Technology Stack
================

Core Technologies
----------------

Backend Framework
~~~~~~~~~~~~~~~~

**FastAPI (v0.115+)**

- **Purpose**: Web framework for building APIs
- **Why**: High performance, automatic API documentation, type hints, async support
- **Features Used**:

  - Automatic OpenAPI schema generation
  - Pydantic data validation
  - Dependency injection
  - Background tasks
  - Security utilities (OAuth2, JWT)

Programming Language
~~~~~~~~~~~~~~~~~~

**Python 3.12+**

- **Why**: Rich ecosystem, excellent AI/ML libraries, readability
- **Key Libraries**:

  - Type hints for better code quality
  - Async/await for concurrency
  - Dataclasses for structured data

Database & Persistence
---------------------

Relational Database
~~~~~~~~~~~~~~~~~~

**PostgreSQL 12+**

- **Purpose**: Primary data store
- **Why**: ACID compliance, advanced features, JSON support, full-text search
- **Features Used**:

  - Complex queries and joins
  - JSON/JSONB columns
  - Foreign key constraints
  - Database triggers and events

ORM
~~~

**SQLAlchemy 2.0+**

- **Purpose**: Object-Relational Mapping
- **Why**: Powerful query API, relationship handling, migration support
- **Features Used**:

  - Declarative models
  - Relationship configurations
  - Session management
  - Query optimization

Database Migrations
~~~~~~~~~~~~~~~~~~

**Alembic 1.16+**

- **Purpose**: Database schema versioning
- **Why**: Track changes, rollback capability, team collaboration
- **Usage**:

  - Auto-generate migrations from model changes
  - Version control for database schema
  - Upgrade/downgrade paths

Caching & Message Broker
------------------------

**Redis 6.4+**

- **Purpose**: Caching, session storage, message broker
- **Why**: In-memory speed, pub/sub messaging, data structures
- **Use Cases**:

  - Celery task queue broker
  - Celery result backend
  - Session caching
  - Application-level caching

Asynchronous Task Processing
---------------------------

**Celery 5.5+**

- **Purpose**: Distributed task queue
- **Why**: Async job processing, scheduling, retry mechanisms
- **Features Used**:

  - Task queuing and execution
  - Task chaining and grouping
  - Periodic tasks
  - Result tracking
  - Retry logic

AI & Machine Learning
--------------------

Large Language Models
~~~~~~~~~~~~~~~~~~~~

**OpenAI-compatible API (v1.75+)**

- **Purpose**: LLM-based text analysis and annotation
- **Why**: Uniform interface for multiple LLM providers
- **Use Cases**:

  - Legal text annotation
  - Provision classification
  - Entity extraction
  - Text generation

Machine Learning
~~~~~~~~~~~~~~

**scikit-learn 1.6+**

- **Purpose**: Traditional ML classification
- **Why**: Proven algorithms, easy training, lightweight
- **Features Used**:

  - Text vectorization (TF-IDF)
  - Classification algorithms (SVM, Random Forest, Logistic Regression)
  - Model persistence (joblib)
  - Cross-validation

**joblib 1.5+**

- **Purpose**: Model serialization
- **Why**: Efficient storage of trained models
- **Usage**: Saving/loading trained classifiers

Natural Language Processing
~~~~~~~~~~~~~~~~~~~~~~~~~~

**spaCy 3.8+**

- **Purpose**: NLP preprocessing
- **Why**: Fast, production-ready, pre-trained models
- **Models Used**:

  - ``en_core_web_sm`` - English language model

- **Use Cases**:

  - Text tokenization
  - Named entity recognition
  - Part-of-speech tagging
  - Dependency parsing

Semantic Web & RDF
-----------------

**SPARQL**

- **Purpose**: RDF query language
- **Why**: Standard for querying knowledge graphs
- **Usage**: Querying EUR-Lex and other SPARQL endpoints via HTTP clients

Authentication & Security
------------------------

**JWT (PyJWT) 2.10+**

- **Purpose**: JSON Web Token handling
- **Why**: Stateless authentication, standard-compliant
- **Features Used**:

  - Token generation
  - Token validation
  - Expiration handling
  - Custom claims

HTTP & Networking
----------------

**httpx**

- **Purpose**: HTTP client
- **Why**: Modern, async-capable, HTTP/2 support
- **Usage**: External API calls

**python-dotenv 1.1+**

- **Purpose**: Environment variable management
- **Why**: Easy configuration management
- **Usage**: Loading ``.env`` files

Document Processing
------------------

**python-docx 1.1+**

- **Purpose**: Microsoft Word document processing
- **Why**: Read/write DOCX files programmatically
- **Usage**: Extracting text from legal documents

Development Tools
----------------

Testing
~~~~~~~

**pytest 8.3+**

- **Purpose**: Testing framework
- **Why**: Simple syntax, powerful fixtures, extensive plugins
- **Plugins Used**:

  - ``pytest-asyncio`` - Async test support
  - ``pytest-cov`` - Coverage reporting
  - ``requests-mock`` - HTTP mocking

**coverage 7.9+**

- **Purpose**: Code coverage analysis
- **Why**: Identify untested code
- **Usage**: HTML and terminal coverage reports

Documentation
~~~~~~~~~~~~

**Sphinx 8.2+**

- **Purpose**: Documentation generation
- **Why**: Python standard, extensible, multiple output formats
- **Extensions**:

  - ``sphinx.ext.autodoc`` - Auto-generate from docstrings
  - ``sphinx.ext.napoleon`` - Google/NumPy docstring support
  - ``sphinx.ext.viewcode`` - Link to source code
  - ``sphinx.ext.intersphinx`` - Cross-project linking

**MyST Parser 4.0+**

- **Purpose**: Markdown support in Sphinx
- **Why**: Write docs in Markdown
- **Features**: CommonMark + extensions

**Sphinx RTD Theme 3.0+**

- **Purpose**: Documentation theme
- **Why**: Clean, responsive, professional

Dependency Management
~~~~~~~~~~~~~~~~~~~~~

**Poetry**

- **Purpose**: Dependency and environment management
- **Why**: Deterministic builds, lock files, virtual env management
- **Usage**:

  - ``pyproject.toml`` - Dependency specification
  - ``poetry.lock`` - Lock file for reproducibility

Data Validation
--------------

**Pydantic**

- **Purpose**: Data validation using Python type hints
- **Why**: Runtime validation, JSON schema generation, editor support
- **Usage**:

  - API request/response models
  - Configuration validation
  - Data serialization

**jsonschema 4.25+**

- **Purpose**: JSON schema validation
- **Why**: Standard-compliant validation
- **Usage**: Validating complex JSON structures

Containerization
--------------

**Docker**

- **Purpose**: Application containerization
- **Why**: Consistent environments, easy deployment
- **Usage**:

  - ``Dockerfile`` for backend image
  - Multi-stage builds for optimization

**Docker Compose**

- **Purpose**: Multi-container orchestration
- **Why**: Local development, integration testing
- **Services**:

  - Backend API
  - Celery Worker
  - PostgreSQL
  - Redis

Web Server (Production)
----------------------

**Uvicorn**

- **Purpose**: ASGI server
- **Why**: High performance, WebSocket support
- **Usage**: Running FastAPI application

**Gunicorn (Optional)**

- **Purpose**: Process manager
- **Why**: Multi-worker management, automatic restarts
- **Usage**: Production deployment with Uvicorn workers

Monitoring & Logging
-------------------

**Python logging**

- **Purpose**: Application logging
- **Why**: Built-in, configurable, handlers
- **Configuration**: Custom formatting, rotation