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Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1465 Chapter 32: Instrumentation Event Log Description Application Enables you to record application-specific events, including whether a certain event was fired, a page was loaded, or a customer made a specific purchase Security Enables you to track security-related issues such as security changes and breaches System Enables you to track system-specific items such as issues that arise with components or drivers From your code, you can write to any of the event logs defined in the preceding table as well as to any custom event logs that you might create. To accomplish this task, create an example ASP.NET page that contains a multiline TextBox control and a Button control. On the Button1_Click event, you register the text you want placed in the text box directly into the Application event log. Your ASP.NET page should be similar to what is presented in Listing 32-2. Listing 32-2: Writing to the Application event log VB <%@ Page Language="VB" %> <%@ Import Namespace="System.Diagnostics" %> <script runat="server"> Protected Sub Page_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) If Not EventLog.SourceExists("My Application") Then EventLog.CreateEventSource("My Application", "Application") End If End Sub Protected Sub Button1_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Dim el As EventLog = New EventLog() el.Source = "My Application" el.WriteEntry(TextBox1.Text) Label1.Text = "ENTERED: " & TextBox1.Text End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Working with Event Logs</title> </head> <body> <form id="form1" runat="server"> <div> <asp:TextBox ID="TextBox1" runat="server" Height="75px" Continued 1465 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1466 Chapter 32: Instrumentation TextMode="MultiLine" Width="250px"></asp:TextBox><br /> <br /> <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Submit to custom event log" /><br /> <br /> <asp:Label ID="Label1" runat="server"></asp:Label> </div> </form> </body> </html> C# <%@ Page Language="C#" %> <%@ Import Namespace="System.Diagnostics" %> <script runat="server"> protected void Page_Load(object sender, EventArgs e) { if (!EventLog.SourceExists("My Application")) { EventLog.CreateEventSource("My Application", "Application"); } } protected void Button1_Click(object sender, EventArgs e) { EventLog el = new EventLog(); el.Source = "My Application"; el.WriteEntry(TextBox1.Text); Label1.Text = "ENTERED: " + TextBox1.Text; } </script> Again, for this to work, you must import the System.Diagnostics namespace. In the Page_Load event of the page, ASP.NET is checking whether the event source exists for My Application .Ifnosuchsource exists in the Application event log, it is created using the CreateEventSource() method. el.CreateEventSource("My Application", "Application") The first parameter of the method takes the name of the source that you are creating. T he second param- eter of this method call takes the name of the event log that you are targeting. After this source has been created, you can start working with the EventLog object to place an e ntry into the system. First, the EventLog object is assigned a source. In this case, it is the newly created My Application .Usingthe WriteEntry() method, you can write to the specified event log. You can also assign the source and the message within the WriteEntry() method in the following manner: el.WriteEntry("My Application", TextBox1.Text); The ASP.NET page produces something similar to what is illustrated in Figure 32-3. After this is done, you can look in the Event Viewer and see your entry listed in the Application event log. Figure 32-4 illustrates what happens when you double-click the entry. 1466 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1467 Chapter 32: Instrumentation Figure 32-3 Figure 32-4 1467 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1468 Chapter 32: Instrumentation Later in this chapter, you see some of the automatic ways in which ASP.NET can record events for you in the event log and in some other data stores (such as Microsoft’s SQL Server). Next, it is time to turn your attention to working with performance counters. Using Performance Counters Utilizing performance counters is important if you want to monitor your applications as they run. What exactly is monitored is up to you. A plethora of available performance counters are at your disposal in Windows and you will find that there are more than 60 counters specific to ASP.NET. Viewing Performance Counters Through an Administration Tool You can see these performance counters by opening the Performance dialog found in the