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vertx-when | java wrappers for standard vert | Reactive Programming library

 by   ef-labs Java Version: Current License: MIT

 by   ef-labs Java Version: Current License: MIT

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kandi X-RAY | vertx-when Summary

vertx-when is a Java library typically used in Programming Style, Reactive Programming applications. vertx-when has no bugs, it has no vulnerabilities, it has build file available, it has a Permissive License and it has low support. You can download it from GitHub.
Provides when.java wrappers for standard vert.x objects to return promises.
Support
Support
Quality
Quality
Security
Security
License
License
Reuse
Reuse

kandi-support Support

  • vertx-when has a low active ecosystem.
  • It has 42 star(s) with 11 fork(s). There are 23 watchers for this library.
  • It had no major release in the last 12 months.
  • There are 3 open issues and 1 have been closed. There are no pull requests.
  • It has a neutral sentiment in the developer community.
  • The latest version of vertx-when is current.
vertx-when Support
Best in #Reactive Programming
Average in #Reactive Programming
vertx-when Support
Best in #Reactive Programming
Average in #Reactive Programming

quality kandi Quality

  • vertx-when has 0 bugs and 0 code smells.
vertx-when Quality
Best in #Reactive Programming
Average in #Reactive Programming
vertx-when Quality
Best in #Reactive Programming
Average in #Reactive Programming

securitySecurity

  • vertx-when has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
  • vertx-when code analysis shows 0 unresolved vulnerabilities.
  • There are 0 security hotspots that need review.
vertx-when Security
Best in #Reactive Programming
Average in #Reactive Programming
vertx-when Security
Best in #Reactive Programming
Average in #Reactive Programming

license License

  • vertx-when is licensed under the MIT License. This license is Permissive.
  • Permissive licenses have the least restrictions, and you can use them in most projects.
vertx-when License
Best in #Reactive Programming
Average in #Reactive Programming
vertx-when License
Best in #Reactive Programming
Average in #Reactive Programming

buildReuse

  • vertx-when releases are not available. You will need to build from source code and install.
  • Build file is available. You can build the component from source.
  • Installation instructions, examples and code snippets are available.
  • It has 2001 lines of code, 250 functions and 33 files.
  • It has medium code complexity. Code complexity directly impacts maintainability of the code.
vertx-when Reuse
Best in #Reactive Programming
Average in #Reactive Programming
vertx-when Reuse
Best in #Reactive Programming
Average in #Reactive Programming
Top functions reviewed by kandi - BETA

kandi has reviewed vertx-when and discovered the below as its top functions. This is intended to give you an instant insight into vertx-when implemented functionality, and help decide if they suit your requirements.

  • Do the actual request .
  • Do a request .
  • Adds dependencies to Promise .
  • Returns a copy of the response headers .
  • Returns a handler for this resolver .
  • Add a header to the request .
  • Gets the result asynchronously .
  • Send message .
  • Deploys a verticle .
  • Executes a blocking code

vertx-when Key Features

Provides when.java wrappers for standard vert.x objects to return promises.

Getting Started

copy iconCopydownload iconDownload
<dependency>
    <groupId>com.englishtown.vertx</groupId>
    <artifactId>vertx-when</artifactId>
    <version>4.0.0</version>
</dependency>

Manual Dependency Creation

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        // Create the vert.x executor for callbacks to run on the vert.x event loop
        VertxExecutor executor = new VertxExecutor(vertx);
        when = WhenFactory.createFor(() -> executor);

        whenVertx = new DefaultWhenVertx(vertx, when);
        whenEventBus = new DefaultWhenEventBus(vertx, when);
        whenHttpClient = new DefaultWhenHttpClient(vertx, when);

Vert.x 2.x

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<dependency>
    <groupId>com.englishtown</groupId>
    <artifactId>vertx-mod-when</artifactId>
    <version>3.0.1</version>
</dependency>

Deploy 1 Verticle

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whenVertx.deployVerticle("com.englishtown.vertx.TestVerticle")
    .then(deploymentID -> {
        // On success
        return null;
    })
    .otherwise(t -> {
        // On fail
        return null;
    });

