reactive-programming

Node.js Streams vs. Observables

自古美人都是妖i 提交于 2019-11-29 18:56:25
After learning about Observables , I find them quite similar to Node.js streams . Both have a mechanism of notifying the consumer whenever new data arrives, an error occurs or there is no more data (EOF). I would love to learn about the conceptual/functional differences between the two. Thanks! m4ktub Both Observables and node.js's Streams allow you to solve the same underlying problem: asynchronously process a sequence of values. The main difference between the two, I believe, is related to the context that motivated its appearance. That context is reflected in the terminology and API. On the

Why use Redux-Observable over Redux-Saga?

浪子不回头ぞ 提交于 2019-11-29 18:41:24
I have used Redux-Saga . Code written with it is easy to reason so far, except JS generator function is messing up my head from time to time. From my understanding, Redux-Observable can achieve the similar job that handles side effects but without using generator function. However, docs from Redux-Observable does not provide many opinions of why it is superior against Redux-Saga. I would want to know whether not using generator function is the only benefit of using Redux-Observable. And what could be the downsides, gotcha or compromises from using Redux-Observable instead of Redux-Saga? Thanks

How To Do Recursive Observable Call in RxJava?

孤街醉人 提交于 2019-11-29 18:41:23
问题 I am quite new to RxJava (and Reactive paradigm in general), so please bear with me. Suppose I have this News and this nested Comment data structure: public class News { public int id; public int[] commentIds; //only top level comments public News(int id, int[] commentIds) { this.id = id; this.commentIds = commentIds; } } public class Comment { public int id; public int parentId; //ID of parent News or parent comment public int[] childIds; public Comment(int id, int parentId, int[] childIds)

Spring 5 Web Reactive - How can we use WebClient to retrieve streamed data in a Flux?

旧时模样 提交于 2019-11-29 15:16:17
The current milestone (M4) documentation shows and example about how to retrieve a Mono using WebClient : WebClient webClient = WebClient.create(new ReactorClientHttpConnector()); ClientRequest<Void> request = ClientRequest.GET("http://example.com/accounts/{id}", 1L) .accept(MediaType.APPLICATION_JSON).build(); Mono<Account> account = this.webClient .exchange(request) .then(response -> response.body(toMono(Account.class))); How can we get streamed data (from a service that returns text/event-stream ) into a Flux using WebClient? Does it support automatic Jackson conversion?. This is how I did

Limiting concurrent requests using Rx and SelectMany

流过昼夜 提交于 2019-11-29 14:57:39
I have a list of URLs of pages I want to download concurrently using HttpClient . The list of URLs can be large (100 or more!) I have currently have this code: var urls = new List<string> { @"http:\\www.amazon.com", @"http:\\www.bing.com", @"http:\\www.facebook.com", @"http:\\www.twitter.com", @"http:\\www.google.com" }; var client = new HttpClient(); var contents = urls .ToObservable() .SelectMany(uri => client.GetStringAsync(new Uri(uri, UriKind.Absolute))); contents.Subscribe(Console.WriteLine); The problem: due to the usage of SelectMany , a big bunch of Tasks are created almost at the

A valid React element (or null) must be returned. You may have returned undefined, an array or some other invalid object

女生的网名这么多〃 提交于 2019-11-29 13:34:37
I'm just new in ReactJS and I have a problem. I can't solve it. It seems everything is all right, but still console puts me: A valid React element (or null) must be returned. You may have returned undefined, an array or some other invalid object. Here's my code: import React from 'react'; import ReactDOM from 'react-dom'; import fetch from 'isomorphic-fetch'; import Pokemon from './Pokemon'; class PokemonList extends React.Component { constructor(props) { super(props); this.state = { species: [], fetched: false, loading: false, }; } componentWillMount(){ this.setState({ loading : true });

Idiomatic way to recover from stream onError

被刻印的时光 ゝ 提交于 2019-11-29 13:18:52
问题 Disclaimer: it is the continuation for the previous Safe update for 2 dependent streams question What is the idiomatic way to handle errors in RxJS (or any other RX implementation) that allows the stream to not terminate? Relevant code is function convert(unit, value) { var request = {}; request[unit] = value; var conversion = $.ajax({ method: 'POST', url: './convert.php', data: request, dataType: 'json' }).promise(); return Rx.Observable.fromPromise(conversion).takeUntil(inInput.merge

Implementing a turnstile-like operator with RxJava

自闭症网瘾萝莉.ら 提交于 2019-11-29 11:31:19
I need help implementing a turnstile-like operator in RxJava (RxScala). I spent quite some time thinking about it, but I seem to be stuck. The type of the function should be the following: def turnstile[T](queue: Observable[T], turnstile: Observable[Boolean]): Observable[T] The idea is that the behavior of the operator should be very similar to a real turnstile. There are people coming ( queue ), and there is a turnstile that is either ready for accepting new single person (a true element in the turnstile, you can imagine it as a token inserted into the turnstile), or closed ( false in the

How do I rate limit requests losslessly using RxJS 5

感情迁移 提交于 2019-11-29 11:25:31
I would like to use make a series of requests to a server, but the server has a hard rate limit of 10 request per second. If I try to make the requests in a loop, it will hit the rate limit since all the requests will happen at the same time. for(let i = 0; i < 20; i++) { sendRequest(); } ReactiveX has lots of tools for modifying observable streams, but I can't seem to find the tools to implement rate limiting. I tried adding a standard delay, but the requests still fire at the same time, just 100ms later than they did previously. const queueRequest$ = new Rx.Subject<number>(); queueRequest$

How to combine 3 firebase observables without losing dynamic updates

五迷三道 提交于 2019-11-29 10:11:21
问题 I have a 3 parallel firebase requires. And I need to join them as 1 single object. Code as below: import {Http} from "@angular/http"; import {AngularFireDatabase} from "angularfire2"; import {Thread} from "../model/thread"; import {Message} from "../model/message"; import {Participant} from "../model/participant"; constructor(private http: Http, private db:AngularFireDatabase) { } loadUserThreads(uid): Observable<AllUserData> { return Observable.forkJoin([ this.db.list('participant/' + uid +