This gem uses a Rack middleware to clear the store object after every request, but that doesn't translate well to background processing with Sidekiq. A companion library, request_store-sidekiq creates a Sidekiq middleware that will ensure the store is cleared after each job is processed, for security and consistency with how this is done in Rack.

Instead of dealing with a mix of before_filters, Rack-middlewares, controller code and callbacks, an endpoint is just another activity and allows to be customized with the well-established Trailblazer mechanics.

// app/middleware/cache.js,`use`ed in app/server.js import LRU from 'lru-cache'; const _cache = new LRU({ max: 500, maxAge: 1000 * 60 * 60 }); async function cache(req, res, next) { req.cache = _cache; next(); }

In this code, we have another function in the middle which allows us to pass through both ctx (context) and a next function call

To make some of this possible, we had to create our webpack configuration API, called webpack-chain. As you may know, webpack exposes a low-level configuration format, but this format isn't well-suited for merging configuration deterministically across middleware, or even across many projects. With webpack-chain, we expose a chainable or fluent API for aggregating a webpack configuration which is much more deterministic.

Neutrino utilizes webpack under the hood for building projects by augmenting it with knowledge about build middleware. Neutrino middleware are discrete pieces of webpack configuration that use a custom configuration API. You can compose many of these middleware together into custom presets, and each will modify the build accordingly.

If you really want to be sure your customisation gets loaded first or last, you can use * as your before or after reference.

before and after also accept arrays of constraints.

Much like the configuration layer, we need to specify a name for this transformation. This will help other modules negotiate their priority over the injector in relation to yours.

Instead of overriding a service with your own implementation, you enhance an existing service with your own concerns. This pattern is known as middleware.

Middleware works a lot like a decorator. It doesn't alter the original API of the service, but it can augment it with new features and concerns. This has the inherent advantage of allowing all thidparty code to have an influence over the behaviour, state, and UI of a component.