When Evennia starts it also spins up its own Twisted-based web server. The webserver is responsible for serving the html pages of the game’s website. It can also serve static resources like images and music.

The webclient runs as part of the Server process of Evennia. This means that it can directly access cached objects modified in-game, and there is no risk of working with objects that are temporarily out-of-sync in the database.

The webserver runs on Twisted and is meant to be used in a production environment. It leverages the Django web framework and provides:

  • A Game Website - this is what you see when you go to localhost:4001. The look of the website is meant to be customized to your game. Users logged into the website will be auto-logged into the game if they do so with the webclient since they share the same login credentials (there is no way to safely do auto-login with telnet clients).

  • The Web Admin is based on the Django web admin and allows you to edit the game database in a graphical interface.

  • The Webclient page is served by the webserver, but the actual game communication (sending/receiving data) is done by the javascript client on the page opening a websocket connection directly to Evennia’s Portal.

  • The Evennia REST-API allows for accessing the database from outside the game (only if `REST_API_ENABLED=True).

Basic Webserver data flow

  1. A user enters an url in their browser (or clicks a button). This leads to the browser sending a HTTP request to the server containing an url-path (like for https://localhost:4001/, the part of the url we need to consider /). Other possibilities would be /admin/, /login/, /channels/ etc.

  2. evennia (through Django) will make use of the regular expressions registered in the urls.py file. This acts as a rerouter to views, which are regular Python functions or callable classes able to process the incoming request (think of these as similar to the right Evennia Command being selected to handle your input - views are like Commands in this sense). In the case of / we reroute to a view handling the main index-page of the website.

  3. The view code will prepare all the data needed by the web page. For the default index page, this means gather the game statistics so you can see how many are currently connected to the game etc.

  4. The view will next fetch a template. A template is a HTML-document with special ‘placeholder’ tags (written as {{...}} or {% ... %} usually). These placeholders allow the view to inject dynamic content into the HTML and make the page customized to the current situation. For the index page, it means injecting the current player-count in the right places of the html page. This is called ‘rendering’ the template. The result is a complete HTML page.

  5. (The view can also pull in a form to customize user-input in a similar way.)

  6. The finished HTML page is packed into a HTTP response and returned to the web browser, which can now display the page!

A note on the webclient

The web browser can also execute code directly without talking to the Server. This code must be written/loaded into the web page and is written using the Javascript programming language (there is no way around this, it is what web browsers understand). Executing Javascript is something the web browser does, it operates independently from Evennia. Small snippets of javascript can be used on a page to have buttons react, make small animations etc that doesn’t require the server.

In the case of the Webclient, Evennia will load the Webclient page as above, but the page then initiates Javascript code (a lot of it) responsible for actually displaying the client GUI, allows you to resize windows etc.

After it starts, the webclient ‘calls home’ and spins up a websocket link to the Evennia Portal - this is how all data is then exchanged. So after the initial loading of the webclient page, the above sequence doesn’t happen again until close the tab and come back or you reload it manually in your browser.