Webswing is a technology that allows java programs to run in a browser.
Greenstone 3.11 and later comes with webswing enabled, so that GLI can be run in a browser, allowing remote users the ability to build and edit collections on the server without having to install Greenstone (and Remote GLI).
To get started using webswing GLI, see tutorial Using Webswing GLI

It is provided as an extension, in greenstone3/ext/webswing. You don't need to compile it up, Greenstone3 ships with a ready-to-go webswing JAR/WAR file.

The webswing framework requires a graphical environment. If you are on a standard desktop, then it will work out of the box. However, if you are on a headless Linux environment, then you will need to install:

• xvfb (x-virtual frame buffer) - for example, sudo apt install xvfb

You may also need the following:

• libxext6
• libxi6
• libxtst6
• libxrender1

To start Greenstone when you are using webswing, please use the new scripts:

• ant-start-with-exts.sh
• ant-stop-with-exts.sh
• ant-restart-with-exts.sh

These will make sure the right environment is set up for Tomcat.

If you Tomcat is running behind an Apache webserver, there are some extra steps to get it running in this situation.

• Apache needs to have the proxy_wstunnel module enabled:
  • (sudo) apachectl -M - to list modules
  • (sudo) a2enmod proxy_wstunnel - to enable the module

See https://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html

You also need to edit the apache configuration file for your VirtualHost (assuming your tomcat is running on port 8383):

    RewriteEngine on

    RewriteCond %{HTTP:Upgrade} =websocket
    RewriteRule /(.*) ws://localhost:8383/$1 [P,L]

    RewriteCond %{HTTP:Upgrade} !=websocket
    RewriteRule /(.*) http://localhost:8383/$1 [P,L]

This file might be in eg /etc/apache2/sites-available/000-default-le-ssl.conf, or /etc/httpd/conf.d/yourcustomname.conf

There is a config file web/ext/webswing/etc/webswing.config.in. You can edit that. When you run an ant restart, webswing.config will be generated from this .in file.

Some useful settings in this file:

• uploadMaxSize - the maximum file size allowed to be uploaded (FileChooser) in MB. Set to 0 for unlimited size. Note, if the size is less than a file you are trying to upload to a collection, it will silently fail and give you no reason why.