PDF Paragraphs Extraction

A Docker-powered service for extracting paragraphs from PDFs

---

This service provides one endpoint to get paragraphs from PDFs. The paragraphs contain the page number, the position in the page, the size, and the text. Furthermore, there is an option to get an asynchronous flow using message queues on redis.

Quick Start

Start the service:

make start

Get the paragraphs from a PDF:

curl -X POST -F 'file=@/PATH/TO/PDF/pdf_name.pdf' localhost:5051

To stop the server:

make stop

Contents

• Quick Start
• Dependencies
• Requirements
• Docker containers
• How to use it asynchronously
• HTTP server
• Queue processor
• Service configuration
• Set up environment for development
• Train the paragraph extraction model
• Execute tests
• Troubleshooting

Dependencies

• Docker Desktop 4.25.0 install link

Requirements

• 2Gb RAM memory
• Single core

Docker containers

A redis server is needed to use the service asynchronously. For that matter, it can be used the command make start:testing that has a built-in redis server.

Containers with make start

Containers with make start:testing

How to use it asynchronously

1. Send PDF to extract

   curl -X POST -F 'file=@/PATH/TO/PDF/pdf_name.pdf' localhost:5051/async_extraction/[tenant_name]

2. Add extraction task

To add an extraction task, a message should be sent to a queue.

Python code:

queue = RedisSMQ(host=[redis host], port=[redis port], qname='segmentation_tasks', quiet=True)
message_json = '{"tenant": "tenant_name", "task": "segmentation", "params": {"filename": "pdf_file_name.pdf"}}'
message = queue.sendMessage(message_json).exceptions(False).execute()

3. Get paragraphs

When the segmentation task is done, a message is placed in the results queue:

queue = RedisSMQ(host=[redis host], port=[redis port], qname='segmentation_results', quiet=True)
results_message = queue.receiveMessage().exceptions(False).execute()

# The message.message contains the following information:
# {"tenant": "tenant_name", 
# "task": "pdf_name.pdf", 
# "success": true, 
# "error_message": "", 
# "data_url": "http://localhost:5051/get_paragraphs/[tenant_name]/[pdf_name]"
# "file_url": "http://localhost:5051/get_xml/[tenant_name]/[pdf_name]"
# }


curl -X GET http://localhost:5051/get_paragraphs/[tenant_name]/[pdf_name]
curl -X GET http://localhost:5051/get_xml/[tenant_name]/[pdf_name]

or in python

requests.get(results_message.data_url)
requests.get(results_message.file_url)

HTTP server

The container HTTP server is coded using Python 3.9 and uses the FastApi web framework.

If the service is running, the end point definitions can be founded in the following url:

http://localhost:5051/docs

The end points code can be founded inside the file app.py.

The errors are reported to the file docker_volume/service.log, if the configuration is not changed (see Get service logs)

Queue processor

The container Queue processor is coded using Python 3.9, and it is on charge of the communication with redis.

The code can be founded in the file QueueProcessor.py and it uses the library RedisSMQ to interact with the redis queues.

Service configuration

Some parameters could be configured using environment variables. If a configuration is not provided, the defaults values are used.

Default parameters:

REDIS_HOST=redis_paragraphs
REDIS_PORT=6379
MONGO_HOST=mongo_paragraphs
MONGO_PORT=28017
SERVICE_HOST=http://127.0.0.1
SERVICE_PORT=5051

Set up environment for development

It works with Python 3.9 [install] (https://runnable.com/docker/getting-started/)

make install_venv

Train the paragraph extraction model

NOTE: The model training was only tested using Python 3.11

Get the labeled data

  git clone https://github.com/huridocs/pdf-labeled-data.git

Place the pdf-labeled-data project in the same folder as this repository

.
├── pdf_paragraphs_extraction       
├── pdf-labeled-data                 

Install the virtual environment and initialize it

  make install_venv
  source .venv/bin/activate

Create the paragraph extraction model

  python src/create_paragraph_extractor_model.py

The trained model is in the following path

  model/paragraph_extraction_model.model

Execute tests

make test

Troubleshooting

Issue: Error downloading pip wheel

Solution: Change RAM memory used by the docker containers to 3Gb or 4Gb