrete computer simulations. During the last few years, EJS has grown for helping to create web-accessible labs in education of scientific and technical disciplines. With this objective in mind, recent releases of EJS support connections with external applications, such as LabView and Matlab/Simulink. Hence, EJS not only is useful to create virtual labs, but also the GUIs of their remote counterparts.

A rich repository of EJS simulations is freely available at:

EJSApp: bridging together Moodle and EJS

To support the one-click deployment of virtual and remote labs into Moodle, we have developed the EJSApp plugin, which has the following features:

  1. Deployment of labs written in EJS. 
  2. Control user access to the deployed labs and distinguish between virtual labs (or simulations) and remote labs.
  3. Allow several resizing options for displaying the embedded applets.
  4. Backup and restore. EJSApp provides maintenance facilities for labs, packaging them into Moodle course backups.

To get the feel of EJSApp, visit UNILabs, which is a moodle site that hosts a rich network of virtual and remote labs for students of the Spanish Open University (UNED) and other Spanish Universities, such as the Huelva, Complutense and Almeria Universities. All labs in UNILabs have been developed using the EJSApp and its extensions (EJSApp "private files" browserEJSApp Booking SystemEJSApp Collab Session and the Open Source Physics repository plugin).


The code repository of this plugin can be found at


Tutorial Videos

Overview of EJSApp

Guide to install and use EJSApp and EJSApp File Browser

Overview of Open Source Physics, a free repository with more than 400 freely available EJS simulations

Overview of UNEDLabs, a network of virtual and remote laboratories developed with EJSApp


This plugin is part of set EJSApp and extensions.


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Picture of Ruben Heradio
Ruben Heradio (Lead maintainer)
Picture of Luis de la Torre
Luis de la Torre: Author
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  • Picture of Germán Valero
    Fri, 3 May 2013, 11:55 PM
    Hello Luis and Rubén,
    I installed the EJSApp module in my local 2.5dev server and when I try to customize my spanish language files, I get an "error writing to database" error. The debugging info is:
    line 429 of \lib\dml\moodle_database.php: dml_write_exception thrown
    line 1089 of \lib\dml\mysqli_native_moodle_database.php: call to moodle_database->query_end()
    line 1131 of \lib\dml\mysqli_native_moodle_database.php: call to mysqli_native_moodle_database->insert_record_raw()
    line 190 of \admin\tool\customlang\locallib.php: call to mysqli_native_moodle_database->insert_record()
    line 60 of \admin\tool\customlang\index.php: call to tool_customlang_utils::checkout()

    It only happens when editing the international spanish language, but not on english or mexican spanish language packs.

    Also, I think this is related to the fact that this plugin does not have its English language files available for translation at AMOS ( ). That usually means that there is something wrong with the code. See .
    In recent months, David Mudrak has been extremely helpful in diagnosing and correcting the problems that prevented other plugins from having their English strings available in AMOS. Maybe it is worth asking for his opinion on this plugin.

    Saludos desde México.
  • Picture of Germán Valero
    Fri, 3 May 2013, 11:59 PM
    Hello Luis and Rubén,
    An update on the "error writing to database" error:

    If I delete the es language folder from the mod/ejsap/lang folder, the error disappears.

    But I still can not translate the English strings in AMOS.

    Saludos desde México
  • Picture of Luis de la Torre
    Sat, 4 May 2013, 12:20 AM
    Hi German,

    Thanks for the warning. We didn't know about this new AMOS procedure and we uploaded the new plugin version with both files: the one with the English strings and the one with the Spanish strings instead of only uploading the English one.

    I'll try to figure out what else can be wrong as soon as posible.
  • Picture of Luis de la Torre
    Sat, 4 May 2013, 12:39 AM
    I have just uploaded a fixed version (twice, by mistake).
    I think everything should be working right now smile
  • Picture of Germán Valero
    Tue, 7 May 2013, 3:05 AM
    Hi Luis,
    I just translated the English strings in AMOS into mexican spanish. Everything looks perfect. Thanks a lot. I will wait 2 hours to download the updated language pack and plugin and check database.
  • Picture of Germán Valero
    Tue, 7 May 2013, 3:30 AM
    Hi Luis,

    The good news: the mexican spanish translation is working perfectly, which means all translations in AMOS will work too.

    The bad news: the es folder with the international spanish translation included within the plugin ZIP file keeps on causing a database error. I would suggest you to completely remove the es language folder from the plugin in Moodle database. I will submit the mex spanish translation to the international spanish pack maintainers at AMOS in 10 minutes. There are a few differences: a quiz is a cuestionario in Spain and an examen in México.
  • Picture of Germán Valero
    Tue, 7 May 2013, 3:40 AM
    Hi Luis,
    I just sent the files to the international spanish language pack maintainers. You can safely delete the spanish translation from the files included in the module ZIP file.
    According to , all language strings (except for English) should disappear from released modules (core and add-ons) and all translated strings only be available through AMOS. It is a complicated task.
  • Picture of Luis de la Torre
    Tue, 7 May 2013, 4:51 AM
    Hello German,

    Thanks for all this feedback. We really appreciate it.
    Let me update then the plugin once more, this time without the es folder.

    I guess I should do the same with the rest of the EJSApp plugins. However, do I need to send their corresponding es language files to the spanish language pack maintainers in AMOS? If that's the case, Im not sure how should I do that.

    I will write again once I have uploaded the zip file without the es folder.

    Gracias a ti, German.
  • Picture of Luis de la Torre
    Tue, 7 May 2013, 5:02 AM
  • MD shot of me from his iphone4
    Mon, 1 Jul 2013, 1:05 PM
    Hi, i was wondering if the source codes to the jar files are available anywhere. Even more, the one included in test directory.
  • Picture of Luis de la Torre
    Mon, 1 Jul 2013, 1:57 PM
    Hi Aparup,

    You can open the EJS model (this is, the "source code") of the jar file included in the test directory by just double-clicking in the jar file (the simulation will load) and then right-clicking at any place of the simulation. A menu will appear with several options.

    If that menu is in english search for the "Open EJS model" option. If it is in Spanish, search for "Abrir modelo EJS".

    Then follow the instructions and EJS will open the source code of that jar file. Let me know if you have any problem.

    PS. Usually, all applets created with EJS have this option but some of them don't. Anyway, the one included in the test directory does.
  • Picture of Luis de la Torre
    Thu, 27 Feb 2014, 7:18 PM
    Hi all,

    Since EJSApp version 1.6 was released two days ago, you can also embedd into your Moodle course the javascript applications created with EJS 5.0
  • Picture of Luis de la Torre
    Mon, 21 Apr 2014, 6:09 PM
    Version 1.7 has been released.

    EJSApp can now automatically sign the EJS applets uploaded to Moodle if you have a trust certificate installed in your Moodle server.
  • Picture of Luis de la Torre
    Sun, 14 Dec 2014, 9:53 PM
    Version 1.8 is out.

    Fixes an important bug when doing a copy or a backup of ejsapp activities that use a signed applet.

    Fixes a bug with some OSP Javascript simulations.

    The 'view personalized variables' options has been moved to the 'edit settings' block.

    Several code improvements.
  • Picture of Luis de la Torre
    Tue, 24 Mar 2015, 6:20 AM
    Version 2.0 is out.

    It allows using alias to your virtual and remote laboratories .jar (Java) or .zip (Javascript) files compiled with EjsS.

    Also, it enhances the personalization of variables in virtual laboratories by allowing teachers to download the values generated for the variables of the lab that are being personalized.

    Finally, it has a cleaner and more optimized code in many aspects.
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