Chains (sequential, router) in Prompt Engineering / GenAI - Full Explanation

Introduction

Imagine you want to complete a task that needs several steps done one after another or choose the right path based on what happens at each step. Chains help organize these steps so the task flows smoothly and correctly.

Explanation

Sequential Chains

Sequential chains connect multiple steps in a fixed order. Each step uses the result from the previous one to continue the process. This way, the output flows through the chain until the final result is ready.

Sequential chains run steps one after another, passing results along.

Router Chains

Router chains decide which path to take based on the input or results from earlier steps. They act like a traffic controller, sending the process down different routes depending on conditions or choices.

Router chains choose the next step based on conditions, directing flow dynamically.

Real World Analogy

Think of making a sandwich where you first lay the bread, then add fillings in order (sequential). But if you want a vegetarian or meat sandwich, you pick the right ingredients based on your choice (router).

Sequential Chains → Following a recipe step-by-step to make a sandwich

Router Chains → Choosing sandwich ingredients based on dietary preference

Diagram

Diagram

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│ Step 1      │ → → │ Step 2      │ → → │ Step 3      │
└─────────────┘     └─────────────┘     └─────────────┘
        ↓
   ┌─────────────┐
   │ Router      │
   ├─────────────┤
   │ Path A      │ → → ┌─────────────┐
   │ Path B      │ → → │ Alternative │
   └─────────────┘     └─────────────┘

Diagram shows sequential steps flowing in order and a router deciding between two paths.

Key Facts

Sequential Chain → A process where steps run one after another, each using the previous step's output.

Router Chain → A process that selects the next step based on input conditions or results.

Chain → A series of connected steps that work together to complete a task.

Common Confusions

Thinking router chains run all paths at once.

Thinking router chains run all paths at once. Router chains select only one path to follow based on conditions, not all paths simultaneously.

Believing sequential chains can skip steps.

Believing sequential chains can skip steps. Sequential chains always run steps in order without skipping any.

Summary

Chains organize multiple steps to complete tasks smoothly.

Sequential chains run steps one after another, passing results along.

Router chains choose the next step based on conditions, directing flow dynamically.