Sane Node Development

Update: A more modern approach (isomorphic react+express+typescript) here: https://github.com/bryanmacfarlane/quotes-feed

Create a sample service which illustrates sane node development avoiding some of the historic problems.

Eliminate Callback Hell

Use async/await along with promises to write logical sane linear code while still maintaining the benefits of async execution

For example, in this example, each insert is sequential but still async.

public async initialize() {
    // insert some sample data for the demo
    let sampleQuote: IQuote;

    sampleQuotes.forEach(async (sampleQuote) => {
        await this._store.insert<IQuote>(sampleQuote);
    });
}

An example which would be much harder to accomplish with callbacks and even solely promises.
Notice async calls inside of loops, sequential code and easy try/catch error handling

// await allows us to write linear code.  
// makes it easy to also call async code in a loop
// offers easy error handling with try catch
var quotes: IQuote[];
var tries: number = 0;
while (true) {
    try {
        ++tries;
        // ASYNC/AWAIT
        quotes = await this._store.find<IQuote>({});
        break;
    }
    catch (err) {
        if (tries == 3) { throw err; }
    }
}

return quotes;

Compile time support

When working in a non-trivial code base, compile time errors are critical for early detection.

I've worked in code bases where it was manageable but became very problematic on that first big refactor.

$ tsc
app.ts(45,49): error TS2346: Supplied parameters do not match any signature of call target. 

Also apparent with intellisense. In this case using VS Code

Share Code Between Server and Client

Specifically:

• (In progress) React components rendered server side for perf and SEO and then shared client side in the brower to resume on AJAX use.
• (Not Started) Share validation between browser and API

Crude pattern illustrated here

Debug

Illustrate how to debug

Highly Testable and Tested

Factor code in a way to ensure all paths are testable and tested.

Tests should be written in the same sequential async/await fashion.

Container Based Micro-Services

Breaking code into micro-services and layers makes code manageable and allows for independent scaling. However, doing so requires common modules and complicates security.

This sample will illustrate using JWT tokens for auth, CORS and a simple role based security model using Node middleware.

Each service is built as containers and is deployed to Kubernetes.

Engineering

Create an effective inner dev loop

• Build and unit test outside source
• Unit tests for inner dev loop
• Full tests against running container
• Container lifecycle for inner dev loop
• Create production package with no source or tests
• Seal build environment and tools in a container

API

Api Service Here

Front End

TODO