Deploy 2 Verticles

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List<Promise<String>> promises = new ArrayList<>();

promises.add(vertxWhen.deployVerticle("com.englishtown.vertx.TestVerticle1"));
promises.add(vertxWhen.deployVerticle("com.englishtown.vertx.TestVerticle2"));

when.all(promises)
    .then(deploymentIDs -> {
        // Handle success
        return null;
    })
    .otherwise(t -> {
        // Handle failure
        return null;
    });

Send 2 messages

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List<Promise<Message<JsonObject>>> promises = new ArrayList<>();

promises.add(whenEventBus.<JsonObject>send("et.vertx.eb.1", new JsonObject().putString("message", "hello")));
promises.add(whenEventBus.<JsonObject>send("et.vertx.eb.2", new JsonObject().putString("message", "world")));

when.all(promises).then(
        replies -> {
            // On success
            return null;
        },
        t -> {
            // On fail
            return null;
        });

Send 2 http requests

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List<Promise<HttpClientResponse>> promises = new ArrayList<>();

promises.add(whenHttpClient.requestAbs(HttpMethod.GET, "http://test.englishtown.com/test1", new RequestOptions()));
promises.add(whenHttpClient.requestAbs(HttpMethod.POST, "http://test.englishtown.com/test2", new RequestOptions()));

when.all(promises).then(
        responses -> {
            // On success
            return null;
        },
        t -> {
            // On fail
            return null;
        }
);

Get a response and body

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RequestOptions options = new RequestOptions().setPauseResponse(true);
whenHttpClient.requestAbs(HttpMethod.GET, "http://localhost:8081/test", options)
    .then(response -> {
        return whenHttpClient.body(response);
    })
    .then(body -> {
        // Do something with the body
        return null;
    })
    .otherwise(t ->
        // On fail
        return null;
    });

Community Discussions

Trending Discussions on Reactive Programming
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  • How to implement the logic without state variables
  • Caching parallel request in Spring Webflux Mono
  • Mirror at most 1 value from source, then temporarily drop values until another observable emits
  • Project Reactor: buffer with parallel execution
  • UseCases or Interactors with Kt Flow and Retrofit
  • DT: Dynamically change column values based on selectinput from another column in R shiny app
  • Send a list of objects one at time in reactive way
  • Changing the target of a `whenever` block from the inside
  • How to apply back pressure with Combine buffer operator to avoid flatMap to ask an infinite demand upstream?
Trending Discussions on Reactive Programming

QUESTION

How to use RXJS to share a pool of resources between multiple consumers

Asked 2022-Mar-31 at 12:55

How can we divide work of consumers over a limited set of resources in RXJS?

I have a Pool class here (simplified):

class Pool<TResource> {

  private readonly resource$: Observable<TResource>;

  constructor(resource$: Observable<TResource>) {
    this.resource$ = resource$.pipe(
      // We use share replay here, so multiple calls to `schedule` will share the resources
      shareReplay()
    );
  }

  /**
   * Schedules a task to be executed on resources in the pool. Each input is paired with a resource, which allows async work to be done.
   * @param input$ The inputs to pair up with a resource.
   * @param task The task to execute on each resource
   */
  public schedule<TIn, TOut>(input$: Observable<TIn>, task: (resource: TResource, input: TIn) => Promise<TOut> | TOut): Observable<TOut> {
    const recycleBin = new Subject<TResource>();
    const resource$ = merge(recycleBin, this.resource$);

    return zip(resource$, input$).pipe(
      mergeMap(async ([resource, input]) => {
        const output = await task(resource, input);
        //  Recycles a resource so its re-emitted from the `resource$` observable.
        recycleBin.next(resource);
        return output;
      }),
      tap({ complete: () => recycleBin.complete() })
    );
  }
}

You can use it like this:

class CalculatorResource {
  expensiveCalculation(n: number) {
    return new Promise<number>(res => setTimeout(() => res(n*2), 1000));
  }
}

const pool = new Pool(of(new CalculatorResource(), new CalculatorResource()));
const input$ = of(1, 2, 3, 4);
const output$ = pool.schedule(input$, (calc, n) => calc.expensiveCalculation(n));
output$.subscribe(console.log)
// ...wait 1 sec
// Logs 2
// Logs 4
// ...wait 1 sec
// Logs 6
// Logs 8

This works as expected.

