Making Outgoing HTTP Requests (TypeScript)

Overview

Golem TypeScript agents run in a WebAssembly environment with a built-in fetch API. Use the standard fetch() function for all outgoing HTTP requests — it is fully supported and works with WASI HTTP under the hood.

Note: The node:http and node:https modules are also available with comprehensive client-side support (the client API passes the majority of Node.js compatibility tests). They can be used as an alternative, especially when porting existing Node.js code. Server-side APIs (http.createServer, net.listen) are not available in WASM.

GET Request


const response = await fetch('https://api.example.com/data');
const data = await response.json();
console.log(data);

GET with Headers


const response = await fetch('https://api.example.com/secure', {
  headers: {
    'Authorization': 'Bearer my-token',
    'Accept': 'application/json',
  },
});
 
if (!response.ok) {
  throw new Error(`HTTP ${response.status}: ${response.statusText}`);
}
 
const result = await response.json();

POST with JSON Body


const payload = { name: 'Alice', email: 'alice@example.com' };
 
const response = await fetch('https://api.example.com/users', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'Accept': 'application/json',
  },
  body: JSON.stringify(payload),
});
 
const created = await response.json();

PUT / DELETE


// PUT
const response = await fetch('https://api.example.com/users/123', {
  method: 'PUT',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ name: 'Updated Name' }),
});
 
// DELETE
await fetch('https://api.example.com/users/123', {
  method: 'DELETE',
});

Reading Response


const response = await fetch(url);
 
// Status
response.status;      // e.g. 200
response.ok;          // true if 2xx
response.statusText;  // e.g. "OK"
 
// Headers
response.headers.get('Content-Type');
 
// Body (choose one)
const text = await response.text();       // as string
const json = await response.json();       // parsed JSON
const buffer = await response.arrayBuffer(); // raw bytes

Error Handling


try {
  const response = await fetch('https://api.example.com/data');
 
  if (!response.ok) {
    const errorBody = await response.text();
    throw new Error(`API error ${response.status}: ${errorBody}`);
  }
 
  return await response.json();
} catch (error) {
  console.error('Request failed:', error);
  throw error;
}

Complete Example in an Agent


import { BaseAgent, agent, endpoint } from '@golemcloud/golem-ts-sdk';
 
type WeatherReport = { temperature: number; description: string };
 
@agent({ mount: '/weather/{city}' })
class WeatherAgent extends BaseAgent {
  constructor(readonly city: string) {
    super();
  }
 
  @endpoint({ get: '/current' })
  async getCurrent(): Promise<WeatherReport> {
    const response = await fetch(
      `https://api.weather.example.com/current?city=${encodeURIComponent(this.city)}`,
      {
        headers: { 'Accept': 'application/json' },
      }
    );
 
    if (!response.ok) {
      throw new Error(`Weather API error: ${response.status}`);
    }
 
    return await response.json();
  }
}

Calling Golem Agent HTTP Endpoints

When making HTTP requests to other Golem agent endpoints (or your own), the request body must match the Golem HTTP body mapping convention: non-binary body parameters are always deserialized from a JSON object where each top-level field corresponds to a method parameter name. This is true even when the endpoint has a single body parameter.

For example, given this endpoint definition:


@endpoint({ post: '/record' })
async record(body: string): Promise<void> { ... }

The correct HTTP request must send a JSON object with a body field — not a raw text string:


// ✅ CORRECT — JSON object with field name matching the parameter
await fetch('http://my-app.localhost:9006/recorder/main/record', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ body: 'a' }),
});
 
// ❌ WRONG — raw text body does NOT match Golem's JSON body mapping
await fetch('http://my-app.localhost:9006/recorder/main/record', {
  method: 'POST',
  headers: { 'Content-Type': 'text/plain' },
  body: 'a',
});

Rule of thumb: If the target endpoint is a Golem agent, always send application/json with parameter names as JSON keys. See the golem-http-params-ts skill for the full body mapping rules.

Key Constraints

Use fetch() as the primary HTTP client — it is the standard and recommended API
node:http and node:https are available with comprehensive client-side support — useful when porting Node.js code or when npm packages depend on them
Server-side APIs (http.createServer, net.listen) are not available in WASM
Third-party HTTP client libraries that use fetch or node:http internally (e.g., axios) generally work; libraries that depend on native C/C++ bindings will not
All HTTP requests go through the WASI HTTP layer, which provides durable execution guarantees
Requests are async — always use await