  This paper introduces a computing framework that combines Flow-Based
Programming (FBP) and Large Language Models (LLMs) to enable Just-In-Time
Programming (JITP). JITP empowers users, regardless of their programming
expertise, to actively participate in the development and automation process by
leveraging their task-time algorithmic insights. By seamlessly integrating LLMs
into the FBP workflow, the framework allows users to request and generate code
in real-time, enabling dynamic code execution within a flow-based program. The
paper explores the motivations, principles, and benefits of JITP, showcasing
its potential in automating tasks, orchestrating data workflows, and
accelerating software development. Through a fully implemented JITP framework
using the Composable platform, we explore several examples and use cases to
illustrate the benefits of the framework in data engineering, data science and
software development. The results demonstrate how the fusion of FBP and LLMs
creates a powerful and user-centric computing paradigm.
