Validate XML against XML Schema using Python

Prerequisites

Python 3 is required.

Install required libraries:

$ pip3 install -r requirements.txt

Usage

Basic usage:

$ python3 validate.py3 root_dir 2> log.txt

Performance

This was written to be super fast:

• Concurrency, using multiprocessing.
• Use of lxml binding to C libxml2 library.
• Downloading of remote XML Schema files only once, and caching to ~/.xmlschemas/ for future runs of the program.
• Caching of libxml2 schema data structure for reuse in multiple concurrent parses.

On my machine, it takes a few seconds to validate a sample set of 20,000 XML files. This is hundreds of times faster than the first attempt, which was a shell script that sequentially runs xmllint (after first pre-downloading remote XML Schema files and passing the local files to xmllint with --schema). The concurrency is a big win, as is the reuse of the libxml2 schema data structure across threads and avoiding having to spawn xmllint as a heavyweight process.

Comparison

I wrote this based on my Rust version of this program, https://github.com/FranklinChen/validate-xml-rust

The Python version is shorter largely because of the existence of lxml.