Control Panel and then Administration Tools if you are using Windows XP. If you are using Windows Vista, select Control Panel ➪ System and Maintenance ➪ Performance Information and Tools ➪ Advanced Tools ➪ Open Reliability and Performance Monitor. Figure 32-5 shows the dialog opened in Windows Vista. Figure 32-5 1468 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1469 Chapter 32: Instrumentation Clicking the plus sign in the menu enables you to add more performance counters to the list. You will find a number of ASP.NET–specific counters in the list illustrated in Figure 32-6. Figure 32-6 The following list details some of the ASP.NET–specific performance counters that are at your disposal along with a definition of the counter (also available by checking the Show Description check box in Vista from within the dialog). ❑ Application R estarts: Number of times the application has been restarted during the Web server’s lifetime. ❑ Applications Running: Number of currently running Web applications. ❑ Audit Failure Events Raised: Number of audit failures in the application since it was started. ❑ Audit Success Events Raised: Number of audit successes in the application since it was started. ❑ Error Events Raised: Number of error events raised since the application was started. ❑ Infrastructure Error Events Raised: Number of HTTP error events raised since the application was started. 1469 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1470 Chapter 32: Instrumentation ❑ Request Error Events Raised: Number of runtime error events raised since the application was started. ❑ Request Execution Time: The number of milliseconds it took to execute the most recent request. ❑ Request Wait Time: The number of milliseconds the most recent request was waiting in the queue. ❑ Requests Current: The current number of requests, including those that are queued, currently executing, or waiting to be written to the client. Under the ASP.NET process model, when this counter exceeds the requestQueueLimit defined in the processModel configuration section, ASP.NET begins rejecting requests. ❑ Requests Disconnected: The number of requests disconnecte d because of communication errors or user terminations. ❑ Requests Queued: The number of requests waiting to be processed. ❑ Requests Rejected: The number of requests rejected because the request queue was full. ❑ State Server Sessions Abandoned: The number of sessions that have been explicitly abandoned. ❑ State Server Sessions Active: The current number of sessions currently active. ❑ State Server Sessions Timed Out: The number of sessions timed out. ❑ State Server Sessions Total: The number of sessions total. ❑ Worker Process Restarts: Number of times a worker process has restarted on the machine. ❑ Worker Processes Running: Number of worker processes running on the machine. These are the performance counters for just the ASP.NET v2.0.50727 category. Here you will find cate- gories for other ASP.NET–specific items such as: ❑ ASP.NET ❑ ASP.NET Applications ❑ ASP.NET Apps v1.0.3705.288 ❑ ASP.NET Apps v2.0.50727 ❑ ASP.NET State Service ❑ ASP.NET v1.0.3705.288 ❑ ASP.NET v2.0.50727 Performance counters can give you a pretty outstanding view of what is happening in your application. The data retrieved by a specific counter is not a continuous thing because the counter is really taking a snapshot of the specified counter every 400 milliseconds, so be sure to take that into account when analyzing the data produced. Building a Browser-Based Administrative Tool In addition to viewing the performance counters available to you through the Performance dialog, you can also get at the performance counter values programmatically. This is possible by working with the System.Diagnostics namespace in the .NET Framework. This namespace gives you access to 1470 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1471 Chapter 32: Instrumentation performance-counter-specific objects such as the PerformanceCounterCategory and PerformanceCounter objects. To show you how to work with these o bjects, this next example creates an ASP.NET page that enables you to view any value from a performance counter directly in the browser. To accomplish this task, create a basic ASP.NET page that includes three DropDownList controls, a Button control, and a Label control. This gives you the results presented in Figure 32-7. Figure 32-7 Listing 32-3 shows the code required for this figure. Listing 32-3: Working with performance counters in ASP.NET VB <%@ Page Language="VB" %> <%@ Import Namespace="System.Diagnostics" %> <%@ Import Namespace="System.Collections.Generic" %> <script runat="server"> Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) If