Option 2: Designing a Feed in Typescript

If you are more comfortable with a text editor, it can be helpful to use language-server TypeScript features to configure feed inputs. For the following demonstration, we'll use bun.sh for its ease of use with TypeScript.

Initialising the Project

1. Create the example directory and navigate to it to initialise the bun project:

   # create the example directory
   mkdir example     
   cd example
   
   # initialise the bun project
   bun init

2. The only dependency you'll need is the Switchboard On-Demand package, @switchboard-xyz/on-demand. Install it with:

   bun add @switchboard-xyz/on-demand

3. Make sure everything is installed correctly:

   bun run index.ts
   # Hello via Bun!

Boilerplate Script

Many developers using Switchboard choose to use Visual Studio Code, this is a great tool for writing Typescript code and makes working with Oracle Jobs pretty straightforward.

To get started, replace the contents of index.tswith the following:

index.ts

import { OracleJob } from "@switchboard-xyz/common"

const jobs: OracleJob[] = [
  new OracleJob({
    tasks: [
      {
        httpTask: {
          url: "https://binance.com/api/v3/ticker/price",
        }
      },
      {
        jsonParseTask: {
          path: "$[?(@.symbol == 'BTCUSDT')].price"
        }
      }
    ],
  }),
];
console.log("Running simulation...\n");

// Print the jobs that are being run.
const jobJson = JSON.stringify({ jobs: jobs.map((job) => job.toJSON()) });
console.log(jobJson);
console.log();

// Serialize the jobs to base64 strings.
const serializedJobs = jobs.map((oracleJob) => {
  const encoded = OracleJob.encodeDelimited(oracleJob).finish();
  const base64 = Buffer.from(encoded).toString("base64");
  return base64;
});

// Call the simulation server.
const response = await fetch("https://crossbar.switchboard.xyz/api/simulate", {
  method: "POST",
  headers: [["Content-Type", "application/json"]],
  body: JSON.stringify({ cluster: "Mainnet", jobs: serializedJobs }),
});

// Check response.
if (response.ok) {
  const data = await response.json();
  console.log(`Response is good (${response.status})`);
  console.log(JSON.stringify(data, null, 2));
} else {
  console.log(`Response is bad (${response.status})`);
  console.log(await response.text());
}

Note: The simulation server is heavily rate-limited. Therefore, the endpoint should be used solely for test development purposes.

Running the Feed

From here, running the example feed is as simple as running:

bun run index.ts

This command should now output something similar to:

Running simulation...

{"jobs":[{"tasks":[{"httpTask":{"url":"https://binance.com/api/v3/ticker/price?symbol=BTCUSDT"}},{"jsonParseTask":{"path":"$.price"}}]}]}

Response is good (200)
{
  "results": [
    "64158.33000000"
  ],
  "version": "RC_06_19_24_03_17"
}