ao Scheduler Utils

The ao Scheduler Utils provides an abstraction for retrieving the location of an ao Process' Scheduler, and checking whether a wallet is a valid ao Scheduler

This sdk will run in a browser or server environment.

• Usage
  • ESM (Node & Browser) aka type: module
  • CJS (Node) type: commonjs
  • API
    • locate
    • validate
    • raw
    • Internal Cache
    • connect
    • Errors

Usage

This module can be used on the server, as well as the browser:

ESM (Node & Browser) aka type: module

import { locate, validate, raw } from "@permaweb/ao-scheduler-utils";

CJS (Node) type: commonjs

const { locate, validate, raw } = require("@permaweb/ao-scheduler-utils");

The duration of this document will use ESM for examples

API

locate

Locate the ao Scheduler assigned to an ao Process.

import { locate } from "@permaweb/ao-scheduler-utils";

let { url, address } = await locate('<process-id>');

If you already know the Scheduler used by the process, you can provide it as a second parameter to locate as schedulerHint:

import { locate } from "@permaweb/ao-scheduler-utils";

let { url, address } = await locate('<process-id>', 'scheduler-owner-id');

This will skip querying the gateway for the process, in order to obtain it's Scheduler tag, and instead will directly query for the Scheduler-Location record.

This is useful when a process has just been spawned, so might not be indexed by the gateway yet.

validate

Check whether the wallet address is a valid ao Scheduler

import { validate } from "@permaweb/ao-scheduler-utils";

const isValid = validate('<wallet-address>')

raw

Return the url in the Scheduler-Location record for the given wallet address

import { raw } from "@permaweb/ao-scheduler-utils";

const { url } = raw('<wallet-address>')

Internal Cache

The library maintains an internal in-memory LRU cache of Scheduler-Location Urls, caching each for their specified Time-To-Live. If a Scheduler-Location exists in the cache, it's value will be returned, instead of fetching the record on chain.

The default size of the cache is 100. If you'd like a smaller or larger cache, you can set the size using connect

connect

If you would like to use config other than the defaults, you can specify those coonfigurations by providing their values connect. You can currently specify

• The GRAPHQL_URL
• The In-Memory cacheSize
• Following Redirects followRedirects, a boolean that optimizes scheduler routing if true
• GRAPHQL_MAX_RETRIES, the maximum amount of retries for failed gateway queries
• GRAPHQL_RETRY_BACKOFF, the initial delay for a gateway query retry. Doubled for each successive retry

If you'd like to use no In-Memory Cache, and load the record from chain every time, then set the cacheSize to 0

import { connect } from "@permaweb/ao-scheduler-utils";

const { validate, locate, raw } = connect({
  GRAPHQL_URL: "...",
  cacheSize: 1000,
  followRedirects: true,
  GRAPHQL_MAX_RETRIES: 0,
  GRAPHQL_RETRY_BACKOFF: 300
});

If any configuration value is not provided, a default will be used. In this sense, invoking connect() with no parameters or an empty object is functionally equivalent to using the top-lvl exports of the library:

import {
 locate,
 validate,
 raw,
 connect
} from "@permaweb/ao-scheduler-utils";

// These are functionally equivalent
connect() == { validate, locate, raw }

Errors

This module's APIs will reject with certain Errors for certain sad-paths:

• TransactionNotFoundError - the transaction id provided can not be found on the gateway. It's name property will be TransactionNotFound
• SchedulerTagNotFoundError - a Scheduler tag was not found on the provided process transaction id. It's name property will be SchedulerTagNotFound
• InvalidSchedulerLocationError - the Scheduler-Location record retrieved does not adhere to the ao Scheduler-Location specification. It's name property will be InvalidSchedulerLocation:
  • It does not have a Url tag
  • It does not have a Time-To-Live tag

You can check for these errors in your code, and handle according to your use-case:

import { locate, TransactionNotFoundError } from "@permaweb/ao-scheduler-utils";

await locate('<process-id>')
  .catch((err) => {
    if (err instanceof TransactionNotFoundError) // using instanceof
    if (err.name === 'TransactionNotFound') // use a static string

    throw err // bubble unknown error
  })