WebSockets in Lucee Docker

Introduction

Thanks to Igal Sapir for the Lucee Websockets Extension.

The original example is now a few years old and a few things have changed.

This repo is an adaptation of Igal's original Chat example, updated to work with Lucee 5.3 and Docker. It doesn't go into great detail - it is just enough to provide a working example.

Thanks to @andreas and @psarin for responding to my Lucee Forum support request, which enabled me to get this example working. :-)

For background and some explanations: here is the original video and the chat example wiki: https://github.com/isapir/lucee-websocket/wiki/Example-Chat

Lucee and Docker

If you are new to Lucee and / or Docker you might want to check this tutorial repo.

I am using the Lucee Tomcat docker image.

To setup this example

Once you have cloned this repo...

1. Make sure Docker Desktop is running (or at least the Docker daemon).
2. From a terminal in this repo: docker-compose up --build
3. Use the VSCode Docker extension to navigate into the Files of the running lucee-websocket-chat_lucee:latest container.
4. Drill down to /usr/local/tomcat/conf/web.xml and open that file for editing.
5. Scroll down to the first <servlet> block and before (or after) that block copy the following into the file. It seems it is not that important where it is placed, as long as you dont break the existing XML syntax.

<filter>
  <filter-name>SessionInitializerFilter</filter-name>
  <filter-class>org.apache.catalina.filters.SessionInitializerFilter</filter-class>
</filter>

<filter-mapping>
  <filter-name>SessionInitializerFilter</filter-name>
  <!-- modify url-pattern to match your websocket endpoint !-->
  <url-pattern>/ws/*</url-pattern>
</filter-mapping>

6. Restart the Lucee container via Docker Desktop (or CLI). If you rebuild the container (instead of restarting it), you will need to repeat steps 3-5.

Note: I could not work out how to insert the filter code block above without the manual editing. Perhaps someone can suggest a more automated approach?

Run the example

1. Browse to this url in (say) Brave Web Browser: http://localhost:8890/WSexamples/chat/?username=Iambrave
2. Browse to this url in some other browser (eg Chrome, Edge, Firefox or Safari): http://localhost:8890/WSexamples/chat/?username=iamchrome
3. For clarity, you can run this on any port you map in the docker-compose.yml file. To illustrate, I set port 8890 in this example, but choose your own (including 8888).
4. Repeat for any other browser instances you want. Each needs a different username which can be anything you like.

Type a message into the input tag then press Enter, or click "Send", and that message should appear in all the open instances.

Hopefully that gets you going with Lucee WebSockets.