frontend-tutorial-framework

This is the Angular frontend of TFW.

The main exposed features are our pre-implemented components based on the src/app/services/websocket.service.ts service. This service provides an RxJS based communication API to the framework backend (TFW server and event handlers).

Another useful feature is a bunch of pre-designed layouts and dynamic switching between them.

To learn more about the framework see the baseimage-tutorial-framework repo. For more on creating, building and running TFW-based tutorials (not just the frontend) consult test-tutorial-framework.

Components

In this section we are going to explore the various pre-made components this project offers.

Generally these components connect to a TFW event handler running on the backend. Communication is handled via simpe APIs exposed by these event handlers – over TFW messages.

These APIs are documented in the baseimage-tutorial-framework repository as docstrings in the lib/tfw/components directory (this is where the event handler implementations live).

Configuration

Most of the time it is not necessary to edit the source code of our components as you can easily customise their behaviour through the src/app/config.ts config file.

The most notable setting available in this file is the enabling of different layouts the user and you can switch between. Layouts describe which components are visible and where they are on the screen.

Terminal (webshell)

A full-fledged xterm terminal emulator based on xterm.js running right in your browser. The emulator is connected to a TerminalEventHandler instance on the backend over websockets.

This event handler spawns a bash session and a pty (pseudoterminal). It connects the master end of the pty to the emulator running in the browser and the slave end to bash.

This essentially provides a fully functional terminal session in the browser. You can write to it (and thus execute commands) and read what commands were executed in bash using the API exposed by the TerminalEventHandler instance.

This enables you to pre-type or execute commands for the user and figure out what they are doing in the terminal.

IDE (webIde)

This component is a simple text editor based on ACE. It always shows all files in a given folder and allows you to switch between those files using the tabs on top. The IDE automatically saves any changes made to the files (the interval is configurable).

It connects to an IdeEventHandler instance on the backend which handles the reading/writing of files and the selection of directories as well.

It is also capable of dynamically displaying any changes made to these files from the terminal or any other process (this means that you always see a live view of the files).

Messages

This is a simple chat-like component you can use to instruct, help and guide your users. It displays messages sent to the frontend with the key message.

The message format used:

{ 
    "key": "message",
    "data":
    {
        "originator": ...,
        "timestamp": ...,
        "message": ...
    }
}

You can use the MessageSender class to send messages from the TFW server or event handlers written in Python.

Web – customisable component

... explain iframing and custom Angular components...

Dashboard

The dashboard is the component that composes all others and organises them into layouts. It also exposes a frontend API to dynamically change layouts any time using a message format as such:

{ 
    "key": "dashboard",
    "data":
    {
        "command": "layout",
        "layout": ...,
        "hide_messages": ...
    }
}

You can use the hide_messages key to hide the message component (sadly it currently still takes up the space it would occupy).