V návaznosti na používání ExceptionTraceru, který pomocí standardní .NET mechanizmů Trace/TraceSource loguje neobsloužené výjimky, jsem dopsal jednoduchý TraceListener, který lze používání pro mailování těchto výjimek na určený mail. Cílovým scénářem je tedy automatické mailování výjimek z consolových/WinForm aplikací, či spíše utilit. Není to zatím příliš vyladěno, spíše takový náznak, jakou cestou se vydat.
Do činnosti se to zapojuje zhruba takto (app.config):
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.diagnostics>
<sources>
<source name="Exceptions" switchValue="Error">
<listeners>
<!-- <add name="XmlListener" initializeData="Exceptions.xml" type="System.Diagnostics.XmlWriterTraceListener"/>
<add name="TextWriterListener" initializeData="Exceptions.log" type="System.Diagnostics.TextWriterTraceListener"/>
-->
<add name="SmtpListener" initializeData="Subject=Chyby z mojí utility;To=errors@firma.cz" type="Havit.Diagnostics.SmtpTraceListener, Havit"/>
</listeners>
</source>
</sources>
</system.diagnostics>
<system.net>
<mailSettings>
<smtp deliveryMethod="Network" from="neco@nekde.cz">
<network host="mail.server.cz"/>
</smtp>
</mailSettings>
</system.net>
</configuration>
Základem je implementovat třídu dědící z předka TraceListener:
/// <summary>
/// TraceListener, který výstup posílá mailem.
/// </summary>
/// <remarks>
/// Inspirováno implementaci System.Diagnostics.XmlWriterListener.
/// </remarks>
public class SmtpTraceListener : TraceListener
{
#region MailTo
/// <summary>
/// E-mailová adresa, na kterou se posílají zprávy.
/// </summary>
public string MailTo
{
get
{
if (_mailTo == null)
{
return "devmail@havit.cz";
}
return _mailTo;
}
set
{
_mailTo = value;
}
}
private string _mailTo;
#endregion
#region Subject
/// <summary>
/// Subject zprávy.
/// </summary>
public string Subject
{
get
{
if (_subject == null)
{
return "SmtpTraceListener";
}
return _subject;
}
set
{
_subject = value;
}
}
private string _subject;
#endregion
#region Constructors
/// <summary>
/// Constructor, který je volán při použití TraceListerneru z app.configu a předává se do něj hodnota atributu initializeData.
/// </summary>
/// <param name="initializeData">hodnota atributu initializeData z app.config</param>
public SmtpTraceListener(string initializeData)
{
if (initializeData == null)
{
return; // použijí se defaulty
}
foreach (string arg in initializeData.Split(';'))
{
string[] paramValue = arg.Split('=');
if (paramValue.Length >= 2)
{
switch (paramValue[0].Trim().ToUpper())
{
case "TO":
MailTo = paramValue[1].Trim();
break;
case "SUBJECT":
Subject = paramValue[1].Trim();
break;
default:
throw new InvalidOperationException("Neznámý parametr konfigurace SmtpTraceListeneru v initializeData.");
}
}
}
}
#endregion
#region SendMessage
/// <summary>
/// Interní implementace odesílání mailu.
/// </summary>
/// <param name="message">zpráva z trace</param>
private void SendMessage(string message)
{
if (String.IsNullOrEmpty(this.MailTo))
{
return;
}
try
{
MailMessage mailMessage = new MailMessage();
mailMessage.To.Add(this.MailTo);
mailMessage.Subject = this.Subject;
mailMessage.Body = message;
SmtpClient smtpClient = new SmtpClient();
smtpClient.Send(mailMessage);
}
catch
{
// NOOP - nechceme, aby nám nefunkční trace-mailing zabil server
#if DEBUG
// při debugování nás to ale zajímá
throw;
#endif
}
// http://www.codeproject.com/KB/trace/smtptracelistenerarticle.aspx
// In the SMTPTraceListener Write method - I call the Flush method. This forces the e-mail output to happen right then, and makes the component more stable.
// With the Flush taken out of the Write method, I was experiencing some inconsistent behavior - i.e. exceptions thrown sometimes but not always...
// goofy problem perhaps someone knows why?