However, when we call schedule in parallel, the resources will also be distributed in parallel. This is not good, we want the resources to be distributed evenly, since the nature of the tasks they do make it so they can't be called in parallel.

const pool = new Pool(of(new CalculatorResource(), new CalculatorResource()));
const input$ = of(1, 2, 3, 4);
const parallelInput$ = of(5, 6, 7, 8);
pool.schedule(input$, (calc, n) =>
  calc.expensiveCalculation(n)
).subscribe(console.log);
pool.schedule(parallelInput$, (calc, n) =>
  calc.expensiveCalculation(n)
).subscribe(console.log);
// Actual output:

// ...wait 1 sec
// Logs 2
// Logs 4
// Logs 10
// Logs 12
// ...wait 1 sec
// Logs 6
// Logs 8
// Logs 14
// Logs 16

// What i would like to see:
// ...wait 1 sec
// Logs 2
// Logs 4
// ...wait 1 sec
// Logs 10
// Logs 12
// ...wait 1 sec
// Logs 6
// Logs 8
// ...wait 1 sec
// Logs 14
// Logs 16

ANSWER

Answered 2022-Mar-31 at 12:55

So the main thing is you need to share the actual part that does the work, not only the resources.

Here's a solution from me:

https://stackblitz.com/edit/rxjs-yyxjh2?devToolsHeight=100&file=index.ts

import { merge, Observable, Observer, of, Subject, zip } from 'rxjs';
import { ignoreElements, concatMap, switchMap } from 'rxjs/operators';

class Pool<TResource> {
  private readonly resourceFree$ = new Subject<TResource>();
  private readonly dispatcher$ = new Subject<{
    execute: (resource: TResource) => any;
    observer: Observer<any>;
  }>();
  private freeResources$ = merge(this.resource$, this.resourceFree$);
  readonly doWork$ = zip(this.freeResources$, this.dispatcher$).pipe(
    switchMap(async ([resource, work]) => {
      try {
        const result = await work.execute(resource);
        work.observer.next(result);
        work.observer.complete();
      } catch (err) {
        work.observer.error(err);
      }
      this.resourceFree$.next(resource);
    }),
    ignoreElements()
  );

  constructor(private resource$: Observable<TResource>) {}

  public schedule<TIn, TOut>(
    input$: Observable<TIn>,
    task: (resource: TResource, input: TIn) => Promise<TOut> | TOut
  ): Observable<TOut> {
    return input$.pipe(
      //you can use mergeMap here as well, depends on how fast you want to consume inputs
      concatMap((input) => {
        const work = {
          execute: (r) => task(r, input),
          observer: new Subject<TOut>(),
        };
        this.dispatcher$.next(work);
        return work.observer;
      })
    );
  }
}

class CalculatorResource {
  expensiveCalculation(n: number) {
    return new Promise<number>((res) => setTimeout(() => res(n * 2), 1000));
  }
}

const pool = new Pool(of(new CalculatorResource(), new CalculatorResource()));
pool.doWork$.subscribe(); //this is to start the pool dispatcher

const input$ = of(1, 2, 3, 4);
const parallelInput$ = of(5, 6, 7, 8);
pool
  .schedule(input$, (calc, n) => calc.expensiveCalculation(n))
  .subscribe(console.log, undefined, () => console.log('1st done'));
pool
  .schedule(parallelInput$, (calc, n) => calc.expensiveCalculation(n))
  .subscribe(console.log, undefined, () => console.log('2nd done'));

setTimeout(() => {
  pool
    .schedule(parallelInput$, (calc, n) => calc.expensiveCalculation(n))
    .subscribe(console.log, undefined, () => console.log('3rd done'));
}, 5000);

Source https://stackoverflow.com/questions/71689376

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install vertx-when

Add a dependency to vertx-when.

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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