tech-arch.md

Technology Architecture

This document is incomplete.

Overview

When producing the data:

• You find or write an egs file in an editor in the style language, which details:
  • where the data comes from,
  • how data is compressed and
  • what it should look like;
  • You produce the data;
• A command-line tool called the style-compiler turns the egs file into a begs file.
• The begs file sits on the backend server and is served to the frontend.
• The style-interpreter in the frontend (in the browser) interprets the begs file.

+--------------+  +----------+
| Data Source  |  | egs file |    <- Data Creator
+--------------+  +----------+
       |               |
       |               v
       |          +----------------+
       |          | style compiler | <- command line
       |          +----------------+
       |               |
       |               v
       |          +-----------+
       |          | begs file |    <- Backend Service
       |          +-----------+
       |               |
       v               v
+---------------------------------+
| genome browser backend service  |
+---------------------------------+
                ||
                \/                 <- THE INTERNET
+---------------------------------+
| style interpreter               | (in the browser)
+---------------------------------+
                 |
                 v
+---------------------------------+
| browser drawing code            | (in the browser)
+---------------------------------+

The style compiler does the 'heavy-lifting' in making egs code efficiently executable and is large and complex, so it sits on the command line. In theory therecould be a "just-in-time" facility in the genome browser backend, but I don't think that will be all that useful in practice.

So the code is divided into a number parts:

• the style-compiler rust which compiles to a command line executable.
• the style-interpreter rust which compiles to web-assembly.
• the webgl drawing etc rust stuff which compiles to web-assembly.
• the python code running the backend service.

The style-compiler and style-interpreter obviously share a great deal of common code. All non-core commands sit in libraries, which have a part for the compiler and a part for the interpreter.

Code is organised into multiple crates to help with modularity.