Not Page.IsPostBack Then Dim pcc As List(Of String) = New List(Of String) For Each item As PerformanceCounterCategory In _ PerformanceCounterCategory.GetCategories() pcc.Add(item.CategoryName) Next Continued 1471 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1472 Chapter 32: Instrumentation pcc.Sort() pcc.Remove(".NET CLR Data") DropDownList1.DataSource = pcc DropDownList1.DataBind() Dim myPcc As PerformanceCounterCategory myPcc = New PerformanceCounterCategory(DropDownList1.SelectedItem.Text) DisplayCounters(myPcc) End If End Sub Protected Sub DisplayCounters(ByVal pcc As PerformanceCounterCategory) DisplayInstances(pcc) Dim myPcc As List(Of String) = New List(Of String) If DropDownList3.Items.Count > 0 Then For Each pc As PerformanceCounter In _ pcc.GetCounters(DropDownList3.Items(0).Value) myPcc.Add(pc.CounterName) Next Else For Each pc As PerformanceCounter In pcc.GetCounters() myPcc.Add(pc.CounterName) Next End If myPcc.Sort() DropDownList2.DataSource = myPcc DropDownList2.DataBind() End Sub Protected Sub DisplayInstances(ByVal pcc As PerformanceCounterCategory) Dim listPcc As List(Of String) = New List(Of String) For Each item As String In pcc.GetInstanceNames() listPcc.Add(item.ToString()) Next listPcc.Sort() DropDownList3.DataSource = listPcc DropDownList3.DataBind() End Sub Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, _ ByVal e As System.EventArgs) Dim pcc As PerformanceCounterCategory pcc = New PerformanceCounterCategory(DropDownList1.SelectedItem.Text) Continued 1472 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1473 Chapter 32: Instrumentation DropDownList2.Items.Clear() DropDownList3.Items.Clear() DisplayCounters(pcc) End Sub Protected Sub Button1_Click(ByVal sender As Object, _ ByVal e As System.EventArgs) Dim pc As PerformanceCounter If DropDownList3.Items.Count > 0 Then pc = New PerformanceCounter(DropDownList1.SelectedItem.Text, _ DropDownList2.SelectedItem.Text, DropDownList3.SelectedItem.Text) Else pc = New PerformanceCounter(DropDownList1.SelectedItem.Text, _ DropDownList2.SelectedItem.Text) End If Label1.Text = "<b>Latest Value:</b> " & pc.NextValue().ToString() End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>Working with Performance Counters</title> </head> <body> <form id="form1" runat="server"> <div> <strong>Performance Object:</strong><br /> <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged"> </asp:DropDownList><br /> <br /> <strong>Performance Counter:</strong><br /> <asp:DropDownList ID="DropDownList2" runat="server"> </asp:DropDownList><br /> <br /> <strong>Instances:</strong><br /> <asp:DropDownList ID="DropDownList3" runat="server"> </asp:DropDownList><br /> <br /> <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Retrieve Value" /><br /> <br /> <asp:Label ID="Label1" runat="server"></asp:Label></div> </form> </body> </html> C# <%@ Page Language="C#" %> <%@ Import Namespace="System.Diagnostics" %> <%@ Import Namespace="System.Collections.Generic" %> Continued 1473 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1474 Chapter 32: Instrumentation <script runat="server"> protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { List<string> pcc = new List<string>(); foreach (PerformanceCounterCategory item in PerformanceCounterCategory.GetCategories()) { pcc.Add(item.CategoryName); } pcc.Sort(); pcc.Remove(".NET CLR Data"); DropDownList1.DataSource = pcc; DropDownList1.DataBind(); PerformanceCounterCategory myPcc; myPcc = new PerformanceCounterCategory(DropDownList1.SelectedItem.Text); DisplayCounters(myPcc); } } void DisplayCounters(PerformanceCounterCategory pcc) { DisplayInstances(pcc); List<string> myPcc = new List<string>(); if (DropDownList3.Items.Count > 0) { foreach (PerformanceCounter pc in pcc.GetCounters(DropDownList3.Items[0].Value)) { myPcc.Add(pc.CounterName); } } else { foreach (PerformanceCounter pc in pcc.GetCounters()) { myPcc.Add(pc.CounterName); } } myPcc.Sort(); DropDownList2.DataSource = myPcc; DropDownList2.DataBind(); } Continued 1474 . other ASP. NET specific items such as: ❑ ASP. NET ❑ ASP. NET Applications ❑ ASP. NET Apps v1.0 .37 05. 288 ❑ ASP. NET Apps v2.0 .50 727 ❑ ASP. NET State Service ❑ ASP. NET v1.0 .37 05. 288 ❑ ASP. NET v2.0 .50 727 Performance. entry. 1466 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1467 Chapter 32 : Instrumentation Figure 32 -3 Figure 32 -4 1467 Evjen c32.tex V2 - 01/28/2008 4:05pm Page 1468 Chapter 32 : Instrumentation Later in this. Performance Information and Tools ➪ Advanced Tools ➪ Open Reliability and Performance Monitor. Figure 32 -5 shows the dialog opened in Windows Vista. Figure 32 -5 1468 Evjen c32.tex V2 - 01/28/2008 4:05pm
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