jsaxonpy 0.5.0

Java Saxon XSLT transformations in your python applications

JSaxonPy

jsaxonpy - the python package to be used for your Java Saxon XSLT transformations in your python applications.

Installation

pip install jsaxonpy

Quick overview

>>> from jsaxonpy import Xslt
>>> t = Xslt()
>>> xml = "<root><child>text</child></root>"
>>> xsl = """
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/">
    <xsl:copy-of select="."/>
  </xsl:template>
</xsl:stylesheet>
"""
>>> t.transform(xml, xsl)
'<?xml version="1.0" encoding="UTF-8"?><root><child>text</child></root>'

You can supply params if you needed as python dictioary with keys & values as strings (str type).

>>> params = {"param1": "value1", "param2": "value2"}
>>> out = t.transform(xml, xsl, params)

xml and xsl arguments could be either string documents (str type) or files names wrapped into pathlib.Path(...) class, before being passed.

Also you can run transformations using threads or multiple processes using concurrent.futures or multiprocessing modules. The only known limitation is not to run transformations (using Xslt class) using multi-processing in parent process, you can successfully run it in children. If you try to run in parent process and in children processes, then you application would hang. With threading instantiation of Xslt class works both in main thread and in children threads.

Examples

Plain

from pathlib import Path

from jsaxonpy import Xslt


t = Xslt()
xml = Path("file.xml")
xsl = Path("file.xsl")
print(t.transform(xml, xsl))

would produce:

<?xml version="1.0" encoding="UTF-8"?><root><child>text</child></root>

Threads

from concurrent.futures import ThreadPoolExecutor
from pathlib import Path

from jsaxonpy import Xslt

def func(args):
    xml, xsl = args
    t = Xslt()
    out = t.transform(xml, xsl)
    return out

xsl_path = Path('file.xsl')
worker_args = []

with ThreadPoolExecutor(max_workers=3) as executor:
  for xml_path in map(lambda f: Path(f), ["file1.xml", ..., "fileN.xml"]):
    worker_args.append((xml_path, xsl_path))
    for out in executor.map(func, worker_args):
      assert out == xml

Processes

from concurrent.futures import ProcessPoolExecutor
from pathlib import Path

from jsaxonpy import Xslt

def func(args):
    xml, xsl = args
    t = Xslt()
    out = t.transform(xml, xsl)
    return out

xsl_path = Path('file.xsl')
worker_args = []

with ProcessPoolExecutor(max_workers=3) as executor:
  for xml_path in map(lambda f: Path(f), ["file1.xml", ..., "fileN.xml"]):
    worker_args.append((xml_path, xsl_path))
    for out in executor.map(func, worker_args):
      assert out == xml

GCP Functions

import os, threading
from timeit import default_timer as timer

import functions_framework

from jdk4py import JAVA, JAVA_HOME, JAVA_VERSION
from saxonhe4py import SAXON_HE_JAR
from jsaxonpy import Xslt

# following env variable must be defined, otherwise pyjnius would fail
os.environ["JAVA_HOME"] = str(JAVA_HOME)
os.environ["JDK_HOME"] = str(JAVA_HOME)

# to find the location of Saxon HE
os.environ["CLASSPATH"] = str(SAXON_HE_JAR)

# setup JVM options
os.environ["JVM_OPTIONS"] = "-Xmx64m"


@functions_framework.http
def transform(request):
    #
    thread_id = threading.get_native_id()
    process_id = os.getpid()

    #
    timer_xslt_started = timer()
    t = Xslt() # do not move this from function.
    timer_xslt_ended = timer()

    #
    xml = "<p>Paragraph text</p>"
    xsl = """
    <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="/">
      <xsl:copy-of select="."/>
    </xsl:template>
    </xsl:stylesheet>
    """

    #
    timer_transform_started = timer()
    output=t.transform(xml, xsl)
    timer_transform_ended = timer()

    return (
      f"{output}\n"
      f"timer(Xslt)      = {timer_xslt_ended - timer_xslt_started:.6f}\n"
      f"timer(transform) = {timer_transform_ended - timer_transform_started:.6f}\n"
      f"thread_id={thread_id} process_id={process_id}\n"
    )

Notes

Supported and tested versions of Saxon are 9, 10, 11.

Before executing you application it is expected you set your java related environment variables, including the CLASSPATH to point to your Java Saxon installation.

You can use JVM_OPTIONS environment variable to set java virtual environment, see example below.

export JVM_OPTIONS="-Xrs -Xmx3024m -XX:ActiveProcessorCount=24";
export CLASSPATH=/usr/local/Saxon-J/saxon-he-11.4.jar;
your_python_app.py

When you pass the same xsl path it is actually being compiled once for the time of the life of the process/thread, which means you do not need to do any special steps to compile those to speed up transformations.