Unlocking Web Worker Magic: RPC and Command Dispatcher Patterns Unveiled!

Earlier this year, I wrote an article on 2 of the interesting patterns in Web Workers.

Here is the link to that article - https://www.linkedin.com/pulse/must-know-patterns-web-workers-arunkumar-srisailapathi/

I will want to bring that article back again and summarize it for this newsletter edition. I certainly hope that it brings in value.

Generally, we use Web Workers to offload some of the computationally heavy tasks from the main thread. This can be performing some complex calculations like Fibonacci, prime numbers, and running a loop of a really larger value for some task.

If we use a dedicated worker just for a single task, then it would be simpler like:

// from main thread
worker.postMessage(fibonacciNumber);
// it could be anything related to the task.

And then in the worker file, we would do something like this:

// worker.js

self.onmessage = (data) => {
    // perform the task with the data value as input
    postMessage(output); // result to main thread.
}

If we happened to use the same worker for multiple tasks, then we would have done something like this:

// from main thread
worker.postMessage('prime|start:2,end:100');
worker.postMessage('fibonacci|num:33');
// This essentially tells our worker to perform the task: fibonacci
// for the num: 33

We would have a method in the worker that splits the strings and identifies the task and the inputs. The same is the case when we use JSON to map them instead of just strings.

We can address these problems using a combination of the following patterns:

1. The RPC (Remote Procedure Call) pattern

2. The Command Dispatcher pattern

RPC (Remote Procedure Call) Pattern

What is it?

The RPC pattern involves serializing function representations and their arguments, creating structured messages for remote execution. This simplifies message handling and enhances code maintainability.

Command Dispatcher Pattern

What is it?

The Command Dispatcher pattern complements RPC and involves handling serialized commands, identifying the correct function, and processing arguments. It emphasizes using a predefined list of valid commands for secure execution.

By incorporating these patterns into your Web Worker code, you can streamline communication, enhance code clarity, and maintain top-notch code quality.

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