Dbos Typescript

# DBOS TypeScript Best Practices

Guide for building reliable, fault-tolerant TypeScript applications with DBOS durable workflows.

When to Use

Reference these guidelines when:

- Adding DBOS to existing TypeScript code

- Creating workflows and steps

- Using queues for concurrency control

- Implementing workflow communication (events, messages, streams)

- Configuring and launching DBOS applications

- Using DBOSClient from external applications

- Testing DBOS applications

Rule Categories by Priority

| Priority | Category | Impact | Prefix |

|----------|----------|--------|--------|

| 1 | Lifecycle | CRITICAL | `lifecycle-` |

| 2 | Workflow | CRITICAL | `workflow-` |

| 3 | Step | HIGH | `step-` |

| 4 | Queue | HIGH | `queue-` |

| 5 | Communication | MEDIUM | `comm-` |

| 6 | Pattern | MEDIUM | `pattern-` |

| 7 | Testing | LOW-MEDIUM | `test-` |

| 8 | Client | MEDIUM | `client-` |

| 9 | Advanced | LOW | `advanced-` |

Critical Rules

Installation

Always install the latest version of DBOS:

npm install @dbos-inc/dbos-sdk@latest

DBOS Configuration and Launch

A DBOS application MUST configure and launch DBOS before running any workflows:

import { DBOS } from "@dbos-inc/dbos-sdk";

async function main() {
  DBOS.setConfig({
    name: "my-app",
    systemDatabaseUrl: process.env.DBOS_SYSTEM_DATABASE_URL,
  });
  await DBOS.launch();
  await myWorkflow();
}

main().catch(console.log);

Workflow and Step Structure

Workflows are comprised of steps. Any function performing complex operations or accessing external services must be run as a step using `DBOS.runStep`:

import { DBOS } from "@dbos-inc/dbos-sdk";

async function fetchData() {
  return await fetch("https://api.example.com").then(r => r.json());
}

async function myWorkflowFn() {
  const result = await DBOS.runStep(fetchData, { name: "fetchData" });
  return result;
}
const myWorkflow = DBOS.registerWorkflow(myWorkflowFn);

Key Constraints

- Do NOT call, start, or enqueue workflows from within steps

- Do NOT use threads or uncontrolled concurrency to start workflows - use `DBOS.startWorkflow` or queues

- Workflows MUST be deterministic - non-deterministic operations go in steps

- Do NOT modify global variables from workflows or steps

How to Use

Read individual rule files for detailed explanations and examples:

references/lifecycle-config.md
references/workflow-determinism.md
references/queue-concurrency.md

References

- https://docs.dbos.dev/

- https://github.com/dbos-inc/dbos-transact-ts