Webswing GLI

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

Assuming your tomcat is running on port 8383:

If your apache is 2.4.47 or later:

ProxyPass "/webswing-server/" "http://localhost:8383/webswing-server/" upgrade=websocket

If your apache is older than 2.4.47, try the following:

    RewriteEngine on

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

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

Note, this doesn't work if you have two greenstone installs running at the same time, on different ports.

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.

• webswing log goes to packages/tomcat/bin/logs/webswing.log. GLI System.err goes there.
• For GLI debugging - add -debug to the args for GathererProg in web/ext/websing/etc/webswing.config.in. Restart tomcat. A GLI log file will go to gli/webswing-users/<username>/debug<date>.txt. Note, this folder is also where the GLI config file is stored for the user - configWebswing.xml. GLI DebugStream.println goes here.

Webswing is used for web-based GLI, Phind and Collage classifiers. If you don't need any of these things you can deactivate webswing by running:

cd <PATH-TO_GS3-INSTALL>/ext
./DEACTIVATE.sh webswing

It can be re-activated by running ./ACTIVATE.sh webswing in the same folder.