this.Flush();
}
#endregion
#region SendTrace
/// <summary>
/// Hlavní interní implementace sestavení mailu.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="eventType">One of the <see cref="T:System.Diagnostics.TraceEventType"/> values specifying the type of event that has caused the trace.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="data">An array of objects to emit as data. Pokud je string, obsahuje přímo text zprávy.</param>
private void SendTrace(TraceEventCache eventCache, string source, TraceEventType eventType, int id, params object[] data)
{
StringBuilder message = new StringBuilder();
foreach (object item in data)
{
if (item != null)
{
message.AppendLine(item.ToString());
}
}
message.AppendLine();
message.Append("CommandLine: ");
message.AppendLine(Environment.CommandLine);
message.Append("CurrentDirectory: ");
message.AppendLine(Environment.CurrentDirectory);
message.Append("MachineName: ");
message.AppendLine(Environment.MachineName);
message.Append("UserDomainName: ");
message.AppendLine(Environment.UserDomainName);
message.Append(".NET Framework: ");
message.AppendLine(Environment.Version.ToString());
if (eventCache != null)
{
message.AppendLine();
message.AppendLine("Call stack:");
message.AppendLine(eventCache.Callstack);
message.AppendLine();
message.AppendLine("Logical operation stack:");
foreach (object item in eventCache.LogicalOperationStack)
{
if (item != null)
{
message.AppendLine(item.ToString());
}
}
message.AppendLine();
message.Append("DateTime: ");
message.AppendLine(eventCache.DateTime.ToString());
message.Append("Timestamp: ");
message.AppendLine(eventCache.Timestamp.ToString());
message.Append("ProcessId: ");
message.AppendLine(eventCache.ProcessId.ToString());
message.Append("ThreadId: ");
message.AppendLine(eventCache.ThreadId);
}
if (!String.IsNullOrEmpty(source))
{
message.Append("Source: ");
message.AppendLine(source);
}
message.Append("EventType: ");
message.AppendLine(eventType.ToString("g"));
message.Append("EventId: ");
message.AppendLine(id.ToString("g"));
SendMessage(message.ToString());
}
#endregion
#region TraceData (override)
/// <summary>
/// Writes trace information, an array of data objects and event information to the listener specific output.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="eventType">One of the <see cref="T:System.Diagnostics.TraceEventType"/> values specifying the type of event that has caused the trace.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="data">An array of objects to emit as data.</param>
/// <PermissionSet>
/// <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/>
/// <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/>
/// </PermissionSet>
public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, params object[] data)
{
if ((Filter == null) || Filter.ShouldTrace(eventCache, source, eventType, id, null, null, null, data))
{
SendTrace(eventCache, source, eventType, id, data);
}
}
/// <summary>
/// Writes trace information, an array of data objects and event information to the listener specific output.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="eventType">One of the <see cref="T:System.Diagnostics.TraceEventType"/> values specifying the type of event that has caused the trace.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="data">An array of objects to emit as data.</param>
/// <PermissionSet>
/// <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/>
/// <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/>
/// </PermissionSet>
public override void TraceData(TraceEventCache eventCache, string source, TraceEventType eventType, int id, object data)
{
if ((Filter == null) || Filter.ShouldTrace(eventCache, source, eventType, id, null, null, data, null))
{
SendTrace(eventCache, source, eventType, id, data);
}
}
#endregion
#region TraceEvent (override)
/// <summary>
/// Writes trace information, a message, and event information to the listener specific output.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="eventType">One of the <see cref="T:System.Diagnostics.TraceEventType"/> values specifying the type of event that has caused the trace.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="message">A message to write.</param>
/// <PermissionSet>
/// <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/>
/// <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/>
/// </PermissionSet>
public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string message)
{
if ((Filter == null) || Filter.ShouldTrace(eventCache, source, eventType, id, message, null, null, null))
{
SendTrace(eventCache, source, eventType, id, message);
}
}
/// <summary>
/// Writes trace information, a formatted array of objects and event information to the listener specific output.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="eventType">One of the <see cref="T:System.Diagnostics.TraceEventType"/> values specifying the type of event that has caused the trace.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="format">A format string that contains zero or more format items, which correspond to objects in the <paramref name="args"/> array.</param>
/// <param name="args">An object array containing zero or more objects to format.</param>
/// <PermissionSet>
/// <IPermission class="System.Security.Permissions.EnvironmentPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/>
/// <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="UnmanagedCode"/>
/// </PermissionSet>
public override void TraceEvent(TraceEventCache eventCache, string source, TraceEventType eventType, int id, string format, params object[] args)
{
if ((Filter == null) || Filter.ShouldTrace(eventCache, source, eventType, id, format, args, null, null))
{
SendTrace(eventCache, source, eventType, id, String.Format(CultureInfo.InvariantCulture, format, args));
}
}
#endregion
#region TraceTransfer (override)
/// <summary>
/// Writes trace information, a message, a related activity identity and event information to the listener specific output.
/// </summary>
/// <param name="eventCache">A <see cref="T:System.Diagnostics.TraceEventCache"/> object that contains the current process ID, thread ID, and stack trace information.</param>
/// <param name="source">A name used to identify the output, typically the name of the application that generated the trace event.</param>
/// <param name="id">A numeric identifier for the event.</param>
/// <param name="message">A message to write.</param>
/// <param name="relatedActivityId">A <see cref="T:System.Guid"/> object identifying a related activity.</param>
public override void TraceTransfer(TraceEventCache eventCache, string source, int id, string message, Guid relatedActivityId)
{
SendTrace(eventCache, source, TraceEventType.Transfer, id, String.Format("{0} : {1}", message, relatedActivityId));
}
#endregion
#region Write, WriteLine (override)
/// <summary>
/// When overridden in a derived class, writes the specified message to the listener you create in the derived class.
/// </summary>
/// <param name="message">A message to write.</param>
public override void Write(string message)
{
TraceEvent(null, "Write", TraceEventType.Information, 0, message);
}
/// <summary>
/// When overridden in a derived class, writes a message to the listener you create in the derived class, followed by a line terminator.
/// </summary>
/// <param name="message">A message to write.</param>
public override void WriteLine(string message)
{
this.Write(message);
}
#endregion
}
