Webswing GLI

Webswing is a technology that allows java programs to run in a browser. Greenstone 3.11 and later comes with webswing enabled.

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

When Tomcat is behind an Apache server

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