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Charts

SignalR Service

Documentation

This example demonstrates real-time data update in a financial chart bound to a SignalR server. Note that data used in this demo is for demonstration purposes only.

using System.Collections.Generic; using DevExtreme.MVC.Demos.Models.SignalRTickData; using Microsoft.AspNet.SignalR; namespace DevExtreme.MVC.Demos.Hubs { public class StockTickDataHub : Hub { private readonly TickDataService _service; public StockTickDataHub() { _service = TickDataService.Instance; } public IEnumerable<TickItem> GetAllData() { return _service.GetAllData(); } } }
using DevExtreme.MVC.Demos.Hubs; using Microsoft.AspNet.SignalR; using Microsoft.AspNet.SignalR.Hubs; using System; using System.Collections.Generic; using System.Threading; namespace DevExtreme.MVC.Demos.Models.SignalRTickData { public class TickDataService { public readonly static TickDataService Instance = new TickDataService(GlobalHost.ConnectionManager.GetHubContext<StockTickDataHub>().Clients); private IHubConnectionContext<dynamic> Clients { get; set; } private readonly object updateStockPricesLock = new object(); private TickItem[] tickData; private int lastTickIndex; private Timer timer; private TickDataService(IHubConnectionContext<dynamic> clients) { Clients = clients; tickData = GenerateTestData(); lastTickIndex = tickData.Length - 1; timer = new Timer(Update, null, 1000, 1000); } public IEnumerable<TickItem> GetAllData() { var data = new List<TickItem>(); lock(updateStockPricesLock) { for(var i = lastTickIndex; data.Count < 10000; i--) { data.Add(tickData[i]); if(i == 0) { i = tickData.Length - 1; } } } return data; } private void Update(object state) { lock(updateStockPricesLock) { lastTickIndex = (lastTickIndex + 1) % tickData.Length; var tick = tickData[lastTickIndex]; tick.Date = DateTime.Now; BroadcastStockPrice(tick); } } private void BroadcastStockPrice(TickItem item) { Clients.All.updateStockPrice(item); } private TickItem[] GenerateTestData() { var lastPrice = 140m; var random = new Random(); var slowRandomValue = random.NextDouble(); var data = new TickItem[60 * 60 * 20]; var curTime = DateTime.Now; for(var i = 0; i < data.Length / 2; i++) { lastPrice = Math.Round(lastPrice * (decimal)(1 + 0.002 * (-1 + 2 * random.NextDouble())), 2); if(i % 50 == 0) { slowRandomValue = random.NextDouble(); if(slowRandomValue > 0.3 && slowRandomValue <= 0.5) slowRandomValue -= 0.2; if(slowRandomValue > 0.5 && slowRandomValue <= 0.7) slowRandomValue += 0.2; } var volume = (int)(100 + 1900 * random.NextDouble() * slowRandomValue); data[data.Length - 1 - i] = new TickItem(lastPrice, volume, curTime.AddSeconds(-1 * i)); data[i] = new TickItem(lastPrice, volume, curTime.AddSeconds(-1 * (data.Length - 1 - i))); } return data; } } }