Using the Reactive Pattern to Cache Streams
Explore how to use the shareReplay operator in RxJS to cache and share the latest emissions from observable streams, transforming cold streams into hot streams. Understand how to minimize HTTP requests by sharing a single stream instance among multiple subscribers and implement periodic cache refresh with timer observables. This lesson helps you optimize data handling in reactive applications through effective stream caching and multicasting techniques.
We'll cover the following...
RxJS ships with a very useful operator to put in place a caching mechanism for streams, which is the shareReplay operator.
The shareReplay operator
The shareReplay operator shares an observable execution with multiple subscribers. It has an optional parameter, which is bufferSize. Now, bufferSize represents the number of emissions that are cached and replayed for every subscriber. In our case, we only need to replay the most recent value; hence, we need to set the bufferSize parameter to 1.
In a nutshell, the shareReplay operator does the following:
Shares an observable execution with multiple subscribers.
Offers the possibility to replay a specified number of emissions to the subscribers.
Our recipes$ stream defined in RecipesService is initially a cold stream.
export class RecipesService {recipes$ = this.http.get<Recipe[]>(`${BASE_PATH}/recipes`);}
This means that the stream’s data is re-emitted for every subscriber, resulting in an ...