Running the Backend

FastAPI Backend

Virtual environment

Make sure python3-venv is in your machine

sudo apt install python3-venv

Make a python virtual environment with the following command:

python3 -m venv .venv

activate the environment

source .venv/bin/activate

Install dependencies

Install the required packages with the following command:

pip install -r requirements.txt

Running the backend

To run the backend server, use the following command:

uvicorn app.main:app --reload

The app will start:

http://127.0.0.1:8000/

Once the application is running, you can access the API documentation provided by Swagger at:

http://127.0.0.1:8000/docs

Here, you can explore and interact with the various API endpoints.

Make changes in the database

execute the following command

./push.sh

Authentication

• using supabase for authentication purpose
• Every path other than login and signup requires bearer token
• the token refreshes after 1 hour

Database

• using postgresql for database
• Hosted the database in supabase
• using sqlalchemy as ORM
• Using Database pooling. Using default pool size = 15

Database Migration Tool

Using Alembic as DB-migration tool

SMTP

• Using Gmail custom smtp (smtp.gmail.com) . Thus confirmation mail goes from our own gmail
• therefore can handle 1100 user mail authentication in 1 hour

chat with knowledge-base

Vector Database

we have used Qdrant for vector database

Embedding model

we have used the text-embedding-3-large model for generating embedding

Pdf Font

used Noto-Sans font from Google fonts

File-ingestion Pipeline

• We receive the "pure bangla text" from the text editor
• we generate a suitable title and caption for the file
• we upload the pdf in supabase bucket and fetch the link of the file
• we generate some metadata for the parsed content
• we vectorize and store the chunks in qdrant

RAG chat pipeline

• The default knowledge base if user's uploaded contents
• User can also customize a chat by adding some public files for that chat only
• User asks a query (in bangla/ banglish)
• With AI agent, we normalize the user query (for better context-ingestion and searching-ready for the vector database)
• we vectorize the standardized prompt and search in the vector database
• we fetch k-most relevant chunks
• then we feed the query and fetched chunks to AI-agent
• AI agent then generates Bengali response using our custom knowledge base

Translation Generation:

For translation, we have tried 2 ways:

Way-1:

• We have used Few-shot prompting that is used as a technique to enable in-context learning
• Our users contribute in geenrating learning samples ({banglish, bangla} pairs)
• admins approve some of them
• The approved pairs are used as few shot inferencing
• Future plan is to run a cron job (after 1 week) to collect the approved samples and use them to train model using openai's fine-tune api. Currently it could not be done due to costing reasons

way-2:

• used Google Transliterate API
• The transliteration is phonetic, meaning it maps input sounds in one script (e.g., Latin/English) to equivalent sounds in the target script (e.g., Bengali).
• This engine primarily relies on rule-based linguistic mappings and possibly some statistical or probabilistic enhancements for ambiguity resolution.
• we chose this option for better latency support

Audio chat Pipeline

• we used OpenAI's whisper-1 model for generating transcript for user speech
• We generated embedding for transcripted text
• we searched vector database for relevant chunks
• we fed knowledge and query to AI-agent. It responded in text
• with browsers SpeechSynthesis api, we can convert the textual response to speech
• After returning the audio response, we did the db-storing activities using FastAPI's background task

Latency Handling at the time of translating Banglish to bangla

• we have used FastAPI's Background task to execute db-operations in a separate thread. When the thread updates the db-operation, we terminate it
• we return the translation as soon as we get

deployment

deployed-site

• used renders docker template for fastapi for deployment
• how dealt with Render's freezing issue?
• there is a dummy GET endpoint in /, Ran a cronjon from a cronjob site