In a tutorial detailing the use of DBOS and LlamaIndex, readers learn how to build an interactive Retrieval-Augmented Generation (RAG) Q&A engine and deploy it serverlessly to the cloud in just nine lines of code. DBOS is highlighted for its cost-efficiency compared to AWS Lambda, billing only for CPU time and offering durable execution that resumes workflows from the last completed step in case of interruptions. The tutorial guides users through setting up a virtual environment, installing necessary dependencies, configuring with an OpenAI API key, and using text from Paul Graham's essay to create a simple AI application with LlamaIndex. It then elaborates on serving responses through HTTP using FastAPI and deploying the application on DBOS Cloud. Additionally, it showcases DBOS's ability to enhance application reliability through durable execution and asynchronous task management with queues, backed by Postgres, providing examples of workflows and rate-limiting for reliable application execution.