在 C# Web MVC 5 项目中连续读取 SslStream [英] Read SslStream continuously in C# Web MVC 5 project
问题描述
tl;dr:我想在 C# 中连续读取 SslStream，但我想不出最好的方法."
tl;dr: "I would like to read an SslStream continuously in C# but I can't figure out the best way."
一些背景:我正在从一个流中获取股票数据，我想在 Web 界面中显示该数据.该流每 5 秒发送一次心跳，您还可以订阅/取消订阅股票价格和新闻等.
Some background: I'm getting stock data from a stream that I would like to present in a web interface. The stream sends a heartbeat every 5 seconds and you can also subscribe/unsubscribe to stock prices and news etc.
https://api.test.nordnet.se/next/2/api-docs/docs/feeds
目前我正在使用 MSDN 示例中的 SslTcpClient 来读取和写入流，并且工作正常.
Currently I'm using SslTcpClient from MSDN example to read and write to the stream and it works OK.
https://msdn.microsoft.com/en-us/library/system.net.security.sslstream.aspx
我的问题是流不断发送数据，我不确定如何使用它并以最佳方式呈现它.
My problem is that the stream continuously sends data and I'm not really sure how to consume this and present it in the best way.
我现在的解决方案是每五秒进行一次ajax调用以清除"流并获取新数据.感觉这不是一个可靠的解决方案，我经常收到错误当另一个读取操作挂起时无法调用读取方法.".
My solution now is to make a ajax call every five seconds to "clear" the stream and get the new data. This does not feel like a robust solution and I'm quite often getting the error "The Read method cannot be called when another read operation is pending.".
更新:
@phuzi:ajax 和 SignalR 调用的区别如下.不幸的是，这并不能帮助我连续读取流，因为我仍然需要每五秒调用一次该方法.一个解决方案可能是 Hangfire 与 SignalR 结合使用，尽管我不知道如何最好地实现这一点.
@phuzi: Difference below between ajax and SignalR call. Unfortunately this does not help me to read the stream continuously since I still need to call the method every five seconds. A solution might be Hangfire in combination with SignalR although I do not know how to best implement this.
$.connection.hub.start().done(function () {
setInterval(function () {
stockHub.server.getHeartBeat();
}, 5000);
});
setInterval(function () {
$.ajax({
url: '@Url.Action("getHeartBeat")',
type: 'POST',
data: {
},
success: function (message) {
console.log(message);
},
error: function () {
}
);
}, 5000);
@usr:以下是一些示例数据:
@usr: Here is some example data:
我使用此字符串订阅特定市场的股票深度
I subscribe to stock depth at a specific market using this string
"{"cmd":"subscribe", "args":{"t":"depth", "i":"5110", "m":11}}\n"
然后我读取提要并向我的读取方法添加一个预期值，响应应包含我正在寻找的字符串，例如:
Then I read the feed and add a expected value to my read method that the response should contain to be the string I'm looking for, for example:
response.Contains("{"type":"depth","data":{"i":"5110","m":11")
然后我得到一个看起来像这样的字符串作为回报:
And then I get a string that looks something like this in return:
"{"type":"depth","data":{"i":"5110","m":11,"tick_timestamp":1439894747189,"bid1":1.02,"bid_volume1":734827,"bid_orders1":30,"ask1":1.03,"ask_volume1":393598,"ask_orders1":8,"bid2":1.01,"bid_volume2":805705,"bid_orders2":35,"ask2":1.04,"ask_volume2":404815,"ask_orders2":15,"bid3":1.00,"bid_volume3":1387177,"bid_orders3":62,"ask3":1.05,"ask_volume3":601579,"ask_orders3":29,"bid4":0.995,"bid_volume4":123610,"bid_orders4":9,"ask4":1.06,"ask_volume4":313060,"ask_orders4":15,"bid5":0.990,"bid_volume5":386543,"bid_orders5":31,"ask5":1.07,"ask_volume5":741100,"ask_orders5":11}}"
解决了当另一个读取操作挂起时无法调用读取方法"的错误.使用锁.
Solved the error "The Read method cannot be called when another read operation is pending." using a lock.
private static readonly object _readBytesLock = new object();
private static volatile bool _readingBytes = false;
public static string ReadMessage(SslStream sslStream, string expectedValue = "heartbeat")
{
// Read the message sent by the server.
// The end of the message is signaled using the
// "<EOF>" marker.
string message;
byte[] buffer = new byte[2048];
StringBuilder messageData = new StringBuilder();
int bytes = -1;
do
{
//bytes = sslStream.Read(buffer, 0, buffer.Length);
bytes = GetBytes(sslStream, buffer);
// Use Decoder class to convert from bytes to UTF8
// in case a character spans two buffers.
Decoder decoder = Encoding.UTF8.GetDecoder();
char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];
decoder.GetChars(buffer, 0, bytes, chars, 0);
message = messageData.Append(chars).ToString();
Debug.WriteLine(messageData);
if (message.Contains(expectedValue))
{
return message;
}
if (Regex.Matches(messageData.ToString(), "heartbeat").Count >= 3)
{
Debug.WriteLine("Something went wrong, 3 heartbeats received and nothing with the expected value: " + expectedValue);
return message;
}
} while (bytes != 0);
return message;
}
public static int GetBytes(SslStream sslStream, byte[] buffer)
{
try
{
if (buffer == null)
return -1;
var bytes = -1;
lock (_readBytesLock)
{
if (!_readingBytes)
{
_readingBytes = true;
bytes = sslStream.Read(buffer, 0, buffer.Length);
}
_readingBytes = false;
return bytes;
}
}
catch (Exception ex)
{
var methodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
Debug.WriteLine("Method " + methodName + " failed " + ex.Message);
return 0;
//throw;
}
}
推荐答案
运行良好的最终代码.非常感谢@usr 和其他所有帮助过的人.
Final code that works really well. A big thanks to @usr and everyone else helping.
private Task _feedTask;
private SslStream _sslStream;
private StreamReader _streamReader;
private static readonly log4net.ILog _logger
= log4net.LogManager.GetLogger(
System.Reflection.MethodBase.GetCurrentMethod()
.DeclaringType);
public void CreateNewTaskAndStartReadingFeed()
{
_feedTask = new Task(() => StartReadingFeed());
_feedTask.Start();
}
public void StartReadingFeed()
{
try
{
while (true)
{
var message = GetStreamMessage();
if (message != null)
{
Debug.WriteLine("StartReadingFeed message: " + message);
OnReceivedSomething(message);
}
else
{
Debug.WriteLine("StartReadingFeed message was null");
}
}
}
catch (Exception ex)
{
var methodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
Debug.WriteLine($"Method {methodName} failed " + ex.Message);
Debug.WriteLine("Creating a new task and starts to reed feed again");
_logger.Error("StartReadingFeed failed", ex);
CreateNewTaskAndStartReadingFeed();
}
}
public string GetStreamMessage()
{
try
{
return _sslStream.CanRead ? _streamReader.ReadLine() : null;
}
catch (Exception ex)
{
var methodName = System.Reflection.MethodBase.GetCurrentMethod().Name;
Debug.WriteLine($"Method {methodName} failed " + ex.Message);
_logger.Error($"{methodName} failed.", ex);
return null;
}
}
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