stock-price-movement

stock price movement display

Prerequisites

• Maven 3.6.1
• JDK >= 8

Technologies

• Spring ( Spring-boot, Webflux )
• Angular
• SSE ( Server Sent Event )
• Event stream.
• Maven frontend plugin

How to run it

• mvn clean spring-boot:run
• open browser http://localhost:5000/
• Screen shot

About data

This is not real data. All data are generated randomly . Price range is 50. Refresh interval is 1 second.

Code Sample

• Server Sent Event

  @GetMapping(value="/stream-sse/[{symbols}]")
  public Flux<ServerSentEvent<StockPrice[]>> streamEvents(@PathVariable List<String> symbols) {
    return Flux.interval(Duration.ofSeconds(5))
      .map(e -> ServerSentEvent.<StockPrice[]> builder()
        .id(String.valueOf(e))
        .event("message")
        .data(getPrice(symbols))
        .comment("Periodic stock price update")
        .build());
  }

• Observable

  getStockPriceList(): Observable<StockPrice[]> {
    return new Observable((observer) => {

      let eventSource = new EventSource(this.stockPriceURL);

      eventSource.onmessage = (event) => {
        let json = JSON.parse(event.data);
        if (json !== undefined && json !== '') {
          this.zone.run(() => observer.next(json));
        }
      };


      eventSource.onerror = (error) => {
        if (eventSource.readyState === 0) {
          eventSource.close();
          observer.complete();
        } 
      }


    });
  }

Test code

Work in progress.

References

• https://dzone.com/articles/tutorial-reactive-spring-boot-part-1-building-a-ko
• https://dzone.com/articles/tutorial-reactive-spring-boot-part-2-a-rest-client
• https://dzone.com/articles/tutorial-reactive-spring-boot-part-3-a-javafx-sprioo
• https://dzone.com/articles/tutorial-reactive-spring-boot-part-4-a-javafx-line
• https://dzone.com/articles/tutorial-reactive-spring-boot-part-5-auto-configur
• https://blog.logrocket.com/how-to-execute-a-function-with-a-web-worker-on-a-different-thread-in-angular/