How does document upload work in the system — where are they uploaded and how are they processed?

The process of uploading documents to the system typically involves several stages:

1. File reception: The user or external system uploads the document via an interface (web, API).

2. Temporary storage: The file is initially saved in temporary storage (e.g., a temporary folder on the server or object storage like S3) to ensure security and allow for verification.

3. Validation and processing: The document is checked for compliance with requirements (format, size, viruses). Processing may be initiated — format conversion, metadata extraction, OCR, etc.

4. Saving to main storage: After successful verification and processing, the document is moved to permanent storage — a file system, database, or specialized document storage.

5. Indexing and registration: Information about the document (metadata, path, upload date) is stored in a database for quick search and management.

6. Access and management: Users gain access to documents through interfaces considering permissions and roles.

Thus, uploading is not just copying a file but a comprehensive process with quality control, security, and system integration.